Annual/Termination Reports:

[04/11/2006] [05/16/2007] [05/30/2008] [06/15/2009] [02/22/2010]

Report Information

Participants

Feng, Yucheng (yfeng@acesag.auburn.edu) - Auburn University; Wommack, Eric (wommack@dbi.udel.edu) - University of Delaware; Sadowsky, Michael (sadowsky@soils.umn.edu) - University of Minnesota; Watson, Jack (JackWatson@psu.edu) - Pennsylvania State University; Clay, Sharon (sharon_clay@sdstate.edu) - South Dakota State University; Radosevich, Mark (mrad@utk.edu) - University of Tennessee; McLain, Jean (jmclain@uswcl.ars.ag.gov) - USDA-ARS, Phoenix, AZ; Williams, Clint (cwilliams@uswcl.ars.ag.gov) - USDA-ARS, Phoenix, AZ; Koskinen, Bill (koskinen@umn.edu) - USDA-ARS, St. Paul, MN; Papiernik, Sharon (papiernik@morris.ars.usda.gov) - USDA-ARS, Morris, MN; Sommers, Lee (lee.sommers@colostate.edu) - Colorado State University; Rodriguez, Luiz (lfr@uiuc.edu) - University of Illinois

Brief Summary of Minutes

The 2006 meeting of W-1082 Evaluating the Physical and Biological Availability of Pesticides and Pharmaceuticals in Agricultural Contexts was held on January 5 and 6, 2006 at the University of Tennessee in Knoxville, TN. Mark Radosevich hosted the meeting. Lee Sommers (Administrative Advisor) provided an overview of the budget outlook for the coming year. He noted that the Western directors are emphasizing accountability for multi-state research projects, requiring reports showing the impact of each committee. Dr. Sommers congratulated the group on a successful proposal. Members discussed progress on the outputs and milestones specified in the proposal and approaches to increase the impact of the committee. The meeting included presentations of research reports by all participants. Mark Radosevich was elected chair for the next W-1082 meeting, and Clinton Williams was elected as secretary. The next meeting will be hosted by Chitaranjan Ray in Hawaii on January 4-5, 2007.

Accomplishments

Objective 1. to identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment<br /> <br /> A. Sorption of Agrochemicals - Sorption-desorption is arguably the most important process affecting the transport of pesticides through soil since it controls the amount of pesticide available for transport. Sorption is usually characterized by determining batch sorption coefficients, which are then used in transport models to predict movement from the soil surface through the subsoils. Variability in subsurface soil properties can significantly affect pesticide transport. Research conducted by USDA-ARS scientists in Morris and St. Paul, MN characterized the sorption-desorption of the insecticide imidicloprid and three of its metabolites (imidacloprid-urea, imidacloprid-guanidine, and imidacloprid-guanidine-olefin) as a function of changing soil properties with depth in two soils. Overall, sorption of imidacloprid and all metabolites increased with increasing organic carbon, clay content, and cation exchange capacity. In each of the four cores, measured sorption coefficients (Kf) and coefficients normalized to the organic carbon content (Koc) or clay content (Kcm) varied over an order of magnitude. If OC contents of the subsoils and the surface Koc value were used to predict subsurface imidacloprid Kf values, predicted subsurface Kf values were 5 to 420% of actual measured values. Similar results were observed for each metabolite. Using multiple linear regression (OC, clay, and pH) of the pooled data did not significantly improve Kf predictions. These data illustrate the importance of evaluation of the sorption data used to predict potential mobility; mobility could be either over- or under-predicted depending on the sorption coefficients used. Desorption hysteresis further complicates prediction of imidacloprid mobility. Understanding the variability of soil properties and processes as a function of soil depth is necessary for accurate prediction of pesticide dissipation.<br /> <br /> As part of a research program to more fully characterize the sorption of organic compounds to soil organic matter (SOM) substances, Connecticut researchers have investigated history-dependent sorption behavior, in particular hysteresis and the conditioning effect. Hysteresis is observed when the sorption and desorption branches of the isotherm do not coincide. In the absence of artifacts it is called true hysteresis, or irreversible sorption. The term conditioning effect refers to the result of enhanced sorption of a test compound following the sorption (and then removal) of a conditioning agent, which could be the same or a different compound. Our working hypothesis is that these two behaviors are related mechanistically and are due to pore expansion and pore creation processes in the solid that are irreversible on the timescale of molecular diffusion in the solid. Such a mechanism is well established for glassy organic polymers. Results indicated that relaxation of the conditioning effect in the SOM solids depended on annealing temperature and, at a given temperature, followed a double additive exponential rate law with a non-zero constant term descriptive of the final state that depends inversely on temperature. By extrapolation, it could be predicted that the conditioning effect may never completely relax at environmentally relevant temperatures. The results provide compelling evidence for the glassy, non-equilibrium nature of natural organic matter solids and for irreversible structural expansion as a cause of irreversible sorption phenomena, such as hysteresis and conditioning.<br /> <br /> A portion of tylosin, a macrolide antimicrobial chemical used in swine, cattle, and poultry production, is excreted unchanged in manure. The sorption characteristics of tylosin to soil and manure will influence its fate in the environment. Researchers at South Dakota State University assessed sorption and desorption of tylosin in three silty clay loam soils of South Dakota and compared soil sorption data to sand and manure. The silty clay loam soils, from a toposequence in eastern South Dakota, standardized sand samples, and swine manure were used in 24-hr batch sorption studies with tylosin concentrations ranging from 25 to 232 ¼mole L-1. Desorption from soil was conducted over a 4-d period. Partition coefficients, based on the Freudlich isotherm (Kf) or Kd values, were calculated. Kf values for the silty clay loams were similar, not influenced by landscape position, and averaged 1350 with isotherm slopes ranging from 0.85 to 0.93. Kf values for sand were dependent on solution/sand ratios and pH, ranging from 1.4 to 25.1. Kd values of manure were dependent on the solution type and ranged from 840 L kg-1 with urine to about 175 L kg-1 when sorbed from water. Desorption of tylosin from each soil over the 4-d period was <0.2% of the amount added. The soils high Kf values and low desorption amounts suggest that once tylosin is in these soils, leaching to lower depths may not occur. However, this does not preclude runoff with soil eroded particles. If tylosin reaches a sand aquifer, through bypass flow or other mechanism(s), movement in the aquifer most likely would occur. <br /> <br /> In experiments conducted by University of California, Riverside scientists, in situ diffuse reflectance spectroscopy (DRIFT) was used to investigate sorption and desorption processes for water vapor on both specimen clay minerals and soils. Results indicated that condensation of vapor phase chemical to a liquid occurs spontaneously within pores of nanoporous dimension because of free energy differences between the bulk and sorbed states. As the liquid advances into the porous network, sorbed chemical in the vapor state must also be present at the liquid meniscus. Intermolecular forces that facilitate capillary flow of liquids both into and out of pores are not effective for molecules in the vapor state which are thus retained for extended periods of time within the pore system. Subsequent condensation events, whether of pollutant chemical or water, provide additional forces that can drive those vapor state molecules further into pore regions where molecular displacement is even more difficult. <br /> <br /> Scientists at Auburn and the University of Arkansas investigated the role of a wheat-residue-derived char in nutritional stimulation and adsorptive inhibition on biodegradation of benzonitrile in a soil. The biodegradation was measured at 78 mg/l of benzonitrile, an initial concentration much higher than the half-saturation constant of the degrading organism (~18 mg/l). The degradation was much faster in the extract of char-amended soil (CAS) than in those of soil and washed-char-amended soil (WCAS). The degradation was also faster in CAS slurry than in slurries of soil and WCAS until ~88% of benzonitrile degraded in char-containing slurries, where the aqueous-phase concentration was ~0.25 mg/l. Cell density was higher in extracts and slurries in the presence of the char nutrients than in the absence of them. Analysis of nutrient elements in extracts, along with measuring degradation in soil extract with nutrient supplements and subsequent stepwise multiple-regression, suggested that the char nutrients stimulated cell growth and degradation of benzonitrile, for which P was primarily responsible. Further degradation of benzonitrile beyond 88% in the presence of char was slow, suggestive of the adsorptive inhibition. The biodegradation of benzonitrile in CAS thus occurred through a fast-to-slow process, the former step being due primarily to the stimulation by soluble P of char and the latter phase to the adsorptive inhibition.<br /> <br /> B. Bioavailability of Agrochemicals - Scientists at the University of California, Riverside have conducted a series of studies to gain a better understanding of the interactions of pyrethroid phase distribution and their bioavailability to aquatic organisms. Contamination of surface streams by synthetic pyrethroids appears to be an emerging water quality issue in California and likely in other regions. Pyrethroid products are in widespread use in both urban and agricultural environments. Although pyrethroids have high aquatic toxicity, their strong adsorption may significantly affect their phase distribution and ultimately their actual toxicity.<br /> <br /> Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment of pesticides. The objective of this study conducted by scientists at the USDA-ARS in St. Paul, MN was to correlate simazine (a triazine herbicide) residue bioavailability in aged soils, as determined by solvent extraction methods, to simazine mineralization by an simazine-degrading bacterium. We identified a 0.01 M CaCl2/methanol solvent extraction procedure that can characterize simazine bioavailability in dissimilar aged soils, which in turn may be useful to determine bioavailability of other compounds in soils, especially other triazine herbicides. Scientists now a relatively easy and inexpensive technique to determine the amounts of one class of pesticides, triazines, available for transport, plant uptake, and microbial degradation, particularly in aged soils, information needed for predicting environmental fate and environmental risk assessment.<br /> <br /> The impact of genetically modified plants containing Bacillus thuringiensis (Bt) toxin on soil processes has recently started to receive attention by scientists. Researchers at the University of Minnesota and the USDA-ARS in St. Paul, MN produced the insecticidal protein, Cry1Ac toxin, to determine the its effect on soil process affecting the herbicide glyphosate in two different soils. Glyphosate is an effective non-residual herbicide used to control a wide range of annual and perennial weeds. The addition of 0.25 to 1.0 µg/g soil of purified insecticidal protein did not significantly affect glyphosate bioavailability, that is degradation or binding, in either a sandy loam or a sandy soil. In contrast,we found that bioavailable glyphosate decreased over the 28-day incubation period in both soils. Our findings suggest that the reduction in the bioavailabily of glyphosate was not influenced by the presence of insecticidal protein, but rather the results of aging or binding processes.<br /> <br /> The influence of crop residue derived char on sorption, desorption, and bioavailability of atrazine was evaluated by scientists at Auburn University and the University of Arkansas using two soils (Hartsells and Grady) in the presence and absence of a wheat char. Both char amended soils produced similar isotherms indicating that the presence of small amount of char in soils dominates the overall sorption processes. The amount of atrazine sorbed by char was 800  3800 times more than the soils. With char amendment, both soils exhibited reduced hysteresis. Pseudomonas sp. strain ADP, capable of mineralizing atrazine, was used to evaluate bioavailability of atrazine. The presence of char in the system reduced both rate and extent of atrazine mineralization, which may be attributed to increased sorption of atrazine in char-containing systems. The results suggest that the presence of char in soils controls the sorption and desorption processes that influence the bioavailability of atrazine and may ultimately affect its environmental fate.<br /> <br /> A study, conducted by South Dakota State University researchers, determined uptake, translocation, and metabolism of ring-labeled-14C-2,4-D in soybean at the third trifoliate (V3) stage of growth. Plants were harvested and partitioned into four parts from 1 hr (HAT) to 10 d (DAT) after treatment. Thin layer chromatography techniques were used to determine if 14C remaining in the tissue was parent chemical or metabolite. 2,4-D uptake ranged from 39% at 1 HAT to 74% 6 DAT. By 10 DAT, 14C translocated to the youngest tissue (10%) and older tissue (8%). All 14C recovered from the treated leaf 1 HAT was parent 2,4-D, however, at 24 HAT and later, only about 30% of the 14C remained as 2,4-D whereas 70% of the 14C was observed as a more water soluble compound. Based on this research and evidence from the literature, the 2,4-D in the soybean plant was being conjugated into more water-soluble forms, either glucose or amino acid conjugates, or both. These reactions would decrease the 2,4-D concentration over time and are similar in the reduction of 2,4-D that is observed in field treated plants. These data would explain why, at the end of the season, no or very little 2,4-D was detected in stems or leaf tissue, although, injury symptoms were very evident. An acidic extraction, that may break the glucose or amino acid bond and change the metabolite back to parent acid, may yield a higher amount of 2,4-D in these plant tissues if further degradation does not occur. <br /> <br /> C. Transformation of Agrochemicals - Researchers at the USDA-ARS in Riverside, CA determined that chloropicrin undergoes an extremely rapid redox reaction in hydrogen sulfide solution. Transformation products indicated reductive dechlorination of chloropicrin by hydrogen sulfide species to produce dichloro- and chloronitromethane. The transformation of chloropicrin in hydrogen sulfide solution significantly increased with increasing pH, indicating that H2S is less reactive toward chloropicrin than HS is. Because of the relatively low smell threshold values and potential environmental persistence of organic sulfur products yielded by the reaction of 1,3-D and HS-, the effects of reduced sulfide species should be considered in the development of alternative fumigation practices, especially in the integrated application of sulfur-containing fertilizers. <br /> <br /> The interactions of stearic acid in a non-aqueous chemical environment with other non-aqueous chemical have not been adequately addressed. Solids researchers have proposed that stearic acid exist in a cubic phase, i.e. they self associate in a group of parallel aligned molecules. Researchers at the USDA-ARS in Beltsville, MD demonstrated that the same explanation holds for predicting the solubility of stearic acid in four of five structurally different solvents. Results suggest molecules that disrupt the stearic acid cubic array may also add to or detract from its desired physical properties in commercial products formulations. <br /> <br /> Scientists at the USDA-ARS in Riverside, CA and Morris, MN developed a chemical tarp approach, termed a reactive surface barrier (RSB), to reduce the emission of fumigant 1,3-dichloropropene (1,3-D) from the soil surface. The agrochemicals thiourea and allylthiourea were tested as active reagents for the construction of a RSB, where these soil amendments react with 1,3-D to form non-volatile isothiuronium ions at the soil surface, and thereby impede fumigant emission into the atmosphere. The present results clearly indicate that this chemical remediation technology has great potential to control the emissions of volatile halogenated organic contaminants and mitigate atmospheric pollution.<br /> <br /> The degradation kinetics of sulfadimethoxine, a widely used sulfonamide antibiotic, in manure under aerobic condition was investigated by USDA-ARS scientists in Riverside, CA. Based on the first-order kinetics and the assumption of the availability of sulfadimethoxine in manure for the degradation process, a new kinetic model was developed and was found to fit the degradation kinetics well. The degradation rate in sterilized manure was found to be much lower than in non-sterilized manure, indicating that microorganisms are responsible for a significant portion of degradation of this antibiotic in manure. Mixing highly contaminated manure with less contaminated, while keeping manure at high moisture and storing the manure in a moderately warm place under aerobic conditions, can greatly enhance the degradation of sulfadimethoxine in manure. This may be an effective approach for eliminating this contaminant from the environment. <br /> <br /> Spreading of contaminated manure into agricultural lands, as fertilizer is the major route through which veterinary antibiotics enter the environment. Researchers at the USDA-ARS in Riverside, CA investigated the degradation of manure-derived sulfadimethoxine, a widely used sulfonamide antibiotic, in manure-amended soil. Sulfadimethoxine degradation was effectively enhanced with the increasing moisture of amended soil. No adverse effect was observed with manure storage on the degradation of manure-derived sulfadimethoxine after application into soil.<br /> <br /> Tylosin (Tyl) and chlortetracycline (CTC) are antimicrobial chemicals used as growth promoters in cattle, swine, and poultry production and can be excreted as the parent compound. Landspreading manure can move these chemicals into soil and thereby change the soil microbial make up or degradative activity. The objective of this study, conducted by South Dakota State University scientists, was to determine if Tyl and CTC changed the growth or herbicide degrading activity of pure cultures of two bacteria, Pseudomonas ADP, an atrazine degrader, and Sphingobium herbicidovorans, a 2,4-D degrader. <br /> <br /> Research conducted by University of Georgia scientists has shown that 4-nonylphenol (4-NP) appears in biosolids at a wide concentration ranges, from several mg kg-1 to several thousands mg kg-1. A pilot scale laboratory-controlled composting experiment was conducted to investigate the effectiveness of 4-NP removal through mixing biosolids with wood shavings at different environmental conditions. The results from this investigation provided further evidence that 4-NP can be effectively degraded during composting. The success of this research will not only have significant economic impact on wastewater treatment plants in the United States and world-wide but also have tremendous environmental impact.<br /> <br /> The overall hypothesis of research conducted by University of Tennessee researchers is that the existing collection of bacteria does not adequately reflect all community member species involved in the breakdown of atrazine in soils and sediments. The focus of the first project year has been on the cultivation of atrazine degrading bacteria from field-incubated BioSep beads. To date, approximately 75 atrazine-degrading bacteria have been isolated from field sites in Ohio and Tennessee. Fifteen of these 75 isolates have been taxonomically identified and fall into one of three categories:1) closely related to known atrazine-degrading bacteria, 2) phylogenetically novel bacteria with few cultured relatives, and 3) strains that are not phylogenetically novel but not previously reported to degrade atrazine. Screening of these isolates for known atrazine catabolic genes is in progress. Several isolates exhibit strong atrazine degradation activity but apparently do not possess any of the known atrazine catabolic genes. These results suggest novel atrazine degradation genes are present in these bacteria.<br /> <br /> D. Improved Analysis of Agrochemicals - An analytical method for the determination of oxytetracycline, a member of tetracyclines, in steer manure was developed at the USDA-ARS in Riverside, CA. The method uses acidified methanol extraction and high performance liquid chromatography analysis. The obtained recoveries of oxytetracycline for all kinds of investigated manure and for the silt loam soil were more than (89.3±2.2)% and less than (102.5±5.0)%, demonstrating that the developed analytical method had a robust extraction ability for oxytetracycline from different manures and provided a reliable quantification of oxytetracycline content in different manures.<br /> <br /> E. Measurement of Agrochemical Fate and Toxicity - University of California, Riverside scientists resolved enantiomers of a number of synthetic pyrethroid and organophosphate insecticides on chiral selective columns, and evaluated occurrence of enantioselectivity in aquatic toxicity and biodegradation. Dramatic differences were observed between enantiomers in their acute toxicity to freshwater invertebrates Ceriodaphnia dubia and Daphnia magna, suggesting that the aquatic toxicity is mostly attributable to only a specific enantiomer in the racemate.<br /> <br /> Tennessee requires engineered wood (products that contain adhesive resins) waste to be placed in landfills rather than recycled. Regulators are concerned with potential adverse human and ecological health effects of resins that contain formaldehyde. Urea formaldehyde resin (UF) for example is used in medium density fiberboard (MDF) and plywood. In 2004-2005 a study was conducted at the University of Tennessee to 1) assess the fate of formaldehyde during the decomposition of land applied medium density fiberboard and 2) determine the effect of MDF application on the production of corn. The results showed that the added MDF residue was quickly degraded and formaldehyde emissions remained below detection throughout the growing season. Further, nitrogen from the MDF was mineralized, adding to the crop-available soil N. Although this did not result in statistically significant increases in corn yield, the plants in MDF-amended plots were obviously greener, more vigorous, and taller than control plots. The study was repeated in 2005 at several additional sites across Tennessee and soil samples were taken at greater depths to determine if any formaldehyde from the added MDFresidue leached below the rooting zone. The results showed that formaldehyde did not leach beneath the rooting zone and the N released from the added MDF increased crop biomass. The results show that land application of engineered wood waste such as MDF or particle board is safe and the formaldehyde is rapidly degraded, is beneficial to crop production, and offers a less expensive disposal alternative to landfills. These findings should significantly affect regulatory decisions regarding disposal of engineered wood waste, which will ultimately have a positive economic impact on industries that use these materials.<br /> <br /> <br /> Objective 2. Integrate chemical and biological process information for use in models applicable across different spatial and temporal scales.<br /> <br /> Fluoroquinolone antibiotics have become widespread in the environment because of their extensive use in human and veterinary medicine. To assess the risk from this contamination, a better understanding of their fate in soils and waters is required. This project conducted at the University of California, Berkeley quantified the fate and toxicological impact of an important antibiotic, ciproflaxin (Cipro), while exploring mechanisms through which it can be detoxified by natural organic matter (humus). Humus can play a crucial role in the environmental fate of pharmaceuticals by interacting with them. Molecular simulations of these interactions are useful as a guide to interpreting the results of both chemical and toxicological experiments. The research summarized here and reported in detail by Sutton et al. (2005) is the first rigorous computational exploration of the behavior of a model humic acid molecule under a variety of chemical conditions typical of soils and natural water. <br /> <br /> Rural domestic wells, particularly farmstead wells are not regulated. Researchers at the University of Hawaii use artificial neural networks (ANNs), an alternative modeling approach, to predict the contamination potential of domestic and farmstead wells using data from several states. In this year, they used data from selected large-scale studies of pesticide and nitrate assessment in North Carolina and Illinois. Human interaction, land use, and hydrogeologic data, in conjunction with the occurrence data were used for predictive simulations. <br /> <br /> Objective 3. To provide information required for field-scale recommendations for the management of agricultural pesticides and pharmaceuticals in the environment.<br /> <br /> Nursery and floriculture production is an important industry in California and many other states. However, commercial nurseries rely on heavy use of pesticides, fertilizers, and irrigation, and consequently, surface runoff is widespread at many nursery sites. Nursery runoffs commonly contain high levels of multiple pesticides, and discharge of nursery runoff contributes directly to water quality impairment of surface streams, especially in urban and suburban watersheds. In southern California, nursery runoff has been identified as an important source of pesticides detected in urban creeks and estuaries. In close collaboration with nursery growers in Orange County and Ventura County, University of California, Riverside scientists have carried out studies to understand the source, fate and distribution of pesticides in nursery runoff, and to develop best management practices (BMPs) to reduce pesticide load in the runoff. They have also worked closely with the State Water Resources Control Board, the Regional Boards, and California Department of Pesticide Regulation to extend the technology to nursery growers through many forms of public outreach and education activities, including training workshops for growers and pesticide applicators, and publication of fact sheets and newsletter articles.<br /> <br /> A GIS-based simulation tool was used by University of Hawaii researchers to calculate leaching characteristics of pesticides based upon soil physical/chemical properties, depth to water, recharge rate, and pesticide properties. The model is used to calculate leaching of existing and new chemicals coming to Hawaii on island-wide scale. Variability in soil organic carbon at various soil classification groups and the variabilities in half-life and organic carbon partition coefficients are taken into consideration while developing this GIS-based model. Soil database for all islands are now available and it was recently updated. Variation in recharge was also considered in the model. The model will be used by the Hawaii Department of Agriculture and pesticide registrants to evaluate relative attenuation of pesticides. If a new chemical appears to be significantly mobile compared to two reference chemicals (one that is frequently observed in drinking waters and the other has never been found so far), restrictive measures will be taken by the state for the registration of these compounds.The model was recently updated to ARC/GIS from Arc/View and all soil, pesticide, and recharge data were updated. The detailed evaluation 13 new chemicals have been completed where the registrants sought their use in Hawaii. <br /> <br /> Scientists at the USDA-ARS in Riverside, CA conducted a large-scale project highlighting a promising emission reduction methodology in the San Joaquin Valley near Buttonwillow, CA. Two fields were treated with 1,3-D and one of the fields received a surface water application (i.e., a water seal) at 11:00 am during the first few days after application. Emissions were determined using two independent measurement methods, aerodynamic and ambient methods. The data are currently being analyzed. Comparisons will be made between fields to determine if water seals are effective in reducing fumigant emissions. This research should lead to low-cost methods to reduce fumigant emission.<br />

Publications

Impact Statements

1. 1. Antibiotics play a crucial role in human and veterinary medicine and animal husbandry. It is important to study their fate and their toxicological effects on aquatic habitats. Humus can play a crucial role in the environmental fate of pharmaceuticals by interacting with them. Our research indicated that molecular simulations of these interactions are useful as a guide to interpreting the results of both chemical and toxicological experiments.
2. 2. Many pesticides contain chiral centers which result in isomers with different biological activities or different behaviors (e.g., persistence) in the environment. Currently, chiral pesticides are mostly used as racemic mixtures and the chiral selectivity is ignored in risk assessment. Our studies showed that great differences exist in aquatic toxicities as well as biodegradation rates among chiral insecticides and that these differences should be considered in risk assessment and regulation.
3. 3. We have updated the pesticide screening model that the State of Hawaii uses for pesticide registration. Recharge, soils, and pesticide chemistry databases have been updated and the model can run under ARC/GIS environment. These vadose zone and saturated zone transport models were used to simulate and validate the transport of land-applied contaminants to drinking water and groundwater, and to evaluate the registration and re-registration of pesticides used in pineapple production.
4. 4. Crop residue derived char can be a significant contributor of black carbon to agricultural soils where frequent burning of crop residues occurs. Our research indicated that char increases the sorption capacity of soil and may influence pesticide efficacy and biodegradation. These results increase our understanding of pesticide sorption/desorption and bioavailability has important ramifications for environmental fate modeling, risk assessment, and the development of remediation strategies.
5. 5. Little information on the sorption-desorption of pesticides in subsurface soils is available. Our research indicated that sorption of imidacloprid and its metabolites in surface to deep subsurface soils could not be accurately predicted from soil properties to obtain a constant sorption parameter such as is desired in simulation modeling. Accurate prediction of pesticide dissipation will require an increased understanding of the effect of soil properties and processes in the subsurface.
6. 6. We directly work with stakeholders to help them meet water quality requirements and to comply with such regulations as Total Maximum Daily Loads (TMDLs). Clientele include commercial nurseries in southern California, pesticide applicators, state regulatory agencies, regional water quality control boards, and county/city water quality managers. The research results may be used for implementing pesticide TMDLs, and improving water quality in impaired waterbodies in urban and suburban watersheds.

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Report Information

Participants

Clinton Williams (USDA-ARS, Arizona; Michael Thompson (Iowa State University); Michael Sadowsky (University of Minnesota); Jack Watson (Pennsylvania State University); Sharon Clay (South Dakota State University); Mark Radosevich (University of Tennessee); Jerzy Dec (Pennsylvania State University); Bill Koskinen (USDA-ARS, St. Paul, MN); Hui Li (Michigan State University); Lee Sommers (Colorado State University  Administrative Advisor); Chittaranjan Ray (University of Hawii); Joel Pederson (University of Wisconsin); Prasanta Kalita (for Mike Hirschi, University of Illinois)

Brief Summary of Minutes

The 2006 meeting of W-1082 'Evaluating the Physical and Biological Availability of Pesticides and Pharmaceuticals in Agricultural Contexts' was held on January 4 and 5, 2007 at the University of Hawaii, Honolulu, HI. Chittaranjan Ray hosted the meeting. Lee Sommers (Administrative Advisor) provided an overview of the budget outlook for the coming year, new funding areas such as Biofuels and food for fitness. He also provided an overview of the Creating Research, Extension and Teaching Excellence for the 21st century (CREATE-21) initiative and referred members to the web site for further details. He noted that the Western directors are emphasizing accountability for multi-state research projects, requiring reports showing the impact of each committee. Dr. Sommers congratulated the group on a successful proposal. Members discussed progress on the outputs and milestones specified in the proposal and approaches to increase the impact of the committee. The meeting included presentations of research reports by all participants. Elections were not conducted, as officers will now serve two-year terms. Mark Radosevich will serve as chair for the next W-1082 meeting, and Clinton Williams will serve as secretary. Clinton Williams will host the next meeting in St. George, UT. Date of next meeting was discussed but not finalized.

Accomplishments

Objective 1. To identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment<br /> <br /> Sorption hysteresis. Sander et al. [2006] conducted conditioning-annealing experiments on a peat soil and a soil humic acid to confirm a glassy polymer model for sorption hysteresis. A glassy polymer, poly(vinylchloride), and a rubbery polymer, polyethylene, were included for comparison. Using chlorobenzene as a conditioning agent and polychlorinated benzenes as test compounds in a second sorption step, conditioning effects observed as shift in the isotherm toward higher sorbed concentrations were found in all solids except polyethylene. The conditioning effect for the two SOM solids, probed by the enhancement in the sorption distribution coefficient of 1,2,4-trichlorobenzene, relaxed upon sample annealing at temperatures between 45C and 91C in a manner similar to the relaxation of free volume and enthalpy of glassy polymers. Relaxation of the conditioning effect in the SOM solids depended on annealing temperature and, at a given temperature, followed a double additive exponential rate law with a non-zero constant term descriptive of the final state that depends inversely on temperature. By extrapolation, it could be predicted that the conditioning effect may never completely relax at environmentally relevant temperatures. The results provide compelling evidence for the glassy, non-equilibrium nature of natural organic matter solids and for irreversible structural expansion as a cause of irreversible sorption phenomena. <br /> <br /> We have also identified a heretofore-unrecognized source of artificial hysteresis that may occur simultaneously with true hysteresis [Sander and Pignatello, 2006]. The study involved sorption of benzene, toluene, and nitrobenzene, both singly and in pairs, to wood charcoal, a black carbon model substance. A previous study [Sander and Pignatello Environ. Sci. Technol., <br /> 39: 1606-1615 (2005)] showed these similarly sized compounds compete for the same set of sorption sites on the char. Single-solute sorption of these compounds was weakly hysteretic at high concentrations. Comparable degrees of hysteresis for these compounds was taken as evidence that hysteresis is true and caused by sorbate-induced deformation of char pores. Hysteresis of a target solute in the presence of a competitor was generally weak at low co-solute concentration but became stronger as co-solute concentration increased. We attribute this growing hysteresis with co-solute concentration to a competitor dilution effect. The competitor dilution effect arises when the target solute re-equilibrates from a sorption state in which competition is relatively high, to a desorption state in which competition is relatively low because the competitor has been diluted along with the target solute. Simulations based on Ideal Adsorbed Solution Theory, a thermodynamic competitive model, support the contribution of the competitor dilution artifact to hysteresis. The co-solute also causes an increase in the linearity of the isotherm, also due to competition thermodynamics. The competitor dilution effect can play a role in pollutant behavior in real systems containing multiple contaminants when competing solutes are diluted or degraded; the target solute may appear to be less accessible with time due to this effect. <br /> Influence of humic substances on the surface activity of biomass char. Environmental black carbon (BC), which includes charcoal and soot particles emitted to the environment, is believed to play an important role in sorption of anthropogenic organic compounds in soils and sediments due to its high porosity and surface area. It is possible, however, that naturally-occurring organic matter attenuates the surface activity of BC. We previously found [Kwon and Pignatello, 2005] that aging of prepared wood char particles in a soil-water suspension lead over a few week period to a strong decline in char total surface area (TSA, by N2 adsorption at 77 K using the B.E.T. equation), and a more modest decline in the solid-water distribution ratio of benzene. The findings indicate that N2 is an unsuitable probe for microporosity in BC and natural organic matter in geosorbents. They also show that adsorption of organic compounds to BC may be attenuated by exposure to humic substances in soil over time. <br /> <br /> Identify mechanisms of ciprofloxacin interaction with metal cations. Interactions of fluoroquinolones with metal cations may play an important regulatory role in the reactions of these antibiotics with both minerals and organic matter. For example, HA carboxylate groups may bind to Cipro via a bivalent metal cation bridge analogous to that between Cipro carboxylates.. The high affinity of fluorquinolones for oxide minerals and layer silicates is attributed to the binding of the antibiotic to structural metal centers at the surfaces of the minerals or to exchangeable cations in clay mineral interlayers facilitated by deprotonated carboxylate moieties of the fluoroquinolones (Nowara et al. 1997, Zhang et al. 2005, Gu et al. 2005). By contrast, adsorption by clays is decreased by about two orders of magnitude when a decarboxylated fluoroquinolone derivative is used as an adsorptive (Nowara et al. 1997). Molecular simulation may prove useful for gaining insights into these interactions and accordingly our MD simulation results will be applied to help understand the binding mechanisms of fluoroquinolone derivatives with organic matter and clays in both soil and aquatic environments. <br /> <br /> Quantifying the Availability of Clay Surfaces in Soils for Adsorption of Nitrocyanobenzene and Diuron. Coverage of clay surfaces by soil organic matter (SOM) may limit the efficacy of the soil mineral fractions for adsorption of organic contaminants and pesticides. Two methods were scrutinized for quantitatively assessing the availability of clay surfaces in a smectitic Webster A-horizon soil for sorption of p-nitrocyanobenzene (p-NCB) and diuron. One method described previously involves the summation of independent contributions of SOM and swelling clays to sorption of organic solutes. For this method, several assumptions must be made and/or procedural difficulties overcome in the determination of certain terms in the equation proposed for calculating the fractional availability of mineral surfaces (fa). To alleviate the methodological limitations, we developed an alternative approach for determining fa. Good agreement between fa values was obtained from both methods for p-NCB but not diuron. For p-NCB sorption, fa values varied between 0.55 and 0.71. For diuron sorption, our alternative equation estimated fa values varied between 0.41 and 0.61; the other approach yielded negative values. The results demonstrate that SOM does reduce the availability of clay surfaces hence suppressing sorption by the Webster A-horizon soil. Our newly developed method provides more reasonable estimates of the availability of soil-clay surfaces for sorption than an earlier published approach.<br /> <br /> Ionic Strength-Induced Formation of Smectite Quasicrystals Enhances Nitroaromatic Compound Sorption. Sorption of organic contaminants by soils is a determinant controlling their transport and fate in the environment. The influence of ionic strength on nitroaromatic compound sorption by K+- and Ca2+-saturated smectite was examined. Sorption of 1,3-dinitrobenzene by K-smectite increased as KCl ionic strength increased from 0.01 to 0.30 M. In contrast, sorption by Ca-smectite at CaCl2 ionic strengths of 0.015 and 0.15 M remained essentially the same. The salting-out effect on the decrease of 1,3-dinitrobenzene aqueous solubility within this ionic strength range was <1.5 % relative to the solubility in pure water. This decrease of solubility is insufficient to account for the observed increase of sorption by K-smectite with increasing KCl ionic strength. X-ray diffraction patterns and light absorbance of K-clay suspensions indicated the aggregation of clay particles and the formation of quasicrystal structures as KCl ionic strength increased. Sorption enhancement is attributed to the formation of better-ordered K-clay quasicrystals with reduced interlayer distances, rather than the salting-out effect. Dehydration of 1,3-dinitrobenzene is apparently a significant driving force for sorption, and we show for the first time that sorption of small, planar, neutral organic molecules, viz. 1,3-dinitrobenzene, causes previously expanded clay interlayers to dehydrate and collapse in aqueous suspension.<br /> <br /> Development of a reliable analytical procedure for monitoring low hormone concentrations in environmental matrices. The commercial use of growth promotants in animal production, and especially in so called concentrated animal feeding operations (CAFOs), creates high enough concentrations of endocrine disrupting chemicals to cause environmental impact, and even naturally occurring hormone levels from some livestock may be cause for concern. Research reports on hormone behavior in the environment indicate their high dissipation through sorption on soil matrices, and degradation by soil microorganisms. However, taking into account the long contact times, and long distances covered by hormones in soil before they reach surface or groundwater, it is surprising that hormone dissipation is incomplete. Frequently, in published sorption studies, hormone concentrations span the range of relatively high concentrations reported for animal manures. However, hormone concentrations comparable with the relatively low levels determined in surface water and groundwater samples, are an area of opportunity for exploration in terms of sorption studies. Having this in mind, we have revisited the problem of hormone sorption with the intention to cover the full span of relevant hormone concentrations, including low, ng L-1, hormone concentrations typically occurring in surface water, groundwater, or manure-unamended soil solution. This became possible owing to the development of more precise analytical methods, such as introducing the highly sensitive mass spectrometric techniques into the analytical procedure, allowing the determination of hormone concentrations at ng L-1 levels. <br /> <br /> Sorption and degradation of veterinary pharmaceuticals. We continue to investigate the sorption and degradation of veterinary pharmaceuticals. Sorption and aerobic degradation studies with cobalt-radiated (sterile) and untreated soil systems were conducted for a synthetic androgen used in the beef industry (trenbolone isomers) and its primary metabolite (trendione); and two ionophore antibiotics monensin and lasalocid common to CAFOs and their primary metabolites. The 17a and 17b isomers of trenbolone appear to follow similar degradation pathways. Degradation is primarily, but not completely, microbial, and concentration-dependent rates were observed. At applied concentrations of 1 mg/kg, half lives ranged from 5-14 h whereas at applied concentrations of 10 mg/kg, half lives increased to 2-3 days. Some concentration dependence seemed apparent for trendione as well with half lives ranging from 3 to 4 days. Degradation of trendione generated from trenbolone was well predicted using rates estimated from independent trendione degradation studies. Degradation of trenbolone to trendione to unknown metabolites was well described assuming pseudo-first order rate processes, no reversible degradation, and no impact from sorption. We recently monitored hormones in manures excreted by cattle implanted with Ravoler-S (140 mg TBA and 28 mg estradiol). Manure from the pits was sampled after mixing immediately prior to flushing to lagoons, which were sampled every 2 weeks starting with the 4th week after implanting. Trenbolone exhibited the highest hormone concentration in both the manure ( > 2 mg/L) and the lagoon (> 0.12 mg/L). Hormone concentrations in cell 2 were the greatest at 4 weeks after implants, but below 0.03 ug/L except for trendione (~ 0.14 mg/L).<br /> <br /> Tetracycline transformation by manganese oxide. Tetracycline antibiotics comprise a class of broad spectrum antimicrobial agents finding application in human therapy, animal husbandry, aquaculture and fruit crop production. To better understand the processes affecting these antibiotics in soils and sediments, the kinetics of oxytetracycline transformation by a hydrous manganese oxide (MnO2) were investigated as a function of reactant concentration, pH and temperature. Oxytetracycline was rapidly degraded by MnO2. Initial reaction rates exhibited pronounced pH dependence, increasing as pH decreased. Reaction of oxytetracycline with MnO2 was accompanied by generation of MnII ions, suggesting oxidative transformation of the antibiotic. At pH 5.6, apparent reaction orders for oxytetracycline and MnO2 were 0.7 and 0.8. Reaction order with respect to H+ was 0.6 between pH 4 and 9. Initial reaction rates increased by a factor of ~2.4 for 10°C temperature increases; the apparent activation energy (60 kJ"mol-1) was consistent with a surface-controlled reaction. Reactivity of tetracycline antibiotics toward MnO2 increased in the following order: rolitetracycline H oxytetracycline d tetracycline H meclocycline < chlortetracycline. The initial rate of chlortetracycline degradation by MnO2 was substantially larger than that of the other tetracycline antibiotics investigated. MnO2 reactivity toward oxytetracycline decreased with time; a retarded rate equation was used to describe oxytetracycline reaction with MnO2 under declining rate conditions. This study indicates that natural manganese oxides in soils and sediments are likely to promote appreciable degradation of tetracycline antibiotics, and that reaction rates are strongly dependent on reaction time scale and solution conditions.<br /> <br /> Tetracycline association with dissolved humic substances. The effect of solution chemistry and sorbate-to-sorbent ratio on the interaction of the antibiotic tetracycline with Elliott soil humic acid (ESHA) was investigated using equilibrium dialysis and FITEQL modeling. Tetracycline speciation strongly influenced its sorption to ESHA over the entire pH range studied. Sorption was strongly pH-dependent with a maximum around pH 4.3, and competition with H+ and electrolyte cation (Na+) was evident. The pH-dependent trend is consistent with complexation between the cationic/zwitterionic species of tetracycline and deprotonated sites in ESHA (mainly carboxylic functional groups) as the primary underlying sorption mechanism. Modification of ESHA by Ca2+ addition increased tetracycline sorption suggesting that ternary complex formation (ESHA-metal-tetracycline) may be important at higher multivalent metal concentrations. The macroscopic data (pH-envelope and sorption isotherms) were successfully modeled using a discrete log K function with the FITEQL 4.0 chemical equilibrium program indicating that ESHA-tetracycline interaction could be reasonably represented as complex formation of a monoacid with discrete sites in humic acid. Sorption-desorption hysteresis was observed; both sorption and desorption isotherms were well described by the Freundlich equation.<br /> <br /> Livestock Antibiotic Effects on Nitrogen Cycling by Soil Microorganisms. This study showed for the first time that all FDA-approved antibiotics used in the poultry industry inhibited at least one N cycling reaction. The extent of inhibition depended on antibiotic concentration and presence of soil minerals. Inhibition of N cycling reactions through land application of antibiotic-laden livestock manure could have favorable or detrimental effects on soil fertility and water quality, depending on the dominant N form in the manure and soils. Antibiotic effects on denitrification were moderated by the soil mineral montmorillonite, presumably by reducing antibiotic exposure to sensitive bacteria. <br /> <br /> Diversity, Composition and Geographical Distribution of Microbial Communities in California Salt Marsh Sediments Contaminated with Pesticides, Metals and Antibiotics. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential of application of microbial community analyses in assessments of the ecosystem health of salt marshes. The results of our study illustrate the importance of considering non-anthropogenic variables in the design and interpretation of ecosystem biomarkers, indicators and other monitoring tools.<br /> <br /> Whole Genome Analysis of Methyl Tert-Butyl Ether (MTBE)-Degrading Beta-Proteobacterium Methylibium petroleiphilum PM1. In this study, we analyzed the whole genome sequence of Methylibium petroleiphilum PM1. Genome analysis of PM1 reveals a ~4-Mb circular chromosome and ~600-kb megaplasmid containing 3831 and 646 genes, respectively. Aromatic hydrocarbon and alkane degradation, metal resistance, and methylotrophy are encoded on the chromosome. The megaplasmid contains an unusual t-RNA island, numerous insertion sequences and large repeated elements including a 40 kb region also present on the chromosome and a 29 kb tandem repeat encoding phosphonate transport and cobalamin biosynthesis. The megaplasmid also codes for alkane degradation and plays an essential role in MTBE degradation. Discrepancies between the IS element distribution pattern, the distribution of best BLASTP hits among major phylogenetic groups, and G+C content of the chromosome (69.2%) and plasmid (66%) together with comparative genome hybridization experiments suggest the plasmid was recently acquired and may carry the genetic information responsible for PM1s ability to degrade MTBE. Comparative genomic hybridization analysis with PM1-like MTBE-degrading environmental isolates (~99% identical 16S rDNA sequences) showed that this plasmid was highly conserved (ca. 99% identical), whereas, the chromosomes were too diverse to conduct resequencing analysis. PM1s genome sequence now provides a foundation to investigate MTBE biodegradation and explore genetic regulation of multiple biodegradation pathways in M. petroleiphilum and other MTBE-degrading betaproteobacteria.<br /> <br /> Influence of soil aging on sorption and bioavailability of simazine. Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. However, pesticide bioavailability in aged soils has been characterized by a variety of methods with limited success, due in part to methodological limitations. The objective of this study was to use solvent extraction methods to correlate simazine residue bioavailability in aged soils to simazine mineralization using a simazine-mineralizing bacterium. Soils from Brazil, Hawaii, and the midwestern United States were treated with UL-ring-labeled [14C]simazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either incubated further, extracted with 0.01 M CaCl2, or extracted with aqueous methanol (80:20 v/v methanol/water). In a parallel experiment, after each incubation period, soils were inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing simazine, and 14CO2 was determined. The inoculated soil samples were then extracted with 0.01 N CaCl2 and with aqueous methanol. This allowed for the evaluation of the bioavailability of aged simazine residues, without the contribution of simazine desorption from soil. Results of these studies indicated that simazine sorption to soil increased with aging and that amounts of simazine in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were highly correlated to amounts of simazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol-extractable simazine in aged soils can be used to estimate bioavailable residues. This technique may be useful in determining the bioavailability of other s-triazine compounds in soils.<br /> <br /> Influence of Cry1Ac toxin on mineralization and bioavailability of glyphosate in soil. The impact of transgenic plants containing Bacillus thuringiensis (Bt) toxin on soil processes has received recent attention. In these studies, we examined the influence of the lepidopterean Bt Cry1Ac toxin on mineralization and bioavailability of the herbicide glyphosate in two different soils. The addition of 0.25-1.0 g g-1 soil of purified Cry1Ac toxin did not significantly affect glyphosate mineralization and sorption in either a sandy loam or a sandy soil. In contrast, extractable glyphosate decreased over the 28 day incubation period in both soils. Our findings suggest that the reduction in the bioavailabily of glyphosate was not influenced by the presence of Cry1Ac toxin but rather the results of aging or sorption processes. Results from this investigation suggest that the presence of moderate concentrations of Bt-derived Cry1Ac toxin would have no appreciable impact on processes controlling the fate of glyphosate in soils.<br /> <br /> Objective 2: Integrate chemical and biological process information for use in models applicable across different spatial and temporal scales.<br /> <br /> Assessment of the vulnerability of farmstead and rural domestic wells to agrichemical contamination. Rural domestic wells, particularly the farmstead wells are not regulated for meeting water quality criteria. As a result, the quality of water pumped from these wells is not tested. It is up to the farmers or well owners to test the water. Recent surveys of ground water pumped from these wells shows the presence of nitrate, pesticides, and their metabolites. As a result, owners/users of these wells are at risk by consuming the contaminated waters. Testing individual wells in a regional setting by regulating agencies is not feasible due to cost and logistics. Traditional modeling approaches are also not suitable to predict the contamination potential of water drawn from a well due to the lack of parameters that are needed in these models to predict contaminant transport. Further, many of the parameters vary in space and time and interact with each other. In our earlier research, we used artificial neural networks (ANNs) as alternative modeling approach to predict the contamination potential of domestic and farmstead wells using data from several states. <br /> In this year, we used data from statewide monitoring well network for pesticide and nitrate assessment in Illinois. Sampling results from 159 wells were used for analysis. Well depth, depth to mid-section of the screen, depth to aquifer material, hydraulic conductivity, and drainage class of the overburden material were used as input variables. <br /> <br /> Transport of selected endocrine disrupting chemicals from wastewater through a Hawaiian Oxisol. Additional experiments (beyond that reported in 2005) were conducted to examine the leachability of two estrogen hormones (17-beta estradiol and estrone) and two surfactant degradation products (octylphenol and nonylphenol) for an Oxisol found on the island of Oahu. Batch sorption experiments were conducted for these four chemicals using soils from two depths: 0-2 ft (referred to as topsoil) and 13-15 ft (referred to as saprolite). Leaching media were (a) deionized water spiked with small amounts of CaCl2 to represent the salts leached out of the columns and (b) recycled water from a local wastewater treatment plant. All four compounds adsorbed strongly to the soil collected from both depths. However, octylphenol and nonylphenol degraded during the sorption experiment. The Freundlich model was suitable to describe the sorption isotherm. Sorption nonlinearity was relatively higher for the saprolite compared to the topsoil. Both physical and chemical nonequilibrium processes were found to affect the mobility of these chemicals in the soil. Transport of these compounds was enhanced with recycled water due to the presence of dissolved organic carbon. Ambient pH had little effect on sorption. Breakthrough experiments in small columns failed to produce any measurable concentrations. Finally, a thin (1 cm) layer of soil was packed in sand to produce breakthroughs. It was difficult to fit the obtain breakthrough to numerical models. <br /> <br /> Simulating Herbicide Volatilization From Bare Soil Affected By Atmospheric Conditions And Limited Solubility In Water. A numerical model that simulates pesticide fate was developed to predict the behavior of triallate after application to a field soil. The model has options that allow water and/or heat transport, and can limit simulated aqueous phase concentrations to triallate solubility in water. Several methods for describing the volatilization boundary condition were tested to assess the accuracy in predicting the volatilization rate, including an approach that requires no atmospheric information and an approach that couples soil and atmospheric processes. Four scenarios were constructed and simulated, to compare with measured volatilization rates. The peak measured volatilization rate (168 g ha1 hr1) was most accurately predicted with the scenario that included the most complex model (100 g ha1 hr1). The simplest model over predicted the peak rate (251 g ha1 hr1) and the others under predicted the peak rate (16  67 g ha1 hr1). The simulations that limited aqueous solubility provided relatively similar values for the total emissions (21%  36% of applied triallate), indicating that simplified models may compare well with measurements (31% of applied). A prospective simulation over a period of 100 days showed that applying triallate to the soil surface would ultimately lead to atmospheric emissions of 80% of the applied material with 6% remaining in soil. Incorporating triallate to depth of 10 cm would reduce emissions to less than 5% and lead to 41% remaining in soil.<br /> <br /> Objective 3. Provide stakeholders with tools for developing strategies to ensure sustainable agriculture and to protect natural resource systems.<br /> <br /> Chemical Leaching and Evaluation of Risk System (CLERS). An ARC/GIS-based simulation tool is used to calculate leaching characteristics of pesticides based upon soil physical/chemical properties, depth to water, recharge rate, and pesticide properties. The model is used to calculate leaching of existing and new chemicals coming to Hawaii on island-wide scale. Variability in soil organic carbon at various soil classification groups and the variabilities in half-life and organic carbon partition coefficients are taken into consideration while developing this GIS-based model. Digital soil information, variation of recharge, and the depth to ground water are now included in the database. The model is now used by the Hawaii Department of Agriculture and pesticide registrants to evaluate relative attenuation of pesticides. If a new chemical appears to be significantly mobile compared to two reference chemicals (one that is frequently observed in drinking waters and the other has never been found so far), restrictive measures will be taken by the state for the registration of these compounds. The updated pesticide leaching assessment model CLERS is now used by the State of Hawaii for pesticide registration. Currently, the State is examining the model for leachability assessment of fipronil, imidacloprid, s-metolachlor, sulfometurin methyl, and trifloxystrobin.<br /> <br /> Leaching of Selected Chemicals in Various Hawaii Soils . Four existing and two new chemicals (four herbicides, one fungicides, and one insecticide) were tested at five sites (three on Oahu, one each on Maui and Kauai) to evaluate their leaching under diverse soil conditions. The leaching study took place over a period of 16 weeks. Laboratory batch sorption and aerobic degradation half-life studies were also completed. In addition, a column experiment was carried out to obtain transport parameters in an undisturbed core. We have conducted displacement experiments with these five chemicals along with atrazine and bromide in one undisturbed column with two flow interruptions. All samples have been analyzed. A draft report was prepared. We are working on three papers.<br /> <br /> Measuring Herbicide Volatilization from Bare Soil. A field experiment was conducted to measure surface dissipation and volatilization of the herbicide triallate after application to bare soil using micrometeorological, chamber, and soil-loss methods. The volatilization rate was measured continuously for 6.5 days and the range in the daily peak values for the integrated horizontal flux method were from 32.4 (day 5) and 235.2 g ha-1 d-1 (day 1), for the theoretical profile shape method were from 31.5 and 213.0 g ha-1 d-1, and for the flux chamber were from 15.7 to 47.8 g ha-1 d-1. Soil samples were taken within 30 min after application and the measured mass of triallate was 8.75 kg ha-1. The measured triallate mass in the soil at the end of the experiment was approximately 6 kg ha-1. The triallate dissipation rate, obtained by soil sampling, was approximately 334 g ha-1 d-1 (98 g d-1) and the average rate of volatilization was 361 g ha-1 d-1. Soil sampling at the end of the experiment showed that approximately 31% (0.803kg/2.56kg) of the triallate mass was lost from the soil. Significant volatilization of triallate is possible when applied directly to the soil surface without incorporation.<br />

Publications

Accinelli, C., W. C. Koskinen, and M. J. Sadowsky. 2006. Influence of Cry1Ac toxin on mineralization and bioavailability of glyphosate in soil. J. Agric. Food Chem. 54:164-169.<br /> <br /> Accinelli, C., W. C. Koskinen, and M. J. Sadowsky. 2006. Influence of Cry1Ac toxin on mineralization and bioavailability of glyphosate in soil. J. Agric. Food Chem. 54:164-169.<br /> <br /> Bondarenko, S., Zheng, W., Yates, S.R., and Gan, J. 2006. Dehalogenation of halogenated fumigants by polysulfide salts. Journal of Agricultural & Food Chemistry. 54:5503-5508. <br /> <br /> Bradford, S.A., Simunek, J., Bettahar, M., van Genuchten, M.Th., S.R. Yates. 2006. Significance of straining in colloid deposition: Evidence and implications. Water Resources Research. 42 (12): Art. No. W12S15 <br /> <br /> Charles, S.M., H. Li, B.J. Teppen, and S.A. Boyd, 2006, Quantifying the Availability of Clay Surfaces in Soils for Adsorption of Organic Contaminants and Pesticides. Environmental Science and Technology, 40:7751-7756.<br /> <br /> Charles, S.M., B.J. Teppen, H. Li, D.A. Laird, and S.A. Boyd. 2006. Exchangeable Cation Hydration Properties Strongly Influence Soil Sorption of Nitroaromatic Compounds, Soil Science Society of America Journal, 70:1470-1479.<br /> <br /> Chen, J. J. Lichwa, M. Snehota, S. Mohanty, and C. Ray. 2006. Determination of hormones and non-ionic surfactants in aqueous samples using LS-ESI-MS-MS and GC-MS, Chromatographia, 64(7/8): 413-418<br /> <br /> Cruz-Guzmán, M., R. Celis, M. C. Hermosín, W. C. Koskinen, E. A. Nater and J. Cornejo. 2006. Heavy metal adsorption by montmorillonites modified with natural organic cations. Soil Sci. Soc. Am. J. 70:215-221.<br /> <br /> Cordova-Kreylos, A., Cao, Y., Green, P., Hwang, H., Kuivila, K.M., LaMontagne, M.G., Van de Werfhorst, L.C., Holden, P.A., and K.M. Scow. 2006. Diversity, Composition, and Geographical Distribution of Microbial Communities in California Salt Marsh Sediments. Appl. Environ. Microb. 72(5):3357-3366. <br /> <br /> Koskinen, W. C., M. J. Calderon, P. J. Rice, and J. Cornejo. 2006. Sorption-desorption of flucarbazone and propoxycarbazone and their benzenesulfonamide and triazolinone metabolites in two soils. Pest Manage. Sci. 62:598-602.<br /> <br /> Koskinen, W. C, T. E. Ochsner, B. M. Stephens, and R. S. Kookana. 2006. Sorption of isoxaflutole diketonitrile degradate (DKN) and dicamba in unsaturated soil. J. Environ Sci. Health B. 41:1071-1083.<br /> <br /> Koskinen, W. C., P. J. Rice, and J. Seebinger. 2006. Experimental variability in characterization of cyfluthrin sorption to soil. J. Environ. Sci. Health, Part B. 41:323-331.<br /> <br /> Li, H., Brian J. Teppen, David A. Laird, Cliff T. Johnston, and Stephen A. Boyd, 2006, Effects of Increasing Potassium Chloride and Calcium Chloride Ionic Strength on Pesticide Sorption by Potassium- and Calcium-Smectite, Soil Science Society of America Journal, 70:1889-1895.<br /> <br /> Nakatsu, C.H., Hristova, K., Hanada, S., Meng, X.Y., Hanson, J.R., Scow, K.M., and Y. Kamagata. 2006. Methylibium petroleiphilum gen. nov., sp. Nov., a novel methyl tert-butyl ether-degrading methylotroph of the Betaproteobacteria. Int. J. Syst. Evol. Micr. 56:983-989. <br /> <br /> Ochsner, T. E., B. M. Stephens, W. C. Koskinen, and R. S. Kookana. 2006. Sorption of a hydrophilic pesticide: effects of soil water content. Soil Sci. Soc. Am. J. 70:1991-1997.<br /> <br /> Papiernik, S. K., W. C. Koskinen, L. Cox, P. J. Rice, S. A. Clay, N. R. Werdin-Pfisterer, and K. A. Norberg. 2006. Sorption-desorption of imidacloprid and its metabolites in soil and vadose zone materials. J. Agric. Food Chem. 54:8163-8170.<br /> <br /> Papiernik, S. K., W. C. Koskinen, L. Cox, P. J. Rice, S. A. Clay, N. R. Werdin-Pfisterer, and K. A. Norberg. 2006. Sorption-Desorption of Imidacloprid and Its Metabolites in Soil and Vadose Zone Materials. J. Agric. Food Chem. 54:8163-8170<br /> <br /> Pignatello, J.J., Y. Lu, E.J. LeBoeuf, W. Huang, J. Song and B. Xing. 2006. Nonlinear and competitive sorption of apolar compounds in black carbon-free natural organic materials J. Environ. Qual.35: 1049-1059. <br /> <br /> Pignatello, J. J., S. Kwon, and Y. Lu. 2006. Effect of Natural Organic Substances on the Surface and Adsorptive Properties of Environmental Black Carbon (char): Attenuation of Surface Activity by Humic and Fulvic Acids Environ. Sci. Technol., 40: 7757-7763. <br /> <br /> Regitano, J. B., W. C. Koskinen, and M. J. Sadowsky. 2006. Influence of soil aging on sorption and bioavailability of simazine. J. Ag. Food Chem. 54:1373-1379.<br /> <br /> Regitano, J. B., W. C. Koskinen, and M. J. Sadowsky. 2006. Influence of soil aging on sorption-desorption and bioavailability of simazine. J. Agric. Food Chem. 54:1373-1379<br /> <br /> Roberts, M.G., H.Li, B.J. Teppen, and S.A. Boyd. 2006. Sorption of Nitroaromatics by Ammonium- and Organic Ammonium-Exchanged Smectite: Shifts from Adsorption/Complexation to a Partition-Dominated Process. Clays and Clay Minerals, 54:426-434.<br /> <br /> Sander, M., Y. Lu, and J.J. Pignatello, 2006. Conditioning-Annealing Studies of Natural Organic Matter Solids Linking Irreversible Sorption to Irreversible Structural Expansion Environ. Sci. Technol., 40: 170-178. [Correction, 40: 6518 (2006)] <br /> <br /> Sander, M. and J.J. Pignatello. 2006. On the Reversibility of Sorption to Black Carbon: Distinguishing True Hysteresis from Artificial Hysteresis Caused by Dilution of a Competing Adsorbate Environ. Sci. Technol., ASAP article. <br /> <br /> Sadowsky, M. J., W. C. Koskinen, J. Seebinger, B. L. Barber, and E. Kandeler. 2006. Automated robotic assay of phosphomonoesterase activity in soils. SSSAJ 70:378-381.<br /> <br /> Sadowsky, M. J., W. C. Koskinen, J. Seebinger, B. L. Barber, and E. Kandeler. 2006. Automated robotic assay of alkaline phosphomonoesterase activity in soils. Soil Sci. Soc. Am. J. 70:378-381.<br /> <br /> Sahoo, G.B., C. Ray, E. Mehnert, and D. A. Keefer. 2006. Use of Neural Networks to Assess Shallow Ground Water Contamination within the Illinois State Monitoring Well Network for Pesticides, The Science of the Total Environment, 367: 234-251.<br /> <br /> Shapir, N., G. Cheng, M. J. Sadowsky, and L. P. Wackett. 2006. Purification and characterization of TrzF: Biuret hydrolysis by allophanate hydrolase supports growth. Appl. Environ. Microbiol. 72:2491-2495.<br /> <br /> Shapir, N., C. Pedersen, O. Gil, L. Strong, J. Seffernick, M. J. Sadowsky, and L. P. Wackett. 2006. TrzN from Arthrobacter aurescens TC1 is a zinc amidohydrolase. J. Bacteriol. 188:58595864.<br /> <br /> Vaneet Aggarwal, Hui Li, and Brian J. Teppen, 2006, Triazine Adsorption by Saponite and Beidellite Clay Minerals, Environmental Toxicology and Chemistry, 25:392-399. <br /> <br /> Vaneet Aggarwal, Hui Li, Stephen A. Boyd, and Brian J. Teppen, 2006, Enhanced sorption of trichloroethene by smectite clay exchanged with Cs+, Environmental Science and Technology, 40: 894-899.<br /> <br /> Wang, D., S. W. Fraedrich, J. Juzwik, K. Spokas, Y. Zhang, and W. C. Koskinen. 2006. Fumigant distribution in forest nursery soils under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin. Pest Manag. Sci. 62: 263-273. <br /> <br /> Wang, Q., Bradford, S.A., Zheng, W., and Yates, S.R. 2006. Degradation kinetics of manure-derived sulfadimethoxine in soil. Journal of Agricultural & Food Chemistry. 54:157-163. <br /> <br /> Wang, Q., Bradford, S.A., Zheng, W., and Yates, S.R. 2006. Sulfadimethoxine degradation as affected by initial concentration, moisture, and temperature. Journal Environmental Quality. 35:21622169. <br /> <br /> Yates, S.R. 2006. Measuring herbicide volatilization from bare soils. Environmental Science and Technology. 40:3223 -3228. <br /> Yates, S.R. 2006.Simulating herbicide volatilization from bare soil affected by limited solubility in water. Environmental Science and Technology. 40:6963-6968. <br /> <br /> Zheng, W., Yates, S.R., Papiernik, S.K. and Wang, Q.Q. 2006. Reducing 1,3-dichloropropene emissions from soil columns amended with thiourea. Environmental Science and Technology. 40:2402-2407. <br /> <br /> Zheng, W., Yates, S.R., Papiernik, S.K., Guo, M., and Gan, J. 2006. Dechlorination of chloropicrin and 1,3-dichloropropene by hydrogen sulfide species: Redox and nucleophilic substitution reactions. Journal of Agricultural & Food Chemistry. 54:2280-2287. <br /> <br /> Zheng, W., Yates, S.R., and Papiernik, S.K. 2006. Conversion of metam sodium and emission of fumigant from soil columns, Atmospheric Environment. 40:70467056. <br /> <br /> Zheng, W., S. R. Yates, S. K. Papiernik, M. Guo, and J. Gan. 2006. Dechlorination of chloropicrin and 1,3-dichloropropene by hydrogen sulfide species: Redox and nucleophilic substitution reactions. J. Agric. Food Chem. 54:2280-2287.<br /> <br /> Zheng, W., S. R. Yates, S. K. Papiernik, and Q. Wang. 2006. Reducing 1,3-dichloropropene emissions from soil columns amended with thiourea. Environ. Sci. Technol. 40:2402-2407.<br /> <br /> Zheng, W., S. R. Yates, S. K. Papiernik, and J. Nunez. 2006. Conversion of metam sodium and emission of fumigant from soil columns. Atmos. Environ. 40:7046-7056.<br />

Impact Statements

1. 1. Studies with three tetracylcines, tylosin, carbadox, monensin, and lasalocid indicate that when these compounds are applied to soil inadvertently with manure or lagoon effluent, they will degrade rapidly and only low levels at most are likely to be observed in nearby water bodies.
2. 2. Chemical incorporation of sulfonamide antimicrobials into soil organic matter (OM) is expected to decrease their mobility and bioaccessibility, and provides an explanation for previous reports of apparent non-extractable residue formation. Results suggest that sulfonamide antimicrobials may form Michael adducts with quinone-like moieties in OM in addition to the Schiff bases previously reported resulting in bound residues that are more likely to persist in soil.
3. 3. A study provided the first fundamental kinetic information on the degradation of tetracycline antibiotics by a manganese oxide mineral found in soils and sediments. Experimental results suggest that reaction with natural manganese oxides may serve as an important route to degradation of tetracycline antibiotics in the environment. Whether these partially degraded antibiotics retain some or any of their biological activity warrants further study.
4. 4. The strong interaction between tetracycline and humic substances is expected to significantly influence the reactivity, mobility and bioavailability of this antimicrobial compound in soils and subsurface environments. Sorption is affected by pH, ionic strength and the presence of polyvalent metal cations.

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Report Information

Participants

Clinton Williams (USDA-ARS, Arizona); Michael Sadowsky (University of Minnesota);Jack Watson (Pennsylvania State University);Sharon Clay (South Dakota State University);Mark Radosevich (University of Tennessee);Bill Koskinen (USDA-ARS, St. Paul, MN);Lee Sommers (Colorado State University  Administrative Advisor);Jay Gan (UC Riverside);Ron Turco (Purdue University);Chitteranjan Ray (University of Georgia);Lance Schideman (University of Illinois)

Brief Summary of Minutes

The 2007 meeting of W-1082 Evaluating the Physical and Biological Availability of Pesticides and Pharmaceuticals in Agricultural Contexts was held on January 14 and 15, 2008 in St. George, UT hosted by Clinton Williams. Lee Sommers (Administrative Advisor) provided an overview of the budget outlook for the coming year and the Farm Bill. He also provided an overview of the Creating Research, Extension and Teaching Excellence for the 21st century (CREATE-21) initiative and referred members to the web site for further details. He noted that the Western directors are emphasizing accountability for multi-state research projects, requiring reports showing the impact of each committee. Members discussed progress on the outputs and milestones specified in the proposal and approaches to increase the impact of the committee. The meeting included presentations of research reports by all participants. Jack Watson was elected Secretary and Clinton Williams will become Chair of the committee. It was determined by consensus of the attending members that next years meeting would be hosted by Jay Gan at UC Riverside on Jan. 8-9, 2009.

Accomplishments

Objective 1. To identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment<br /> <br /> Modeling tillage-induced redistribution of soil mass and its constituents within different landscapes. - Soil movement by tillage (tillage erosion) is recognized as a major force in redistributing soil in cultivated landscapes. The redistribution of soil constituents is affected by soil movement by tillage and mixing of subsoil into the tilled layer. Tillage erosion affects soil productivity and environmental quality by redistributing soil mass and soil constituents in the landscape. In this study, a model (TillTM) was developed to simulate the tillage erosion process. The TillTM model is a diffusion model, which is conceptually simple. This model was used to describe the redistribution of soil mass and soil organic carbon (an example soil constituent) on landscapes with different topographic features. We determined that the rate of soil movement by tillage is mainly dependent on topography, whereas the redistribution of soil constituents was primarily affected by landscape topography, tillage direction, and time. The TillTM model was tested against field measurements. It was shown that the TillTM model can precisely estimate the pattern of soil constituent redistribution by tillage, but may require detailed field measurements to accurately represent the changing contents of soil constituents in the landscape. These results will enable land managers, extension personnel, consultants, and agricultural researchers to predict the effects of tillage erosion on the movement of soil mass and soil constituents in landscapes and to better describe landscapes affected by tillage erosion. These results will be useful in designing and evaluating cropping practices to reduce soil erosion.<br /> <br /> Herbicide sorption coefficients in relation to soil properties and terrain attributes on a cultivated prairie.- Pesticide fate models are used to assess the risk of water contamination by pesticides on a national basis. Sorption coefficients (measures of the extent to which pesticides are bound to the soil) are important variables in pesticide fate models. Accounting for the variation in pesticide sorption coefficients across landscapes could reduce uncertainties in regional-scale assessments of pesticide behavior. In these experiments, we measured the sorption coefficients of two common herbicides, 2,4-D and glyphosate, in 286 soil samples collected throughout a hilly field. Soil properties are highly variable in this field because erosion has removed topsoil from some areas of the field. Herbicide sorption coefficients are dependent on soil properties and thus were also highly variable. We found that including information about slope curvature and other factors describing the terrain could improve predictions of herbicide sorption in this field. The changes in soil properties and terrain factors had a larger impact on the sorption of a herbicide that is weakly bound by the soil (2,4-D) than for a herbicide that is strongly bound (glyphosate). These results suggest that this approach may help increase the accuracy of pesticide fate models. These results will help guide additional research to determine how including information about field terrain can improve pesticide fate models.<br /> <br /> Effects of soil fumigants on methanogenic activity. - Methane is a potent greenhouse gas. Soils from various agricultural experiment stations, forest nurseries, and a landfill were evaluated for effects of three soil fumigants on methane oxidation capacities. All three fumigants evaluated significantly reduced methane oxidation rates in historically non-fumigated soils. Chloropicrin universally decreased oxidation capacity regardless of fumigation history. These results support the conclusion that methane oxidation effects are fumigant specific and that prior fumigation history plays a vital role in determining the impact on the methane oxidizer community. This research documents some of the impacts of human activity on the amount of greenhouse gases in the atmosphere. The oxidation of methane by soil bacteria is the only known biological sink for atmospheric methane. Without this sink, atmospheric methane levels could potentially increase, resulting in a larger greenhouse effect. This research documents the impacts of soil fumigants on these bacteria and thereby creates the foundation for examining better soil fumigation practices to minimize this impact.<br /> <br /> Sorption reversibility: distinguishing true hysteresis from artificial hysteresis caused by dilution of a competitor - Sorption in soils and sediments is generally modeled as a reversible process. However, sorption hysteresis is a commonly observed phenomenon. If due to real causes and not experimental artifacts, hysteresis has important implications for the mobility and bioavailability of anthropogenic chemicals. We examined the reversibility of sorption by wood char from water of benzene, toluene, and nitrobenzene, both singly and in pairs. Artificial causes of hysteresis such as slow diffusion and mass loss were ruled out in controls. <br /> <br /> Single-solute sorption was weakly hysteretic at high concentrations and approximately the same for the three adsorbates; this finding is taken as evidence that hysteresis is true and supports irreversible pore deformation by the incoming adsorbate as the cause, as demonstrated in previous studies for natural organic matter. Simulations using a thermodynamic competition model, Ideal Adsorbed Solution Theory, support the hypothesis.<br /> <br /> Laccase-mediated Michael addition of sulfapyridine to a model humic constituent - Chemical incorporation of sulfonamide antimicrobials into natural organic matter may represent an important process influencing the fate of these synthetic, bacteriostatic agents in soil and sediment environments. We show that fungal laccase-mediated reaction of sulfapyridine with the ortho-dihydroxyphenol protocatechuic acid yields a Michael adduct. To enable elucidation of the covalent linkage(s) formed between sulfapyridine and protocatechuic acid by NMR, we synthesized 15N-enriched sulfapyridine. 1H-15N heteronuclear multiple bond correlation experiments and tandem mass spectrometry demonstrated that the sulfapyridine anilinic nitrogen engaged in a Michael addition reaction to oxidized protocatechuic acid forming of an anilinoquinone. Michael adducts are substantially more stable than the previously reported imine linkages between sulfonamides and 2,6-dimethoxyphenols. Formation of Michael adducts between sulfonamide antimicrobials and quinone-like structures in soil organic matter is expected to result in their immobilization and reduced biological activity.<br /> <br /> Tetracycline association with dissolved humic substances - The effect of solution chemistry and sorbate-to-sorbent ratio on the interaction of the antibiotic tetracycline with Elliott soil humic acid (ESHA) was investigated using equilibrium dialysis and FITEQL modeling. Tetracycline speciation strongly influenced its sorption to ESHA over the entire pH range studied. Sorption was strongly pH-dependent with a maximum around pH 4.3, and competition with H+ and electrolyte cation (Na+) was evident. The macroscopic data (pH-envelope and sorption isotherms) were successfully modeled using a discrete log K function with the FITEQL 4.0 chemical equilibrium program indicating that ESHA-tetracycline interaction could be reasonably represented as complex formation of a monoacid with discrete sites in humic acid. Sorption-desorption hysteresis was observed; both sorption and desorption isotherms were well described by the Freundlich equation.<br /> <br /> Mineralization of the Bacillus thuringiensis Cry1Ac endotoxin in soil - Cconflicting information on persistence of this class of insecticidal toxins exists. In the present study, 14C from glucose was incorporated into the B. thuringiensis Cry1Ac endotoxins and radiolabeled toxin was used to study its mineralization in soil samples incubated under controlled conditions. Fifty-nine percent of the radio-labeled Cry1Ac was recovered as 14CO2 at the end of the 20-day incubation period. Addition of 4.5% of corn residues stimulated mineralization of [14C]Cry1Ac toxin. Since low mineralization (approximately 6%) of the radio-labeled toxin was observed in autoclaved soil, our findings indicate a major role of microbial processes in the dissipation of the Cry1Ac endotoxin. This study demonstrates that there would be no risk of bioaccumulation of Cry1Ac in soil eventually released by Bt-protected crops. This study demonstrates that there would be no risk of bioaccumulation of the Cry1Ac toxin in soil eventually released by Bt-protected crops and that producers can safely use these crops.<br /> <br /> Effects of the Fluoroquinolone Antibiotic Ciprofloxacin on Estuarine Sediment Microbial Communities. - Fluoroquinolones, a widely used class of antibiotics, are frequently detected in sediments and surface waters. Given their antimicrobial properties, the presence of these compounds may alter the composition of microbial communities and promote antibiotic resistance in the environment. The purpose of this study was to measure sorption, and effects of ciprofloxacin on microbial community composition, in sediment samples from three California salt marshes. Sediments were exposed to a ciprofloxacin concentration gradient (0 to 200 µgml-1 ciprofloxacin) and microbial community composition characterized using phospholipid fatty acid (PLFA) analysis. Sorption coefficients, expressed as log Kd, were calculated from fits using the Freundlich isotherm model. Ciprofloxacin strongly sorbed to all sediments and had log Kd values, ranging from 2.9 to 4.3. Clay content was positively (r2=0.98) and pH negatively (r2=0.99) correlated to Kd values. Biomass, richness, sulfate reducer and gram-negative bacterial markers increased with ciprofloxacin concentrations, while the 17cy/precursor and saturated/unsaturated biomarker ratios, indicators of starvation stress, decreased. The magnitude of the effect of ciprofloxacin on microbial communities was inversely correlated to the degree of sorption to the sediments. Despite the fact that ciprofloxacin is a wide-spectrum antibiotic, its impact on sediment microbial communities was selective and appeared to favor sulfate reducing bacteria and gram-negative bacteria.<br /> <br /> Impacts of Triclosan and Triclocarban on Soil Microbial Communities. - Triclosan (TCS), [2,4,4-trichloro-2-hydroxydiphenylether], and Triclocarban (TCC), [N-(4-chlorophenyl)-N-(3,4-dichlorophenyl)-urea], are broad range antibacterial agents widely used in common household products (i.e. shampoo, soap, detergent, toothpaste, cosmetics, sanitizers, etc). Preliminary experiments were performed to explore the potential effects on TCS and TCC on soil microbial communities, using phospholipid fatty acid (PLFA) analysis as a screening method. Biomass decreased in both TCS (from 65.2 to 43.9 nmol/g dry soil) and TCC (from 65.2 to 44.7 nmol/g dry soil) treatments in comparison to the controls. The decrease of biomass was higher at 100-ug/g TCS and TCC treatments. On exposure to 10-ug/g TCC, the community was no different from an unexposed community, whereas exposure to 10-ug/g TCS, a relatively low concentration, substantially altered the community composition. At 100-ug/g, both compounds affected the community and the responses were quite variable. In conclusion, the more strongly sorbedTCC had less of an impact than the more water soluble TCS, perhaps due to differences in availability or toxicity. Fungal biomarkers remained unchanged, but abundance of monounsaturated fatty acids decreased in antimicrobial treated soils. <br /> <br /> Carbamazepine Distribution in a Treatment Wetland Receiving Effluent from a Sewage Treatment Facility - Artificially constructed wetlands offer a low cost treatment alternative to remove a number of pollutants found in effluent water from industry, mining, agriculture, and urban areas. Wetlands can be used to mechanically remove suspended solids through sedimentation. Dissolved nutrients, biochemical oxygen demand (BOD), heavy metals, and potentially harmful anthropogenic compounds can all be removed in constructed wetlands through geochemical and biological processes. The anti-epileptic drug carbamazepine has been shown to be recalcitrant in sewer treatment facilities and in the environment. Carbamazepine concentrations were measured on two different dates within a 1.2 ha treatment wetland that receives treated municipal effluent. On July 7, 2005 carbamazepine concentration ranged from 5.6 ng L-1 to 45.1 ng L-1. The concentration at the inlet was 22.8 ng L-1 and 23.4 ng L-1 at the outlet. The highest concentration was found internally within the wetland and the outlet concentration was higher than the inlet. Carbamazepine concentrations from the August 9, 2005 sampling were significantly lower than the July sampling event and ranged from 1.0 ng L-1 to 5.4 ng L-1. The concentration at the inlet was 10.6 ng L-1 and 3.2 ng L-1 at the outlet. Results indicate that there is evidence for carbamazepine removal within the wetland due to photodegradation and sorption followed by sedimentation. Concentrations within the wetland are also highly variable and depend on loading from the treatment plant as well as potential dilution due to precipitation.<br /> Hydroxyatrazine N-ethylaminohydrolase (AtzB): An amidohydrolase superfamily enzyme catalyzing deamination and dechlorination - Hydroxyatrazine N-ethylaminohydrolase (AtzB) is the sole enzyme known to catalyze the hydrolytic conversion of hydroxyatrazine to N-isopropylammelide. AtzB, therefore, serves as the point of intersection of multiple s-triazine biodegradative pathways and is completely essential for microbial growth on s-triazine hebicides. Here, atzB was cloned from Pseudomonas sp. ADP, purified to homogeneity, and characterized. AtzB was found to be dimeric, with subunit and holoenzyme molecular weights of 52 kDa and 105 kDa, respectively. The kcat and Km of AtzB with hydroxyatrazine as a substrate were 3 sec-1 and 20 µM, respectively. Purified AtzB had a 1:1 zinc to subunit stoichiometry. Sequence analysis revealed that AtzB contained the conserved mononuclear amidohydrolase superfamily active site residues: His74, His76, His245, Glu248, His280, and Asp331. An intensive in vitro investigation into the substrate specificity of AtzB revealed that 20 of the 51 substrate analogs tested were substrates for AtzB; this allowed for the identification of specific substrate structural features required for catalysis. Substrates required a monohydroxylated s-triazine ring with a minimum of one primary or secondary amine substituent, and either a chloride or amine leaving group. AtzB catalyzed both deamination and dechlorination reactions with rates within a range of one order of magnitude. This differs from AtzA and TrzN, which do not catalyze deamination reactions, and AtzC, which is not known to catalyze dechlorination reactions.<br /> <br /> Environmental fate of two sulfonamide antimicrobials agents in soil - Veterinary antimicrobial agents have been detected in a number of environmental samples, including agricultural soils. In this study, we investigated the persistence and sorption of the sulfonamides sulfamethazine (SMZ) and sulfachloropyridine (SCP) in soil and their potential effects on soil microorganisms. The sulfonamides dissipated more rapidly from the silt loam soil as compared to the sandy soil. Average half-lives of SMZ and SPC among the two soils were 18.6 and 21.3 days, respectively. The presence of liquid swine slurry (5% v/w) decreased sulfonamide persistence in the silt loam soil. The lower persistence of the antimicrobials in liquid swine slurry-amended soil was likely due to higher microbial activity, as compared to unamended soil, and/or to the greater bioavailability of the sulfonamides to degrading microorganisms, as estimated by sorption isotherms. Concentrations of SMZ and SPC up to 100 g g-1 had no effect on antimicrobial degradation rates and soil microorganisms. These studies suggest that higher sulfonamide concentrations would be necessary to affect the main processes controlling their environmental fates in soil, but at the concentrations normally found in the environment, there would be little or no effects.<br /> <br /> Formation and fate of nitrosamines from pesticides and pharmaceuticals in environmental matrices and (under conditions of) the human digestive tract. - We determined the formation of nitrosamine derivatives of nitrosatable pesticides and pharmaceuticals (a) in the presence of nitrite in vitro, emphasizing conditions simulating the human digestive tract and (b) during chloramination for disinfection of drinking water. <br /> <br /> (a) Nitrosation from Reaction with Nitrite at Acidic pH. Aqueous phase experiments provided strong evidence for the formation nitrosamine derivatives of atrazine (ATZ), ethambutol (ETB), furosemide (FSM), procainamide (PCA) and ranitidine (RTD) from reaction with nitrite under acidic conditions. Evidence of small amounts of nitrosamine derivatives of cefadroxil (CFD) and metoprolol (MTP) was also found but not confirmed. Considerable loss of parent compound was observed for ETB, FSM, PCA and RTD. The rate of transformation for ATZ was relatively slow. HPLC and LS/MS analyses demonstrated that ETB, FSM, RTD, and ATZ, in the presence of nitrite at pH 3, were nitrosated to produce mono-N-nitrosoethambutol (MNEB) and di-N-nitrosoethambutol (DNEB), N-nitrosofurosemide (NFSM), N-nitrosoranitinde (NRTD), and mono-N-nitrosoatrazine (MNAT) as the primary transformation product. For PCA, LC/MS analyses indicated that a small quantity of the expected N-nitrosoprocainamide (NPCA) was produced while hydroxy-procainamide (HCPA) was produced as the major transformation product.<br /> <br /> (b) Nitrosation from Reaction with Chloramines. The potential for amine pharmaceuticals and atrazine to form nitroso compounds (NOCs) and their derivatives from reaction with monochloramines (MC) at neutral pH was also evaluated. A Cl:N ratio of 0.7:1 was optimum for the formation of MC, but no dichloramine (DC) was formed. At a Cl:N ratio of 1.1:1, the MC concentration decreased as DC increased. These results indicate that the production of chloramines is highly dependent upon pH, and the ratio of chlorine to ammonia-nitrogen. Reaction with chloramines resulted in considerable loss of cefadroxil (CFD), chlorpheneramine (CPA), furosemide (FSM), metoprolol (MPL), ranitidine (RTD), and atrazine (ATZ). The pharmaceuticals showed relatively high transformation rates on a molar basis under standardized conditions. By comparison, the rate of ATZ transformation was relatively slow. The loss of parent compound during 4-h incubations was consistently greater than after 1 h.<br /> <br /> Atrazine-Degrading Microbial Populations in Soils and Wetlands: Linking Degradation to Diversity - <br /> Using Bio-Sep® beads containing varying concentrations of atrazine, we were able to monitor shifts in microbial community structure due to in situ enrichment using atrazine as a substrate in agricultural soils that varied in their atrazine exposure history. Fluorescent in situ hybridization (FISH) with 16S rDNA-based phylogenic probes and 16S rDNA denaturing gradient gel electrophoresis (DGGE) were used to assess the community composition of bacteria that colonized the beads. Atrazine dissipation in soil in which the beads were deployed was rapid indicating that atrazine-degrading bacteria responsive to atrazine additions were present in the soils selected for bead deployment. DGGE analysis revealed that the soil and bead communities were distinctly different. Atrazine concentration within the beads appeared to influence the community composition to a greater extent than the prior atrazine treatment history to the soils in which the beads were buried. Eubacterial biomass increased by approximately 5-40 fold in atrazine containing beads relative to atrazine-free beads suggesting an enrichment in atrazine-degrading bacteria within the baited beads. The phylogenetic distribution within the bead communities varied depending upon i) atrazine concentration and ii) the prior history of atrazine application to the soil in which the beads were buried. In beads buried in soil with a recent history of atrazine application, the abundance of Actinobacteria increased approximately 80 fold in beads containing 20 mg atrazine kg-1 of beads. In the beads from non-history soil, Actinobacteria were enriched by only 10 fold while the greatest enrichment was observed for the gamma-Proteobacteria and Planctomycetes which increased by 60 and 25 fold respectively. While a number of atrazine-degrading bacteria classified within the gamma-Proteobacteria have been isolated, no such bacteria have been described within the Planctomycetes. Very few cultivated representatives from this phylum have been reported but their apparent role in protein decomposition and anaerobic ammonia oxidation (Anammox reaction) has been documented. In enrichment cultures derived from soil incubated Bio-Sep beads, bacteria from this phylum were detected and we hypothesize that the growth of these bacteria in atrazine-degrading enrichment cultures is supported by oxidation of alkylamines released during the degradation of atrazine by other members of the consortia. Attempts to isolate these bacteria to date have been unsuccessful. At the higher atrazine concentration (200 mg atrazine kg-1 of beads) the gamma Proteobacteria were enriched by 120 and 230 fold in the beads buried in history and non-history soil, respectively. The alpha-Proteobacteria were enriched to a much lesser extent; 10 and 20 fold in the history and non-history beads, respectively. Interestingly, the relative enrichment of Actinobacteria and Planctomycetes that were observed at the lower atrazine concentration did not occur in beads containing the higher atrazine concentration of 200 mg atrazine kg-1 of beads. <br /> The results demonstrate that BioSep beads are a suitable matrix for recruiting a highly diverse subset of the bacterial community involved in atrazine degradation and have the potential for isolation of other novel soil bacteria with unique metabolic phenotypes such production of antibiotics, other pharmaceuticals, and commercially valuable enzymes.<br /> <br /> Objective 2: Integrate chemical and biological process information for use in models applicable across different spatial and temporal scales.<br /> <br /> Transport of selected endocrine disrupting chemicals from wastewater through a Hawaiian Oxisol - Additional experiments (beyond that reported in 2006) were conducted to examine the leachability of two estrogen hormones (17-beta estradiol and estrone) for three soils found on the island of Oahu. One of the three soils is an Oxisol and samples were collected from two depths: 0.6 m and 2.5 m. The second soil is a Mollisol and it was collected from similar depths. The third soil is volcanic cinder, which was collected from 0.3 m below ground. Batch sorption experiments were conducted for these two chemicals using (a) deionized water spiked with small amounts of CaCl2 to represent the salts leached out of the columns and (b) recycled water from a local animal waste lagoon. The two compounds adsorbed strongly to the Oxisol and Mollisol collected from both depths. However, they weakly adsorbed to volcanic cinder. In column tests, both physical and chemical nonequilibrium processes were found to affect the mobility of these chemicals. Transport of these compounds was enhanced with lagoon effluent due to the presence of dissolved organic carbon. <br /> <br /> Pathogen Transport in Hawaii Soils - We are studying the transport of two bacteria viruses (MS-2 and jX-174) in the same three soils described above. In general, the Oxisols and Mollisols are effective in attenuating the transport of these two bacteriaphages. However, in the Mollisol we found breakthroughs in less than 25 pore volumes when lagoon effluent was injected along with the phages. For cinder, breakthrough was quick. All transport experiments were conducted in saturated conditions with low-ionic strength buffers. Also, two specific organic buffers (TRIS  pH 8 and MES  pH 5.5) were tested to examine their effect on transport. In selected cases, TRIS produced breakthroughs of jX-174.<br /> <br /> Formation and fate of nitrosamines from pesticides and pharmaceuticals in environmental matrices and (under conditions of) the human digestive tract - In a related project (funded through the USDA-CSREES National Integrated Water Quality Program), we are developing index models to assess vulnerability to contamination from pesticide leaching and runoff based solely on landscape characteristics (landscape perspective) and on both landscape and pesticide properties (landscape and chemical perspective). Details were provided in the initial proposal. The emphasis of the past year has been on refining the landscape vulnerability model. We have introduced mathematical functions for all process variables into the model. The model is currently being applied to map landscape vulnerability to pesticide leaching, solution runoff, and particle adsorbed runoff in the four-county Blue River watershed at the Nebraska-Kansas border.<br /> <br /> Objective 3. Provide stakeholders with tools for developing strategies to ensure sustainable agriculture and to protect natural resource systems.<br /> <br /> Leaching of Selected Chemicals in Various Hawaii Soils - The State of Hawaii uses an ARC/GIS-based screening tool to assess leachability of a pesticide based upon soil physical/chemical properties, depth to water, recharge rate, and pesticide properties.<br /> Modeling aquifer recovery in response to the ban certain agricultural chemicals in Hawaii - DBCP and ethylene dibromide (EDB) were extensively used in 1960s and 1970s in Hawaiian pineapple. Unfortunately, this use has lead to widespread ground water contamination. DBCP was banned for use in Hawaii in 1978 and EDB was banned 5 years later. As of 2007, many of the contaminated wells show concentrations at their peak. We developed a set of linked models to estimate the concentrations as they moved through the vadose zone to the basal ground water. In the absence of measured data, various inverse methods were employed to estimate reasonable transport parameters for water and chemicals. We showed that the residual contamination can exist for several more decades although these chemicals were banned for use three decades ago.<br />

Publications

Accinelli, C., W. C. Koskinen, J. M. Becker, and M. J. Sadowsky. 2007. Environmental fate of two sulfonamide antimicrobial agents in soil. J. Agric. Food Chem. 55:2677-2682.<br /> <br /> Ahn M.-Y., A.R. Zimmerman, C. E. Martínez, D.D. Archibald, J.-M. Bollag, and J. Dec. 2007. Characteristics of Trametes villosa laccase adsorbed on aluminum hydroxide. Enzyme and Microbial Technology 41:141-148.<br /> <br /> Anhalt, J. C., T. B. Moorman, and W. C. Koskinen. 2007. Biodegradation of imidacloprid by an isolated soil microorganism. J. Environ. Sci. Health B, 42:509-514.<br /> <br /> Bench, S.R., T.E. Hanson, K.E. Williamson, D. Ghosh, M. Radosevich, K. Wang, and K. E. Wommack. 2007. Metagenomic Characterization of Chesapeake Bay Virioplankton. Appl. Environ. Microbiol. 73:7629-7641.<br /> <br /> Bialk, H.M.; Hedman, C.; Castillo, A.; Pedersen, J.A. Laccase-mediated Michael addition of 15N-sulfapyridine to a model humic constituent. Environ. Sci. Technol. 2007, 41, 3593-3600. doi: 10.1021/es0617338.<br /> <br /> Budd, R., S. Bondarenko, D. Haver, J. Kabashima, and J. Gan. 2007. Occurrence and bioavailability of pyrethroids in sediment in a mixed land use watershed. Journal of Environmental Quality 36: 1006-1012.<br /> <br /> Byappanahalli, M. N., R. L. Whitman, D. A. Shively, J. Ferguson, S. Ishii, and M. J. Sadowsky. 2007. Population structure of Cladophora-borne Escherichia coli in nearshore water of Lake Michigan. Water Res. 41:3649-3654. <br /> <br /> Cabrera, A., L. Cox, P. Velarde, W. C. Koskinen, and J. Cornejo. 2007. Fate of diuron and terbuthylazine in soils amended with two-phase olive oil mill waste. J. Agric. Food Chem. 55:4828-4834.<br /> <br /> Chang, W.-S., W. L. Franck, E. Cytryn, S. Jeong, T. Joshi, D. W. Emerich, M. J. Sadowsky, D. Xu, and G. Gary Stacey. 2007. An oligonucleotide microarray resource for transcriptional profiling of Bradyrhizobium japonicum. Molec. Plant Microbe Interact. 20:12981307. <br /> <br /> Chirnside, A.E.M., W.F. Ritter, and M. Radosevich. 2007. Isolation of a selected microbial consortium from a pesticide-contaminated mix-load site soil capable of degrading the herbicides atrazine and alachlor. Soil Biol. Biochem. 39:3056-3065.<br /> <br /> Cordova-Kreylos, AL and KM Scow, KM. 2007. Effects of ciprofloxacin on salt marsh sediment microbial communities. ISME J. 1:585-595 <br /> <br /> Cytryn, E..J., D. P. Sangurdekar, J. G. Streeter, W. L. Franck, W. S. Chang, G. Stacey, D. W. Emerich, T. Joshi, D. Xu, and M. J. Sadowsky. 2007. Transcriptional and physiological responses of Bradyrhizobium japonicum to desiccation-induced stress. J. Bacteriol. 189:6751-6762. <br /> <br /> Gadepalli, R.S., J. Rimoldi, F. Fronczek, M. Nillos, J. Gan, X. Deng, G. Rodriguez-Fuentes, and D. Schlenk. 2007. Synthesis of fenthion sulfoxide and fenoxon sulfoxide enantiomers: Effect of sulfur chirality on acetylcholinesterase activity. Chemical Research in Toxicology 20:257-262.<br /> <br /> Giraud E, Moulin L, Vallenet D, Barbe V, Cytryn E, Avarre JC, Jaubert M, Simon D, Cartieaux F, Prin Y, Bena G, Hannibal L, Fardoux J, Kojadinovic M, Vuillet L, Lajus A, Cruveiller S, Rouy Z, Mangenot S, Segurens B, Dossat C, Franck WL, Chang WS, Saunders E, Bruce D, Richardson P, Normand P, Dreyfus B, Pignol D, Stacey G, Emerich D, Vermeglio A, Medigue C, and M. J. Sadowsky. Legumes symbioses: absence of Nod genes in photosynthetic bradyrhizobia. Science 316:1307-1312.<br /> <br /> Govere E.M., M. Tonegawa, M.A. Bruns, E.F. Wheeler, K.B. Kephart, J. W. Voigt, and J. Dec. 2007. Using minced horseradish roots and peroxides for the deodorization of swine manure: A pilot scale study. Bioresource Technol. 98:11911198.<br /> <br /> Gu, C.; Karthikeyan, K.G.; Sibley, S.D.; Pedersen, J.A. Complexation of the antibiotic tetracycline with humic acid. Chemosphere 2007, 66, 1494-1501. doi: 10.1017/j.chemosphere.2006.08.028 <br /> <br /> Hristova, K. R., Schmidt, R., Chakicherla, A. Y., Legler, T. C., Wu, J., Chain, P. S., Scow, K. M., Kane, S. R. 2007. Comparative Transcriptome Analysis of Methylibium petroleiphilum PM1 Exposed to the Fuel Oxygenates Methyl tert-Butyl Ether and Ethanol. Appl. Environ. Microbiol. 73: 7347-7357<br /> <br /> Ishii, S., D. L. Hansen, R. E. Hicks, and M. J. Sadowsky. 2007. Beach sand and sediments are temporal sinks and sources of Escherichia coli in Lake Superior. Environ. Sci. Technol. 41:2203-2209.<br /> <br /> Ishii, S., K. P. Meyer, and M. J. Sadowsky. 2007. Relationship between Phylogenetic Groups, Genotypic Clusters, and Virulence Gene Profiles of Escherichia coli Strains Isolated from Diverse Human and Animal Sources. Appl. Environ. Microbiol. 73: 5703-5710.<br /> <br /> Kane SR, Chakicherla AY, Chain PS, Schmidt R, Shin MW, Legler TC, Scow KM, Larimer FW, Lucas SM, Richardson PM, Hristova KR. 2007. Whole-genome analysis of the methyl tert-butyl ether-degrading beta-proteobacterium Methylibium petroleiphilum PM1. J Bacteriol. 189:1931-45<br /> <br /> Ksoll, W, B., S. Ishii S, M. J. Sadowsky, and R. E. Hicks. 2007. Presence and sources of fecal coliform bacteria in epilithic periphyton communities of Lake Superior. Appl. Environ. Microbiol. 73:3771-3778.<br /> <br /> Lin, K.D., C. Xu, S.S. Zhou, W.P. Liu, and J. Gan. 2007. Enantiomeric separation of imidazolinone herbicides using chiral high performance liquid chromatography. Chirality 19: 171-178.<br /> <br /> Lin, K.D., F. Zhang, S.S. Zhou, W.P. Liu, and J. Gan. 2007. Stereoisomeric separation and toxicity of nematicide fosthiazate. Environmental Toxicology and Chemistry 26:2339-2344.<br /> <br /> Ma, X., P. J. Novak, J. Ferguson; M. J. Sadowsky, T. M. LaPara, M. J. Semmens , and R. M. Hozalski. 2007.The impact of H2 addition on dechlorinating microbial communities. Bioremed. J. 11:45-55.<br /> <br /> Mackay, D. M., N. R. de Sieyes, M. D. Einarson, K. P. Feris, A. A. Pappas, I. A. Wood, L. A Jacobson, L. G. Justice, M. N. Noske, J.T. Wilson, C. Adair, and K.M. Scow. 2007. Impact of Ethanol on the Natural Attenuation of MTBE in a Normally Sulfate-Reducing Aquifer. Environmental Science & Technology 41: 2015-2021.<br /> <br /> MacLean, A. M, T. M. Finan, and M. J. Sadowsky. 2007. Genomes of the symbiotic nitrogen-fixing bacteria of legumes. Plant Physiol. 144:615-622.<br /> <br /> Marek, L. J., and W. C. Koskinen. 2007. Multiresidue analysis of seven anticoagulant rodenticides by high-performance liquid chromatography/electrospray/mass spectrometry. J. Agric. Food Chem. 55:571-576.<br /> <br /> Nillos, M.G., G. Rodriguez-Fuentes, J. Gan, and D. Schlenk. 2007. Enantioselective acetylcholinesterase inhibition of the organophosphorus insecticides profenofos, fonofos and crotoxyphos. Environmental Toxicology and Chemistry 26: 1949-1954.<br /> <br /> Papiernik, S. K., Lindstrom, M. J., Schumacher, T. E., Schumacher, J. A., Malo, D. D. and Lobb, D. A. Characterization of soil profiles in a landscape affected by long-term tillage. Soil Tillage Res. 93:335-345. 2007.<br /> <br /> Papiernik, S. K., S. R. Yates, W. C. Koskinen, and B. L. Barber. 2007. Processes affecting the dissipation of the herbicide isoxaflutole and its diketonitrile metabolite in agricultural soils under field conditions. J Agric. Food Chem. 55:8630-8639.<br /> <br /> Papiernik, S. K., Yates, S. R., Koskinen, W. C., and Barber, B. Processes affecting the dissipation of the herbicide isoxaflutole and its diketonitrile metabolite in agricultural soils under field conditions. J. Agric. Food Chem. 55:8630-8639. 2007.<br /> <br /> Qin, S.J., and J. Gan. 2007. Abiotic enantiomerization of permethrin and cypermethrin: Effect of organic solvents. Journal of Agricultural and Food Chemistry 55:5734-5739.<br /> <br /> Rungvetvuthivitaya, M., C. Ray, R.E. Green. 2007. Post-audit Study of DBCP and EDB Contamination in the Pearl Harbor Aquifer, J. Hydrologic Engineering, 12(6): 549-558.<br /> <br /> Sakaliene, O., Papiernik, S. K., Koskinen, W. C. and Spokas, K. Sorption and predicted mobility of herbicides in Baltic soils. J. Environ. Sci. Health. 42:641-647. 2007.<br /> <br /> Sakaliene, O., S. K. Papiernik, W. C. Koskinen, and K. A. Spokas. 2007. Sorption and predicted mobility of herbicides in Baltic soils. J Environ. Sci. Health B. 42:641-647.<br /> <br /> Sander, M. and J.J. Pignatello, On the Reversibility of Sorption to Black Carbon: Distinguishing True Hysteresis from Artificial Hysteresis Caused by Dilution of a Competing Adsorbate, Environ. Sci. Technol., 41: 843-849 (2007).<br /> <br /> Seffernick, J. L., A. Aleem, J. P. Osborne, G. Johnson, M. J. Sadowsky, and L. P. Wackett. 2007. Hydroxyatrazine N-ethylaminohydrolase (AtzB): An amidohydrolase superfamily enzyme catalyzing deamination and dechlorination. J. Bacteriol. 189: 6989-6997.<br /> <br /> Shapir, N., E. F. Mongodin, M. J. Sadowsky, S. C. Daugherty, K. E. Nelson, and L. P. Wackett. 2007. Evolution of catabolic pathways: genomic insights into microbial s-triazine metabolism. J. Bacteriol.189:674-682.<br /> <br /> Son, A., Dosev, D., Nichkovac, M., Mab, Z., Kennedy, I., Scow, K., and Hristova, K. 2007. Quantitative DNA hybridization in solution using magnetic/luminescent core-shell nanoparticles. Anal. Biochem. 370: 186-194 <br /> <br /> Spokas, K. A., King, J., Wang, D., and Papiernik, S. K. Effects of soil fumigants on methanotrophic activity. Atmos. Environ. 41:8150-8162. 2007.<br /> Stenemo, F., C. Ray, R.S. Yost, and S.Y. Matsuda. 2007. An updated tool for groundwater vulnerability assessment of pesticide leaching for the islands of Hawaii, USA, Pesticide Management Science), 63(4): 404-411.<br /> <br /> Wang, H.Y., Q.F. Ye, J. Gan, and L.C. Wu. 2007. Biodegradation of Cry 1Ab protein from Bt transgenic rice in aerobic and flooded paddy soils. Journal of Agricultural and Food Chemistry 55:1900-1904.<br /> <br /> Wang, L.M., W.P. Liu, C.X. Yang, Z.Y. Pan, J. Gan, C. Xu, M.R. Zhao, and D. Schlenk. 2007. Enantioselectivity in endocrine disruption potential and uptake of bifenthrin. Environmental Science and Technology 41:6124-6128.<br /> <br /> Williamson, K.E., M. Radosevich, D.W. Smith and K.E. Wommack. 2007. Incidence of lysogeny within temperate and extreme soil environments. Environ. Microbiol. 9:2563-2574.<br /> <br /> Wong, T.P., C. Ray, M. Byappanahalli, and B. Yoneyama. 2007. An evaluation of the mobility of pathogen indicators, Escherichia coli and bacteriophage MS-2, in a highly weathered tropical soil under unsaturated conditions, Int. Journal of Water and Health, 6: 131-140. <br /> <br /> Yang, W.C., J. Gan, W. Hunter, and F. Spurlock. 2007. Bioavailability of permethrin and cyfluthrin in surface waters with low levels of dissolved organic matter. Journal of Environmental Quality 36:1678-1685<br /> <br /> Yan, T., and M. J. Sadowsky. 2007. Determining sources of fecal bacteria in waterways. Environ. Monit. Assess. 129:97-106<br /> <br /> Yan, T., M. Hamilton, and M. J. Sadowsky. 2007. High throughput and quantitative procedure for determining sources of Escherichia coli in waterways using host-specific DNA marker genes. Appl. Environ. Microbiol. 73:890896.<br /> <br /> Zheng, W., Gan, J., Papiernik, S. K., and Yates, S. R. Identification of volatile/semivolatile products derived from chemical remediation of cis-1,3-dichloropropene by thiosulfate. Environ. Sci. Technol. 41:6454-6459. 2007.<br />

Impact Statements

1. A study was carried out at the USDA-ARS US Arid Land Agricultural Research Center to evaluate a treatment wetland for its ability to remove carbamazepine from treated wastewater leaving a sewer treatment plant. Very little carbamazepine removal is occurring within the wetland but there is a potential for carbamazepine to be removed within the wetland by sorption followed by sedimentation as well as photodegradation.
2. Organic rich wetland sediments from a vegetated wetland had the ability to remove carbamazepine from water. These results offer a management strategy for reducing pharmaceuticals in reclaimed water, and suggest that constructed treatment wetlands should be designed with ample vegetation, shallow water, and a large sediment surface area to maximize contact between reclaimed water and sediment.
3. Chemical incorporation of sulfonamide antimicrobials into organic matter is expected to decrease their mobility and bioaccessibility, and provides an explanation for previous reports of apparent non-extractable residue formation. Our results suggest that sulfonamide antimicrobials may form Michael adducts with quinone-like moieties in organic matter in addition to the Schiff bases previously reported.
4. The strong interaction between tetracycline and humic substances is expected to significantly influence the reactivity, mobility and bioavailability of this antimicrobial compound in soils and subsurface environments. Sorption is affected by pH, I and the presence of polyvalent metal cations. The results obtained in this study may be useful in assessing the sorption behavior of other tetracycline compounds.
5. Ciprofloxacin is capable of modifying microbial community composition at concentrations as low as 20 ug ml-1 in anaerobic sediments. Based on analysis of biomarkers, Gram negative bacteria, including Desulfovibrio, Desulfobulbus and Desulfobacter, appeared more resilient to the effects of ciprofloxacin than did Gram positive bacteria;concentration actually available to microorganisms was likely even lower due to substantial sorption to sediments (an estimated 80-90% sorbed).

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Report Information

Participants

Clinton Williams (USDA-ARS, Arizona);Michael Sadowsky (University of Minnesota);Jack Watson (Pennsylvania State University);Michael L. Thompson (Iowa State University);Thomas Borch (Colorado State University);Patrick Shea (University of Nebraska  Lincoln);Joe Pignatello (Connecticut Experiment Station);Bill Koskinen (USDA-ARS, St. Paul, MN);Jay Gan (UC Riverside);Ron Turco (Purdue University);Scott Yates (USDA-ARS, Riverside, CA);Yucheng Feng (Auburn University);Lance Schideman (University of Illinois);Shad Nelson (Texas A&M, Kingsville);Walter Farmer (UC Riverside)

Brief Summary of Minutes

The 2008 meeting of W-1082 Evaluating the Physical and Biological Availability of Pesticides and Pharmaceuticals in Agricultural Contexts was held on January 8 and 9, 2008 in Riverside, CA hosted by Jay Gan. Lee Sommers (Administrative Advisor) was unable to attend. Nancy Cavallaro (USDA-CSREES) sent a Powerpoint presentation. The meeting included presentations of research reports by all participants. Jack Watson served as Secretary and Clinton Williams served as Chair of the committee. It was determined by consensus of the attending members that next years meeting would be hosted by Clinton Williams at USDA-Maricopa, Az in October 2009, for the development of the new project proposal.

Accomplishments

Objective 1<br /> To identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment.<br /> <br /> USDA-ARS-Maricopa, Az<br /> Laboratory sorption experiments were conducted to determine the extent to which soil organic matter derived from guayule residues can affect the sorption of pendimethalin. Soils where guayule had been grown for 0 to 38 months were collected for sorption experiments from beneath actively growing plants. An additional treatment was collected prior to planting cotton in a field one year after the final harvest of guayule that had been grown for 36 months was also included. Continuous guayule cultivation resulted in a modest increase in soil organic carbon from 0.29% (±0.01%) to 0.76% (±0.03%) after 38 months of production. Pendimethalin sorption to the soil increased with increasing guayule organic deposition as measured by time under cultivation. Soils where guayule was grown for 38 months had a KOC 23 times greater than the control soil where guayule had not been grown (389,400 vs 16,900 L kg-1). However, in the treatment prior to planting cotton the combination of time and cultivation resulted in a reduction of KOC from 389,400 to 21,500 L kg-1. The use of pendimethalin in a guayule - cotton rotation requires sufficient time and primary tillage prior to planting cotton. In addition, the use of pendimethalin during re-growth of guayule from the stump following harvest may require higher application rates to control weeds. Adsorption of pendimethalin to soil using batch equilibrium indicated that soil beneath actively growing guayule has a higher sorption capacity for pendimethalin than soil without guayule.<br /> <br /> USDA-ARS - Morris, MN<br /> In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. One approach to remediate these eroded landforms is moving soil from areas of topsoil accumulation to areas of topsoil depletion, termed here soil-landscape rehabilitation. Rehabilitation resulted in an increase in grain yield of 63-65% in the upper backslope. Results indicate that addition of accumulated topsoil from lower slope positions to eroded upper slope positions can result in large yield increases in upper slope positions and more consistency in crop yields across the landscape. Information regarding the impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides is critical to the development of improved pesticide management practices. We quantified the rate of S-metolachlor dissipation in an eroded landform following application in the fall and in the spring. Despite large differences in soil properties, the rate of metolachlor dissipation from the top 1 m was essentially the same at all landscape positions. The results of this research suggest that fall-applied metolachlor may not provide economic weed control and presents an increased risk of water contamination; therefore, metolachlor should not be applied in the fall in the northern Corn Belt. Information regarding pesticide mobility is critical for the evaluation of pesticide management practices. We used repacked field lysimeters to evaluate the leaching and plant uptake of the herbicides pendimethalin, clopyralid, mecoprop (MCPP), and dicamba following fall and spring application to soil cropped to winter rye (Secale cereale L.). In most fall and spring trials, mass loss of herbicide through leaching was <3% of the amount applied. Based on this 6-year experiment, it appears that clopyralid is the most mobile of the tested herbicides in this soil, followed by dicamba, mecoprop, and pendimethalin. None of the herbicides was present in rye grain or straw at concentrations that exceed current EU or US tolerances. <br /> <br /> Colorado State University<br /> The presence of steroid hormones in Colorados Cache la Poudre River water is being investigated by solid-phase extraction, derivatization, and gas chromatographytandem mass spectrometry (GC-MS/MS). Rainfall simulations were also conducted on an agricultural field applied with municipal biosolids to investigate the potential for steroid hormone runoff and leaching. Laboratory experiments also are being conducted to investigate the potential for steroid hormone biodegradation and photodegradation under simulated natural conditions. Estrogens and androgens were observed at multiple sites along the river. Preliminary data from our rainfall simulation study shows significant concentrations of estrogens, androgens and progestins in the runoff. Androgens and progesterone were found to a larger extent in the runoff than estrogens. Biodegradation of 17²-estradiol, testosterone and progesterone by manure-borne microorganisms in pig manure was observed and multiple degradation products were detected by liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS). Using UV-A lamps direct photodegradation of testosterone and progesterone was observed, and indirect photodegradation of testosterone and 17²-estradiol was observed in the presence of 5 mg/L humic acid. Several novel photodegradation products were observed by mass spectrometry. These findings suggest that steroid hormones are present in the Cache la Poudre River of Colorado, and have the potential to undergo biodegradation and photodegradation. In addition, humic acid (acting as a photosensitizer) can facilitate the indirect photodegradation of some steroid hormones. Finally, our preliminary data shows that steroid hormones have the potential to runoff from agricultural fields applied with biosolids during a heavy rainfall event. <br /> <br /> Iowa State University<br /> Understanding sorption mechanisms and processes is critical for predicting the fate of organic pollutants in soils and for development of effective remediation strategies for contaminated soils. Of particular interest is how organic compounds interact with mineral surfaces that are physically organized with one another in different ways depending on the type of saturating cation and the water content of the system. A novel suspension x-ray diffraction (XRD) technique used to elucidate the influence of the size and swelling of K- and Ca-smectite quasicrystals in aqueous suspensions on adsorption of 4,6-dinitro-o-cresol (DNOC). XRD analysis is a valuable tool for gaining insight into interactions between smectites and organic molecules, but caution must be used in extrapolating data based on XRD patterns of air-dried and oven-dried smectite films to processes that may occur in aqueous smectite suspensions. The fate of organic contaminants in soils and sediments is influenced by sorption of the compounds surfaces of soil materials. The interactions among sorption of an organic compound, cation exchange reactions, and both the size and swelling of smectite quasicrystals were investigated. Results suggest that interactions among cation exchange and organic sorption reactions are controlled by an inherently hysteretic feedback process that is regulated by changes in the size and extent of swelling of smectite quasicrystals. The estrogenic hormones, e.g., 17²-estradiol (E2) and estrone (E1), are regarded as some of the most potent of natural endocrine-disrupting compounds (EDC). At levels of a few ng L-1, E2 and E1 can interfere with normal sexual development in some aquatic species. Both E2 and E1 have been added to soil through livestock waste from concentrated animal feeding operations. However, the fate and transport of these compounds in soils are not easily predicted, partly as a result of analytical challenges at low environmental concentrations and because of weak understandings of adsorption mechanisms at the water-soil interface. The comparisons of sorption parameters (n, Kd, and Koc) over the range of concentrations studied, demonstrate the essentially empirical nature of the models used to assess the interactions of hydrophobic solutes like estrogens and solid-phase sorbents like soil. It is possible to over-interpret the significance of sorption parameters, since they can depend on the concentration range explored and how the sorption reactions themselves affect concomitant reactions such as precipitation or condensation of sorbate molecules. <br /> <br /> South Dakota State University<br /> The runoff potential of tylosin and chlortetracycline from soils was assessed from soils treated with manure from swine fed rations containing the highest labeled rate of each chemical. Slurry manures from the swine contained either chlortetracycline (CTC) at 108 ¼g/g or tylosin at 0.3 ¼g/g. These manures were surface applied to clay loam, silty clay loam, and silt loam soils at a rate of 0.22 Mg/ha. The total amount of CTC collected ranged from 0.9 to 3.5% of the amount applied whereas tylosin ranged from 8.4 to 12%. These data indicate that if surface applied manure contains antimicrobials, runoff could lead to offsite contamination. The data from this study in combination with data from other studies indicate that manure from animals treated with antimicrobial chemicals should be handled carefully. While leaching of these antimicrobial chemicals into and through the soil profile may be limited, their movement in runoff to offsite areas may be an unintended consequence of manure application. Additional studies using manure from swine fed rations with and without CTC and biosolids with and without tetracycline (TET) changed soil microbial diversity and community structure with changes observed out to 42 DAT. The changes observed, in turn, may lead to changes in microbial function. A third study investigated the effects of the two universally administered animal feed additives, tylosin and chlorotetracycline (CTC), during batch anaerobic swine manure digestion. Both compounds are poorly absorbed within the swine intestines and consequently, these compounds and bioactive metabolites are excreted. Data suggested that swine manure from pigs administered CTC containing feed will take longer to stabilize under anaerobic conditions compared to tylosin or no-antimicrobial treatments. Residual concentrations of CTC are a concern when considering that land application of stabilized manure into the environment is common practice, and may subsequently result in potential dissemination of antimicrobial compounds or antimicrobial-resistant bacteria into the environment. <br /> <br /> Auburn University<br /> There have been increasing concerns regarding antimicrobials in the environment. Sorption of two antimicrobials, sulfadimethoxine (SDM) and ormetoprim (OMP), was investigated in two soils and sand using a series of batch experiments. Currently, limited research exists on the fate of these compounds once they are discharged in human and animal waste. This study showed relatively low sorption of SDM and OMP in two southeastern U.S. soils, suggesting the potential for these compounds to reach surface and ground water. Recent studies have found widespread occurrence of anthropogenic organic compounds in the surface waters in the U.S. Most of these compounds are present at low concentrations and the risks to human and ecosystem health are largely unknown, especially for mixtures of compounds. Catoma Creek is on Alabamas 303(d) list due to organic enrichment and high fecal coliform concentrations. Occurrence of five anthropogenic compounds was monitored for a six-month period in this mixed landuse watershed. Water samples were collected monthly at six sampling sites and analyzed for caffeine, 1,7-dimethylxanthine, acetaminophen, sulfamethoxazole, and DEET (N, N-diethyl-m-toluamide) using LC/MS/MS. All five target compounds were detected in the watershed with DEET, caffeine, and sulfamethoxazole being detected more frequently. One of the six sampling sites was located in an urban area and more target compounds at higher concentrations were found at this site. DEET was detected in all blank samples at an average concentration of 8.7 ng/L.<br /> <br /> Penn State University<br /> Most of the previously reported saturated column experiments conducted to determine sorption of organic chemicals to soil have utilized glass columns, which adsorb very little estrone. However, due to the fragile nature of such glass columns, it is very difficult to connect any additional instruments to measure parameters such as water content and potential. Since these measurements are essential in unsaturated column experiments, an alternative column material was required. A brief sorption test was conducted using 3H-estrone and several different column materials. The materials that were tested included PVC, polycarbonate, type 316 stainless steel, type 302 stainless steel, Teflon, and glass. Polycarbonate, PVC and both types of stainless steel apparently adsorbed estrone. Based on these results, teflon was chosen as the column material for unsaturated column experiments.<br /> <br /> Connecticut AES<br /> Hysteresis, a frequently observed phenomenon in sorption experiments, is inconsistent with the key assumption of sorption reversibility in most fate and bioavailability models. This study of hysteresis has several important implications for the environmental behavior of organic compounds. The results confirm and broaden our previous findings that sorption hysteresis in natural organic matter can be due to creation of long-lifetime metastable states that arise in response to sorbate loading. We have shown that "irreversible" effects are similar for nonpolar aromatic molecules of comparable size; that they depend on concentration; and that this concentration dependence depends on sorbent properties. The results have important implications for modeling solute transport and bioavailability of pollutants because existing models are based on sorption reversibility. The finding that matrix deformation influences uptake and release rates suggests a role for relaxation kinetics in transport models.<br /> <br /> University of Wisconson<br /> Recent research indicates the rapid formation of non-extractable sulfonamide residues and the long-term persistence of these polar antimicrobial agents. Chemical incorporation of sulfonamide antimicrobials into Natural Organic Matter (NOM) may provide an explanation for these reports of apparent non-extractable residue formation. Our results suggest that Michael adduct formation with quinone-like moieties in NOM is likely a more important process for sulfonamide antimicrobial immobilization than are reactions producing Schiff bases. This finding has implications for the environmental stability of bound sulfonamide residues. Bound residues formed by Michael addition reactions are more likely to persist in soil than those formed by Schiff base reactions (e.g., imines); the latter are more easily hydrolyzed in aqueous solution. Reports of non-extractable sulfonamide residues in soil may therefore reflect Michael addition to quinone moieties in soil NOM. The importance of covalent coupling of sulfonamides with NOM vis-à-vis other potential mechanism of non-extractable residue formation warrants investigation. Chemical incorporation of sulfonamide antimicrobials into soil organic matter is expected to diminish their biological activity, and therefore reduce the selective pressure of these compounds for antimicrobial resistant microorganisms. <br /> The association of the cationic macrolide antimicrobial clarithromycin (CLA) with dissolved Elliot soil humic acid (ESHA) was investigated as a function of solution chemistry. Despite its low Kow value, CLA+ association with ESHA is similar in magnitude to the binding of many nonpolar organic contaminants (e.g., anthracene, pyrene) with other humic acids. Association of CLA+ (and similar macrolides) with humic acids may afford the antimicrobial(s) protection from degradation processes and reduce bioaccessibility to microorganisms, diminishing potential selective pressure for antibiotic resistant organisms. Association with humic acid may increase the total dissolved concentration of CLA+ in soil and sediment interstitial water, potentially facilitating subsurface transport, and reduces the freely dissolved CLA+ concentration which controls interactions with solid phases and bioavailability. These findings can be extended to complex environmental matrices and soils, while the ability of particulate-bound humic substances to interact with macrolides requires investigation.<br /> <br /> University of California-Riverside<br /> Many pesticides contain stereogenic chiral centers and therefore optical isomers that may have different biological activities or different behaviors (e.g., persistence) in the environment. However, currently chiral pesticides are mostly used as racemates and the chiral selectivity is ignored in risk assessment. Our studies showed that great differences exist in aquatic toxicities as well as biodegradation rates among chiral insecticides and these differences should be considered in risk assessment and regulation.<br /> <br /> Univeristy of California-Davis<br /> Triclosan (TCS) and Triclocarban (TCC) are broad range antibacterial agents widely used in common household products (i.e. shampoo, soap, detergent, toothpaste, cosmetics, sanitizers, etc). Recent research has identified TCS in soil, fish tissue, and human breast milk and has caused the American Medical Association (AMA) to question the necessity and effectiveness of TCS and other antibacterial agents in personal care products. All available evidence suggests that TCS and TCC are likely to accumulate in soils that are amended with biosolids. Preliminary experiments were performed to explore the potential effects on TCS and TCC on soil microbial communities, using phospholipid fatty acid (PLFA) analysis as a screening method. Biomass decreased in both TCS and TCC treatments in comparison to the controls. The decrease of biomass was higher at 100-ug/g TCS and TCC treatments than at 10-ug/g treatments. At low exposures to TCC, the community was no different from an unexposed community, whereas even low exposure to TCS substantially altered the community composition. At higher exposures, both compounds affected the community and the responses were quite variable. In conclusion, the more strongly sorbedTCC had less of an impact than the more water soluble TCS, perhaps due to differences in availability or toxicity. Fungal biomarkers remained unchanged, but abundance of monounsaturated fatty acids decreased in antimicrobial treated soils. Thus this initial characterization of effects demonstrated that significant changes in microbial community could be expected in agricultural soils at concentrations as low as 10-ug/g of TCS and that there may be differences in the impacts of the two antimicrobial compounds.<br /> <br /> Univiersity of Nebraska-Lincoln<br /> Experimental evidence was obtained supporting the formation of nitrosamine derivatives of atrazine (ATR), cyanazine (CYA), simazine (SIM), and desisopropylatrazine (DIA) from reaction with sodium nitrite under acidic aqueous conditions. Optimum temperature programs were also developed for GC-MS analysis of nitrosoatrazine, nitrosocyanazine, nitrososimazine and nitrosodesisopropylatrazine. Although maintaining thermal stability during analysis was a concern, the GC-MS method provides an alternative means of detecting nitrosotriazines. Soil sorption data was obtained for atrazine and nitrosoatrazine. KD values for atrazine and nitrosoatrazine adsorption were 2.5 and 5.4 L/kg. Desorption KDs were 10.0 and 16.7 L/kg, respectively. Based on a soil organic carbon content of 2%, the corresponding Koc values are 125 and 270. These results indicate that the soil retention of nitrosoatrazine is similar to or slightly greater than atrazine. Results of recovery studies of nitrosomorpholine and nitrosoatrazine demonstrated recoveries decreased with increasing soil incubation time. Recoveries after 35 d were 60 and 80%, respectively. Results indicated considerable stability of these nitrosamines in soil. The presence of vitamins B-12 and B-9 resulted in a 50 and 30% reduction in the amount of nitrosoranitidine formed under simulated digestive tract conditions. Vitamins B-12 and B-9 resulted in a 60 and 20% reduction in the amount of nitrosoethambutol formed. The presence and denitrosation of nitrosated compounds in egg yolk may affect the nitric oxide (NO) content within cells, which is critical for normal development. <br /> <br /> USDA-ARS, St. Paul and University of Minnesota<br /> An extraction procedure was identified using aqueous methanol (a water/alcohol mixture) that can characterize triazine herbicide bioavailability in dissimilar aged soils, which in turn may be useful to determine bioavailability of other compounds in soils, especially other related herbicides. Scientists now have a relatively easy and inexpensive technique to determine the amounts of one class of pesticides, triazines, available for transport, plant uptake, and microbial degradation, particularly in aged soils. This is valuable information for predicting environmental fate and environmental risk assessment.<br /> <br /> University of California-Berkley<br /> Antibiotics were developed to have specific mechanisms of action for well-defined therapeutic purposes, when these compounds are released into the environment they can exhibit unpredicted toxic effects on endogenous soil bacteria and sensitive aquatic organisms. Fluoroquinolone (FQ) antibiotics, exhibit a broad spectrum of activity towards pathogenic bacteria and are widely used in both human and veterinary medicine. They are now detected in surface waters worldwide at concentrations up to 150 ¼M. FQs and related compounds have been shown to affect the growth or species diversity of photosynthetic organisms, including higher plants, phytoplankton, and cyanobacteria. One study reported here appears to be the first to reveal that chloroplasts of photosynthetic organisms are also the inhibitory target of a fluorinated quinolone, ciprofloxacin (Cipro). The results indicated significant reductions in plant growth and development, as well as inhibition of Photosystem II, both of which imply that the antibiotic may deter chloroplast replication by a mechanism related to its antibacterial action and that it may interfere with photosynthetic electron transport.<br /> <br /> Objective 2<br /> Integrate chemical and biological process information for use in models applicable across different spatial and temporal scales.<br /> <br /> Incorporating slope and slope length data generated from relatively high resolution 10 m digital elevation models (DEMs), increased sensitivity to topography at the SSURGO polygon level. Although discontinuities occur between counties, model output can identify the most vulnerable areas in each county. The results enhance the ability to correctly identify landscape areas vulnerable to pesticide leaching and runoff in spite of county soil map interpretation differences. Results aid pesticide applicators and environmental managers identify areas most sensitive to surface and ground water contamination so that management practices can be properly targeted to minimize contamination. <br /> <br /> Objective 3<br /> Provide stakeholders with tools for developing strategies to ensure sustainable agriculture and to protect natural resource systems.<br /> <br /> Univeristy of California-Riverside<br /> Pesticide residues remain on concrete and are available for contaminating runoff for a prolonged time, and the long persistence may be an important cause for non-point source contamination of pesticides in urban watersheds. Clientele (including commercial nurseries in southern California, pesticide applicators, the Regional Water Quality Control Boards, State regulatory agencies - Department of Pesticide Regulation and Department of Food and Agriculture, and county/city water quality managers) may use the research results to implement pesticide TMDLs, and improve water quality in impaired waterbodies in urban and suburban watersheds.<br /> <br /> University of Nebraska-Lincoln<br /> Analysis of survey data revealed significant positive relationships between the use of conservation tillage and instrumental motivation, internal self-concept, and goal internalization, as well as education, farm sales, and percent of income derived from farming. Significant negative relationships were found between conservation tillage and an external self-concept, age, and years of farming. Farmers who believe they cannot maintain autonomous control over farming practices when using conservation tillage are less likely to use the technology. Habitual tendencies are large drivers in conservation tillage adoption decisions. Preferences for control impact the conservation tillage intensity decision. These findings support the idea that an intricate mix of financial incentives and moral suasion may be required to convince farmers to incorporate conservation tillage strategies on working farms.<br />

Publications

Accinelli, C., W. C. Koskinen, J. M. Becker, and M. J. Sadowsky. Mineralization of the Bacillus thuringiensis Cry1Ac endotoxin in Soil. J. Agric. Food Chem. 56:1025-1028. 2008.<br /> <br /> <br /> Anhalt, J. C., T. B. Moorman, and W. C. Koskinen. Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils. J. Environ. Sci. Health B. 43:207-213. 2008.<br /> <br /> Aristilde, L., and Sposito, G. (2008) Molecular modeling of metal complexation by a fluoroquinolone antibiotic. Environ. Toxicol. Chem. 27:2304-2310.<br /> <br /> <br /> Bialk, H.M.; Pedersen, J.A. NMR investigation of enzymatic coupling of sulfonamide antimicrobials with humic substances. Environ. Sci. Technol. 2008, 42, 106-112.<br /> <br /> <br /> Cabrera , A., L. Cox, W. C. Koskinen, and M. J. Sadowsky. Availability of triazine herbicides in aged soils amended with olive oil mill waste. J. Agric. Food Chem. 56:4112-4119. 2008.<br /> <br /> <br /> Chatterjee, R., D.A. Laird, and M.L. Thompson. 2008. Interactions among K+-Ca2+ exchange, sorption of m-dinitrobenzene, and smectite quasicrystal dynamics. Environ. Sci. Technol. 42:9099-9103.<br /> <br /> <br /> Coffelt, T.A. and C.F. Williams. Characterization and recycling of waste water from guayule latex extraction. Industrial Crops Prod. 29:648-653. 2009.<br /> <br /> <br /> Devlin, D. et al. (P.J. Shea). 2008. Pesticide Management for Water Quality Protection in the Midwest. Heartland Regional Water Coordination Initiative. Kansas State University, Manhattan, KS. (http://www.oznet.ksu.edu/library/h20ql2/mf2822.pdf) <br /> <br /> Farenhorst, A., Papiernik, S. K., Saiyed, I., Messing, P., Stephens, K. D., Schumacher, J. A., Lobb, D. A., Sheng, L., Lindstrom, M. J., and Schumacher, T. E. Herbicide sorption coefficients in relation to soil properties and terrain attributes on a cultivated prairie. J. Environ. Qual. 37:1201-1208. 2008.<br /> <br /> Feng, Y. 2008. Soil microbiology. In: Encyclopedia of Soil Science, W. Chesworth (ed). Springer Publishing Company, New York, NY. <br /> <br /> Koskinen, W. C., and P. A. Banks. Soil movement and environmental fate of triazine herbicides. p. 355-385. In H. M. LeBaron, O. C. Burnside, and J. McFarland (eds.) The Triazine Herbicides. Elsevier Science, Amsterdam, The Netherlands. 2008. (Book Chapter)<br /> <br /> Laird. D. A., and W. C. Koskinen. Triazine soil interactions. p. 275-299. In H. M. LeBaron, O. C. Burnside, and J. McFarland (eds.) The Triazine Herbicides. Elsevier Science, Amsterdam, The Netherlands. 2008. (Book Chapter)<br /> <br /> Papiernik, S. K., Schumacher, T. E., Lobb, D. A., Lindstrom, M. J., Lieser, M. L., Eynard, A., and Schumacher, J. A. Soil properties and productivity as affected by topsoil movement within an eroded landform. Soil Tillage Res. 102:67-77. 2009.<br /> <br /> Pereira, T.R., D.A. Laird, M.L. Thompson, C.T. Johnston, B.J. Teppen, H. Li, and S.A. Boyd. 2008. Role of smectite quasicrystal dynamics in adsorption of dinitrophenol. Soil Sci. Soc. Am. J. 72:347-354.<br /> <br /> Reiman, M., D.E. Clay, C.G. Carlson, S.A. Clay, G. Reicks, D.W. Clay, and D.E. Humburg. 2009. Manure placement depth impacts on crop yields and N retained in soil. J. Envrion. Sci. Health (B). 44:76-85.<br /> <br /> Regitano, J. B. and W. C. Koskinen. Characterization of nicosulfuron availability in aged soils. J. Agric. Food Chem. 56:5801-5806. 2008.<br /> <br /> Sakaliene, O., Papiernik, S. K., Koskinen, W. C., Kavoliknaite, I., and Brazenaitei, J. Using lysimeters to evaluate the relative mobility and plant uptake of four herbicides in a rye production system. J. Agric. Food Chem. Accepted Dec. 18, 2008.<br /> <br /> Sakaliene, O., S. A. Clay, W. C. Koskinen, and G. Almantas. Early Season Weed suppression in buckwheat using clopyralid. Weed Tech. 22:707-712. 2008. <br /> <br /> Sakaliene, O., W. C. Koskinen, G. Blazauskiene, and I. Petroviene. Level and fate of chlorpropham in potatoes during storage and processing. J. Environ. Sci. Health B. 44:1-6. 2009. <br /> <br /> Sanders, S.M., P. Srivastava, Y. Feng, J.H. Dane, J. Basile, and M.O. Barnett. 2008. Sorption of the veterinary antimicrobials sulfadimethoxine and ormetoprim in soil. J. Environ. Qual. 37:1510-1518.<br /> <br /> Sheng, L., Lobb, D. A., Lindstrom, M. J., Papiernik, S. K., and Farenhorst, A. Modeling tillage-induced redistribution of soil mass and its constituents within different landscapes. Soil Sci. Soc. Am. J. 72:167-179. 2008.<br /> <br /> Sibley, S.D.; Pedersen, J.A. Interaction of the macrolide antimicrobial clarithromycin with disolved humic acid. Environ. Sci. Technol. 2008, 42, 422-428.<br /> <br /> Walker, C., and H. Lin. 2008. Soil property changes after four decades of wastewater irrigation: A landscape perspective. Catena 73:63-74<br /> <br /> Wortmann, C.S. et al. (P.J. Shea). 2008. Targeting of Watershed Management Practices for Water Quality Protection. Heartland Regional Water Coordination Initiative. University of Nebraska-Lincoln, Lincoln, NE. (http://www.ianrpubs.unl.edu/epublic/live/rp195/build/rp195.pdf).<br /> <br /> Xie, B., S.K. Khanal, J. van Leeuwen, S.W. Veysey, and M.L. Thompson. 2008. Sorption of steroidal hormones by two Iowa soil materials: Detection and modeling. Soil Sci. 173:602-612.<br /> <br /> Zheng, W., Yates, S. R., and Papiernik, S. K. Transformation kinetics and mechanism of the sulfonylurea herbicides pyrazosulfuron ethyl and halosulfuron methyl in aqueous solutions. J. Agric. Food Chem. 56:7367-7372. 2008.<br /> <br />

Impact Statements

1. Incorporating slope and slope length data generated from relatively high resolution 10 m digital elevation models (DEMs), increased sensitivity to topography at the SSURGO polygon level. Although discontinuities occur between counties, model output can identify the most vulnerable areas in each county. The results enhance the ability to correctly identify landscape areas vulnerable to pesticide leaching and runoff in spite of county soil map interpretation differences.
2. Pesticide residues remain on concrete and are available for contaminating runoff for a prolonged time, and the long persistence may be an important cause for non-point source contamination of pesticides in urban watersheds. The research results improve the ability to implement pesticide TMDLs, and improve water quality in impaired waterbodies in urban and suburban watersheds.
3. Great differences exist in aquatic toxicities as well as biodegradation rates among chiral insecticides and these differences should be considered in risk assessment and regulation.

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Report Information

Participants

Clinton Williams (USDA-ARS, Arizona); Jack Watson (Pennsylvania State University); Patrick Shea (Univ of Nebraska- Lincoln); Bill Koskinen (USDA-ARS, St. Paul, MN); Ron Turco (Purdue University); Sharon Clay (South Dakota State University); Lee Sommers(Colorado State University)

Brief Summary of Minutes

The 2009 meeting of W-1082, 'Evaluating the Physical and Biological Availability of Pesticides and Pharmaceuticals in Agricultural Contexts' was held on November 12 and 13, 2009 in Chandler, AZ hosted by Clinton Williams. Lee Sommers (Administrative Advisor) was available by conference call. The meeting included presentations of research reports by all participants. Jack Watson served as Secretary and Clinton Williams served as Chair of the committee. Joe Pignatello was elected (in absentia) to serve as Secretary for the next two years. It was determined by consensus of the attending members that next year's meeting would be hosted by Chitteranjan Ray at the University of Hawaii - Manoa Campus in January 2011.

Accomplishments

Objective 1: To identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment.<br /> <br /> Alabama: Stabilized iron oxide nanoparticles have potential for in-situ environmental remediation. However, little is known regarding the impact of these nanoparticles on soil microorganisms. This study aimed to investigate the effects of Fe3O4 nanoparticles on four pure cultures of bacteria, i.e., Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Enterococcus faecalis. The effect of commercial and lab-prepared Fe3O4 nanoparticles was examined through growth experiments and observation of cell-nanoparticle interactions. The results show that Fe3O4 nanoparticles at concentrations of 0.3, 0.6, and 1.0 g Fe/L were neither toxic nor inhibitory to the four organisms tested. In some cases, growth stimulation was observed. After the addition of culture to nanoparticle suspensions, there was a loss of particle stability manifested by the formation of large aggregates. Scanning electron microscopy was performed on the aggregates formed in E. coli culture to examine the cell-nanoparticle interactions. Nanoparticles were found to cover cell surfaces and bridge cells together in clusters, but no damage to cell integrity was observed. E. coli cells blanketed by nanoparticles retained the shape of healthy cells. Aggregates formed in the presence of bacteria consisted of nanoparticles and bacterial cells held in the nanoparticle matrix. The results suggest that stabilized nanoparticles may interact with bacterial surfaces without causing damage sufficient to inhibit cell growth.<br /> Arizona: Guayule is the only commercial source of domestic latex currently available in the US. Laboratory sorption experiments were conducted to determine the extent to which soil organic matter derived from guayule residues can affect the sorption of pendimethalin. Soils where guayule had been grown for 0 to 38 months were collected for sorption experiments from beneath actively growing plants. An additional treatment was collected prior to planting cotton in a field one year after the final harvest of guayule that had been grown for 36 months was also included. Continuous guayule cultivation resulted in a modest increase in soil organic carbon from 0.29% (±0.01%) to 0.76% (±0.03%) after 38 months of production. Pendimethalin sorption to the soil increased with increasing guayule organic deposition as measured by time under cultivation. Soils where guayule was grown for 38 months had a KOC 23 times greater than the control soil where guayule had not been grown (389,400 vs 16,900 L kg-1). However, in the treatment prior to planting cotton the combination of time and cultivation resulted in a reduction of KOC from 389,400 to 21,500 L kg-1. The use of pendimethalin in a guayule - cotton rotation requires sufficient time and primary tillage prior to planting cotton. In addition, the use of pendimethalin during re-growth of guayule from the stump following harvest may require higher application rates to control weeds. Adsorption of pendimethalin to soil using batch equilibrium indicated that soil beneath actively growing guayule has a higher sorption capacity for pendimethalin than soil without guayule.<br /> <br /> California-Berkeley: Investigating a simplified model of the acid-base chemistry of humic substances. Tetracycline and ciprofloxacin, two widely-used, environmentally-important antibiotics, are either cations or zwitterions over the range of pH typical of soils and receiving waters, implying a significant potential for adsorption by humic substances, which are anions in the same pH range. Recent studies of antibiotic adsorption by humic substances (see, e.g., our 2007 progress report) have confirmed this possibility, showing that humic substances may play an important role in controlling the fate of these and other cationic antibiotics in soil and aquatic environments. The available data also indicate that the affinity of humic substances for cationic or zwitterionic antibiotics is pH-dependent as a result of the variable charge of the adsorptive antibiotic and the humic adsorbent. Chemical modeling of this pH-dependent adsorption thus requires a suitable characterization of the acid-base chemistry of humic substances, an ongoing challenge in current research because of the complexity of these organic materials.<br /> <br /> We developed a model with three proton affinity classes to describe the acid-base chemistry of representative HS samples from both terrestrial and aquatic sources. The three pre-designated pKa values in our model, 3, 6, and 8, reflected proton dissociation constants inferred from recent comprehensive examinations of the acid-base chemistry of humic and fulvic acids. Our model was optimized on new blank-corrected base titration data that were properly renormalized, with model validation then achieved through comparing the optimized relative content of each affinity class with an independent quantitation of the acidic functional groups in the HS samples.<br /> <br /> UC-Riverside: Chiral pesticides currently constitute about 25% of all pesticides used, and this ratio is increasing as more complex structures are introduced. Despite the great public concerns associated with the use of pesticides, the environmental significance of chirality in currently used insecticides is poorly understood. Our research activities in 2009 on this topic include evaluation of chiral coversion induced by alcohols.<br /> <br /> Epimerization of Cypermethrin Stereoisomers in Alcohols. Isomerization induced by light, heat and organic solvents has been shown to occur for some pyrethroid insecticides. Alcohols are popular solvents that are used in sample extraction, storage and analysis. Thus, alcohol-induced epimerization may contribute to the incorrect interpretation of results from enantioselective chemical analysis and bioassay of pyrethroids like cypermethrin. In this study, we investigated the relationship between the rate of epimerization of cypermethrin stereoisomers: 1R-cis-±R and 1R-trans-±R and short-chain alkyl alcohol properties. In the present study, complete epimerization of 1R-cis-±R produced an almost equal fraction of 1R-cis-±S and that of 1R-trans-±R yielded 1R-trans-±S. For both stereoisomers, epimerization was most rapid in ethanol. The same stereoisomers underwent relatively rapid epimerization in methanol, n-propanol, 2-methyl-1-propanol and n-butanol, but were stable in 2-butanol, suggesting that secondary alcohols have reduced reactivity, likely due to steric hindrance. We further evaluated epimerization of 1R-cis-±R and 1R-trans-±R stereoisomers of cypermethrin as a function of water content in methanol. The presence of water in methanol generally increased the epimerization rate. For 1R-cis-±R, epimerization was most rapid at a water content of d 2%, while for 1R-trans-±R, epimerization was most rapid at 10% water content. Results from this study clearly show that contact with commonly used primary alcohols may result in rapid abiotic epimerization, underscoring the importance to consider configurational stability in ensuring the analytical integrity and correct interpretation of bioassay data for stereoisomers of cypermethrin and similar pyrethroids. <br /> <br /> Bioavailability of hydrophobic contaminants: Hydrophobic contaminants such as synthetic pyrethroids and PAHs are extremely hydrophobic and their biological effects are governed by their bioavailability. In 2009 we expanded our research on the phase distribution and bioavailability of pyrethroids and PAHs in soil and sediment. The following are brief summaries of two representative publications on this subject.<br /> Simultaneous determination of free and total concentrations. Hydrophobic contaminants partition between water and sorbent phases such as dissolved organic matter (DOM) in environmental matrices. Consideration of bioavailability increasingly requires the measurement of freely dissolved concentration (Cfree) in addition to the total chemical concentration (Ctotal). However, current practices require the use of separate methods and samples to derive Cfree and Ctotal, and no method affords simultaneous measurement of both concentrations. We employed a method by coupling solid phase microextraction (SPME) with the use of an isotope labeled internal standard and gas chromatography  mass spectrometer (GC-MS) for detection. The method was demonstrated using 8 pyrethroids as model compounds and 13C-cis-permethrin as the labeled internal standard. Analysis of 4 spiked sediment porewater and 4 field-contaminated samples showed that Ctotal obtained by this method was in close agreement with the spiked concentrations or the total concentrations measured after whole-sample solvent extraction, while Cfree was only a small fraction of Ctotal, suggesting pronounced association of these compounds with DOM. The method displayed good reproducibility with average relative standard deviation < 20%, and high sensitivity with method detection limits in the range of 1-5 ng L-1. The method uses a small sample volume (< 20 mL, as opposed to 1 L for conventional analysis), and is solvent-less and fast. The concurrent measurements also allow for estimation of KDOC, a key parameter that is difficult to derive otherwise. The simultaneous determination of Cfree and Ctotal provides information for better relating chemical concentrations with potential ecotoxicological effects.<br /> <br /> <br /> Colorado: Some chemicals have the apparent ability to disrupt normal endocrine system functions after exposure to concentrations so small that they are difficult to detect in the environment. The objectives of this study were to investigate the presence of steroid sex hormones in northern Colorados Cache la Poudre River, to determine the potential for steroid sex hormone biodegradation and photodegradation under natural conditions, and to characterize the mobility of selected steroid sex hormones in agricultural fields using a rainfall simulator. The study determined that steroid sex hormones are present in the Cache la Poudre River, at concentrations ranging from 0.6 ng L1 (epitestosterone) to 22.6 ng L1 (estrone). The study also determined that testosterone, progesterone, and 17²-estradiol can be degraded by manure-borne bacteria, and that testosterone degradation is faster under aerobic conditions and at higher temperatures (i.e., 37°C vs. 22°C), but little affected by changes in pH (from 6 to 7.5) or glucose amendments. In ultraviolet light » > 340 nm, the study observed direct photodegradation of testosterone and progesterone, and indirect photodegradation of testosterone and 17²-estradiol in the presence of Elliot soil humic acid. On the other hand, in ultraviolet light » > 310 nm, direct photodegradation of androstenedione was substantially faster than direct photodegradation of testosterone in ultraviolet light » > 310 nm, and no indirect photodegradation observed. The study detected and identified three testosterone biodegradation products (dehydrotestosterone, androstenedione, and androstadienedione), and detected several products of testosterone and androstenedione photodegradation which appear to retain their steroid structure, and possibly their endocrine disrupting potential. Finally, the study generally observed that androgen runoff concentrations follow runoff rates and decrease after successive rainfall events, while runoff concentrations of other analytes (e.g., estrone) peak after the maximum runoff rate and first rainfall event. Sample and data analysis from the study are continuing, and comprehensive finding and recommendations are expected after the date of this report.<br /> <br /> Hawaii: Crop losses, impact on native vegetative populations - causing changes in ecosystems, have been correlated to increases in invasive snail populations. These in turn have had major economic impact on developing countries, raised environmental concerns in developed countries, and impacted crop production/yields worldwide. Invasive tropical snails are carriers of disease, which greatly impact human health in under-developed tropical countries. Their effect on human health impacts productivity, self-sufficiency and economic development.<br /> <br /> Iowa: This project deals with the fate of hormones in soils where they are added by land application of cattle manure. Our long-term goal is to improve risk assessment of hormones in the environment, especially those derived from concentrated animal feeding operations (CAFOs). We are determining how colloidal materials in manure and soils retain the two hormones estradiol and estrone. We found that WDCs had markedly higher organic carbon contents than their parent soil materials and were dominated by smectite in the mineral fraction for these three soils. The organic carbon contents were strongly correlated with adsorption intensity for these three Iowa soils and their WDCs, as evidenced by similar Koc values. But not all soil organic matter was the same with respect to adsorption. There were differences in log Koc values among the two alluvial soils and one till-derived soil. Moreover, water-dispersible colloids had higher Koc values than their parent soil materials. This was particularly true of the clay-rich that had also previously received biosolids amendments. In the remaining project period, we will explore the conditions under which the retention of these hormones by colloidal components either enhances or retards their movement in the soil and over the soil. These experiments are crucial in the development, parameterization, calibration, and validation of hormone transport models that will be used to guide both management and regulation of land-applied manure.<br /> <br /> Michigan: Clay minerals may be an important unrecognized sorptive phase for dioxins in soils and clay deposits. Smectites, especially Cs-saponite, effectively adsorbed dibenzo-p-dioxin from water, reaching 0.8 % (wt/wt). Adsorption was promoted by exchangeable cations with low hydration energies, and negative charge in the smectite arising from the tetrahedral siloxane sheets. X-ray diffraction measurements revealed that as dioxin loading increased to e 8,000 mg/kg the clay basal spacing increased abruptly from 12.3 to 15.2 angstrom demonstrating dioxin intercalation. The 12.3-angstrom spacing provides an interlayer distance that closely matches the molecular thickness of dioxin. In this configuration dioxin is essentially dehydrated as it interacts with the opposing hydrophobic siloxane sheets and with co-planar Cs+ via one of the dioxin ring oxygens. Ab initio calculations suggest that geometrical structures form at higher loadings in which intercalated dioxin molecules adopt a butterfly geometry sandwiched between dehydrated interlayer Cs+ and the siloxane surface, consistent with the 15.2 angstrom spacing, wherein Cs+ interacts with dioxin ring oxygens and benzene ring pi-electrons. Fourier transformation infrared measurements confirm that adsorbed dioxin is present in orientations that are not parallel with the interlayer planar siloxane surfaces of smectite. Clay minerals also strongly sorb many pharmaceuticals. Lincomycin, an antibiotic widely administered as a veterinary medicine, is frequently detected in water. Little is known about the soil-water distribution of lincomycin despite the fact that this is a major determinant of its environmental fate and potential for exposure. Cation exchange was the primary mechanism responsible for lincomycin sorption by soil clay minerals. This was evidenced by pH-dependent sorption, and competition with inorganic cations for sorptive sites. As solution pH increased, lincomycin sorption decreased. The extent of reduction was consistent with the decrease in cationic lincomycin species in solution. The presence of Ca2+ in solution diminished lincomycin sorption. Clay interlayer hydration status strongly influenced lincomycin adsorption. Smectites with the charge deficit from isomorphic substitution in tetrahedral layers (i.e. saponite) manifest a less hydrated interlayer environment resulting in greater sorption than that by octahedrally substituted clays (i.e. montmorillonite). Strongly hydrated exchangeable cations resulted in a more hydrated clay interlayer environment reducing sorption in the order of Ca- < K- < Cs-smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces. <br /> <br /> USDA-ARS, Minneapolis, MN: An enrichment culture approach was used to isolate a pure culture of the yeast Lipomyces kononenkoae, which had the ability to grow on the herbicide picloram. The yeast rapidly and completely degraded 50 µg/mL picloram by 48 hr of growth. While L. kononenkoae was found to use both N atoms of picloram as a sole nitrogen source for growth, it failed to mineralize the herbicide or use it as a sole C source. Product analysis done using LC-ESI-MS indicated that biodegradation of picloram by L. kononenkoae proceeds via a didechlorinated, dihydroxylated pyridinecarboxylic acid derivative. Our results are consistent with the hypothesis that the majority of picloram degradation in the soil is likely due to microbial catabolic processes.<br /> <br /> USDA-ARS, Morris, MN: Information regarding the impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides is critical to the development of improved pesticide management practices. We quantified the rate of S-metolachlor dissipation after fall and spring application in eroded and rehabilitated landforms in which topsoil was moved from the lower slope to the upper slope. Despite large differences in soil properties, including soil organic carbon contents that varied by up to a factor of 4, the rate of metolachlor dissipation from the top 1 m was essentially the same at all landscape positions. Most of the fall-applied metolachlor was depleted from the root zone during the winter (presumably by leaching and runoff), so that only 20% of the applied metolachlor remained in the top 1 m of the soil profile at the beginning of the growing season. S-metolachlor dissipated in the spring with a half-life of 24 to 29 d. Bromide and metolachlor were depleted from the root zone at nearly the same rate during most of the growing season, suggesting that metolachlor degradation and plant uptake acted together to result in a dissipation rate similar to that for a non-reactive tracer, which was primarily dissipated through plant uptake. In these trials, fall-applied metolachlor dissipated prior to spring planting to such an extent that it provided no control of annual grasses. The results of this research suggest that fall-applied metolachlor may not provide economic weed control and presents an increased risk of water contamination. Although landscape position and bulk soil movement within the landform had a large impact on soil properties, we observed no significant differences in metolachlor dissipation between different landscape positions and between eroded and rehabilitated landforms.<br /> <br /> Missouri: Vegetative buffer strips (VBS) are postulated to be one management tool that can reduce VA transport to surface water resources. The objectives of this study were to (1) investigate oxytetracycline (OTC) and sulfadimethoxine (SDT) sorption to agroforestry buffer, grass buffer, and cropland soils, (2) evaluate differences in VA sorption to soils collected from different vegetative managements and soil series, and (3) elucidate relationships between soil properties and VA sorption. Sorption/extraction isotherms for OTC were well-fitted by the Freundlich isotherm model (r2 > 0.86). Oxytetracycline was strongly adsorbed by all soils and the VA was not readily extractable. Oxytetracycline and SDT solid to solution partition coefficients (Kd) values are significantly greater for soils planted to VBS relative to grain crops. Significant differences in OTC and SDT Kd values were also noted among the soil series studied. Linear regression analyses indicate that clay content and pH were the most important soil properties controlling OTC and SDT adsorption, respectively. Greater clay content in the VBS is hypothesized to occur due to improved aggregation and stabilization of soil by permanent vegetation and the deposition of clay particles and clay aggregates as runoff waters pass through VBS. Lower soil pH in VBS is attributed to lack of liming VBS. Results from this study suggest that agroforestry and grass buffer strips may effectively mitigate antibiotic loss from agroecosystems, in part, due to enhanced antibiotic sorption properties. <br /> <br /> Pennsylvannia: Sample cleanup and concentration procedures have been worked out for soil samples such that we have confidence in results. Maintenance of a unit hydraulic gradient in the soil columns has been an issue and recently solved with some modifications from earlier designs. Samples have been collected from a few locations in an effluent irrigated location to determine distribution of three estrogens by depth. One set of samples have been analyzed for estrone, indicating that for the sample site, deeper sampling depths than those originally expected are needed. We have obtained data comparing the degree of sorption of estrone to soil organic carbon at relatively high concentrations (from approximately 5% to 50% of the estrone aqueous solubility concentration), using radiolabeled techniques as well as non-radiolabeled techniques using batch isotherms and extraction of soil sorbed estrone. The collaboration with USDA-ARS in AZ has proven quite beneficial, as the equipment available for research has yielded dependable results. Based on conversation with the extension program leader for the environment, the college strategic plan includes an emphasis by both the water quality and crop nutrient management groups on emerging contaminants. This research work has been cited internally as support for the educational programs being developed. So the impact has not yet reached citizens directly, but will during the next 5 year plan of work, because of the internal impact related to extension program planning.<br /> <br /> South Dakota: This study investigates the effects of two universally administered animal feed additives, tylosin and chlorotetracycline (CTC), during batch anaerobic swine manure digestion. Both compounds are poorly absorbed within the swine intestines and consequently, these compounds and bioactive metabolites are excreted. The breakdown of insoluble organic matter through anaerobic hydrolysis reactions were faster for manure containing CTC compared with tylosin or no-antimicrobial treatments, however volatile fatty acid (VFA) accumulation, including acetate, butyrate, and propionate, was significantly greater for CTC compared to the tylosin and no-antimicrobial control treatments. Aceticlastic methanogen abundance for CTC treatments (Methanosaetaceae and Methanosarcinaceae spp.) were less than no-antimicrobial control treatments, and methane and carbon dioxide generation rates were inhibited due to the presence of CTC. For tylosin, effects on manure degradation were limited, however their was a significant shift in the relative abundance of aceticlastic methanogens Methanosaetaceae and Methanosarcinaceae spp. compared to no-antimicrobial control treatments, suggesting that other C-1 VFA compounds in addition to acetate appear to be effectively utilized during methanogenesis in the presence of tylosin. <br /> <br /> Life cycle assessment of tylosin and chlortetracycline antimicrobial use at swine production facilities - This study investigates the environmental effects associated with tylosin and chlortetracycline (CTC) antimicrobial sub-theraputic use within Midwestern US swine production facilities following life cycle assessment (LCA) methodology. Environmental LCA-associated impacts were modeled using SimaPro and assessed using EcoIndicator 99 for antimicrobial manufacturing, feed blending and transport, metabolic and manure emissions, and facility operations for starter, grower, and finishing swine operations. LCA results suggest current high energy demands associated with manufacturing fermentation processes and large transport distances to producers of CTC and tylosin increased disability adjusted life year (DALY) climate change impacts compared to no antimicrobial use. Feeding CTC resulted in several local positive changes including 20% increase in feed utilization and reduced manure greenhouse gas emissions. However, these positive changes in the local environment did not offset negative global impacts associated with material manufacturing and transport. Using renewable energy sources for production and transport would result in net environmental enhancement. <br /> <br /> Wisconsin: Assessing occurrence, persistence and biological effects of hormones released from livestock waste. The overall goal is to determine the presence, persistence and biological effects of natural and synthetic hormones that may be released into the environment from concentrated animal feed operations (CAFOs), and evaluate the effects of different animal waste disposal practices on the fate and activity of these compounds. This research will help to evaluate whether CAFO waste is an important source of endocrine disrupting chemicals in the environment.<br /> <br /> Seven hormones were identified and quantified using HPLC-MS/MS in the snow-melt grab samples. These include: estradiol, a-zearalanol, zearalenone, 4-androstene-3,17-dione, 17b-nortestosterone, progesterone, and 17,20-dihydroxyprogesterone. Levels of most hormones were <100 ng/L, though concentrations of the most prevalent hormones (progesterone, 17,20-dihydroxy-progesteone, and zearalenone) ranged up to 350 ng/L. Estrogenic activity from the snow melt samples were also determined using the E-screen bioassay. In this assay, the only target compounds that should elicit a response would be estriol, estradiol, estrone and the zearanols. In general, trends in the E-screen bioassay were consistent with the chemical profiles of the samples.<br /> <br /> Fathead Minnow Exposures - Three percent CAFO effluent (from a steer facility) had no effect on the number of eggs produced by fathead minnows during a three week exposure. In addition, the levels of vitellogenin expression in the exposed males were similar to their respective controls. The levels of hormones may have been too low to cause an effect due to the dilution of effluent (necessary to prevent ammonia toxicity to the fish) or rapid degradation of hormones associated with the liquid manure. <br /> <br /> We completed a study using Computer Assisted Sperm Analysis (CASA) to investigate the acute effects of various progestins on sperm motility in fathead minnows. Semen samples were exposed short-term in vitro to various doses of progesterone, 17a,20b-P, or melengestrol acetate (MA). The sperm were activated, video recorded, and analyzed for the following parameters using CASA: percent motility, curvilinear velocity, velocity average path, straight line velocity, and percent linearity. Preliminarily, short-term progesterone exposure had a slight, but significant effect on fathead minnow sperm motility. <br /> <br /> Objective 2: Integrate chemical and biological process information for use in models applicable across different spatial and temporal scales.<br /> <br /> USDA-ARS, Morris, MN: Metolachlor transport in eroded and rehabilitated prairie landforms - Information regarding the impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides is critical to the development of improved pesticide management practices. We quantified the rate of S-metolachlor dissipation after fall and spring application in eroded and rehabilitated landforms in which topsoil was moved from the lower slope to the upper slope. Despite large differences in soil properties, including soil organic carbon contents that varied by up to a factor of 4, the rate of metolachlor dissipation from the top 1 m was essentially the same at all landscape positions. Most of the fall-applied metolachlor was depleted from the root zone during the winter (presumably by leaching and runoff), so that only 20% of the applied metolachlor remained in the top 1 m of the soil profile at the beginning of the growing season. S-metolachlor dissipated in the spring with a half-life of 24 to 29 d. Bromide and metolachlor were depleted from the root zone at nearly the same rate during most of the growing season, suggesting that metolachlor degradation and plant uptake acted together to result in a dissipation rate similar to that for a non-reactive tracer, which was primarily dissipated through plant uptake. In these trials, fall-applied metolachlor dissipated prior to spring planting to such an extent that it provided no control of annual grasses. The results of this research suggest that fall-applied metolachlor may not provide economic weed control and presents an increased risk of water contamination. Although landscape position and bulk soil movement within the landform had a large impact on soil properties, we observed no significant differences in metolachlor dissipation between different landscape positions and between eroded and rehabilitated landforms.<br /> <br /> Objective 3: Provide stakeholders with tools for developing strategies to ensure sustainable agriculture and to protect natural resource systems.<br /> <br /> California-Riverside: Oxidative Removal of Bisphenol A (BPA) by Manganese Dioxide - Bisphenol A (BPA) is a ubiquitous environmental contaminant with endocrine disruption potential. In this study, exploiting the outstanding oxidative capacity of manganese dioxide (´-MnO2), we explored for the first time the efficacy and mechanisms of BPA removal by MnO2. In aqueous solutions, MnO2 displayed an extremely efficient capacity to remove BPA. Nearly all BPA (> 99%) was eliminated in 6 min in a pH 4.5 solution initially containing 800 ¼M MnO2 and 4.4 ¼M BPA. While humic acid showed negligible inhibition on BPA removal, co-existing metal ions such as Mn2+, Ca2+, Mg2+, and Fe3+ displayed suppressive effects and the inhibitive capacity followed the order of Mn2+ > Ca2+ > Mg2+ H Fe3+. A total of 11 products or intermediates were indentified and a detailed reaction scheme was suggested. The products could be ascribed to a suite of reactions of radical coupling, fragmentation, substitution, and elimination, triggered by the BPA radical formed through electron transfers to MnO2. The exceptional efficiency of MnO2 in removing BPA represents a perspective use of MnO2 to treat waters containing phenolic compounds, and also suggests a potentially important role of oxide-facilitated abiotic transformations in BPA attenuation in natural soil and sediment environments.<br /> Use of Constructed Wetlands to Remove Pesticides in Tailwaters. Pollutants in agricultural irrigation return flow (tailwater) constitute a significant non-point source of pollution in intensive agricultural regions such as the Central Valley of California. Constructed wetlands (CWs) represent a feasible mitigation option to remove pollutants including pesticides in the tailwater. In this study, we evaluated two CWs in the Central Valley for their performance in removing pyrethroid and organophosphate insecticides under field-scale production conditions. Both CWs were found to be highly effective in reducing pyrethroid concentrations in the tailwater, with season-average concentration reductions ranging from 52 to 94%. The wetlands also reduced the flow volume by 68-87%, through percolation and evapotranspiration. When both concentration and volume reductions were considered, the season-average removal of pyrethroids ranged from 95 to 100%. The primary mechanism for pyrethroid removal was through sedimentation of pesticide-laden particles, which was influenced by hydraulic residence time and vegetation density. The season-average removal of chlorpyrifos ranged 52-61%. The wetlands, however, were less effective at removing diazinon, likely due to its limited sorption to sediment particles. Analysis of pesticide partitioning showed that pyrethroids were enriched on suspended particles. Mass balance calculation of suspended solids suggests that the sediment basin served as the primary sink for pesticides on a mass basis, and the CWs were able to remove fine particles enriched with pesticides. Results from this study show that flow-through CWs, when properly designed, are an effective practice for mitigating hydrophobic pesticides in the irrigation tailwater.<br /> <br />

Publications

Wang, L.M., S.S. Zhou, K.D. Lin, M.R. Zhao, J. Gan, and W.P. Liu. 2009. Enantioselective estrogenicity of o,p2-dichlorodiphenyltrichloroethane in the MCF-7 human breast carcinoma cell line. Environmental Toxicology & Chemistry 28: 1-8.<br /> <br /> Hunter, W., Y. Yang, F. Reichenberg, P. Mayer, and J. Gan. 2009. Measuring pyrethroids in sediment porewater using matrix-solid phase microextraction. Environmental Toxicology & Chemistry 28: 36-43.<br /> <br /> Yang, Y., W. Hunter, S. Tao, and J. Gan. 2009. Effects of black carbon on pyrethroid bioavailability in sediments. Journal of Agricultural & Food Chemistry 57: 232-238.<br /> <br /> Wang, H.Z., J. Gan, J.B. Zhang, J.M. Xu, S.R. Yates, J.J. Wu, and Q.F. Ye. 2009. Kinetics 14C-metsulfuron-methyl residues in paddy soils under different moisture conditions. Journal of Environmental Quality 38: 164-170.<br /> <br /> Zhao, M.R., Y. Zhang, C. Wang, Z.W. Fu, W.P. Liu, and J. Gan. 2009. Induction of macrophage apoptosis by an organochlorine insecticide acetofenate. Chemical Research in Toxicology 22: 504-510.<br /> <br /> Lin, K.D., D. Haver, L. Oki, and J. Gan. 2009. Persistence and sorption of fipronil degradates in urban stream sediments. Environmental Toxicology & Chemistry 28: 1462-1468.<br /> <br /> Cáceres-Jensen, L. J. Gan, M. Báez, R. Fuentes, and M. Escudey. 2009. Adsorption of glyphosate on variable-charge Chilean soils. Journal of Environmental Quality 38: 1449-1457.<br /> <br /> Yang, Y., W. Hunter, S. Tao, and J. Gan. 2009. Microbial availability of different forms of phenanthrene in soils. Environmental Science & Technology 43: 1852-1857.<br /> <br /> Mangiafico, S.S., J. Newman, D.J. Merhaut, J. Gan, B. Faber, L. Wu. 2009. Nutrients and pesticides in stormwater runoff and soil water in production nurseries and citrus and avocado groves in California. HortTechnology 19: 360-367.<br /> <br /> Budd, R., A. OGeen, K. Goh, S. Bondarenko, and J. Gan. 2009. Efficacy of constructed wetlands in pesticide removal from tailwaters in the Central Valley, California. Environmental Science & Technology 43: 2925-2930.<br /> <br /> Bondarenko, S., and J. Gan. 2009. Simultaneous determination of free and total concentrations of hydrophobic compounds. Environmental Science & Technology 43: 3772-3777.<br /> <br /> Lao, W., and J. Gan. 2009. Evaluation of triproline and tri-±-methylproline chiral stationary phases: Retention and enantioseparation associated with hydrogen bonding. Journal of Chromatography A 1216:5020-5029.<br /> <br /> Nillos, M., K. Lin, J. Gan, S. Bondarenko, and D. Schlenk. 2009. Enantioselectivity in fipronil aquatic toxicity and degradation. Environmental Toxicology & Chemistry 28: 1825-1833.<br /> <br /> Lin, K.D., W.P. Liu, and J. Gan. 2009. Oxidative removal of bisphenol-A with manganese dioxide: Kinetics, products, and pathways. Environmental Science & Technology 43: 3860-3864.<br /> <br /> Lin, K.D., W.P. Liu, and J. Gan. 2009. Reaction of tetrabromobisphenol A (TBBPA) with manganese dioxide: Kinetics, products, and pathways. Environmental Science & Technology 43: 4480-4486.<br /> <br /> Lao, W., and J. Gan. 2009. Doubly tethered tertiary amide linked and ionically bonded diproline chiral stationary phase. Journal of Separation Science 32: 2359-2368.<br /> <br /> Yang, Y., W. Hunter, S. Tao, D. Crowley, and J. Gan. 2009. Effect of activated carbon on microbial bioavailability of phenanthrene in soils. Environmental Toxicology and Chemistry 28: 2283-2288.<br /> <br /> Nillos, M.G., S.J. Qin, C. Larive, D. Schlenk, and J. Gan. 2009. Epimerization of cypermethrin stereoisomers in alcohols. Journal of Agricultural & Food Chemistry 57: 6938-6943.<br /> <br /> Sakaliene, O., W. C. Koskinen, G. Blazauskiene, and I. Petroviene. 2009. Level and fate of chlorpropham in potatoes during storage and processing. J. Environ. Sci.Health B. 44:1-6.<br /> <br /> Sadowsky, M..J., W. C. Koskinen, M. Bischoff, B. L. Barber, J. M. Becker, and R. F. Turco. 2009. Complete degradation of the herbicide picloram by Lipomyces kononenkoa. Agric. Food Chem. 57:4878-4882. <br /> <br /> Papiernik, S. K., W. C. Koskinen, and S. R. Yates. 2009. Solute transport in eroded and ehabilitated prairie landforms. 1. Nonreactive solute. J. Agric. Food Chem. 57:7427-7433.<br /> <br /> Papiernik, S. K., W. C. Koskinen, and S. R. Yates. 2009. Solute transport in eroded and rehabilitated prairie landforms. 2. Reactive solute. Agric. Food Chem. 57:7434-7439.<br /> <br /> Sakaliene, O., Papiernik, S. K., Koskinen, W. C., Kavoliunaite, I., Brazenaitei, J. 2009. Using Lysimeters to Evaluate the Relative Mobility and Plant Uptake of Four Herbicides in a Rye Production System. Journal of Agricultural and Food Chemistry. 57:1975-1981.<br /> <br /> Spokas, K. A, W. C. Koskinen, J. M. Baker, and D. C. Reicosky. 2009. Impacts of woodchip biochar additions on soil carbon net, CH4 oxidation and sorption/desorption of two herbicides in a Minnesota soil. Chemosphere 77(4):571-581.<br /> <br /> Gao, J.; Pedersen, J.A. Sorption of sulfonamide antimicrobial agents to humic-clay complexes. J. Environ. Qual. 2010, 39, 228-235.<br /> <br /> Hemming, J., Hedman, C., Havens, S., Landreman, A., Mieritz, M., Barry, T., Geis, S., Schauer, J., and Shafer, M. (2007) Evaluating methods for measuring hormones in livestock waste. Poster presentation. National SETAC meeting, Milwaukee, WI November 11-15.<br /> <br /> Havens, S., Barry, T., Geis, S., Hedman, C., Hemming, J., Mieritz, M., Shafer, M., and Schauer, J. (2008). Validation of hydrochloric acid for the preservation of endocrine disrupting compounds. Platform presentation. National SETAC meeting. Tampa, FL. November 16-20.<br /> <br /> Havens, S., Barry, T., Hedman, C., Hemming, J., Mieritz, M., Shafer, M., and Schauer, J. (2009). Preservation and analysis of endocrine disrupting compounds using hydrochloric acid and isotope dilution. Platform presentation. Midwest SETAC meeting. LaCrosse, WI. March 30  April 1.<br /> <br /> Hedman, C., Hemming, J., Mieritz, M., Havens, S., Shafer, M., Geis, S. (2009) Bioassay Directed Fractionation of CAFO Runoff Samples. Platform presentation. Midwest SETAC meeting. LaCrosse, WI. March 30  April 1.<br /> <br /> Reiman, M., D.E. Clay, C.G. Carlson, S.A. Clay, G. Reicks, D.W. Clay, and D.E. Humburg. 2009. Manure placement depth impacts on crop yields and N retained in soil. J. Envrion. Sci. Health (B). 44:76-85.<br /> <br /> Hoese, A. S.A. Clay, D.E. Clay, J. Oswald, T. Trooien, R. Thaler, and C.G. Carlson. Chlortetracycline and tylosin runoff from soils treated with antimicrobial containing manure. J. Envrion. Sci. Health (B) 44:371-378.<br /> <br /> Stone, J.J., S.A. Clay, Z. Zhu, K.L. Wong, L.R. Porath, and G.M. Spellman. 2009. Effect of antimicrobial compounds tylosin and chlortetracycline during batch anaerobic swine manure digestion. Water Research. Doi:10.1016/j.watres.2009.08.005.<br /> <br /> Stone, J., K. Aurand, S.A. Clay, and R. Thaler. 2010. Life cycle assessment of tylosin and chlortretracycline antimicrobial use at swine production facilities. ACS Div. Environ. Chem. 239th ACS Meeting, San Francisco.<br /> <br /> Wu, S.-H. 2009. Adsorption of isoxaflutole degradates to hydrous aluminum and iron oxides. M.S. Thesis. University of Missouri. Columbia, MO.<br /> <br /> Walker, C.W., J.E. Watson and R.S. Thomas. 2009. Design of a flow-through electrical conductivity probe. Applied Engineering in Agriculture 25:373-376. <br /> <br /> Williams, C.F., T.A. Coffelt and J.E. Watson. 2009. Increased soil sorption of Pendimethalin due to deposition of guayule derived detritus. Soil Sci. Soc. Am. J. 73:1952-1957. <br /> <br /> Walker, C.W. and J.E. Watson. 2010. Adsorption of Estrogens to Laboratory Materials and Filters during Sample Preparation. J. Envir. Qual. 39:1-5 (2010) doi:10.2134/jeq2009.0017<br /> <br /> Lin, C.H., K.W. Goyne, R.J. Kremer, R.N. Lerch, H.E. Garrett. 2009. Rhizodegradation of sulfamethazine and their associated impacts on soil microbial activities. In M.A. Gold and M.M. Hall (eds). Agroforestry Comes of Age: Putting Science Into Practice. 11th North American Agroforestry Conference. 31 May  3 June 2009. Columbia MO.<br /> <br /> Chu, B.*, K.W. Goyne, S.H. Anderson, R.P. Udawatta, and C.H. Lin. 2009. Veterinary antibiotic sorption to agroforestry buffer, grass buffer and cropland soils. p. 31-40. In M.A. Gold and M.M. Hall (eds). Agroforestry Comes of Age: Putting Science Into Practice. 11th North American Agroforestry Conference. 31 May  3 June 2009. Columbia MO.<br /> <br /> Cuiping Wang, Yunjie Ding, Brian J. Teppen, Stephen A. Boyd, and Hui Li, 2009, Role of Interlayer Hydration in Lincomycin Sorption by Smectite Clays. Environmental Science and Technology, 43:6171-6176.<br /> <br /> Cun Liu, Hui. Li, Brian. J. Teppen, Cliff. T. Johnston, and Stephen. A. Boyd, 2009, Mechanisms Associated with the High Adsorption of Dibenzo-p-dioxin from Water by Smectite Clays. Environmental Science and Technology, 43:2777-2783.<br /> <br /> Prater, Jacob R., R. Chatterjee, T. Chua, M.L. Thompson. and R. Horton. 2009. Impacts of Colloidal Material on the Fate of Estrogens in Soils. Abstract of presentation at the Soil Science Society of America International Annual Meeting, Pittsburgh, PA.<br /> <br /> Coffelt, T.A. and C.F. Williams. 2009. Characterization and recycling of waste water from guayule latex extraction. Industrial Crops Prod. 29:648-653. <br /> <br /> Williams, C.F., T. A. Coffelt and J. E. Watson. 2009. Increased Soil Sorption of Pendimethalin due to Deposition of Guayule Derived Detritus. Soil Sci. Soc. Am. J.73:1952-1957.<br /> <br /> Loganathan, V.A., Y. Feng, G.D. Sheng, and T.P. Clement. 2009. Influence of sorption and desorption on bioavailability of atrazine in soils amended with crop-residue-derived char. Soil Sci. Soc. Am. J. 73:967-974.<br /> <br /> Srivastava, P., S.M. Sanders, J.H. Dane, Y. Feng, J. Basile, and M.O. Barnett. 2009. Fate and transport of sulfadimethoxine and ormetoprim in two southestern U.S. soils. Vadose Zone J. 8:32-41.<br /> <br /> Qiu, Y.P., H. Pang, Z.L. Zhou, P. Zhang, Y. Feng, G.D. Sheng. 2009. Competitive biodegradation of dichlobenil and atrazine coexisting in soil amended with a char and citrate. Environ. Pollut. 157:29642969.<br /> <br /> Starr, K.F., Y. Feng, Q. Liang, and D. Zhao. 2009. Carboxymethyl cellulose stabilized magnetite nanoparticles are nontoxic to bacteria. Conference Proceedings: International Conference on the Environmental Implications and Applications of Nanotechnology, University of Massachusetts Amherst, June 9-11, 2009. http://scholarworks.umass.edu/tei, p.91-95.<br /> <br />

Impact Statements

1. Nanotechnology offers a wide range of applications including consumer products, remediation of contaminated soil and water, medical imaging, and targeted drug delivery. Zero-valent iron and iron oxide nanoparticles designed for environmental remediation are released into the environment intentionally. Our results show that nanoscale magnetite were not toxic to Gram-negative and Gram-positive bacteria tested and provide evidence that releasing these nanoparticle for environmental cleanup may pose minimal risk to bacteria.
2. Cationic antibiotics such as tetracycline and ciprofloxacin can be adsorbed by humic substances that therefore may play an important role in controlling the fate of these pharmaceuticals in soil and aquatic environments. We have developed a simple chemical model of humic substance acid-base chemistry that is optimized on new potentiometric titration data that have been correctly analyzed to provide the basis for quantitative modeling of antibiotic adsorption.
3. Steroid sex hormones can be biodegraded under aerobic conditions by manure-borne bacteria to other potential endocrine disrupting compounds. Steroid sex hormones can undergo photolysis in the presence of UVA light (sunlight) forming other potential endocrine disrupting compounds. Steroid hormones have the potential for rain-induced runoff after application of biosolids to an agricultural field.
4. We demonstrated that soils planted to vegetative buffer strips(VBS) exhibit greater sorption of veterinary antibiotics from two different classes of antibiotics. Thus, it may be possible to control veterinary antibiotic loss from agroecosystems where surface runoff is a problem through the implementation of VBS within or at the edge of agricultural fields receiving manure amendments.
5. Our applied research aims at developing and eveluating tools for mitigating pollution. We found that bisphenol A and other similar contaminants are oxidized by manganese oxides.This finding may have applications by the environmental industry for developing techniques to remove these contaminants in the environment.

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