Duration: 10/01/2005 to 09/30/2010

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Agricultural production can result in the contamination of soil, air, and water resources. Identifying and quantifying the physical, chemical, and biological processes that control the behavior of organic chemicals in the environment is imperative for improving management of agrochemicals, minimizing contamination of natural resources, and remediating currently contaminated environments. This research project will address two significant issues: (1) the persistence and availability in the environment (including bioavailability, transport, uptake, and degradation) of pesticides used in agricultural production and (2) the fate of pharmaceuticals in land-applied animal manures and biosolids.

Use of organic chemicals in agricultural production has resulted in contamination of soil, air, and water. To justify their use, chemical technologies must have greater societal benefits than risks. So it is critical that chemicals are employed in ways that minimize future contamination. Remediation of environments currently contaminated with organic chemicals is also an important goal. Evaluating and quantifying the behavior of organic chemicals in soil and water is vital for the development of sound strategies that ensure sustainable agriculture by protecting natural resources.

About 2 billion kilograms of chemicals are used as pesticides each year in the U.S., with agricultural usage accounting for ~77% (Aspelin and Grube, 1999). It is hoped that future pesticide use will decline as a result of improved integrated pest management strategies. Nevertheless, pesticides will remain a mainstay in many production systems. Research is needed to optimize pesticide efficiency with minimal environmental impacts. Newly developed pesticides, many of which are applied at rates one-tenth or less those of conventional pesticides, are often highly toxic to nontarget crops or aquatic organisms; thus, considerable knowledge of the transport and fate of these substances is needed.

The environmental fate of pharmaceutically active substances such as antibiotics and hormones is also a growing concern. Almost half of the 23 million kilograms of antibiotics produced annually in the United States is used for agriculture, with the majority being used as animal-feed additives to promote growth. With increases in the use of antibiotics and hormones in concentrated animal feeding operations and land application of manure, there are concerns that excreted pharmaceuticals will migrate in the environment, with potential impacts on water supplies and the production of antibiotic-resistant microbial populations. Thorough scientific studies of the potential of these organic substances to affect ground and surface waters, their impact on soil microbial communities, and their overall persistence in the environment are in their beginning stages. A better understanding of the environmental fate of antibiotics and hormones is needed to assess the environmental risk involved in releasing animal wastes to the environment.

Other organic chemicals related to agriculture are also of interest. For example, petroleum products are commonly used on farms and "inert" materials (e.g., solvents and emulsifiers) are often present in pesticide formulations. In addition, fundamental studies of the behavior of model organic compounds can help us understand the mechanisms by which more complex compounds interact with solid, solution, and vapor phases in the environment. Both urban and rural sectors of the economy can benefit from basic and applied studies of organic chemicals whether they are used in agricultural production, are used in home gardens and lawn care, or enter the environment through regulated or unregulated waste disposal.

The fate and accumulation of organic compounds and their degradation products are mediated by various -- often tightly coupled -- processes, including advection and diffusion, sorption and desorption, biodegradation, and chemical reactions. These processes occur within and between intimately associated environmental compartments (soil, water, air, and biota). For example, chemical interactions with the soil regulate persistence, release into water and air, and bioavailability, which in turn impact pesticide efficacy, degradation, and off-site transport. Because the interactions between organic chemicals and environmental media are so complex and occur at disparate spatial and temporal scales, research involving environmental pollution requires a multidisciplinary approach. A unique strength of this research project is the collaboration among its members from different scientific disciplines who, outside the committee, do not have sufficient opportunity to communicate with one another. This project provides a forum where specialists in mechanisms of chemical behavior, microbial ecology, transport behavior, mathematical modeling, and field assessment techniques can exchange information gleaned from individual research efforts as well as work on collaborative projects. Such cooperative efforts among research groups representing different kinds of expertise and diverse geographical areas are imperative to develop appropriate management techniques for minimizing environmental contamination and risk.

The long-term goal of this project is to minimize environmental contamination from pesticides, pharmaceuticals, and related organic chemicals. We propose to conduct a cooperative research program that elucidates fundamental mechanisms of chemical behavior and applies this knowledge at multiple spatial and temporal scales. In combination with mechanistic models, the principles of chemical behavior will be incorporated into management models. Research conducted will be useful in the continued development of best management practices for minimizing environmental contamination, as well as in the development of efficient and comparatively inexpensive strategies for remediating contaminated environments. Results of the research conducted by members of this multistate project group will be applicable to both agricultural ecosystems and to urban systems. Thus it will help to fulfill USDA goals to enhance protection of soil and water resources in both agricultural and urban sectors of the economy. By developing better management techniques, the risks of adverse environmental and health effects of chemical technology will be minimized.

A multistate approach is needed to address these issues because the cost of doing research demands a high level of communication among researchers, because comparison and contrast of the behavior of organic chemicals in a variety of soils and local climates is critical to improving predictions of behavior, and because it will help to standardize methodological approaches used to evaluate the fate and transport of pharmaceuticals and pesticides in the environment. Moreover, a concerted multistate effort has the great likelihood of effectively and credibly communicating research results to stakeholders such as the U.S. Environmental Protection Agency, state and federal extension personnel, waste water specialists, agricultural industries, and farmers.

Related, Current and Previous Work

Pesticide Sorption and Desorption Processes

Previous W-82 committees have played a leading role in elucidating mechanisms of sorption of agricultural organic chemicals and in refining methodologies for studying sorption processes. However, there remain gaps in our knowledge of adsorption-desorption processes in soil, gaps that significantly affect our ability to manage pesticide use, to optimize remediation strategies, and to define ecologically acceptable endpoints. To improve models describing pesticide availability for transport and biodegradation in soil we must better understand the complex interactions of adsorption-desorption and degradation processes for newly developed pesticides and aged pesticide residues and for both parent compounds and their main metabolites.

(1) New pesticides - As new pesticides are developed and marketed, it is important to explore fully the environmental ramifications of their use. An example is isoxaflutole, a pre-emergence herbicide used in corn production throughout the world. Because of restrictions imposed to protect water quality, isoxaflutole is not currently registered in Minnesota, Wisconsin, and Michigan. When it is applied to soil, isoxaflutole is hydrolyzed to its diketonitrile (DKN) derivative, which is the active ingredient. Previous research has indicated that isoxaflutole is sorbed more strongly to soil than DKN (Taylor-Lovell et al., 2000; Beltran et al., 2002) and that DKN can persist over periods of months in soil (Taylor-Lovell et al., 2002). Thus, isoxaflutole and DKN may have a tendency to leach to groundwater or to be transported to surface water via runoff.

(2) Aging and Hysteresis - Increased pesticide-soil contact time, i.e. aging, has been shown to affect adsorption-desorption processes in soil. Aging effects on sorption processes have been characterized by calculation of apparent sorption coefficients, Kd-app, for the pesticide remaining after an incubation period (Bresnahan et al., 2000, 2002; Koskinen et al., 2001, 2002, 2003). It is generally accepted that increasing sorption intensity that results from aging decreases the availability of the pesticide for transport, plant uptake, and microbial degradation. However, adsorption-desorption processes are complex and cannot be adequately modeled with a single numerical value (Koskinen and Harper, 1990). For instance, desorption of many pesticides cannot be predicted from their sorption isotherms due to hysteresis that increases over time. Less chemical is desorbed than is predicted by sorption isotherms that assume reversible chemical reactions. To improve predictions of pesticide fate, future studies must explore and document such hysteretic effects in detail.

(3) Impact of Charcoal on Sorption of Pesticides - Some soil components, such as charcoal, may have a large impact on pesticide sorption and thus availability for microbial degradation. Burning crop residues in the field is a common post-harvest practice for residue and for land clearing in many parts of the world. The resulting ashes may contain char. In heavily agricultural regions with frequent burning of crop residues, high levels of char may be expected (Skjemstad et al., 1996; 2002). W82 collaborator Sheng and colleagues have found that sorption of diuron by the wheat-residue-derived char described above was 400-2500 times higher than that by a soil with 2.1% organic matter (Yang and Sheng, 2003). Similarly, effective adsorption of benzonitrile by the char resulted in a 10-fold increase in sorptivity of the soil amended with 1% of char. As a result of the enhanced sorption that dramatically reduced the aqueous-phase benzonitrile concentration, biodegradation of benzonitrile in the 1% char-amended soil was substantially reduced (Zhang et al., 2004).


Biodegradation of Pesticides

A central issue in both bioremediation and risk assessment of soil containing residues of agricultural chemicals is the bioavailability of residual forms of the contaminants in these media. The physical process of sorption may remove molecules from direct access by organisms that are too small to penetrate soil nanopores and organic matter phases. The concentration of molecules in the soil solution where they can be readily accessed by cells may be limited by molecular diffusion from remote sorption sites within soil particles. Moreover, physical changes in the sorbent can lead to molecular entrapment in pores. The result may be a significant fraction of the pesticide that strongly resists both desorption and biodegradation. Several studies have shown that the bioavailability of atrazine decreased as soil-atrazine contact time increased (Chung and Alexander, 1998; Kelsey et al., 1997; Sharer et al., 2003).

Generally, soil-sorbed organic contaminants and pesticides have been considered unavailable for biodegradation without prior desorption (Ogram et al., 1985; Squillace and Thurman, 1992). However, some evidence suggests that that desorption into bulk solution is not a prerequisite for biodegradation (Guerin and Boyd, 1993; Calvillo and Alexander, 1996; Tang et al., 1998; Feng et al., 2000; Park et al., 2001, 2002). Possible mechanisms that allow microbial access to sorbed contaminants include production of biosurfactants, local alterations of soil organic matter by the biofilm causing release of sorbed chemicals, and creation of steepened concentration gradients by the biofilm near the solid surface. Exploration of these mechanisms can help us find new ways to increase the bioavailability of aged pesticides in contaminated soils and sediments.

The rates of atrazine biodegradation generally increase in soils with a history of atrazine exposure (Ostrofsky et al., 1997; Vanderheyden et al., 1997; Yassir et al., 1999). Repeated applications of atrazine may enrich the soil in microbial populations with the capacity to utilize the chemical as a carbon and energy source. Such correlations have been documented for 2,4-dichlorophenoxy acetate, 2-methyl-4-chlorophenoxyacetate, EPTC, and carbofuran (e.g., Ka et al., 1995; Karpouzas et al., 1999; Kotoulasyka et al., 1997), but generally not for atrazine. Until recently, the acclimation process has not been characterized at the microbial community level, and the environmental and biological factors underlying this history effect remain obscure.

Pyrethroid insecticides are widely used insecticides and are considered as replacements for organophosphate and carbamate insecticides. Pyrethroids are chiral compounds. The bioavailability of pyrethroids in surface streams and sediment and the enantioselectivity of pyrethroids in aquatic toxicity and biodegradation processes have been recently studied by members of this research project (Lee et al., 2004; Liu and Gan, 2004a, b, c, d; Liu et al., 2004a, b). Results indicate that in surface water, the presence of suspended solids and dissolved organic matter may significantly reduce the aquatic toxicity of pyrethroids. This reduced bioavailability should be considered in risk assessment and regulation. Moreover, enantioselectivity in aquatic toxicity and biodegradation occurs widely for pyrethroids. While some isomers are acutely toxic, other isomers are largely inactive. Thus the environmental risks of chiral pesticides may depend mainly on the behavior of the biologically active isomers. Additional research concerning enantioselectivity is essential to build a database for future risk assessment and regulation.


Chemical Remediation of Pesticide-Contaminated Soil

Various treatment strategies have addressed the need to prevent and mitigate pesticide contamination of the environment. Unfortunately, few currently available practices are both environmentally benign and economically feasible. Chemical remediation, defined as the use of nucleophilic chemicals or redox agents to destroy contaminants in soil and aquatic environments, offers a rapid and economical approach to clean up contaminated sources (Gan et al., 2002; Loch et al., 2002). To use the technology safely, it is essential to find appropriate remediation reagents. Using agrochemicals (e.g., fertilizers and nitrification inhibitors) as remediation reagents provides an innovative approach to remove unwanted agricultural contaminants (such as pesticide residues) with minimal change to the agricultural system. Thiourea, a sulfur-based nitrification inhibitor (Bremner and Yeomans, 1986; Bharati et al., 2000), has been discovered to accelerate the degradation of halogenated fumigants in aqueous solution and soil via an SN2 nucleophilic substitution reaction (Zheng et al., 2003a, 2004). Furthermore, thiourea was found to increase the rate of fumigant dissipation in soils compared to aqueous systems. This led to the development of a reactive surface barrier as an alternative to the use of plastic tarps to reduce halogenated fumigant emissions from the soil surface (Zheng et al., 2004). In addition to halogenated fumigants, thiourea may react with many other organic pesticides that have halide substitution on aliphatic carbons, such as chloroacetanilide herbicides.


Mobility of Pesticides in Eroded Sediments

Once in runoff, fate and distribution of pesticides will affect the likelihood that they will reach a receiving water body. The persistence and phase distribution of synthetic pyrethroids between sediment and water phases has been evaluated by Lee et al. (2003) and Gan et al. (2004). Their results show that some pyrethroids have very long persistence in sediment, likely due to their strong affinity to the solid phase (Lee et al., 2004). Bonderanko and Gan (2004a, b) studied transformation and distribution of commonly used organophosphate and carbamate insecticides in surface water and sediments from the Newport Bay and San Diego Creek watershed. Persistence of these pesticides was affected by redox conditions as well as by salinity of the water. Adsorption in sediment increased as the contact time increased. Similar research that documents the extent to which other pesticides are mobilized with eroded soil materials is needed to improve pesticide management strategies in general.


Pharmaceutical Compounds and Personal Care Products in Land-Applied Wastes

Chemicals representing active ingredients in pharmaceuticals and personal care products (PPCPs) have emerged as environmental contaminants with potentially widespread environmental impacts. The concentrations, fate, and environmental impacts of some PPCPs have been discussed in a series of review articles (Halling-Sørensen et al., 1998; Daughton and Ternes, 1999; Jørgensen and Halling-Sørensen, 2000; Daughton and Jones-Lepp, 2001; Nwosu, 2001; Snyder et al., 2003). A wide range of PPCPs has been detected in a variety of environmental samples at levels ranging from ng kg-1 up to g kg-1. Although limited information is available on the effects of PPCPs on soil biota and plants, reported phytotoxic concentrations ranged from 0.05 to 400 mg kg-1 depending on plant species and the growth medium used (Jjemba, 2002). Also, Fox et al. (2001, 2004) demonstrated that phytoestrogen signaling and symbiotic gene activation during plant-bacterial symbiosis can be disrupted by many endocrine-disrupting chemicals, including nonylphenol (NP).

PPCPs used by humans are normally discharged into waste water treatment plants (WWTPs) where they can remain unchanged or undergo transformation before being discharged into the environment via effluent and land-applied biosolids. Most veterinary pharmaceuticals (antibiotics and growth hormones) are minimally metabolized by the host animal, resulting in a significant fraction of the drug being excreted in the feces and urine along with metabolites, which are often uncharacterized as to their biological activity (Fedeniuk and Shand, 1998; Loke et al., 2002; Morales-Munoz et al., 2004). These animal wastes may be composted or directly applied to fields as fertilizers. Effluents of WWTPs are the most direct sources of PPCP contaminants to waterways (Halling-Sørensen et al., 1998; Calamari et al., 2003; Kolpin et al., 2002). However, PPCPs associated with land-applied biosolids may be mobilized in soil and leach to groundwater or enter surface water through runoff (Jjemba, 2002; Golet et al., 2003; Yang and Carlson, 2003; Pedersen et al., 2003). During the wastewater treatment processes, PPCP molecules can slowly become sequestered into microsites within the solid phase matrix, which may reduce their biodegradability and mobility (Kelsey et al., 1997; Nam et al., 1998; Alexander, 2000; Hatzinger and Alexander, 1997). Linking the contribution of biosolids and animal wastes from land application to the occurrence of PPCPs in the aquatic environment has been limited by our lack of information on the concentrations of PPCPs in these waste products (Esiobu et al., 2002). Furthermore, the chemical and physical reactions involving pharmaceuticals once they are released to the environment are largely unknown, including sorption/desorption processes, association with dissolved colloids, degradation rates, biological activity of metabolites, and bioavailable concentrations -- all of which affect the potential for these compounds to cause adverse environmental consequences. PPCPs associated with animal waste solids may similarly be protected from degradation, thus increasing their persistence in soil environments when land applied (Nwosu, 2001).

There have been few investigations on the mobility and transport of antibiotics in soils, especially biosolids-amended soils. Rabølle and Spliid (2000) reported that the weakly adsorbing olaquindox (an antibiotic, log Kow = 0.11) completely leached through soil columns, whereas the stronger adsorbing antibiotic tylosin (log Kow = 3.14) was retained at different depths, depending on the soil properties. Boxall et al. (2002) observed that sulfachloropyridazine, an ionic antibiotic with low sorption coefficients (0.9 - 1.8 L kg-1) was rapidly transported to surface waters after application to land. Thiele-Bruhn (2003) suggested that fast leaching through soils by macropore or preferential transport -- facilitated by dissolved soil colloids -- was the major transport process for strongly sorbed PPCPs. How wastes are applied to soil may also impact their persistence and leachability. In a two-year study, Kay et al. (2004) assessed application of pig manure slurries to a tile-drained field consisting of clayey soils before and after the soil was disked. Significant levels of both sulfachloropyridazine and oxytetracycline were found in soils and in tile-drain water, but disking before application reduced losses significantly.


Fundamental Studies of the Sorption of Model Organic Compounds by Soil Components

In addition to documenting the fate and transport of specific organic contaminants n the environment, it is important that we understand the molecular-scale mechanisms that govern the interactions of organic compounds and soil. For example, most organic contaminants in soils are expected to interact primarily with natural organic matter (NOM) in soil, but the exact mechanisms that allow contaminant molecules to be retained strongly by NOM remain unclear. Recent studies have identified pi-pi electron donor-acceptor (pi-pi EDA) interaction as a powerful explanatory model. pi-pi EDA interactions are known to play a role in membrane structure, base pair stacking in DNA, tertiary protein conformation, porphyrin aggregation, drug interactions with biopolymers, binding and geometries of host-guest complexes, chromatographic separations, and in directing pathways of chemical reactions (Hunter and Sanders, 1990; Brindle and Albert, 1997; Janiak, 2000; Kim et al., 2000; Hunter et al., 2001). Yet their role in association of aromatic pollutants with NOM or engineered sorbents used in pollution control has gone largely unexplored.

A number of papers have postulated "pi-pi charge-transfer" processes between pesticides (triazine, urea, and bipyridylium herbicides) and humic substances based on elevated free radical concentrations measured by ESR spectroscopy (Senesi, 1992; Senesi et al., 1994; Sposito et al., 1996). Whatever the source of these free radicals, however, it is not related to the reversible reaction referred to here, as the spins of electrons of the donor and acceptor molecules are paired. Furthermore, actual formation of free radicals would likely result in irreversible loss of the original compound by chemical transformation (e.g., reaction with O2) or covalent attachment to the solid. McDermott and McCreery (1994) obtained evidence by scanning tunneling microscopy that the surface of highly oriented pyrolytic graphite near defects is negatively polarized, offering donor sites for pi-acceptor molecules such as quinones. Collaborators on the proposed project have recently found evidence consistent with this hypothesis in sorption of polynitrotoluenes compared to substituted benzenes of neutral character on graphite and a wood charcoal (Zhu and Pignatello, in press; Sander and Pignatello, in press). Further fundamental work is necessary to collect direct evidence for pi-pi interactions between pi-interactive pollutants and complementary acceptor or donor functional groups on natural carbonaceous solids, including humic substances and black carbon, and to be able predict such interactions with new compounds.


Uniqueness of This Project

The proposed project is distinct from and also complements three other multistate projects.

Scientists working under the auspices of Project W45 (Agrochemical Impacts on Human and Environmental Health: Mechanisms and Mitigation) focus primarily on identifying, predicting, and mitigating any adverse impacts of agricultural chemicals to human, animal, and ecosystem health. An additional goal of that project is to identify, develop, and validate trace residue analytical methods, immunological procedures, and biomarkers for agricultural chemicals. In contrast, the currently proposed project is directed less to biological responses to pesticides and pharmaceuticals and more toward predicting and managing the interactions of these chemicals in soil and water before adverse health impacts develop.

Scientists working under the auspices of Project W1188 (Characterization of Flow and Transport Processes in Soils at Different Scales) seek to improve understanding of how physical properties and processes govern mass and energy transport in soils and how these processes mediate biogeochemical interactions at different scales. Although the environmental fate and transport of pesticides and pharmaceuticals are clearly linked to physical properties and processes, the emphasis of the presently proposed project is on chemical properties of the chemicals and on the chemical, mineralogical, and surface properties of potential solid-phase sorbents in soils and sediments.

Scientists working under the auspices of Project W1170 (Chemistry, Bioavailability, and Toxicity of Constituents in Residuals and Residual-Treated Soils) evaluate the fate of nutrients, trace elements, and contaminants applied to soils with residual amendments such as biosolids. While some research associated with W1170 deals with organic chemicals, much of W1170's focus is on potentially toxic trace metals, nitrogen, and phosphorus that are land-applied with biosolids. In contrast, collaborators in the currently proposed project work entirely with the fate of organic chemicals, i.e., pesticides that are applied in normal agricultural operations as well as with pharmaceuticals that may be dispersed to the environment subsequent to land applications of biosolids or animal manure. To ensure communication about research activities of these two projects, M.L. Thompson (Iowa) and K. Xia (Georgia) have been appointed to both projects and will serve as liaison officers.

Objectives

1. To identify and quantify fundamental chemical, physical, and biological processes relevant to agricultural pesticides and pharmaceuticals in the environment,
   
2. To evaluate existing pesticide transport models for predicting the fate and transport of agricultural pesticides and pharmaceuticals in the environment, and
   
3. To provide information required for field-scale recommendations for the management of agricultural pesticides and pharmaceuticals in the environment.
   

Methods

Objective 1 Sorption and desorption of organic compounds by and from soil, subsurface material, soil components, and organo-clays will continue to be characterized by batch equilibration techniques, by steady-state flow and interrupted-flow miscible displacement techniques, as well as by thermodynamic, kinetic, spectroscopic, and solvent-extraction techniques. These experiments are fundamental and common to most of the research activities that will be conducted in this project. Experiments will be conducted under different soil-to-water ratios from unsaturated to flooded conditions, with varying temperatures, residence times, and the presence or absence of soil amendments, surfactants, colloids, or co-solutes. In selected studies, model sorbents that include polymers, lignin, resins, and soil extracts will be employed to aid in identification of molecular-scale mechanisms. Although many of the basic principles for conducting sorption and desorption experiments have not changed over time, we now know that the use of simple equilibrium partitioning coefficients based on freshly treated samples under slurry conditions is no longer adequate to predict pesticide fates. New models that describe sorption and desorption of organic compounds and that are commensurate with the complexity of soil-water systems must be developed. In the research planned by project collaborators, both long-term and short-term sorption kinetics and the formation of irreversibly bound residues will be studied after varying incubation periods, including use of soil materials contaminated and aged in the field and laboratory. Chromatographic, spectroscopic, and radiolabeled assay techniques will be used to monitor chemical concentrations and chemical alterations in the soil-water system. Soil organic matter will be characterized by 13C-NMR spectroscopy as well as by infrared and ultraviolet spectroscopy. An important collaborative effort in the project consists of communication among researchers about these techniques so that they can be implemented in ways that allow direct comparison among studies. (1) New pesticides. - Sorption, desorption, and biodegradation of emerging pesticides (such as isoxaflutole, as discussed above) will be investigated by a number of project collaborators (MN-USDA/ARS, TX, CA-USDA/ARS). (2) Sorption hysteresis - In the coming 5-year period, collaborators at the Connecticut Agricultural Experiment Station and Minnesota (USDA-ARS) will be investigating the reasons for sorption hysteresis, including hypotheses related to changes in the physical structure of soil organic matter over time. (3) Charcoal sorption mechanisms - Studies of how soil chars affect pesticide efficiency, bioavailability, and degradation rates will be led by collaborators at the University of Arkansas. (4) pi-pi bonding - Researchers at the Connecticut Agricultural Experiment Station will investigate pollutant compounds and natural organic matter structures with strong pi-donor/acceptor properties through computational modeling, structure-activity correlations in model systems towards parameterization of the pi-pi EDA force, and adsorption of pi-interactive chemicals on the polycyclic aromatic surface of black carbon. Biodegradation of Pesticides Collaborators on this proposal will be undertaking studies of biodegradation from several points of view. Experiments planned at the University of Tennessee - Knoxville are designed to discover previously uncultured atrazine degrading bacteria in soils and wetlands using a novel in situ enrichment technique (bead samplers) that will allow sampling of autochthonous microbial communities while avoiding the inherent biases of classical liquid enrichment techniques. A variety of molecular and radiocarbon techniques will be used to characterize autochthonous atrazine-degrading communities from soils and wetlands and to link taxonomic groups of organisms to atrazine biodegradation. It has long been assumed that pesticides strongly sorbed to the soils solid phase would not be available to microorganisms and therefore would not be degradable. To establish the degradation of sorbed substrate requires that the effects of both the extent of desorption and the rate of desorption on bioavailability be fully accounted for. Collaborating scientists in Alabama and Arkansas will be investigating the challenging issue of how some bacteria may be able to degrade atrazine sorbed by soil. Novel degradation pathways will be explored, too. For instance, in the next five years, scientists at the University of Minnesota will explore the use of transgenic plants that have the ability to degrade atrazine in soils and groundwater. To utilize these plants to their fullest, they will also investigate how s-triazine contaminated water is transported across fields and how this water can be captured and degraded by transgenic atrazine-degrading plants. Bioavailability and Activity of Chiral Compounds An important, relatively new approach to understanding pesticide fate in the environment is the observation that the biological and chemical activity of many pesticides is closely related to the stereochemistry of their molecules. New analytical methods are needed to resolve and identify the enantiomers of chiral pesticides. Chiral methods to be developed at the University of California - Riverside will be based on gas chromatography and high performance liquid chromatography with enantioselective stationary phases. These methods will improve our understanding of the activity of pesticides in aquatic ecosystems and the impact of enantioselectivity of chiral pesticides other environmental media. Scientists at the University of California - Riverside will also conduct studies to evaluate the interactions of phase distribution and pesticide bioavailability in surface aquatic ecosystems, and to use the information to understand the influence of these interactions on the ecotoxicity of aquatically toxic pesticides. Solid-phase micro-extraction (SPME) or similar methods will be used to measure the dissolved-phase concentration, and lethal concentrations (LC50s) will be measured for a number of pyrethroid insecticides using indicator invertebrates. Correlation will be made between the SPME measurement, LC50, and presence of suspended solids and/or dissolved organic matter in the test system. Studies will also be conducted to understand how enantioselectivity of chiral pesticides affects their ecotoxicity, with an emphasis on synthetic pyrethroids and chiral organophosphate insecticides and their aquatic toxicity. Individual isomers will be isolated using enantioselective chromatographic methods and used to measure LC50 or other toxicity end-points. Mobility of Pesticides during Leaching, Runoff, and Erosion Non-point source contamination is considered the biggest challenge in water quality restoration and protection for many watersheds in the country. In particular, pesticide runoff from agricultural and urban sources to surface aquatic streams may cause ecological effects to affect the beneficial uses of the surface water, such as toxicity to aquatic organisms. Consequently, total maximum daily loads (TMDLs) are expected to be established for pesticides in many streams around the nation. Understanding the origin, fate, and ecological effects of such pesticides in runoff and receiving water systems -- and devising practices to mitigate the risk -- is imperative. Field dissipation studies of pesticide leaching and persistence will be conducted at several collaborating institutions (SD, MN-USDA/ARS, GA, TX, IN, AZ-USDA/ARS, CA-Riverside). Runoff will be assessed both in the field and in laboratory studies. These studies will indicate the importance of various factors (including slope, rainfall intensity, surface roughness, precipitation timing relative to herbicide application, and others) on the runoff of pesticides and their metabolites. At some locations, rainfall simulation will be used to generate runoff from soil trays (MN-USDA/ARS); others will evaluate runoff under natural precipitation conditions. Runoff (aqueous and sediment phases) will be collected and pesticide residues will be determined. Pharmaceuticals and Personal Care Products There is increasing concern about the environmental dispersion of pharmaceutical chemicals such as antibiotics and hormones in animal waste and biosolids as well as compounds derived from personal-care products. Project collaborators in Indiana, Georgia, Hawaii, South Dakota, California, and Arizona (USDA-ARS) perform laboratory batch and column studies, as well as field studies, to characterize the fate of selected PPCPs, including their release from biosolids and manure, sorption by soils and sediments, association with dissolved colloids, biodegradation in biosolids, manures, and waste-soil mixes, transport from waste-amended soils, and subsequent fate in receiving waters. Field-based leaching experiments will be conducted to explore the fate of pharmaceuticals, nonylphenol, and flame retardants that are applied to soils in sewage effluent or biosolids. These studies will take place in irrigated contexts where fields are instrumented with lysimeters (AZ-USDA/ARS) or by using rainfall simulation in small field plots (GA). Summary of Major Compounds to Be Investigated by Collaborators on this Proposal Pesticides: 2,4-D, clomazone, metsulfuron, 2,4-dinitro-o-cresol (DNOC), dacthal, nicosulfuron, anthraquinone, diquat, picloram, diuron, propoxycarbazone, atrazine, flucarbazone, pyrethroids, benzonitrile, glyphosate, s-metolachlor, bromacil, imazapic, sulfometuronmethyl, carbamate pesticides, imazaquin, sulfonyl urea herbicides (specifically, halosulfuron and trifloxysulfuron), chloroacetanilide herbicides, imazethapyr, trifloxystrobin, chloropicrin, imidacloprid, 1,3-dichloropropene, chlorothalonil, isoxaflutole, metam sodium, metabolites of atrazine and metolachlor, lindane, and methyl iodide Pharmaceutical compounds: carbadox, 17-² estradiol, estrone, 17±-ethinylestradiol, mestranol, diethylstilbestrol, testosterone, trenbolone, moninsen, tylosin, fluoroquinolones, sulfonamides, and tetracyclines Other related organic compounds: octylphenol, nonylphenol, polycyclic aromatic hydrocarbons, chlorinated benzenes, quinines, allelochemicals (plant root exudates that have biological activity, i.e. sorgoleone); fluorinated compounds (e.g., perfluorinated octanyl acids) Objective 2 Processes that regulate the persistence and movement of pesticides and pharmaceuticals in soils are manifested across the landscape at different spatial and temporal scales, at different intensities at each scale, and with different consequences. The focus of objective 2 is to integrate the information obtained on fundamental processes in objective 1 and to develop or refine tools that predict a specific process or group of processes for use in interpretive and management models. Results can be incorporated into larger scale models, and they can provide realistic inputs for computer simulation models. The current and previous W-82 projects have established considerable basic knowledge that will contribute to the completion of the proposed project, integrating the understanding of basic processes with useful interpretive and management models. Three examples of planned work follow. (1) At the USDA-ARS Salinity Laboratory a two-dimensional numerical model to simulate the fate and transport of fumigants from the fumigated fields will be developed, tested and evaluated. The numerical simulation will simultaneously solve water, heat, and solute transport equations and include chemical transport in the vapor phase. Two volatilization boundary conditions will be explored to assess their accuracy in predicting the volatilization rates. One boundary condition will follow stagnant boundary layer theory and use no atmospheric information. The second boundary condition will couple soil and atmospheric processes and will be tested to determine if it provides a more accurate simulation of the instantaneous volatilization rates compared to a stagnant boundary layer condition. (2) A risk assessment model will be developed to assess the exposure of bystanders located near fumigated fields to toxic chemicals. The model will include several soil-based transport processes: water flow, soil diffusion, chemical transformation, chemical adsorption, and volatilization. Chemical movement in the atmosphere will be simulated using the Gaussian plume approach coupled to the soil fate and transport model. Later development may utilize more comprehensive models of atmospheric dispersion. (3) The applicability of existing hydrology/water quality models previously used to assess the vulnerability of a watershed to pesticides will be extended to simulate movement of antibiotics and hormones in runoff, reaching shallow groundwater, and considering with tile flow. A small, well-defined watershed in Indiana will be used to validate the model. The models and statewide data sets will then be used to estimate the potential magnitude of antibiotics and hormones reaching receiving waters. Collaborative work on these models and other similar models will be a core activity of the project, leading to development of best management practices for pesticides and pharmaceuticals used in agricultural contexts. Objective 3 Research conducted by committee members provides information needed to develop management strategies that can reduce soil and water contamination from pesticides, pharmaceuticals, and other toxic organic compounds. This information includes (1) identification of key parameters controlling the environmental fate of a particular contaminant or contaminant class, (2) expanding the environmental fate information database, (3) quantifying fate relative to various environmental parameters, (4) development of realistic inputs for computer simulation models, and (5) development of algorithms to characterize specific group of processes that can then be incorporated into larger scale models. Research efforts of collaborators on this proposal will support process models that describe the retention, transformations, and transport of pesticides and pharmaceuticals under a range of soil, climatic, and environmental conditions, landscape settings, and soil management practices. The multi-disciplinary knowledge base resulting from performance of Objectives 1 and 2 can be used as tools by stakeholders for developing sound strategies for ensuring sustainable agriculture and protecting natural resource systems. Stakeholders include farmers, chemical manufacturers and other industry groups, natural resource managers, regulators, policy makers, extension educators, agricultural and environmental consultants, and the general public as well as other research scientists. Transfer of research information can sometimes be slow and limited to a small section of the scientific community. The collaborators on this multistate research project are committed to making a substantial effort to transfer user-friendly information to a variety of stakeholders in the next 5-year project period. Included in this renewal proposal are individuals that hold partial or complete extension appointments, e.g., Jack Watson (Pennsylvania) and Mike Hirschi (Illinois). They will be instrumental in identifying ways to engage critical stakeholders in the research process so that research results of the committee are used and valued. Dr. Hirschi, for example, is the Water Quality Program Coordinator for University of Illinois Extension, and he serves on the Great Lakes Regional Water Quality Leadership team that implements the USDA-CSREES Section 406 Regional WQ Coordination grant. In that role, he is in an ideal position to help us target dissemination of our work to extension personnel and water-quality professional in other disciplines. Dr. Watson and Dr. Hirschi will play active roles in technology transfer as well as encourage and facilitate technology transfer by the rest of the committee. The collaborators will work towards enhancing communication and distribution to various users group throughout the next 5-year project period in several planned outputs (below).

Measurement of Progress and Results

Outputs

• Members of the multistate research project commit to the following outputs during the five-year course of the project. Institutions committed to collaborative leadership for each output are indicated in parentheses.
• * Draft a white paper for the Environmental Protection Agency concerning the fate of pharmaceuticals entering the environment by agricultural practices. [CA-Berkeley, CT, HI, IN, IA, KY, MI, PA]
• * Sponsor a symposium on fate of agricultural pharmaceuticals in the environment at the annual meeting of an appropriate professional society. [CT, IN, IA, KY, USDA-ARS-Phoenix]
• * Submit joint research proposals dealing with agricultural pharmaceuticals or pesticides to national funding agencies. [AL, CA-Berkeley, CT, GA, HI, IN, KY, MI, MN, SD, TN, TX, USDA-ARS-Phoenix]
• * Hold a working meeting on agricultural pharmaceuticals with extension specialists in soil and water quality at the annual meeting of an appropriate professional society. [HI, IL, IA]
• Output 6 * Publish a special journal issue, book chapter, or a regional research bulletin to summarize committee findings concerning pesticides and agricultural pharmaceuticals. [CA-Berkeley, CT, GA, HI, MI, MN, TN, TX, USDA-ARS-Phoenix] Output 7 * Development of technical documents for best management practices for pesticides and pharmaceuticals in agricultural contexts. [AL, CA-Riverside, IL, KY, TX] Output 8 * Publish peer-reviewed journal articles and review articles. [AL, AR, CA-Berkeley, CA-Riverside, CT, GA, HI, IN, IA, KY, MI, MN, SD, TN, TX, USDA-ARS-Morris, USDA-ARS-Phoenix] Output 9 * Participate in extension publications and field days dealing with pesticides and pharmaceuticals in agricultural contexts. [AL, CA-Riverside, IL, SD, USDA-ARS-Morris]

Outcomes or Projected Impacts

• A more sophisticated understanding of molecular-scale mechanisms of sorption will improve predictive models of fate and transport of pesticides and pharmaceuticals by identifying and quantifying the relative importance of environmental variables that influence contaminant fate.
• Studies by collaborators in this project will provide critical data sets to validate current models of pesticide and pharmaceutical mobility in the environment and to ascertain the uncertainties associated with model predictions.
• More accurate predictions of how fast pesticides and pharmaceuticals can move from the point of application and into surface or ground water (and in what forms) will provide the scientific basis for design of water-quality monitoring protocols where these chemicals are applied to soils.
• Increased public and scientific awareness of critical issues concerning fate and transport of agricultural pharmaceuticals and pesticides resulting from about 40 scientific and technical transfer presentations over the period of the project.
• Best management practices that could reduce fumigant emissions by 20% by 2008: (1) Develop a feasible and efficient practice for application of fumigant mixtures to broaden the spectrum of pest control and improve efficacy. This practice has the potential to reduce fumigant application rates; for example, a 10 to 20% reduction in metam sodium application rates may be expected, which may result in a 10 to 20% reduction in emissions of the toxic compound methyl isothiocyanate. (2) Integrate soil fumigation with agrochemical application to control fumigant emissions using reactive surface barrier technology. Atmospheric emissions of the fumigants 1,3-D, chloropicrin, methyl iodide would be expected to decrease by approximately 20% or more using this technology, compared to current fumigant applications.

Milestones

(2006): Sponsor a symposium on fate of agricultural pharmaceuticals in the environment the annual meeting of an appropriate professional society (by Y1)

(2007): Submit joint research proposals dealing with pesticides or agricultural pharmaceuticals to national funding agencies(Years 2007-2010)

(2008): Hold a working meeting on agricultural pharmaceuticals with extension specialists in soil and water quality at the annual meeting of an appropriate professional society

(2009): Develop technical documents for methodological protocols and best management practices for pesticides and agricultural pharmaceuticals

(2010): Publish a special journal issue, book chapter, or a regional research bulletin to summarize research with pesticides and agricultural pharmaceuticals

(10):raft a white paper for EPA dealing with agricultural pharmaceuticals in the environment 2005-2010: Publish peer-reviewed journal articles and review articles

Projected Participation

View Appendix E: Participation

Outreach Plan

Outreach Plan

The results of collaborative projects described above will be made available to intended users in several ways:

Peer-reviewed journal articles and review articles are published in the scientific literature and available by subscription, at libraries, or on-line.

Participants in the symposium on the fate of agricultural pharmaceuticals in the environment will hear research results at the symposium and will have opportunity to interact with project members who are presenting results.

Extension specialists in soil and water quality will participate in the meeting on agricultural pharmaceuticals and will learn about the group's activities by presentations and informal interactions at the meeting.

Technical reports concerning methodological protocols and best management practices for pesticides and agricultural pharmaceuticals will be posted on the project's web site.

Extension publications will be issued by participating experiment stations. Members will present the latest information about pesticides and agricultural pharmaceuticals to the general public at agricultural field days in the participating states.

A special journal issue, book chapter, or a regional research bulletin summarizing the group's research concerning pesticides and agricultural pharmaceuticals will organized and distributed to audiences that are appropriate to each medium (e., libraries, book buyers, and extension specialists). Where possible, we will also post these materials on the project's website.

A white paper concerning the fate of pharmaceuticals entering the environment by agricultural practices will be written and sent to key scientists and administrators in the U.S. Environmental Protection Agency.

Organization/Governance

The project will be coordinated among the collaborating scientists by

(a) five meetings of the participants organized on an annual basis,

(b) e-mail and conference calls, and

(c) the project's organizational structure: a chair and secretary elected at annual meetings by the membership for two-year terms beginning 2006.

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Attachments

Land Grant Participating States/Institutions

AL, AZ, CA, CO, CT, DE, HI, IA, IL, IN, KY, MI, MN, MO, MT, NE, NJ, PA, SD, TN, WI

Non Land Grant Participating States/Institutions

Johns Hopkins University, University of Illinois at Urbana-Champaign, USDA-ARS/Arizona, USDA-ARS/Minnesota, USDA/ARS-California