Annual/Termination Reports:

[07/11/2008] [06/23/2009] [07/19/2010]

Report Information

Participants

Kevin Armbrust, Office of the State Chemist, Mississippi; Jay Gan, UC Riverside; Vince Hebert, Washington Agricultural Experimental Station; Jeff Jenkins, Oregon Agricultural Experimental Station; Bob Krieger, UC Riverside; Ann Lemley, Cornell University Agricultural Experiment Station; Qing Li, Hawaii Agricultural Experiment Station; Glenn Miller, Nevada Agricultural Experiment Station; Larry Olsen, Michigan State University; Chris Pritos, University of Nevada; Pam Rice, USDA-ARS, St. Paul, Minnesota; Maria Sepulveda, Purdue University; Daniel Sudakin, Oregon State University; John Thomas, University of Florida Agricultural Experimental Station; Kun Yan Zhu, Kansas Agricultural Experiment Station; Ron Pardini, University of Nevada (Administrative advisor; Guests: Dr. Joel Coats, Iowa State University and Dr. Donald G. Crosby, UC Davis,

Brief Summary of Minutes

Accomplishments

Accomplishments<br /> <br /> <p>Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers.<br /> <br /> <p>Scientists at Mississippi State University developed a new direct gas chromatography procedure (headspace solid phase microextraction) for the quantitative determination of methanol in biodiesel. The analysis was performed by exposing a Carboxen-Polydimethylsiloxane SPME fiber assembly to the headspace of biodiesel samples. The gas chromatography method used a HP-5 capillary column and a flame ionization detector. A polynomial relationship was observed between the methanol concentration and its peak area. This method showed good reproducibility (average relative standard deviation 7.06%) and recovery (average recovery 100.2%).<br /> <p>Scientists at University of California Riverside, in collaboration with California Department of Pesticide Regulation and Pyrethroid Working Group, conducted research on approaches to characterize the bioavailability of pyrethroid residues in sediments. Pyrethroids are highly hydrophobic, and toxicity from sediment-borne pyrethroids is expected to depend closely on their desorption rate. In the present study, we evaluated the effect of aging on desorption kinetics of sediment-borne pyrethroids. Two sediments spiked with four pyrethroids were incubated for 7, 40, 100, and 200 d at room temperature. Desorption measured using sequential TenaxÒ extractions was well described by a three-compartment model. The estimated rapid desorption fraction (Frapid) decreased quickly over time and was accompanied by an increase of the very slow desorption fraction (Fvs). The aging effect on desorption kinetics followed a first-order model, with half-lives for the decrease in Frapid for all four pyrethroids in both sediments ranging from two to three months. When coupled with degradation, the estimated half-lives of the rapidly desorbing fraction (thus, the potentially bioavailable concentration) were £ two months for all four pyrethroids. Two field-contaminated sediments displayed distinctively different desorption kinetics. The sediment with fresh residues exhibited rapid desorption, while the other sediment containing aged residues was highly resistant to desorption. The observation that desorption of pyrethroids decreased quickly over contact time implies that the bioavailability of sediment-borne pyrethroids may diminish over time, and that the use of non-selective extraction methods may lead to overestimation of the actual sediment toxicity from pyrethroid contamination.<br /> <p>There has been a distinct decrease in fur seal (Callorhinus ursinus) population noted in their primary breeding grounds in the Bering Sea. Environmental pollution is a prime suspect. Scientists at University of Hawaii measured the concentrations of polychlorinated biphenyl (PCB) congeners and organochlorine pesticides (OCPs) in eight tissues of fur seals from St. Pauls Island to provide a better perspective of congener distribution and use various congener specific metrics of different toxicities. Concentrations of 145 PCB congeners 12 OCPs or their metabolites were measured with gas chromatography-ion trap mass spectrometry in eight different tissues of 10 male northern fur seals. The mean concentrations of OCPs ng/g wet weight (ww) were found to be 855 in blubber, 61.9 in heart, 46.5 in liver, 41.8 kidney, 23.9 in brain, 19.4 in muscle, 16.4 reproductive tissues (reprod), and 8.8 in lung. Among the OCPs analyzed, p,p-DDE is dominant in all tissues, accounting for more than 60% of the total concentration of OCPs. Among the 4 hexachlorocyclohexane (HCH) isomers, b-HCH is the main isomer in all tissues except brain where a-HCH is the dominant isomer and accounts for more than 30% of the OCPs analyzed. The mean concentrations of PCBs ng/g ww were 578 in blubber, 47 in heart, 34 in liver, 31 in kidney, 13 in muscle, 16 in reprod, 10 in brain, and 5 in lung. Dioxin-like toxic equivalent (PCB-TEQs) showed moderately high values except in brain and lung. Neurotoxic equivalent (NEQ) analyses showed a similar distribution with brain and lung having low but possibly toxic levels and other tissues much higher levels. Enzymatic activity-based classification indicated mixed oxidase inducers present in high concentrations in most tissues while biological action-based grouping indicated problematic estrogenic activity in reproductive tissue for males. Analyses of 145 PCBs and toxicity grouping evaluation suggest that PCB contamination could cause the decrease in population of northern fur seals.<br /> <p>Scientists at University of Florida conducted field studies in Florida to compare the effect of three different plastic films on subsurface distribution and surface emissions of (Z)- and (E)-1,3-dichloropropene (1,3-D) and chloropicrin (CP) after conventional chisel injection of Telone C35 to field beds using N2 or CO2 as propellant/dispersant. The three plastic films were black virtually impermeable film (VIF), metallic polyethylene (PE), and blue PE. All treatments were carried out in three replications. Previous studies have shown that the three VIF covered beds had a better capacity to retain (Z)- and (E)-1,3-D than all the PE covered beds. The use of CO2 with Telone C35 provided quicker and deeper distribution initially compared to application by N2 pressurization. The deeper distribution of Telone C35 components found with CO2 application may have lowered the initial concentration of Telone C35, but it did not appreciably alter the disappearance rate of the three compounds. Although the faster vertical distribution in the bed of the Telone C35 by CO2 did enhance volatilization of the three compounds into the atmosphere compared to volatilization of similar reduced rate applied by N2, the total amount volatilized from the carbonated fumigant beds was still lower than the total amount volatilized to the atmosphere by full rate of Telone C35 using N2. <br /> <br /> <br /> <br /> <p>Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems.<br /> <br /> <p>Scientists at University of Cornell advanced the application potential of anodic Fenton treatment through a study on the adsorption and degradation of carbaryl, mecoprop and paraquat were studied in an Swy-2 Na+-montmorillonite clay slurry. Adsorption isotherms for these three agrochemicals were obtained at given experimental conditions. The d spacing (d001) of the clay layer before and after adsorption or degradation was measured by X ray diffraction (XRD). Based on the change of d spacing, molecular disposition at the clay interlayer was inferred: both mecoprop and paraquat form a monolayer sitting flat and parallel to the clay siloxane surfaces. Results show that, due to different adsorption mechanisms, the adsorption effect on chemical degradation by anodic Fenton treatment (AFT) varies with pesticide: strong and tight adsorption of paraquat at the clay interlayer protects paraquat from being attacked by hydroxyl radicals; loosely adsorbed carbaryl or mecoprop is readily degraded. XRD analysis clearly indicates that AFT is capable of effectively degrading interlayer non-cationic organic chemicals that are not usually available for biodegradation.<br /> <p>Scientists at University of Nevada Reno continued the examination of photochemical processes on arid land soil surface, particularly the photochemical and thermal fixation of atmospheric nitrogen on arid lands soils and titanium dioxide. Photochemical fixation of nitrogen on soils was established over 20 years ago, but has received less attention in recent years. During the previous year we have provided strong evidence that nitrogen is also fixed thermally on titanium dioxide and soils to produce nitrate. On titanium dioxide, nitrate production was observed at 70oC, with a maximum rate of production at approximately 200oC. At temperatures above 400oC, some production of nitrate was observed, but the rate of loss of nitrate increased substantially. The pH of an aqueous rinsing of thermally treated titanium dioxide was lower than the controls, consistent with the production of nitric acid. Addition of base (either sodium hydroxide or potassium hydroxide) increase the rate of production substantially. Soils were generally less active in nitrate production, and varied with the type of soil used.<br /> USDA-ARS scientists in St. Paul, MN, studied runoff transport of pesticides from irrigated turf systems and evaluated mitigation options. The use of pesticides in highly managed turf systems has raised questions concerning the contribution of runoff from managed turf. Experiments were designed to measure the quantity of pesticides transported with runoff from turf plots maintained as a golf course fairway, and to evaluate the ability of management practices to reduce the transport of applied chemicals with runoff. Half of the plots were managed with solid tine aerification while the remaining plots received hollow tine aerification. Management practices were initiated 2 and 63 days prior to chemical application and simulation of precipitation. Runoff volumes and quantities of pesticides transported with runoff were reduced in fairway turf plots managed with hollow tines relative to solid tines. Similar trends in pesticide loads between the two aerification practices were observed when the duration of time between management practice and runoff increased from 2d to 63d; however, the difference between pesticide loads associated with the two aerification practices declined with time. Understanding chemical transport with runoff and identifying strategies that reduce off-site transport of applied chemicals will increase their effectiveness at intended sites of application and will minimize undesirable impacts to surrounding areas.<br /> <br /> <br /> <p>Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems.<br /> <br /> <p>Pyrethroids are increasingly used for pest control as the use of many organophosphate products is restricted. Scientists at Oregon State University examined the effect of dietary esfenvalerate uptake in aquatic insects representing different functional feeding groups. We utilized three field-collected aquatic insect species: a grazing scraper Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae), an omnivorous filter feeder Brachycentrus americanus Banks (Trichoptera: Brachycentridae), and a predator Hesperoperla pacifica Banks (Plecoptera: Perlidae). Laboratory-cultured algae were pre-exposed for 24h to esfenvalerate concentrations of 0, 0.025, 0.05, and 0.1 ¼g/L and provided to two C. reticulata age classes, small and final-instar nymphs. Reduction in small nymph growth was observed following three weeks feeding on algae exposed to 0.05 and 0.1 ¼g/L esfenvalerate, and the highest dietary exposure reduced egg production in final-instar nymphs. The diet for B. americanus and H. pacifica insects consisted of dead third-instar Chironomus tentans larvae; these were pre-exposed to esfenvalerate concentrations ranging between 0.1 and 1.0 ¼g/L. Consumption of the larvae exposed to 0.5 to 1.0 ¼g/L esfenvalerate caused case-abandonment and mortality in B. americanus caddisfly larvae. Although H. pacifica nymphs readily consumed esfenvalerate-exposed larvae, no adverse effects of consumption were observed during the course of this study. Further, there was no evidence of esfenvalerate-induced feeding deterrence in any of the species tested, suggesting that aquatic insects may not be able to distinguish between pyrethroid-contaminated and uncontaminated food sources.<br /> <p>Hydrogen cyanide (HCN) fumigation of closed transport trailers protects citrus from California red scale and other surface pests of citrus. California red scale is a serious pest that can be transported on oranges, lemons, grapefruit and other citrus. Transmission of red scale from California to citrus growing regions of Arizona has been a significant concern since the 1930s. Scientists at University of California Riverside studied HCN residues following HCN fumigation of transport trailers at the maximum rate (1-ounce sodium cyanide per 100 ft3). Standard procedures produce HCN residues of less than 1 ppm in whole fruit at the primary distribution center in Phoenix, AZ. USEPA Method #335.2, a spectrophotometric procedure with a Minimum Reportable Level of about 0.04-0.05 ppm, analyzed residues. The oranges (n = 20) contained 0.69 ± 0.29 ppm HCN and the lemons (n = 10) contained 0.78 ± 0.38 ppm HCN at the Arizona distribution center. The citrus residue tolerance is 50 ppm. The citrus residue is of neither of regulatory nor health significance.<br /> The majority of metabolomic studies used in ecotoxicology have implemented 1H NMR analysis. Despite constant improvement, major limitations of NMR-based techniques include relatively low sensitivity that results in an examination of a limited number of metabolites. Scientists at Purdue University explored an alternative approach by using liquid or gas chromatography (GC) for separation of metabolites and mass spectrometry (MS) for their quantification and identification. The objective of the study was to develop a two dimensional GC coupled with time of flight MS (GCxGC/TOF-MS) coupled with multivariate analysis to compare metabolite profiles of Diporeia under different environmental conditions. We compared metabolite profiles between Diporeia collected from Lake Michigan (declining populations) to those residing in Lake Superior (stable populations), and also between Diporeia exposed to a chemical stressor (atrazine) and controls. Overall, 76 and 302 total metabolites were detected from the lake comparison and atrazine studies, respectively. Many of the identified metabolites included fatty acids, amino acids, and hydrocarbons. Furthermore, we observed unique and almost non-overlapping metabolite profiles in both studies. In conclusion, we established the feasibility of using GCxGC/TOF-MS for detecting metabolites as well as developed software to align and merge chromatographic peaks to compare metabolite differences between invertebrate groups sampled under different environmental conditions. This ability to detect unique metabolite profiles under different environmental conditions will increase our understanding on the physiological processes and whole-organism responses occurring as a result of exposure to different environmental stressors. <br /> <p>Geographic Information Systems (GIS) can be utilized to store, display, and analyze spatial data. Spatial scan statistics can be utilized to investigate spatial and temporal clustering in epidemiological studies. Scientists at the Oregon State University analyzed five years of PCC data to test whether there are significant geographic differences in pesticide exposure incidents resulting in serious (moderate, major, and fatal) outcomes. A Poison Control Center provided data on pesticide exposure incidents for the time period 2001-2005. These data were abstracted to identify the geographic location of the caller, the location where the exposure occurred (residential, workplace, or other), and the medical outcome (no effect, minor, moderate, major effects, death). The results yielded 299 incidents resulting in moderate (n=284), major effects (n=12), or fatalities (n=3). Analysis of these data using spatial scan statistics resulted in the identification of a geographic area consisting of 2 contiguous counties (one urban, one rural) where statistically significant clustering of serious outcomes was observed. The relative risk of a moderate, major, or fatal outcome was 1.9 in this geographic cluster (p=0.0012). Poison Control Center data, GIS, and spatial scan statistics can be effectively utilized to identify geographic clustering of serious incidents involving human exposure to pesticides. These analyses may be useful for public health officials to target preventive interventions. Further investigation is warranted to better understand the potential explanations for geographical clustering, and to assess whether preventive interventions have an impact on reducing pesticide exposure incidents resulting in serious medical outcomes.<br /> Application of DNA microarray technology for gene expression profiling to examine cellular and molecular responses of an affected organism to environmental stressors promises a significant advance. In order to develop a cDNA microarray of the aquatic midge (Chironomus tentans), an ecologically important bioindicator species, scientists at Kansas State University sequenced a total of 10,368 clones from a C. tentans cDNA library. The analysis of 10,367 high-quality expressed sequence tags (ESTs) resulted in a total of 2,912 putative transcripts including 2,095 singletons and 817 contigs. These putative transcripts were functionally annotated and sorted into 14 biological process, 17 cellular component, and 10 molecular function categories. Eighty nine of the transcripts likely encode different types of hemoglobin that are involved in the oxygen storage and/or transport. Twenty nine and 11 transcripts putatively encode cytochrome P450 enzymes and glutathione S-transferases (GSTs), respectively. These enzymes play an important role in the biotransformation of toxic chemicals and endogenous substrates in an organism. Further analysis of the 11 GST ESTs revealed that seven enzymes belong to three cytosolic classes (2 in delta, 4 in sigma and 1 in omega), and the remaining four did not come up with proper classifications. Furthermore, these genes appear to be widely expressed in different tissues of C. tentans larvae. These ESTs will be used to develop a DNA microarray for gene expression profiling to examine cellular and molecular responses of midges to various environmental stressors.<br /> <br /> <p>Objective 4: Develop technologies that mitigate adverse human and environmental impacts.<br /> <br /> <p>South Franklin County, Washington State is currently undergoing rapid residential and commercial growth into traditional large production agricultural lands. There have been public health concerns that residential expansion could contribute to increased risks for human inhalation exposure to agricultural fumigants in this region. The purpose of the 2007 monitoring work herein was to assess if off-target methyl isothiocyanate (MITC) concentrations in residential ambient air exceeded the EPA Office of Pesticide Protection (EPA OPP) human equivalent concentration (HEC) criteria for acute and subchronic residential inhalation exposure. The 2007 air monitoring was conducted in a similar manner to an earlier 2005 MITC residential air study. As in 2005, off-target MITC emissions were monitored at 24-hr periods three times weekly over the fumigation season. However, during the week before the irrigation cut-off in late October, residential air was monitored more intensively at 4-hr instead of 12-hr TWA intervals to better assess possible short-term acute inhalation exposure. The12-hr time weighted averaged (TWA) MITC residue concentrations ranged from detectable (>0.01 ppb) to 12 ppb. An observed TWA 4-hour concentration maximum air concentration of 40 ppb taken days before the Countys irrigation cut-off date appreciably exceeded the EPA OPP acute HEC value of 22 ppb. The seven-week TWA seasonal concentration of 1.5 ppb exceeded the established California EPA subchronic reference exposure level (REL) of 1 ppb but was less than EPA OPP 5 ppb subchronic HEC. The results in this 2007 air monitoring study were comparable to monitoring observations in 2005 and again indicated that MITC residential air concentrations were fairly uniform among all sampling locations within this basin. Moreover, appreciably higher air residues were observed, as in 2005, towards the end of the fumigation season just days before irrigation waters were cut off. It is reasonable to conclude that the shorter 4-hr air interval samplings taken during this later period are a better indication of acute inhalation exposure than from our earlier 12-hour averaged MITC residues over this similar period in 2005. <br /> <br />

Publications

Impact Statements

1. The methods described in this report are currently being vetted as regulatory methods for adoption by both ASTM as well as the European Union. The methods have formed the basis of legislation and resulting regulations in Mississippi dictating the specifications for biodiesel quality sold at retail establishments.

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Participants

Monday, June 8

Present: Armbrust (Chair), Miller, Lemley, Wilson, Jenkins, Zhu, Rice, Sterling, Hapeman, Thomas, Hebert, Felsot, Papiernik, Li, Pardini (Administrative Advisor), Johnson (CSREES representative), Felsot (guest and former W-1045 member)


Tuesday, June 9, 2009

Present: Lemley, Jenkins, Johnson, Zhu, Rice, Sterling, Hapeman, Armbrust, Thomas, Hebert, Felsot, Papiernik, Pardini, Li

Brief Summary of Minutes

Accomplishments

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers.<br /> <br /> The authentication of foods is an important aspect of quality control and food safety. Scientists at the University of Hawaii (Honolulu) developed a fast and reliable method to determine the geographical origin of honey based on fingerprinting and barcoding of proteins in honey by using matrix assisted laser desorption ionization tandem time of flight mass spectrometry (MALDI TOF MS) and MALDI BioTyperTM software, respectively. The protein mass spectra of 16 known Hawai'i-origin honey samples were obtained and useful peak information was extracted and used to generate protein fingerprints. This information was then transformed into spectral barcodes for use as a spectral database library. The differentiation ability of the database library was validated using 5 of the 16 known Hawai`i-origin honey samples obtained directly from the producers. Validation results showed that the protein fingerprints of honeys have better comparability with those honeys in the library known to be from the same region than with those of honey samples from other regions. The protein fingerprints were used to differentiate the geographical origins of commercially purchased honey samples with labels indicating that they were produced in different countries and various states, including Hawai'i. A mass spectrum profile of proteins can be acquired in a few seconds, and MS spectral data can be readily transformed into protein fingerprint barcodes via MALDI BioTyperTM software. The results showed that using these techniques protein fingerprinting and barcoding can be a rapid, simple and practical method for determining the geographical origin of honeys sold in commerce.<br /> <br /> The muck soils of the north shore of Lake Apopka (FL) are high in organic matter, inorganic nutrients, and water content. Ideally suited for agriculture, these soils have been subjected to a wide variety of agrochemicals. Some of the more recalcitrant organochlorine pesticides, such as DDT and its degradation products DDD and DDE, have persisted in the soil for over thirty years. Scientists at University of Florida (Gainsville) used the extracellular enzymes from white rot fungi and demonstrated that it is possible to substantially reduce the amount of DDT, DDD, and DDE in this soil by more than 60% in three weeks.<br /> <br /> Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems.<br /> <br /> Land application of biosolids is a common practice throughout the world. However, concerns continue to be raised about the safety of this practice because biosolids may contain trace levels of organic contaminants. Scientists in Mississippi evaluated the levels of triclocarban (TCC), triclosan (TCS), 4-nonylphenol (4-NP), and polybrominated diphenyl ethers (PBDEs) in biosolids from waste water treatment plants and in soils from field plots receiving annual applications of biosolids for 33 years. All of the four contaminants evaluated were detected in most of the biosolids at concentrations ranging from hundreds of mg kg-1 levels to thousands of mg kg-1 levels (dry weight basis). They were detected at mg kg-1 levels in the biosolids-amended soil but their concentrations decreased sharply with increasing the soil depth, indicating limited mobility. The levels of all four compounds in the surface soil increased with increasing biosolids application rate. The mass balance estimations show that most of the PBDEs and smaller percentage of the 4- NP, TCC, and TCS introduced in the soil were recovered in the top 120-cm soil layer. These observations suggest slow degradation of PBDEs but rapid degradation of 4-NP, TCC, and TCS in the biosolids-amended soils.<br /> <br /> Excess nutrients and agrochemicals from non-point sources contribute to water quality impairment in the Chesapeake Bay watershed, with loading rates related to land use, agricultural practices, hydrology, and pollutant fate and transport processes. USDA-ARS scientists in Beltsville, MD, characterized monthly baseflow stream samples from 15 agricultural subwatersheds of the Choptank River, Maryland (2005 to 2007) for nutrients, herbicides, and transformation products. Streams were gauged to determine loading rates. High resolution digital maps of land use and hydrologic features were derived from remote sensing imagery. Mean nitrate concentrations (overall mean 4.9 mg/L) were correlated positively with percent agriculture (R2 = 0.60) and negatively with percent forest (R2 = 0.75); however, concentrations were higher in the well-drained upland (WDU) subwatersheds than in poorly-drained upland (PDU) subwatersheds (p = 0.02) suggesting increased denitrification in the PDU landscape due to prevalence of hydric soils. Springtime atrazine concentrations (overall mean 0.29 µg/L) were higher in WDU subwatersheds where riparian stream buffers were prevalent than in PDU subwatersheds where forested patches are typically not near streams (p = 0.02). Strong correlation with percent forest in the WDU subwatersheds provided evidence for capture of herbicide drift by the riparian forest canopy and subsequent wash-off during rainfall. <br /> <br /> Scientists at Cornell University studied the Fenton degradation of 4,6-dinitro-o-cresol (DNOC) under different experimental conditions using Amberlyst 15 ion exchange resin containing ferrous ion. DNOC was found to be effectively degraded under most conditions, and it was observed that, with the addition of HCl, the desorption of ferrous ion from the resin into the solution played a major role in this degradation. The total iron concentration in the reaction solution was found to increase with the addition of HCl, and a pseudo-first order kinetic model was applied to the desorption of ferrous ion from the resin based on the assumption of a first-order ion exchange process. The degradation rate of DNOC also increased as a function of HCl. A kinetic model was developed to simulate the degradation of DNOC under different operating conditions, assuming the first order desorption of ferrous ion. It was found that a lower pH could lead to faster degradation of the target compound. Degradation of DNOC under different delivery rates of H2O2 was studied and optimal conditions were determined.<br /> <br /> Scientists at University of Nevada (Reno) have continued the examination of photochemical processes on arid land soil surface, particularly the photochemical and thermal fixation of atmospheric nitrogen on arid lands soils and titanium dioxide. Photochemical fixation of nitrogen on soils was established over 20 years ago, but has received less attention in recent years. During the previous year we have provided strong evidence that nitrogen is also fixed thermally on titanium dioxide and soils to produce nitrate. For work completed since the last report, we have utilized isotopic (15N) methods for providing confirmation of atmospheric nitrogen incorporation into nitrate under thermal conditions. The results of this study support the production of nitrate, both by thermal and photochemical processes. However, the amount of nitrate produced containing the heavier isotope is less than expected and resulted in an incomplete understanding of the nitrogen fixation process. <br /> The impact of varying soil, landscape, and climate conditions on the off-site transport of pesticides must be determined to develop improved pesticide management practices. In collaboration with USDA-ARS scientists in St. Paul and Riverside, USDA-ARS scientists in Morris (MN) quantified the rate of S-metolachlor dissipation after fall and spring application in eroded and rehabilitated landforms in which topsoil was moved from areas of soil accumulation (lower slope) to areas of topsoil depletion (upper slope). Fall-applied metolachlor provided no control of annual grasses because ~80% was removed from the root zone during the winter and early spring, presumably by leaching and runoff. S-metolachlor dissipated in the spring with a half-life of 24 to 29 d. These results 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 /> Pesticides applied to turf grass have been detected in surface waters raising concerns of their affect on water quality and interest in their source, hydrological transport and use of models to predict transport. TurfPQ, a pesticide runoff model for turf grass, predicts pesticide transport but has not been rigorously validated for larger storms. USDA-ARS scientists in St. Paul (MN) evaluated TurfPQs ability to accurately predict the transport of pesticides with runoff following more intense precipitation. The study was conducted with creeping bentgrass [Agrostis palustris Huds.] turf managed as a golf course fairway. A pesticide mixture containing dicamba, 2,4-D, MCPP, flutolanil, and chlorpyrifos was applied to six adjacent 24.4 m x 6.1 m plots. Rainfall simulations yielded 13 events with which to test TurfPQ. Measured mean percentage of applied pesticide recovered in the runoff for dicamba, 2,4-D, MCPP, flutolanil, and chlorpyrifos was 24.6, 20.7, 14.9, 5.9, and 0.8 %, respectively. The predicted mean values produced by TurfPQ were 13.7, 15.6, 15.5, 2.5, and 0.2 %, respectively. Comparisons of the model estimates with our field observations indicate that TurfPQ under predicted pesticide runoff during 69.5 ± 11.4 mm, 1.9 ± 0.2 h, simulated storms. Sensitivity analyses indicated that errors in the organic carbon partition coefficient (KOC) of the pesticide and organic carbon (OC) estimates of the turf may contribute but were not the main cause of under predictions. The greatest source of error was in the timing of predicted infiltration and runoff, which influenced the predicted availability of pesticides for transport with runoff.<br /> <br /> Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems.<br /> <br /> Scientists at Oregon State University evaluated the effectiveness of adapted and native woody plant species as drift barriers between cherry orchards and surface water resources in Wasco County (Middle Columbia-Hood Subbasin), Oregon. Wasco County contains nearly 9,000 acres of cherry orchards. Pest management includes the use of organophosphate insecticides, applied by airblast ground sprayers or fixed-wing aircraft. Two sites were chosen, one along Threemile Creek and the other along Mill Creek. Sites were chosen based on prevailing wind direction and riparian vegetation. At both sites the orchards slope down to the creek. However the two sites were distinct as to the distance from the edge of the application site to the creek. This distance is approx. 150m at the Threemile site and approx. 25m at the Mill Creek site. At each site two sampling areas were selected - an area with riparian vegetation between the orchard and the creek and an area without riparian vegetation. Spray deposition samplers consisted of Whatman No. 1 filter paper (23 x 26 cm), attached to rectangular aluminum frames. At each location a sampler was positioned horizontally at a height just above the orchard tree canopy, approx. 5m. Four or 5 samplers were located along two transects extending from within the orchard towards the creek. For one transect the sampler at the creek was intercepted by riparian vegetation and the other was not. Application of malathion ULV was by fixed-wing aircraft. Wind speed and direction, and temperature were monitored. Analysis was by gas chromatography with mass selective detection. During June, 2007 2 applications were sampled at each site. At the Threemile Creek site malathion concentrations within the orchard ranged from <0.01 to 1.47 ug/cm2. Malathion concentrations at Threemile Creek were 0.45 and 0.16 ug/cm2 for the transect without riparian vegetation, and 0.05 and 0.16 ug/cm2 with riparian vegetation. At the Mill Creek site malathion concentrations within the orchard ranged from <0.01 to 0.77 ug/cm2. Malathion concentrations at Mill creek were 0.09 and 0.13 ug/cm2 for the transect without riparian vegetation, and 0.05 and 0.08 ug/cm2 with riparian vegetation. These data suggest that the presence of riparian vegetation can result in a small reduction in pesticide stream loading via drift.<br /> <br /> Scientists at Purdue University analyzed liver proteome response of largemouth bass (Micropterus salmoides) exposed to environmental contaminants to identify novel biomarkers of exposure. Adult male bass were exposed to cadmium chloride, atrazine, PCB 126, phenanthrene, or toxaphene via intraperitoneal injection with target body burdens of 0.00067, 3.0, 50, 100, and 2.5 ¼g/g, respectively. After a 96 hr exposure, hepatic proteins were separated with two-dimensional gel electrophoresis and differentially expressed proteins (vs. controls) recognized and identified with MALDI TOF/TOF mass spectrometry. We identified, 30, 18, 18, five, and eight proteins as differentially expressed within the cadmium chloride, atrazine, PCB 126, phenanthrene, and toxaphene treatments, respectively. Alterations were observed in the expression of proteins associated with cellular ion homeostasis (toxaphene), oxidative stress (phenanthrene, PCB 126), and energy production including glycolysis (cadmium chloride, atrazine) and ATP synthesis (atrazine). This work supports the further evaluation of several of these proteins as biomarkers of contaminant exposure in fish.<br /> <br /> African rue (Peganum harmala) is an invasive herbaceous perennial that primarily invades disturbed areas. This species is toxic to cattle and sheep, and has been reported in eight western states, with its largest center of distribution is southern New Mexico and West Texas. Established populations are persistent and difficult to control. We evaluated the long-term response of African rue and associated vegetation to three herbicides (hexazinone, imazapyr, and metsulfuron). Scientists at University of New Mexico tested the effects of herbicide type, application date, and plant moisture stress on necrosis, African rue seedling density, and density of associated grasses and broadleaf plants at two locations in southern New Mexico. Herbicides were applied in Spring, Summer, or Fall 2004, and evaluated annually through 2007. At both sites, target plants sprayed with hexazinone and imazapyr were at least 30 to 40% more necrotic after 3 growing season relative to non-sprayed controls. Early necrotic response to metsulfuron was short-lived, and was not sustained after 2 growing seasons. Hexazinone was most effective when sprayed in June, whereas effects of application date were site-dependent for imazapyr. Imazapyr and metsulfuron reduced African rue seedling density after the first growing season, but this effect was short-lived. Density of African rue seedlings was significantly reduced by hexazinone, and a reduction of at least 50% was sustained through 3 growing seasons. Metsulfuron was least damaging to associated grasses and forbs. Both hexazinone and imazapyr significantly reduced associated vegetation. Supplemental water had negligible effect on herbicide efficacy. Overall, hexazinone provided the most effective control of mature plants and seedlings of African rue, but was also most detrimental to associated vegetation.<br /> <br /> Scientists at UC Davis evaluated farmworker exposure to cholinesterase pesticides. Court-ordered monitoring of blood cholinesterases (ChEs) from orchard workers in Washington State is underway. In 2008, the mean red blood cell acetylcholinesterase (AChE, EC 3.1.1.7) activity was 9.65 + 1.11 umoles/min/ml (n = 1793) and the mean serum (BChE, 3.1.1.6) activity was 5.19 + 0.90 umoles/min/ml (n = 1811). Determinations were made using the Ellman assay and automated equipment of Pathology Associates Medical Laboratories (PAML), Spokane, Washington. This will be one of the largest studies reported to date of farmworker baseline blood data.<br /> <br /> Scientists at Kansas State University sequenced and characterized 11 complete cDNAs encoding glutathione S-transferases (GSTs) in Chironomus tentans. Phylogenetic analysis revealed seven GSTs in three different cytosolic classes including 2 in delta (CtGSTd1, CtGSTd2), 4 in sigma (CtGSTs1, CtGSTs2, CtGSTs3, CtGSTs4) and 1 in omega (CtGSTo1). The remaining four GSTs (CtGSTu1, CtGSTu2, CtGSTu3, CtGSTu4) were unclassified due to their low relatedness to currently known classes of insect GSTs. Reverse-transcription (RT)-PCR analysis of the 11 GST genes showed that CtGSTd1, CtGSTu2, CtGSTu4, CtGSTs1, CtGSTs2, CtGSTs3, CtGSTs4 and CtGSTo1 were expressed in all tissues examined, including salivary glands, hemolymph, midgut, Malpighian tubules, fatbodies and carcass, whereas CtGSTd2 and CtGSTu1 were expressed in a limited number of tissues. RT-PCR analysis also revealed that CtGSTs1 and CtGSTs4 were only two genes that showed significant levels of expression in eggs, whereas all the 11 GST genes showed various levels of expression in all the four larval instars. Real-time quantitative PCR confirmed that the herbicide alachlor increased CtGSTd1, CtGSTs2 and CtGSTs3 gene expression by 2.1-, 2.8- and 4.3-fold, respectively, when fourth-instar midges were exposed to alachlor at 1,000 mg/L for 72h. Such increased expressions were associated with decreased total GST activities, and could be a counteractive measure at the transcriptional level to compensate the reduced GST activity in aquatic midges. <br /> <br /> <br /> Objective 4: Develop technologies that mitigate adverse human and environmental impacts.<br /> <br /> There is scant field fumigation emission rate information specific to Pacific Northwest cooler fall season application conditions. To help fill this fumigant emissions data gap, scientists at Washington State University (Tri Cities) applied Sectagon 42 (42% solution of metam sodium) to two treatment plots (1.7 acres for drizzle boom and 1.8 acres for shank injection) within a 122 acre field circle in Franklin County, WA in the fall of 2008. This study was developed to assess emission rates and total cumulative field loss of metam sodiums gaseous by-product, methyl isothiocyanate (MITC) during and four days post-application under typical Pacific Northwest potato pre-plant fumigation conditions. For each treatment plot, MITC concentrations (in ¼g m-3) were generated from air collected through activated charcoal at eight receptors spaced around the periphery before, during, and throughout the 4-day post application period. MITC field emission rates (¼g m-2 sec-1) together with total cumulative MITC loss over the 4-day post application period were estimated using an Industrial Source Complex Short Term (ISCST3) emissions model that utilized hourly meteorological data gathered at the field study location over the study time frame. California Department of Pesticide Regulations criteria for generating these near-field emission estimates. Drizzle boom test plot measured and modeled emission data were usually well correlated allowing emission rate estimation by linear regression. Upwind estimated MITC contribution from the higher emission drizzle boom plot, however, influenced the reliability for directly correlating field measured/modeled shank emission rates and necessitated a more conservative mean measured/mean flux estimation approach during application and up to 20 hours post-application. We did not attempt to subtract the estimated upwind MITC source contribution to the shank plot when calculating periodic emission rates or estimating total cumulative loss. Following Cal DPR emission criteria, the estimated total cumulative MITC loss by drizzle boom was 47% compared to 13% by soil incorporated shank injection. It is reasonable to anticipate some over-estimation of shank field emission rates. These two concurrent emission assessments provide flux data typical of the cooler fall climatic conditions when PNW fumigations are occurring. <br /> <br />

Publications

Impact Statements

1. The data in this report has formed the basis of a developing regulatory program to investigate the potential of contaminates in biosolids to occur in forage used for livestock feed. Such data will be used to assess the safety of continuation of the use of land applied biosolids in agricultural applications where livestock feed is grown.

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Participants

Monday, June 7 2010 Present: Gan (Chair), Rice (Secretary, Host), Papiernik (Host), Armbrust, Hapeman, Jenkins, Lemley, Li, Miller, Pritsos, Sepulveda, Sterling, Thomas, Wilson, Zhu, Pardini (Administrative Advisor), Johnson (CSREES representative); Tuesday, June 8 2010 Present: Armbrust, Gan, Hapeman, Jenkins, Johnson, Lemley, Li, Miller, Papiernik, Pardini, Pritsos, Rice, Sepulveda, Sterling, Thomas, Wilson, Zhu

Brief Summary of Minutes

Accomplishments

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers.<br /> <br /> Cyromazine is used as an additive in poultry feed to inhibit the development of fly larvae in chicken manure. U.S. Environmental Protection Agency (EPA) method AG-555, modified from method AG-376, has been the standard method for cyromazine analysis in poultry feed. However, these methods are time-consuming (3 h) and require large volumes (200 mL) of solvent. Scientists at Mississippi State University developed an extraction procedure using the QuEChERS method that is faster (30 min) and uses 20 times less solvent than the AG-555 method. After extraction using the QuEChERS method, the extractant was subjected to cleanup using a C-18 solid phase extraction (SPE) followed by filtering through a 0.45 ¼m syringe Teflon filter before liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Recovery of 75.0 ± 6.2% was achieved. The method detection limit (MDL) and the limit of quantitation (LOQ) were 0.028 and 0.094 ppm, respectively. Analyses of commercial poultry feed samples using the QuEChERS method yielded results similar to those obtained via EPA method AG-555.<br /> <br /> Organochlorine pesticides (OCPs) are of concern due to their contamination in foods. Scientists from the University of Hawaii (Honolulu) measured quantities of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), chlordane and hexachlorobenzene (HCB) in 38 honeys labeled from different geographic regions using gas chromatography/ion trap mass spectrometry after accelerated solvent extraction. Mean concentrations (ranges) of HCHs, DDTs, chlordane, and HCB in tested honeys were 2.23 (0.21-8.70), 1.14 (0.10-4.35), 0.45 (0.02-3.75), and 0.17 (nd-1.16) ng g-1, respectively. Concentration ranges of total HCHs (SHCHs), SDDTs, and Schlordane and HCB were 0.21-8.70, 0.10-4.35, 0.02-3.75, and nd-1.16 ng g-1, respectively, in the 38 honeys. Honey samples from developing countries generally contained higher concentrations of SHCHs, SDDTs, Schlordane, and HCB than those from developed countries. Comparison of the ratios of highest and lowest concentrations of SHCHs, SDDTs, Schlordane, and HCB in honeys from developing and developed countries showed relatively similar concentrations of the OCPs in honeys from developing countries and large variation in honeys from developed countries.<br /> <br /> Scientists from Kansas State University evaluated the expression of two chitin synthase genes, AgCHS1 and AgCHS2, to determine if they would be repressed by the chitosan/AgCHS double-stranded RNA (dsRNA)-based nanoparticles through larval feeding in Anopheles gambiae. The AgCHS1 mRNA level and chitin content were reduced by 62.8 and 33.8%, respectively, in the larvae fed on the chitosan/AgCHS1 dsRNA nanoparticles compared with those of the control larvae fed on the chitosan/green fluorescent protein (GFP) dsRNA nanoparticles. The study demonstrated the larvae that fed on the nanoparticles had increased susceptibility to diflubenzuron, and calcofluor white or dithiothreitol, respectively. These results suggest a great potential of using such a nanoparticle-based RNAi technology for developing novel strategies for insect pest management. <br /> <br /> Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems.<br /> <br /> Minimizing atmospheric emissions of soil fumigants is critical for protecting human and environmental health. Covering the soil surface with a plastic tarp is a common approach to restrict fumigant emissions. The mass transfer of the fumigant vapors through the tarp is often the rate-limiting factor in fumigant emissions. Scientists from Morris, MN, developed an approach for standardizing measurements of film permeability based upon determining the resistance (R) of films to diffusion of fumigants. Using this approach, R values were determined for more than 200 film-chemical combinations under a range of temperature, relative humidity, and film handling conditions. Resistance to diffusion was specific for each fumigant/film combination with the largest range of values observed for the fumigant chloropicrin. For each fumigant, R decreased with increasing temperature. Changes in film permeability due to increases in temperature or field installation were generally less than a factor of five. For one film, R values determined under conditions of very high relative humidity (~100%) were at least 100 times lower than when humidity was very low (~2%). This approach simplifies the selection of appropriate films for soil fumigation by providing rapid, reproducible, and precise measurements of their permeability to specific fumigants and application conditions.<br /> <br /> Scientists from the Oregon Agricultural Experiment Station (Corvallis) evaluated the effectiveness of adapted and native woody plant species as drift barriers between cherry orchards and surface water resources in Wasco County (Middle Columbia-Hood Subbasin), Oregon. Wasco County contains nearly 9,000 acres of cherry orchards. Pest management includes the use of organophosphate insecticides, applied by airblast ground sprayers. A site along Mill Creek was chosen based on prevailing wind direction and riparian vegetation. Two sampling areas along the creek were selected - an area with riparian vegetation between the orchard and the creek and an area without riparian vegetation. Spray deposition samplers consisted of nylon screens (23 x 26 cm), attached to rectangular aluminum frames. At each location a sampler was positioned horizontally at a height just above the orchard tree canopy, at approximately 5 meters. Four samplers were located along two transects extending from within the orchard towards the creek. For one transect the sampler at the creek was intercepted by riparian vegetation and the other was not. The ground trials were conducted in a simulated creek scenario approximately 5 meters from Mill Creek. The distance between the edge of the simulated creek and the pear orchard was 20 meters. Two types of sprayers were evaluated: the Accutech Orchard Tower sprayer (Blueline Manufacturing Company Inc, Moxee, WA) and the standard air blast sprayer (Air-O-Fan, Reedley, CA). In addition, the air blast sprayer was operated both normally and modified with a plywood doughnut affixed to the rear of the sprayer. The doughnut restricts air intake (cut to reduce the area of the fan by half) to reduce airflow through the sprayer, resulting in a reduction in drift. Deposition data suggest that riparian vegetation was generally effective in reducing deposition near the creek for applications using the Accutech sprayer. Results for the Air-O-fan were inconclusive. <br /> <br /> Constructed wetlands (CWs), along with other vegetative systems, are increasingly being promoted as a mitigation practice to treat non-point source runoff to rid contaminants such as pesticides. However, studies so far have mostly focused on demonstrating contaminant removal efficiency. In this study, using two operational CWs located in the Central Valley of California, we explored the mechanisms underlying the removal of pyrethroids and chlorpyrifos from agricultural runoff water, and further evaluated the likelihood for the retained pesticides to accumulate within the CWs over time. In the runoff water passing through the CWs, pyrethroids were associated overwhelmingly with suspended solids >0.7 ¼m, and the sorbed fraction accounted for 62-93% of the total concentrations. The derived Kd values for the suspended solids were in the order of 104-105, substantially greater than those reported for bulk soils and sediments. Distribution of pyrethroids in the wetland sediments was found to mimic organic carbon distribution, and was enriched in large particles that were partially decomposed plant materials, and clay-size particles (<2 ¼m). Retention of suspended particles, especially the very large particles (>53 ¼m) and the very fine particles, is thus essential in removing pyrethroids and chlorpyrifos in CWs. Under flooded and anaerobic conditions, most pyrethroids and chlorpyrifos showed moderate persistence. However, the retained pyrethroids were very stable in dry and aerobic sediments between irrigation seasons, suggesting a possibility for accumulation over time. Therefore, the long-term ecological risks of CWs should be further understood before their wide adoption.<br /> <br /> Scientists in Beltsville, MD, evaluated water quality in the Choptank River estuary, a tributary of the Chesapeake Bay that since 1998 has been classified as impaired waters under the Federal Clean Water Act. Multiple water quality parameters (salinity, temperature, dissolved oxygen, chlorophyll a) and analyte concentrations (nutrients, herbicide and herbicide degradation products, arsenic, and copper) were measured at seven sampling stations in the Choptank River estuary. Samples were collected under base flow conditions in the basin on thirteen dates between March 2005 and April 2008. As commonly observed, results indicate that agriculture is a primary source of nitrate in the estuary and that both agriculture and wastewater treatment plants are important sources of phosphorus. Concentrations of copper in the lower estuary consistently exceeded both chronic and acute water quality criteria, possibly due to use of copper in antifouling boat paint. Concentrations of copper in the upstream watersheds were low, indicating that agriculture is not a significant source of copper loading to the estuary. Concentrations of herbicides (atrazine, simazine, and metolachlor) peaked during early-summer, indicating a rapid surface-transport delivery pathway from agricultural areas, while their degradation products (CIAT, CEAT, MESA, and MOA) appeared to be delivered via groundwater transport. Some in-river processing of CEAT occurred, whereas MESA was conservative. This work provides a baseline against which to compare future changes in water quality and may be used to design future monitoring programs needed to assess restoration strategy efficacy.<br /> <br /> The anodic Fenton treatment method (AFT) has been successfully applied to the removal of Ciprofloxacin (CIP), a widely used fluoroquinolone antibiotic, from aqueous solution. Degradation kinetics were found to be species dependent. At initial pH 3.2, CIP remained in its cationic form and the kinetics followed a previously developed AFT model. At an initial near-neutral pH, CIP speciation changed during the degradation, due to pH changes over the process, and no obvious model fit the data. Density functional theory (DFT) calculations indicated a protonated species-dependent reaction affinity toward hydroxyl radicals. Scientists from Cornell University (Ithaca, NY) derived a new model based on the AFT model with the addition of species distribution during the degradation, and it was shown to describe the degradation kinetics successfully. Degradation of reference compounds further confirmed that the free carboxylic acid group, which contributes to the species changes, plays a key role in the observed degradation pattern. Furthermore, degradation of reference CIP-metal complexes confirmed that the formation of these complexes does not have a major effect on the degradation pattern. By the end of the AFT treatment, neither CIP nor its degradation products were detected, indicating successful removal of antibacterial properties.<br /> <br /> Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems.<br /> <br /> Proteomics has gained popularity in the field of ecotoxicology as a holistic tool for unraveling novel mechanisms of toxicity. The holo-artic amphipod Diporeia spp. is declining at precipitous rates in the Great Lakes. Scientists from Purdue University (West Lafayette, Indiana) evaluated the use of the well studied amphipod model Hyalella azteca as a surrogate for Diporeia. A proteomics approach determined whether these two species of amphipods responded similarly to the same chemicals (atrazine, ATZ, and one of its metabolites, desethylatrazine, DEA) and enhanced the understanding of the mechanisms of toxicity of ATZ and DEA in aquatic invertebrates. Disruption in energy production and mitochondrial function was observed. Proteins associated with hormonal disruptions in vertebrates were identified, suggesting potential endocrine disruption. In addition, H. azteca and Diporeia spp. responded with similar proteomic profiles after ATZ and DEA exposure suggesting that H. azteca may be used as a surrogate model organism for Diporeia spp. <br /> <br /> The impact of non-lethal agrochemical/environmental exposures on non-target avian species are difficult to access particularly in terms of developing Natural Resource Damage Assessments (NRDA). Scientists from the University of Neveda (Reno) used a homing pigeon model developed at UNR for assessing the impact of environmental exposures of methylmercury on flight time of avian species. During the control and dosed flight studies, water consumption, temperature and humidity were monitored on a daily basis in order to determine the relationship between these parameters. The data show that flight activity, temperature and humidity impact water consumption rates in these birds and need to be considered when developing NRDAs. Flight time effects from methylmercury exposure are currently being assessed. <br /> <br /> Objective 4: Develop technologies that mitigate adverse human and environmental impacts.<br /> <br /> Pesticides associated with the turfgrass industry have been detected in storm runoff and surface waters of urban watersheds; invoking concern of their potential environmental effects and a desire to reduce their transport to non-target locations. Scientists from St. Paul, MN, quantified levels of chlorpyrifos, dicamba, dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-D), flutolanil, and mecoprop-p (MCPP) transported in runoff from bentgrass (Agrostis palustris) fairway turf managed with solid tine (ST) or hollow tine (HT) core cultivation to determine which cultivation practice is more efficient at mitigating environmental risk. Plots receiving HT core cultivation showed a 10% and 55% reduction in runoff volume and a 15 to 57% reduction in pesticide transport with runoff at 63 d and 2 d following core cultivation. Estimated environmental concentrations of the pesticides in a surface water receiving runoff from turf managed with ST core cultivation exceeded the median lethal concentration (LC50) or median effective concentration (EC50) of nine aquatic organisms evaluated. Replacing ST core cultivation with HT core cultivation reduced surface water concentrations of the pesticides to levels below the LC50 and EC50 for most these aquatic organisms. Results of this research provide quantitative information that will allow for informed decisions on cultural practices that can maximize pesticide retention at their site of application; improving pest control in turf while minimizing environmental contamination and adverse effects associated with the off-site tranpsort of pesticides. <br /> <br /> The north shore of Lake Apopka, located near Orlando, FL, is heavily contaminated with various agrochemicals. These muck soils are roughly 40% organic matter and 40% water with a large capacity for storing nutrients and pesticides. Some of the organochlorine compounds such as DDT and its metabolites, DDD and DDE, have contaminated the soil from the last time DDT was applied over thirty years ago. Scientists from the University of Florida (Gainesville) discovered that two wood-rot fungi, Phenarochaete chrysosporium and an indigenous Nectrai species, are equally effective in remediating the soil, once the proper conditions are met. In four months, the concentration of p,p-DDT for the 0 3 inch (0 - 8 cm) depth declined by 65.3, 57.8% and 53.3% when the surface of the mesocosm soil was sprinkled weekly with 3.3 liters of P. chrysosporium rinse, or Nectria sp.rinse or tap water only, respectively. The tap water treatment was hypothesized to be effective due to a >50% reduction in soil nitrate, a known inhibitor of extracellular enzyme production by wood-rot fungi. The extracellular enzymes allowed the indigenous Nectria species to actively remediate DDT, DDE, and DDD in situ.<br /> <br /> The United States has been using pyridostigmine bromide (PB) as a prophylactic to the toxic effects of soman, a potent chemical warfare agent, since the first Gulf War. Scientists from the University of California (Davis) and colleagues showed that PB protected a significant percentage of human intercostal muscle AChE in vitro. They reported that inhibition of bovine red blood cell (RBC) AChE is similarly protected by PB from several organophosphates (OP) pesticides including chlorpyrifos oxon, diazinon oxon, paraoxon and DFP but AChE inhibition from malaoxon was not given the conditions of the study. Even though bovine RBC AChE is similar in its properties to human AChE, further study is needed of the extent of protective effect of PB on pesticides and human AChE. The findings suggest that pretreatment with PB might be of use in protecting growers and farmworkers from the effects of selected pesticides in the absence of protective clothing and to the public, in general, in the event of terrorist attacks. <br /> <br /> Biofuel crops can potentially be grown on arid lands that do not compete with other food and feed crops. Grindelia squarrosa, commonly known as gumweed, is a flowering plant species common to Nevada that is found in many areas of the inter-mountain west, particularly along roadsides where increased precipitation is available from runoff. A preliminary analysis of numerous desert plants by Lemaire in 1982 (unpublished) singled out gumweed as a strong candidate for crude oil production. High oil yield per acre, along with minimal watering requirements, makes gumweed a strong crop for biodiesel production in the western United States. Scientists from the University of Nevada (Reno) reported that processed gumweed provides an average of 12-23 % crude oil by dry weight, depending on the plant stand collected and the method of sample drying. While the majority of hydrocarbons present in the extracts are at the heavy end of diesel fuel, a derivatized B20 blended biodiesel was shown to meet ASTM standards for flash point, kinematic viscosity, and sulfur content. Gumweed biodiesel blends offer a useful source of additional fuel that can be produced from crops grown in arid environments with minimal irrigation needs, while reducing the competition between food and biofuel crops. No additional engine modifications are needed for the use of B5 or B20 biofuels. <br />

Publications

Impact Statements

1. The data in this report represent scientific discoveries that improve the efficiency of pesticide analysis and biofuel production, advances the understanding of pesticide fate in the environment, and describes mechanisms and efficacies of agrichemical toxicity, mitigation and remediation. These discoveries will facilitate the development of technologies that can improve pest management and minimize adverse human and environmental impacts.

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