Brief Summary of Minutes of Annual Meeting

Participants: Alvin Smucker, Michigan State University Kang, Xia, Virginia Tech; Nancy Cavallaro  NIFA; Gimenez, Daniel Rutgers University; Sasha Kravchenko, Michigan State University; Ganga Hettiarachchi, Kansas State University; Peter Tomlinson, Kansas State University; Strawn, Daniel, University of Idaho; James Harsh, Washington State University The annual meeting of the Multistate Research Project, NC1187 convened Tuesday, Nov 5, 2013 at 5 PM in Tampa, Florida in conjunction with the ASA-CSA-SSSA Annual International Meeting. This was the beginning year for the new committee: Daniel Gimenez, the new chair, Dan Strawn, vice-chair, and Ganga Hettiarachchi, secretary. Daniel Gimenez welcomed participants, and asked for approval for the 2012 Annual Meeting minutes. This was moved to approve by Alvin Smucker and seconded by Nancy Cavallaro. Gimenez also asked for last year report from the group to be compiled in the annual report. Prior to this meeting in FL he sent a form to be used for this and reminded everyone to fill that out. We welcomed new participants, Peter Tomlinson from Kansas State University and Sasha Kravchenko from Michigan State University. For the benefit of our new as well as all participants, each participant highlighted some of his or her current work relevant to NC1187. Daniel Gimenez suggested that the group can work together on a white paper and collaborative grant proposals and group talked about how to move forward with those two ideas. Alvin Smucker offered to share the proposal and the program for the conference on Synchrotron Characterization of Airborne Particulates Originating from Agricultural Soils and other Modified Ecosystems organized by members of this group as a framework for the future white paper and discussion. Discussion will be continued through email with Gimenez taking the lead. The next item was a report from Nancy Cavallaro on RFPs from NIFA that would be relevant to our project. Dr. Cavallaro mentioned that there will be no big cuts in the formula funds or competitive grants; AFRI programs will continue. Cavallaro again reminded the group how important it is not to give a Hatch Project the title as a NIFA grant because it can be mistakenly perceived as duplicate funding issues. Mandatory program areas to be funded next year involve Biomass initiatives, Food safety and Food security. She also mentioned that AFRI Foundational Program RFPs will be announced in December 2013 and those will be primarily focus on Water Sustainability- Research, Education and Extension. Questions were raised regarding 2013 Carbon Cycle proposals and Dr. Cavallaro said agencies involved are looking at these proposals but funding situations need to be clarified prior to making any decisions. At the conclusion, Gimenez stated that he would compile the last year reports and work on creating an outline of a white paper.

Members of this project are applying a wide range of analytical tools to elucidate mechanisms of physical and chemical protection of carbon in soils, colloid transport through soil, removal of soil contaminants, effect of climate change on soil structure, and deposition of synthetic nanoparticles on the human respiratory system. More detailed description of research outcomes by the different groups is presented below. Drs. Alexandra Kravchenko and Alvin Smucker together with their co-workers continued their work on the characterization of the internal structure of soil aggregates in relation to the ability of microorganisms to move and grow in a physically and chemically heterogeneous environment. The structure of intra-aggregate pores governs accessibility of C to microbial decomposition within the aggregates and therefore substantially contributes to C sequestration in soils. The goal of their work is to identify and quantitatively describe relationships between soil intra-aggregate structure, soil C processes, microbial activity, and microbial community compositions using X-ray computed micro-tomography (CT) tools. The working hypothesis of the group at Michigan is that when greater micro-scale spatial heterogeneity of soil physical structure is generated by enhanced plant root activities it becomes one of the key forces enabling physical protection of C in soils of terrestrial ecosystems. Their work has demonstrated that continuous vegetative coverage strongly enhances formation of soil aggregates with greater internal heterogeneity of intra-aggregate pore distributions. In such aggregates, pore characteristics can restrict the movement of microorganisms only to areas accessible via medium sized pores, while relatively large intra-aggregate domains can remain inaccessible to microorganisms moving with water flow. Moreover they are finding that indigenous microbial community composition can be also affected by intra-aggregate physical structure, with some bacterial groups being more prevalent in the intra-aggregate areas with greater presence of large pores. They also found that spatial patterns in intra-aggregate pore structure appear to be related to content of total soil C, higher values of which were found associated with greater intra-aggregate pore heterogeneity. Their preliminary results indicate that pore structure has a major effect on the rate of decomposition of the freshly added plant residue as well as on the processes of decomposition of inherent soil organic matter associated with presence of plant residue, also known as the priming effect. Dr. Stephen Anderson and his group also used X-ray computed tomography, but in their case to study chemical dispersivity in soil. Chemical dispersivity is a common parameter needed for pollutant fate and transport models in geomedia environments. Dr. Andersons group conducted a study to estimate the effect of distance on dispersivity measured in columns using X-ray computed tomography. Columns containing natural and homogeneous media were evaluated. The convection-dispersion equation appeared to be appropriate for the column distances used in this study. Dispersivity was found to be a function of distance from the upstream end in the column studies for the natural porous media but not the homogeneous porous media. Dispersivities were estimated using the average breakthrough slope for selected scan planes (mean slope method), using the solution of the convection-dispersion equation fit to the average breakthrough for selected scan planes (curve fit method), and using groups of pixels in the selected scan planes (group pixel method). Values estimated using the mean slope method or the curve fit method were found to be scale dependent; however values with the group pixel method were not. Fractal dimension values appeared within appropriate ranges when estimated for the core samples using the mass versus radius relationship. Results suggest dispersivity may be dependent upon the sampling volume rather than the straight-line length solute travels through media. Dr. Daniel Giménez and his group continued investigating the effect of climatic variables sustained for several years on soil structure. In July 2013, an experiment at the Konza Prairie Biological Station near Manhattan, Kansas (39°059 N, 96°359 W), was sampled. This experiment was established in 1991 and consisted of altering the natural precipitation regime of the area through selective irrigation. The objective of this sampling was to determine if a change in precipitation regime (amount and frequency) induced changes in soil structure and related water retention. The design of this long-term experiment includes two irrigated plots alternated in space with two non-irrigated plots. Each plot spans a distance of about 140 m over a topographic gradient between summit and footslope of about 7 m. Irrigation is achieved with sixteen 1.0-m tall high-impact rotating sprinkler heads placed at a separation interval of 10 m. The irrigation protocol is aimed at maintaining the average volumetric soil water content in the root zone (0-30 cm) at a level of 0.25 or higher throughout the growing season. The two replicates of irrigated and non-irrigated plots were sampled at the footslope and summit positions (4 plots x 2 positions: 8 sampling locations). Sampling procedures at each site included the excavation of a large undisturbed block for determination of the fractal dimension of mass and the extraction of two soil cores for measurement of water retention properties. In addition, fifteen determinations of infiltration rates were made in the field at each sampling site with automated tension infiltrometers. Each determination consisted of measurements of steady state at infiltration rates at equilibrium with 5 pressure potentials (-0.5, -1.5, -2.5,-3.5 and -4.5 cm). Infiltration rates were corrected for temperature and expressed at a temperature of 20 °C. Combination of 2D and 3D determinations of soil volume allowed us to cover an unprecedented range of soil volumes. These data will be used to estimate one or more fractal dimensions over the measured range, which, in turn, will be used to infer changes in soil structure that may have resulted from changes in the amount and frequency of water inputted to a soil through rainfall or rainfall plus precipitation. The analysis of infiltration rates show that treatment (irrigated vs. non-irrigated) as well as position (summit vs. footslope) influenced infiltration rates. This is an important result stressing the importance of considering soil properties when projecting the effects of climate change on ecosystem processes. Infiltration rates at various tensions can be used as a proxy for pore size distribution. In this case, irrigated plots had less porosity in the range of pore sizes between 0.6 and 1 mm corresponding to pressure potentials of -2.5 cm and -1.5 cm, respectively. The mechanisms leading to lower infiltration rates in irrigated plots are currently under investigation, but they are likely related to an increase in root biomass. Dr. James Harsh and co-workers applied transmission electron microscopy and energy dispersive X-ray to study the elemental composition of colloids migrating through a lysimeter sampled from the US Department of Energy Hanford site. The Hanford site is located in a semiarid region and has a deep vadose zone with low recharge rates. The overall goal of the project was to study colloid-facilitated movement of contaminants originating from nuclear waste processing under low recharge rates. The hypothesis of the work was that the low recharge rates and low water contents in semiarid regions would tend to inhibit movement of colloidal particles, thereby reducing the risk for colloid-facilitated contaminant transport. The goal of this study was to investigate whether in situ natural colloids can be mobilized and transported in undisturbed, deep vadose zone sediments at the Hanford site under typical, semiarid recharge rates. An undisturbed sediment core (i.d. 50 cm, 59.5 cm height) was sampled from a depth of 17 m below ground at the Hanford 200 Area. The core was set up as a laboratory lysimeter and exposed to an infiltration rate of 18 mm/yr by applying simulated pore water onto the surface. Particle concentrations were quantified in the column outflow, and selected samples were examined microscopically using transmission electron microscopy and for elemental composition with energy dispersive X-ray. Measured water contents and potentials were used to calibrate a numerical model (HYDRUS-1D), which was then applied to simulate colloid mobilization from the sediment core. During 5.3 years of monitoring, natural colloids like silicates, aluminosilicates, and Fe-oxides were observed in the core outflow, indicating the continuous mobilization of in situ colloids. The total amount of particles mobilized during 5.3 years corresponded to 1.1% of the total dispersible colloids inside the core. Comparison of the amounts of colloids released with weathering rates suggests that mineral weathering can be a major source of the mobilized colloids. The fitted colloid release rate coefficient was 6 to 7 orders of magnitude smaller than coefficients reported from previous studies, where disturbed Hanford sediments and higher flow rates were used. Their findings demonstrate that even under low recharge rates and water contents typical for semiarid, deep vadose zone sediments, particles can continuously be mobilized, although the total mass of particles is low. In a related study, the same group used electron microscopy and energy-dispersive X-ray analysis to study the transport of Europium (Eu) colloids in the vadose zone at the semiarid Hanford site. Eu-hydroxy-carbonate colloids, Eu(OH)(CO3 ), were applied to the surface of field lysimeters, and migration of the colloids through the sediments was monitored using wick samplers. The lysimeters were exposed to natural precipitation (145 231 mm/year) or artificial irrigation (124 348 mm/year). Wick outflow was analyzed for Eu concentrations, supplemented by electron microscopy and energy-dispersive X-ray analysis. Small amounts of Eu colloids (<1%) were detected in the deepest wick sampler (2.14 m depth) 2.5 months after application and cumulative precipitation of only 20 mm. They observed rapid transport of Eu colloids under both natural precipitation and artificial irrigation; that is, the leading edge of the Eu colloids moved at a velocity of 3 cm/day within the first 2 months after application. Episodic infiltration (e.g., Chinook snowmelt events) caused peaks of Eu in the wick outflow. While a fraction of Eu moved consistent with long-term recharge estimates at the site, the main mass of Eu remained in the top 30 cm of the sediments. This study illustrates that, under field conditions, near-surface colloid mobilization and transport occurred in Hanford sediments. Dr. Kang Xia and co-workers have used the phage display technique to identify peptides that specifically bind to montmorillonite (2:1 layersilicate) and kaolinite (1:1 layersilicate), hematite (Fe2O3), alumina (Al2O3), and silica (SiO2). Using synchrotron-based spectroscopy, it was demonstrated that small peptides adsorbed at a titled angle relative to surface of montmorillonite, however, the binding motif of a peptide significantly affects the degree of molecular orientation angle. The group found strong evidence of preferential accrual of peptides/proteins over other organic nitrogen compounds associated with soil minerals in three independent undisturbed ecosystems developed across 4000, 20,000, and 60,000-year chronosequences, respectively. The result from this investigation strongly support that peptide/protein-mineral interaction plays an important role in affecting terrestrial N cycle. They have found that the mineral-associated organic C consists of four major species: aromatic-C, phenolic-C, aliphatic-C, carboxylic-C, and O/N-alkyl-C. The mineral-associated organic C speciation composition varied significantly during the soil development for all 3 independent soil chronosequences. The results from this investigation suggest that there is continuous mineral sequestration and stabilization of aliphatic-C and O/N-alkyl-C compounds during soil development, while the aromatic-C compounds associated with soil minerals were continuously transformed into other C species. Bioavailable amino acids and organic C speciation in soils of north-south and west-east transects of continental United States were assessed. This study suggested that precipitation has more impact on modifying amino acid composition and soil organic C speciation than temperature. Dr. Ganga Hettiarachchi and her group are using new generation analytical techniques such as synchrotron based-STXM-NEXAFS, -XANES, and XRD, and 13C NMR as well as traditional wet chemical analysis such as iron/aluminum fractionation techniques to understand physical, chemical, and mineralogical mechanisms of carbon (C) sequestration. Chemical protection of soil organic carbon (SOC), due to adsorption of SOC onto mineral surfaces through different bonding mechanisms and chemical recalcitrance, protects SOC from decomposition. On the other hand differences in mineralogy, physical locations of organic carbon, and SOC and mineral distribution could result in differences in SOC protection and therefore, a differential response to global climate change. Overall objective of this research is to understand process-level physico-chemical mechanisms that control soil aggregate development and stabilization. The research focuses on gathering information on how interactions between physical location, OC chemistry, and mineralogy of soil aggregate contribute to SOC sequestration. In 2013, Dr. Hettiarachchi and her group did research on soil aggregates collected from two long-term field sites in temperate and tropical climates. They were under differing management practices (such as tillage, crop rotation, manure addition, and/or fertilization), which led to different levels of aggregation, soil C, and microbial communities. The group applied new generation analytical techniques such as synchrotron based-STXM-NEXAFS, -XANES, and XRD, and 13C NMR as well as traditional wet chemical analysis such as iron/aluminum fractionation techniques to understand physical, chemical, and mineralogical mechanisms of C sequestration. This work is mainly supported by the NSF Award No. EPS-0903806 and K-State Research and Extension. Other ongoing projects by Dr. Hettiarachchi focused on investigating mobility, availability and reaction products of phosphorus fertilizers in different soils; and using synchrotron based x-ray techniques to obtain contaminant (lead, arsenic, zinc or selenium) speciation to understand/explain contaminant mobility and/or bioavailability in soils. Dr. Daniel Strawn and co-workers applied X-ray absorption spectroscopy to the study of molecular analysis of copper solution treated with sugar beet lime. They found that the copper adsorbed on the lime waste as a hydroxide mineral on the lime surface. Dr. Donald Sparks and his group have shown in numerous publications that mixed metal (e.g., Ni and Zn) hydroxide precipitates, of the layered double hydroxide (LDH) type, form on mineral surfaces and in contaminated field soils. The formation of these phases greatly sequesters the metal and reduces its bioavailability. Such precipitate formation is an important natural attenuation strategy for immobilizing toxic trace metals such as Co, Ni, and Zn in soils. However, in soils the presence of anionic ligands may affect the metal precipitation formation. They therefore studied the role of glyphosate (GPS), one of the most widely used herbicides in agricultural production systems, on Zn sorption/precipitation on ³-alumina using a batch technique, Zn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and 31P NMR spectroscopy. The EXAFS analysis revealed that, in the absence of glyphosate, Zn adsorbed on the aluminum oxide surface mainly as bidentate mononuclear surface complexes at pH 5.5, whereas ZnAl layered double hydroxide (LDH) precipitates formed at pH 8.0. In the presence of glyphosate, the EXAFS spectra of Zn sorption samples at pH 5.5 and 8.0 were very similar, both of which demonstrated that Zn did not directly bind to the mineral surface but bonded with the carboxyl group of glyphosate. Formation of ³-alumina-GPS-Zn ternary surface complexes was further suggested by 31P solid state NMR data which indicated the glyphosate binds to ³-alumina via a phosphonate group, bridging the mineral surface and Zn. Additionally, they showed the sequence of additional glyphosate and Zn can influence the sorption mechanism. At pH 8, ZnAl LDH precipitates formed if Zn was added first, and no precipitates formed if glyphosate was added first or simultaneously with Zn. In contrast, at pH 5.5, only ³-alumina-GPS-Zn ternary surface complexes formed regardless of whether glyphosate or Zn was added first or both were added simultaneously. Dr. Gediminas Mainelis and co-workers modeled deposition of particles released from nanotechnology-based consumer sprays in the human respiratory system. Five nanotechnology-based and five regular spray products were included in these calculations. Modeling was performed using ICRP lung deposition model. For seven out of ten sprays, the highest inhalation exposure was observed for the coarse (2.5  10 ¼m) particles, while being minimal or below the detection limit for the remaining three sprays. Nanosized aerosol particles (14  100 nm) were released, which resulted in low, but measurable inhalation exposures from all the investigated consumer sprays. Eight out of ten products produced high total deposited aerosol doses on the order of 101  103 ng/kg bw/application, ~85  88% of which were in the head airways and only <10% in the alveolar region and <8% in the tracheobronchial region. One nano and one regular spray produced substantially lower total deposited doses (by 2  4 orders of magnitude less), only ~52  64% of which were in the head while ~29  40% in the alveolar region. Outputs 1. Drs. Alexandra Kravchenko and Alvin Smucker are developing a new set of tools to enable researchers to take full advantage of data obtained with X-ray CTs. In particular, ability to use X-ray CT to identify presence, quantities, and characteristics of particulate organic matter (POM) within intact soil samples will be of great use for soil C research. They have developed and tested a procedure for POM determination using X-ray CT images of intact soil samples. The procedure combined image pre-processing steps with discriminant analysis classification. Image pre-processing was used for preliminary POM identification based on the range of gray values (GV) along with shape and size of POM pieces. Final POM identification was achieved with discriminant analysis conducted using statistical and geostatistical characteristics. POM identified in the intact individual soil aggregates using the proposed procedure was in a good agreement with POM measured in the studied aggregates using conventional lab method (R2 of 0.78 and RMSE of 0.0028 g/g). The manuscript describing the developed procedure has been submitted to the Soil Science Society of America Journal. 2. Dr. Daniel Strawn and co-workers investigated a method for efficient removal of copper from spent dairy cow hoof baths. The method will allow copper to continue to be used as a fungicide while preventing copper from being added to agricultural soils with the manure. 3. Research by Dr. Ganga Hettiarachchi and her group will help to develop or improve management options for climate change adaptation or mitigation. Finally understanding the relative importance of chemical and mineralogical contribution for carbon stabilization is needed to develop process-based soil carbon models. Speciation of phosphorus and contaminants in soils will help to design better and efficient P fertilizers and P management practices for various soils and remediation or management of contaminants in soils, respectively. 4. This project facilitated the training of graduate students and postdocs at the participating institutions. At Michigan State University, one postdoctoral research associate worked on research related to the project, a PhD student and multiple undergraduate students participating in soil and image analyses were trained. At the University of Missouri, a graduate student completed a PhD degree studying the environmental benefits of agroforestry buffers for claypan soils assessed using APEX and fuzzy logic models. At Virginia Tech, two postdoctoral researchers gained experience on designing and conducting independent research and synthesizing experiment results for presentation and publication and two graduate students were trained at two state of- the-art international research facilities to utilize synchrotron-based X-ray absorption spectroscopy for research on C and N biogeochemistry. At Kansas State University, eight beamtime proposals had allocated beamtime and six graduate students have had opportunities to train and/or conduct synchrotron based research work at the APS, ALS and CLS. At the University of Delaware, the project assisted on the training of three graduate students and a postdoctoral researcher. One doctoral student, who conducted research associated with the project, received his Ph.D. degree in December, 2013. At Rutgers University, a graduate student participating in this project became proficient in the use of sophisticated aerosol measurement equipment used to measure airborne nano-sized particles (Mainelis). Sampling at the Konza Prairie Biological Station (Giménez) was achieved with the help of two undergraduate students from Rutgers University and one MS visiting student from the Ecole d'Ingénieurs de PURPAN (France). One MS student from the University of Kansas also participated in data collection.

Chu, B., K.W. Goyne, S.H. Anderson, C.H. Lin, and R.N. Lerch. 2013. Sulfamethazine sorption to soil: Vegetative management, pH, and dissolved organic matter effects. J. Environ. Qual. 42:794-805. Chu, B., S.H. Anderson, K.W. Goyne, C.H. Lin, and R.N. Lerch. 2013. Sulfamethazine transport in agroforestry and cropland soils. Vadose Zone J. 12(2):1-14. http://dx.doi.org/doi:10.2136/vzj2012.0124 Senaviratne, G.M.M.M.A., R.P. Udawatta, C. Baffaut, and S.H. Anderson. 2013. Agricultural Policy Environmental eXtender simulation of three adjacent row-crop watersheds in the claypan region. J. Environ. Qual. 42: 726-736. Anderson, S.H., and J.W. Hopmans. 2013. Soil-water-root processes: Advances in tomography and imaging. 304 pp. Soil Science Society of America Special Publication 61, Madison, WI. Udawatta, R.P., S.H. Anderson, C.J. Gantzer, and S. Assouline. 2013. Computed tomographic evaluation of earth materials with varying resolutions. p. 97-112. In S.H. Anderson and J.W. Hopmans (eds.) Soil-Water-Root Processes: Advances in Tomography and Imaging, Soil Science Society of America Special Publication 61, Madison, Wisconsin. Anderson, S.H., B. Haeffner, and R.L. Peyton. 2013. Chemical dispersivity affected by homogeneous and fractal porous media. Procedia Computer Science 15:(in press). Anderson, S.H., H.J. Shieh, and R.L. Peyton. 2013. Chemical transport in undisturbed soils estimated using transfer function models. Procedia Computer Science 15:(in press). Anderson, S.H., H.J. Shieh, and R.L. Peyton. 2013. Chemical transport in undisturbed soils estimated using transfer function models. Complex Adaptive Systems Conference Abstracts, 13-15 November, Baltimore, MD. Anderson, S.H., B. Haeffner, and R.L. Peyton. 2013. Chemical dispersivity affected by homogeneous and fractal porous media. Complex Adaptive Systems Conference Abstracts, 13-15 November, Baltimore, MD. Senaviratne, A., R.P. Udawatta, C. Baffaut, and S.H. Anderson. 2013. APEX simulation: Environmental benefits of agroforestry and grass buffers for corn-soybean watersheds. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Senaviratne, A., R.P. Udawatta, S.H. Anderson, C. Baffaut, and A.L. Thompson. 2013. Performance of geno-fuzzy model on rainfall-runoff predictions in claypan watersheds. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Simmons, L.A., and S.H. Anderson. 2013. Soil physical properties as affected by logging activities in a Central Hardwood Forest. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Ananyeva, K., W. Wang, A.J.M. Smucker, M.L. Rivers, A.N. Kravchenko. 2013. Intra-aggregate pore structures are related to total C distribution within soil macro-aggregates. Soil Biology and Biochemistry 57:868-875. Anderson, S.H., and J.W. Hopmans. 2013. Soil-water-root processes: Advances in tomography and imaging. 304 pp. Soil Science Society of America Special Publication 61, Madison, WI. Anderson, S.H., B. Haeffner, and R.L. Peyton. 2013. Chemical dispersivity affected by homogeneous and fractal porous media. Procedia Computer Science 15:(in press). Anderson, S.H., B. Haeffner, and R.L. Peyton. 2013. Chemical dispersivity affected by homogeneous and fractal porous media. Complex Adaptive Systems Conference Abstracts, 13-15 November, Baltimore, MD. Anderson, S.H., H.J. Shieh, and R.L. Peyton. 2013. Chemical transport in undisturbed soils estimated using transfer function models. Procedia Computer Science 15:(in press). Anderson, S.H., H.J. Shieh, and R.L. Peyton. 2013. Chemical transport in undisturbed soils estimated using transfer function models. Complex Adaptive Systems Conference Abstracts, 13-15 November, Baltimore, MD. Aramrak, S., M. Flury, J.B. Harsh, R.L. Zollars and H.P. Davis. 2013. Does Colloid Shape Affect Detachment of Colloids by a Moving Air-Water Interface? Langmuir 29: 5770-5780. doi:10.1021/la400252q. Chu, B., K.W. Goyne, S.H. Anderson, C.H. Lin, and R.N. Lerch. 2013. Sulfamethazine sorption to soil: Vegetative management, pH, and dissolved organic matter effects. J. Environ. Qual. 42:794-805. Chu, B., S.H. Anderson, K.W. Goyne, C.H. Lin, and R.N. Lerch. 2013. Sulfamethazine transport in agroforestry and cropland soils. Vadose Zone J. 12(2):1-14. http://dx.doi.org/doi:10.2136/vzj2012.0124 Fahrenfeld, N., K. Knowlton, L. A. Krometis, W. C. Hession, K. Xia, E. Lipscomb, K. Libuit, B. L. Green, A. Pruden. 2013. Effect of Manure Application on Abundance of Antibiotic Resistance Genes and their Attenuation Rates in Soil: Field-Scale Mass Balance Approach. Environ. Sci. Technol. (in review). Giménez , D., G.B. Runion, J.S. Caplan, B. Clough, S.A. Prior, and H. A.Torbert. 2013. Changes in Soil Structure Resulting From Elevated Carbon Dioxide and Nitrogen Levels in a Pasture System. ASA-CSSA-SSSA 2013 International Annual Meetings, November 3-6, Tampa, Florida. Gunatilake, S. R., S. Steelhammer, J. W. Kwon, J. Rodriguez, K. Xia, K. Armbrust, and T. E. Mlsna. 2013. Analysis of Estrogens in Wastewater using solid phase extraction, the QuECHERS cleanup, and liquid chromatography tandem mass spectrometry. J. AOAC International. 96: 1440-1447. Hildebrandt, B., A.N. Kravchenko, T.L. Marsh. 2013. Biogeochemical processes controlling soil carbon storage in conventional and cover-crop-enhanced row crop agro-ecosystems. Presented at the 5th Annual Argonne Soil Metagenomics Meeting, Oct 24, Bloomingdale, IL. Ippolito, J.A., D.G. Strawn, and K.G. Scheckel. 2013. Investigation of copper sorption by sugar beet processing lime waste. J. Environ. Qual., 42:919-924. Kravchenko A., H.-C. Chun, M. Mazer, W. Wang, J.B. Rose, A. Smucker, and M. Rivers. 2013. Relationships between intra-aggregate pore structures and distributions of Escherichia coli within soil macro-aggregates. Applied Soil Ecology 63:134-142. Lami, R., L.C. Jones, M. Cottrell, B. Lafferty, M. Ginder-Vogel, D.L. Sparks, and D. Kirchman. 2013. Arsenite modifies structure of soil microbial communities and arsenite oxidation potential. FEMS Microbiology Ecology 84:270-279. Li, J., G. Evanylo, K. Xia, J. Mao. 2013. Soil carbon characterization ten to fifteen years after organic residuals application: Carbon (1s) K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy Study. Soil Science. (in press). Li, W., X. Feng, Y. Yan, D.L. Sparks, and B.L. Phillips. 2013. Solid state NMR spectroscopic study of phosphate sorption mechanisms on aluminum (hydr)oxides. Environ. Sci. Technol. 47(15): 8308-8315. Li, W., Y. Wang, M. Zhu, T.T. Fan, D-M. Zhou, B.L. Phillips and D.L. Sparks. 2013. Inhibition mechanism of Zn precipitation on aluminum oxide by glyphosate. A 31P NMR and Zn EXAFS study. Environ. Sci. Technol. 47(9):4211-4219. Liu, Z.R., M. Flury, J.B. Harsh, J.B. Mathison and C. Vogs. 2013. Colloid mobilization in an undisturbed sediment core under semiarid recharge rates. Water Resources Research 49: 4985-4996. doi:10.1002/wrcr.20343. Liu, Z.R., M. Flury, Z.F. Zhang, J.B. Harsh, G.W. Gee, C.E. Strickland, et al. 2013. Transport of Europium Colloids in Vadose Zone Lysimeters at the Semiarid Hanford Site. Environmental Science & Technology 47: 2153-2160. doi:10.1021/es304383d. Ma, L., K. Xia, M. A. Williams, and D. B. Smith. Bioavailable Amino Acids in Soils of North-South and West-East Transects of Continental United States. ASA-CSSA-SSSA International Annual Meetings, Tampa, FL. Nov. 3-6, 2013. Moon J., M. Williams, K. Xia. July 2013. Proteomics to characterize soil ecosystem development. Soil Ecology Society Meeting, Rutgers, New Jersey. July 2013. Moon J., M. Williams, K. Xia. June 2013. Proteomics to characterize soil pedogenesis. DOE-JGI Workshop. Walnut Creek, California. June 2013. Negassa W., A. Guber, A. Kravchenko, and M. Rivers. 2013. Soil pore structure influences rates of soil organic carbon and plant residue decomposition: Evidence from coupled incubation and X-Ray computed tomography analyses. Presented at the annual meeting of the American Society of Agronomy, Nov 1-3, Tampa, FL. Negassa W., A. Guber, A. Kravchenko, B. Hildebrandt, T. Marsh, and M. Rivers. 2013. Does X-ray computed Tomography affect soil respiration and microbial activity? Presented at the annual meeting of the American Society of Agronomy, Nov 1-3, Tampa, FL. Senaviratne, A., R.P. Udawatta, C. Baffaut, and S.H. Anderson. 2013. APEX simulation: Environmental benefits of agroforestry and grass buffers for corn-soybean watersheds. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Senaviratne, A., R.P. Udawatta, S.H. Anderson, C. Baffaut, and A.L. Thompson. 2013. Performance of geno-fuzzy model on rainfall-runoff predictions in claypan watersheds. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Senaviratne, G.M.M.M.A., R.P. Udawatta, C. Baffaut, and S.H. Anderson. 2013. Agricultural Policy Environmental eXtender simulation of three adjacent row-crop watersheds in the claypan region. J. Environ. Qual. 42: 726-736. Shi, Z., D.M. DiToro, H.E. Allen, and D.L. Sparks. 2013. A general model for kinetics of heavy metal adsorption and desorption on soils. Environ. Sci. Technol. 47(8):3761-3767. Simmons, L.A., and S.H. Anderson. 2013. Soil physical properties as affected by logging activities in a Central Hardwood Forest. 2013 American Society of Agronomy/Soil Science Society of America International Meeting Abstracts [CD-ROM]. 3-6 November, Tampa, Florida. Sosienski, T., K. Xia, R. O. Maguire, and S. Kulesza. 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