P020 (DAV-1117-036518) Determination of Potential Transformation Products and Reaction Pathways of Selected Organophosphate Pesticides in Several Waters.
Start time: 8:00 AM
Davis, E¹, Haley, M¹, Anthony, J¹, ¹ US Army Edgewood Chemical Biological Center (ECBC), MD
Degradation experiments were performed on three organophosphate pesticides, mevinphos, dicrotophos, and dichlorvos in natural and distilled waters using an Agilent 1100 Series high performance liquid chromatography (HPLC) with reversed phase separation (RP) coupled with UV detection. A further method was developed to investigate the identification of the degradation products in these waters by mass spectroscopy (LC-MS) using atmospheric chemical ionization (APCI) in the positive ion mode. The MS detection was accomplished using total ion current (TIC) mode in order to elucidate potential structures that could provide evidence for suggested hydrolysis pathways. No sample pretreatment was required for the analysis. Under the conditions determined for the separation of the pesticides, the MS detection gave peaks with an m/z equal to +1, except for dichlorvos, indicating ionization of the pesticides from a charge transfer of a proton. No products were found using negative ion mode, APCI.

P021 (FOR-1117-839973) A method for pesticides and degradates in soil and sediment using pressurized fluid extraction and GC/MS.
Start time: 8:00 AM
Foreman, W.¹, Jha, V.¹, Skaates, S.¹, Madsen, J.¹, Sandstrom, M.¹, Stroppel, M.¹, Capel, P.², ¹ U.S. Geological Survey, Denver, CO, U.S.A.² U.S. Geological Survey, Minneapolis, MN, U.S.A.
A method for the determination of multiple classes of pesticides and degradates in soil, bed and suspended sediment has been developed that uses pressurized fluid extraction (PFE), extract cleanup with graphitized carbon column and gel permeation chromatography, and analysis by gas chromatography/mass spectrometry (GC/MS) operated in selected ion-monitoring mode. The method was validated for 42 parent pesticides and 24 degradates, with acceptable (60-120% mean) performance obtained for the majority of analytes in most tested matrices. Estimated method detection limits ranged from 0.4-2 ug/kg for a 50-g dry-weight sample. Estimated reporting levels, accounting for recovery, ranged from 1-30 ug/kg (or 5-150 ng/L for a 10-L suspended-sediment sample collected on filter media). Advantages and limitations of the method will be presented, including operational parameters for PFE, clean-up steps, GC/MS, and analyte stability and standard issues. The method was developed to support studies by the U.S. Geological Survey National Water-Quality Assessment Program's Agricultural Chemicals Team (NAWQA–ACT) to investigate the sources, transport, and fate of selected agricultural chemicals in a variety of agricultural settings across the Nation. Field results from NAWQA–ACT pilot studies using this method will be presented.

P022 (STR-1117-828505) In-use pesticide concentrations in Canadian Areas of Concern of the lower Great Lakes.
Start time: 8:00 AM
Struger, J.¹, Marvin, C.¹, Sverko, E.¹, Dove, A.¹, ¹ Environment Canada, Burlington, ON, Canada
Surface water samples were collected in 2002 and 2003 from seven Canadian Areas of Concern (AOCs) in the lower Great Lakes. They include: three sites in the St. Clair River, three sites in the Detroit River, one site in Wheatley Harbour, two sites in the Niagara River, four sites in Hamilton Harbour, three sites in the Toronto AOC and three sites in the Bay of Quinte. Samples were analyzed for triazine, neutral and phenoxy acid herbicides and organophosphorous insecticides. Frequently detected pesticides included atrazine, DEA (desethyl atrazine), metolachlor, 2,4-D and dicamba. Several OP insecticides were also occasionally detected including diazinon and dimethoate. Maximum pesticide concentrations detected were 3060 ng/L for atrazine, 825 ng/L for metolachlor, 580 ng/L for dicamba, 522 ng/L for 2,4-D, 416 ng/L for DEA and 91 ng/L for diazinon. In general, pesticide concentrations increased from AOCs located near Lake Huron to AOCs located in Lake Ontario. Concentrations were highest in AOCs where sampling occurred close to possible pesticide inputs (e.g. Hamilton Harbour, Toronto, and Wheatley Harbour). Concentrations were lower in AOCs that received less direct input such as the St. Clair, Detroit and Niagara rivers and the Bay of Quinte. Aquatic life guidelines were rarely exceeded.

P023 (GRU-1118-066283) Active ingredients, formulated products, and tank mixes: What should be regulated?
Start time: 8:00 AM
grue, christian¹, Curran, Catherine¹, Cabarrus, Jennifer¹, Smith, Bridget¹, King, Kerensa¹, Grassley, James¹, Gardner, Susan², ¹ University of Washington, seattle, WA, USA² Centro de Investigaciones Biologicas del Noroeste, La Paz, BCS, Mexico
The assumption that within end products, active ingredients represent the greatest hazard to non-target species and therefore should be the primary, if not sole, focus of pesticide regulations is not always valid. Type of formulation, impurities, inert ingredients, adjuvants, and the mixture of active ingredients are all important in assessing hazards and risks associated with the use of end products. After all, it is the end product that is released into the environment. However, this is not adequately reflected in the existing regulatory frameworks within FIFRA and TSCA in the United States. Inconsistency in the regulatory classification of chemicals within end products other than active ingredients - and therefore how these chemicals are treated within and between FIFRA and TSCA - is a concern. We define these terms, review the evidence indicating the non-target toxicity of formulations and tank mixes can vary from that of active ingredients, describe the regulatory frameworks by which active ingredients and other components of end products are regulated in the United States and elsewhere, and suggest that a new regulatory strategy is needed. The hazards end products pose to non-targets need to be assessed and the information made available to federal and state regulators, natural resource managers and pesticide applicators.

P024 (BUD-1117-832751) Survey for Synthetic Pyrethroids within the San Diego Creek/Newport Bay Watershed.
Start time: 8:00 AM
Budd, R¹, Bondarenko, S¹, Gan, J¹, ¹ UC, Riverside, CA, USA
The Upper Newport Bay is an ecological reserve located within Orange County, CA. It is a marine estuary that provides habitat for nearly 200 species of birds, and several species of fish, mammals and native plants. The primary freshwater inlet for the estuary is the San Diego Watershed, which is the primary drainage area for the cities of Santa Ana, Tustin, Lake Forest and Irvine. With the increasing encroachment of urban sprawl, there has been a dramatic shift in land use within the San Diego Watershed from agricultural to urban landscapes. There is a concern that this shift in land use will result in an increase of non-source pollution from individual homesteads that use pesticides to aid in insect and weed control. The use of pyrethroids has increased steadily in both agricultural and urban settings as a replacement for organophosphate insecticides. Pyrethroids commonly have high aquatic toxicity, and contamination of surface streams by pyrethroids is of concern. In addition, nursery use has also increased drastically since 1995 as mandated for red and imported fire ant quarantine. The objective of this study was to determine the presence and spatial variability of pyrethroids within the watershed. Sediment grab samples were taken from locations within the watershed. Samples were collected during wet and dry seasons to compare storm water runoff with base flow concentrations. The samples were collected at the outlets of existing nurseries, within drainage channels, and within the estuary. Samples were analyzed for pyrethroids using gas chromatography with electron-capture detection. A spatial analysis was conducted to assess correlation between land use and pyrethroid concentrations.

P025 (MUI-1117-835206) Atmospheric deposition and bioaccumulation of current use pesticides in remote lakes in Ontario, Canada.
Start time: 8:00 AM
Muir, D.¹, Teixeira, C.¹, Wang, X.¹, ¹ National Water Research Institute, Environment Canada, Burlington, ON, Canada
The objective of this study was to determine the extent of deposition and bioaccumulation of a wide range of current use pesticides (CUPs) in remote and isolated lakes within or just to the north of the Great Lakes basin. The basin is a major pesticide use area with 160 major products used and over 28 kilotonnes applied for agricultural pest control. CUPs were determined in surface and subsurface waters from 3 small lakes in southwestern Ontario and 7 lakes in north/central Ontario from May to July 2003 and 2004. Precipitation samples and XAD-based passive air samplers (PAS) were collected at 3 southern sites and 2 north/central locations from April the end of August. Zooplankton (>100 um) and phytoplankton (approx 1-100 um) were collected at 3 lakes. Gas chromatography with electron ionization or chemical ionization MS with selected ion monitoring was used for quantification of the CUPs. Of the 51 target CUPs (including degradation products) 23 were detected in lake water, 28 in precipitation, 24 in PAS and 13 in zooplankton. Major compounds in lake water were ametryn, atrazine, desethyl atrazine, chlorothalonil, chlorpyrifos, dacthal, dyfonate, diazinon, endosulfan, metolachlor, metribuzin, and trifluralin. Most of these compounds also were prominent in precipitation and air, along with alachlor and pendamethalin. Water concentrations of two major herbicides, atrazine and metolachlor were similar in lakes from within the agricultural area of southwestern Ontario and in north/central Ontario lakes that were more than 200 km from the nearest intensively farmed area. A low detection frequency of CUPs was found in zooplankton compared to other media and concentrations were generally <1 ng/g wet wt. Major CUPs detected in zooplankton were chlorpyrifos, disulfoton, dyfonate, endosulfan and pendamethalin. Bioaccumulation factors (lipid wt) for these CUPs ranged from 103 -106 and were higher than expected based on their reported laboratory bioconcentration factors.

P026 (JOH-1117-835471) Dynamic sonicator-assisted extraction for organophosphates and carbamate insecticides from avian tissue and gut contents.
Start time: 8:00 AM
Paulson, B.¹, Sandercock, B.², Johnson, K.^{1, 3}, ¹ Department of Chemistry, Southern Illinois University, Edwardsville, IL, USA² Division of Biology, Kansas State University, Manhattan, KS, USA³ Environmental Sciences Program, Southern Illinois University Edwardsville, Edwardsville, IL, USA
A great amount of effort has been put into the reduction of non-target insecticide exposure to wildlife. However, insecticide effects on wildlife remain a threat to many non-target species, especially avian species. Organphosphorus (OP) and carbamate (CB) insecticides are widely used around the world and have replaced the more persistent organochlorinated insecticides such as DDT. Currently, OPs and CBs are being phased out in the United States. They are, however, widely used in third world countries and will remain in use for some time. As such, it is important to have affordable methods available to monitor these insecticides in a variety of matrices. Traditional methods include Soxhlet extractions, which are time consuming, costly, and generate a large volume of solvent waste. Currently, a number of researchers are developing methods using accelerated solvent extractions. These techniques use low volumes of solvents and can take as little as 25 minutes; however, the instrumentation can be cost prohibitive. To aid those with cost constraints, we have developed a method to extract trace amounts of insecticides in 1- to 25 g tissue/gut content samples using a dynamic sonication with an in-situ cleanup. Briefly, solvent is pumped through coiled tubing that is in a heated water bath with a sonicator containing a large diameter column with the sample inside. The sample is packed in the column such that the solvent first flows through the sample, then anhydrous sodium sulfate, followed by florisil. A variety of parameters, such as solvent, pressure, flow rate, water bath temperature, and solvent volume were evaluated. Recoveries of a number OPs and CBs were over 90% using this novel method compared to 80% using a modified separatory funnel method. Currently, this technique is being utilized in a study evaluating the ecotoxicity of insecticides on neotropical migratory shorebirds.

P027 (PRI-1117-838891) Examination of the fate of Bt Cry3Bb1 protein in aerobic and anaerobic aquatic systems.
Start time: 8:00 AM
Prihoda, K¹, Coats, J¹, ¹ Iowa State Universtiy Pesticide Toxicology Laboratory, Ames, IA, USA
Transgenic crops containing Bacillus thuringiensis (Bt) insecticidal proteins were introduced to the agricultural market in 1996. Despite increasing worldwide usage, relatively little is known regarding Bt protein fate in the environment. Persistence and movement of Bt proteins are important parameters governing exposure to non-target organisms, however, there have been few studies thus far examining the fate of Bt proteins from transgenic crops in the aquatic environment. There is potential for transport of Bt proteins into aquatic environments via runoff/wind erosion of crop residue and protein bound to soil particles. In two laboratory experiments, microcosms were used to investigate the fate of the beetle-active Cry3Bb1 protein in an aerobic or anaerobic aquatic system. Sediment and water samples were collected from Iowa State University Horticulture Research Field Station Pond (Gilbert, IA). In each experiment (aerobic or anaerobic), either purified Cry3Bb1 protein, ground corn material containing Cry3Bb1 protein, or ground corn material of the nearest isoline was added to the sediment/water system. The aerobic experiment had seven time-points (0, 1, 3, 7, 14, 21, and 30 days). The anaerobic experiment had six time-points (0, 30, 60, 90, 180, and 360 days); methylene blue was used to confirm the anaerobicity of the system. At each time point, six microcosms were removed from each experiment and dissolved oxygen, pH, hardness, and alkalinity of the water were measured. Bt concentration in the water was measured using enzyme-linked immunosorbent assay (ELISA). The sediment was sieved to remove any remaining corn material. The sediment and remaining corn material were extracted using a high-salt buffer and analyzed using ELISA. The half-life of the Bt protein and the measured dissipation curve observed in these studies will be presented.

P028 (BAC-1117-466903) Liquid chromatography/tandem mass spectrometry in sulfonylurea herbicide analysis in natural waters: optimization and comparison of electrospray ionization and atmospheric pressure photoionization.
Start time: 8:00 AM
Backus, S¹, Struger, J¹, Batchelor, S¹, Hewitt, L¹, ¹ Environment Canada, Burlington, ON, Canada
The applicability of liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the detection of sulfonylurea herbicides in natural waters was examined. Electrospray ionization (ESI) and atmospheric pressure photoionization (APPI) methods were compared with respect to specificity and detection limit. Although both methods proved suitable, LC/APPI MS/MS with a methanol-water gradient including 0.05 % acetic acid was found best for the purpose. Multiple reaction monitoring allowed the determination of sulfonyl ureas at low nanogram per milliliter levels. LC/MS/MS exhibited high sensitivity and specificity for the detection of sulfonyl ureas in natural waters.

P029 (AGA-1117-733643) Influence of two antibiotics on glutathione s-transferases activity in Maize and Pinto beans.
Start time: 8:00 AM
Farkas, M¹, Berry, J¹, Aga, D¹, ¹ State University of New York at Buffalo, Buffalo, New York, United States
The common agricultural practice of using livestock manure as cropland fertilizer can introduce non-metabolized antibiotics, excreted by treated animals, into the soil. A preliminary study was conducted to determine the effect of two common veterinary antibiotics, flavomycin and chlortetracycline, in maize (Zea maize) and pinto bean (Phaseolus vulgaris) plants. Two sets of each plant species were grown and transplanted in two separate soil pots: one in soil containing 20 ppm of the test antibiotic, and the other in antibiotic-free soil (control). After thirty days, the plants were harvested and total protein was extracted from the roots and leaves. The total protein was subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Clear differences were observed in the silver-stained banding patterns of total protein from antibiotic treated versus untreated plants. Of particular interest was a sharp increase in the intensity of bands within the size range of 25-30 kDa, indicative of an induction by antibiotics of plant glutathione s-transferases (GSTs). A GST activity assay using 1-chloro-2,4-dinitrobenzene as substrate revealed an increase in GST activity, relative to the untreated control. Antibiotic-treated soil samples, incubated with and without growing plants, were analyzed for antibiotics after 30 days of application using liquid chromatography/mass spectrometry (LC/MS). Antibiotic concentrations were decreased ten-fold in soils that supported plant growth. These results suggest uptake of the antibiotic from soil by maize and pinto beans, and implicate induction of GST as a potential mechanism used by these plants to detoxify the antibiotics.

P030 (LUE-1117-831003) Kepone in James River Fish: 1976-2002.
Start time: 8:00 AM
Luellen, D¹, Vadas, G¹, Unger, M¹, ¹ Virginia Institute of Marine Science, Gloucester Point, VA, USA
In late 1975, it was discovered that a manufacturing facility had not only exposed workers to the chlorinated pesticide, Kepone, but had also severely contaminated the James River estuary. Kepone is an extremely persistent organic pollutant that does not break down readily under aerobic or anaerobic conditions. To assess the potential for the public to be exposed to Kepone through the consumption of contaminated seafood, the Commonwealth of Virginia initiated a finfish-monitoring program in late 1975. Over 13,000 samples have been collected and analyzed as part of this on going effort. The average Kepone concentration found in most species began falling when the production of Kepone ended, but the average concentrations remained over the action limit of 0.3 mg g-1 until the early 1980s. By 1988 few fish contained concentrations greater than the action limit. Kepone concentrations in fish were dependant on location, trophic level, and life history. The average concentration in fish has remained unchanged for the last 10-15 years, and it is still detected in 94% of white perch and striped bass samples taken from the James River. It appears that Kepone levels have reached a steady-state in the James River.

P031 (HEW-1117-830643) Assessing runoff impacts on aquatic ecosystems in Atlantic Canada.
Start time: 8:00 AM
Hewitt, L¹, Batchelor, S¹, Rees, H², Chow, L², MacRae, A³, Edwards, L³, Jardine, C⁴, Teather, K⁴, ¹ National Water Research Institute, Burlington, ON, Canada² Potato Research Centre, Fredericton, NB, Canada³ Crops and Livestock Research Centre, Charlottetown, PEI, Canada⁴ University of Prince Edward Island, Charlottetown, PEI, Canada
As part of ongoing studies in Atlantic Canada on the fate and effects of potato pesticides, we have established protocols for regular collections of surface waters in a small (Black Brook, NB) and large watershed (Wilmot River, PEI), both areas of intensive potato production. We also established the collection of runoff in Black Brook and at a field scale site where a runoff flume with autosampler has been developed and installed. Work on effects-based assessments has resulted in the development and validation of a Japanese medaka bioassay to study sediment-related toxicity. Our studies have resulted in the development of a multi-residue method for pesticides on a new LC-MS-MS system. With the new method we have provided the first information from systematic sampling of surface waters for pesticides in both watersheds and are showing significant inputs for linuron and imidacloprid are occurring via runoff. Medaka assays have shown the ability to reproduce toxicity with whole sediments retreived from areas affected by intensive potato agriculture and is being used to investigate causative factors.

P032 (STR-1117-657527) Methoprene and metabolite levels in urban stormwater catch basins and streams in southern Ontario.
Start time: 8:00 AM
Struger, J.¹, Sverko, E.¹, Grabuski, J.¹, Gilmer, E.¹, Marvin, C.¹, Fletcher, T.², ¹ Environment Canada, Burlington, ON, Canada² Ontario Ministry of the Environment, Toronto, ON, Canada
In recent years West Nile Virus has become a major health concern in eastern North America. In response to these health concerns in 2003, municipalities in southern Ontario initiated a mosquito control program using the insecticide methoprene. In 2003 methoprene was applied in pellet form to stormwater catch basins periodically (1-3 times) during May to August. During the application period, surface water sampling was carried out at several catch basins and urban streams located downstream of stormwater inputs in the cities of Hamilton, Burlington and Ottawa. Water samples were collected in catch basins and streams during dry and wet events. Methoprene determinations were conducted by using solid phase extraction cartridges analyzed by GC-MS. Methoprene was detected twice in streams and only during wet (storm)events. It was frequently detected in catch basins during dry and wet events. The maximum concentration measured in the streams was 0.65 ug/L and 4.35 ug/L in the catch basins. In 2004, targetted studies were conducted during precipitation events which also included methoprene metabolite analyses. The metabolites analyzed included: methoprenic acid, citronellic acid, methoprene epoxide and citronellal. These data will be discussed in relation to analytical issues and toxicity information.

P033 (MAR-1117-652364) Multi-media assessment of current-use pesticides in an agricultural area of southern Ontario.
Start time: 8:00 AM
Marvin, C.¹, Struger, J.¹, Sverko, E.¹, Burniston, D.¹, Froude, F.², Blanchard, P.², ¹ Environment Canada, Burlington, ON, Canada² Environment Canada, Downsview, ON, Canada
Environment Canada routinely conducts current-use pesticide monitoring in a number of media. In 2004, this multi-media sampling was coordinated at two different locations in southern Ontario. Air (filter and PUF), surface water, and precipitation were collected at Vineland, Ontario, and Egbert, Ontario. The site of Vineland is located on an active field and represents an area of intensive agriculture, while the site of Egbert is removed from direct agricultural activities and is potentially indicative of the influence of long-range transport of pesticides. Samples were analyzed for a comprehensive suite of pesticides including triazines, neutral and phenoxy acid herbicides, and organophosphorus insecticides. Pesticides that are applied in growing of fruits and vegetables were frequently detected in all media at both sites. Interestingly, levels of some pesticides including bromoxynil, dicamba, and 2,4-D in May and June in air at Egbert (5-63 ng/m3) were similar to corresponding levels at Vineland (4-42 ng/m3). Conversely, concentrations of 2,4-D in Vineland surface waters (ND-8240 ng/L) were roughly an order of magnitude greater than levels measured in a creek near the Egbert site(ND-48.9 ng/L). These results suggest that surface water may be a better indicator of locally-applied pesticides, while air samples represent a combination of local, regional, and continental sources of pesticides

P034 (CHA-1117-597088) Anaerobic soil metabolism of ¹⁴C-Metamifop under chemically reduced condition with sodium sulfide.
Start time: 8:00 AM
Chang, H.-R.¹, Yang, K.-W.², Chung, B.-J.², Kim, K.¹, Kim, Y.-H.¹, ¹ Korea Institute of Toxicology, Daejeon, Republic of Korea² Dongbu Hannong Chemical Co., Ltd.
A laboratory study was conducted to develop a method requiring shorter incubation time in anaerobic soil metabolism by introducing a chemically reduced condition with sodium sulfide and to determine the transformation rate and identify major metabolites of ¹⁴C-metamifop, a new herbicide developed in Korea, in non-sterile and sterile anaerobic soils. ¹⁴C-metamifop was applied to chemically reduced anaerobic soil at a rate of 0.1 ppm, equivalent to approximately field application rate of 100 g of active ingredient per hectare. The soil treated with ¹⁴C-metamifop was incubated in the flow-through systems in the dark at 20±2°C for 90 days. Under chemically reduced anaerobic condition with sodium sulfide, the redox potential declined below -200 mV without pre-incubation and the range of pH, dissolved oxygen(DO), and microbial activities were comparable to the incubation method of OECD guideline(TG307) and conventional anaerobic metabolism studies. The half-life of ¹⁴C-metamifop in non-sterile and sterile anaerobic soil were 53 and 78 days, respectively. Two metabolites were identified: HPFMPA and MFA. A major metabolite with levels of more than 10% of the applied radioactivity was HPFMPA. This study confirmed that use of a chemical reducing agent could shorten the pre-incubation time of the anaerobic soil metabolism study, while the incubation method of the OECD guideline could not generate the anaerobic condition within 30 days after flooding. Further study is needed to confirm the wide applicability of the chemically reduced anaerobic soil metabolism to the other pesticides.

P035 (JAB-1117-575453) Dissipation of penoxsulam, a new sulfonamide herbicide, in simulated rice field conditions.
Start time: 8:00 AM
Jabusch, T¹, Tjeerdema, R¹, ¹ University of California, Davis, CA, USA
Penoxsulam (trade name Granite) is a new acetolactate synthase (ALS) inhibitor herbicide for post-emergence control of annual grasses, sedges, and broadleaf weeds in rice culture. This laboratory study ascertains microbial and photochemical degradation rates and transformation pathways as well as partition constants under conditions simulating flooded rice field conditions. Soil sorption values were inversely related with the pH and ranged from 0.14 to 5.3, indicating that penoxsulam is qualitatively mobile and there is no significant retention in the soil. Penoxsulam did not partition into air at any measurable rate at 20°C or 40°C and its K_H (pH 7) was estimated at 4.6 x 10^-15 Pa × L × mol^-1 based on available water solubility and vapor pressure data. Preliminary results from biodegradation studies in microcosms simulating flooded conditions in a silty clay soil revealed a DT₅₀ value of 45 h and three detectable but transient transformation products. Additional experiments are in progress for a thorough determination of transformation rates and products in the tested soil and three additional soils. In addition, results from a photodegradation study in a photoreactor and in 'outdoor' experiments will be presented. Based on the molar absorptivity of penoxsulam and the maximum photoreaction rate for spring and summer conditions in California, a minimum half-live of 1.2 h (spring) and 43 min (summer) was calculated. Results imply that dissipation of penoxsulam in flooded rice fields is rapid and controlled by microbial and photochemical degradation rates.

P036 (BON-1117-749339) Evaluation of K_d for Synthetic Pyrethroids Using Solid Phase Microextraction and Solvent Extraction.
Start time: 8:00 AM
Bondarenko, S¹, Qin, S¹, Gan, J¹, ¹ UC Riverside, Riverside, CA, USA
Sorption on sediment regulates the fate and bioavailability of contaminants in the aquatic environment. A common way to measure adsorption capacity of organic compounds in soil or sediment is to use the batch equilibration-solvent extraction method in which the solid and aqueous phases are separated by centrifugation and the aqueous phase concentration C_w is determined after exhaustive solvent extraction. However, this method may give artificially depressed K_d for strongly adsorbing compounds such as pyrethroids, as small colloidal particles and dissolved organic matter are not eliminated from the aqueous phase and may increase C_w. Solid phase microextraction (SPME) selectively detects the freely dissolved concentration and thus may be used to improve K_d measurement. K_d values for eight pyrethroid insecticides were determined using both solvent extraction (LLE) and SPME to measure C_w. K_d obtained with SPME was 2-100 times greater than that with the solvent extraction method. For instance, K_d values for cypermethrin measured by SPME and LLE were 1.16×10⁴ L/kg and 0.85×10³ L/kg, respectively. The difference was more significant for sediments with higher organic matter content. K_d measured with SPME is expected to be useful for predicting the bioavailability or toxicity of sediment-borne pyrethroids, as it correlates with the free or bioavailable concentration.

P037 (BRO-1117-731252) Are doormats effective in reducing a source of pesticide contamination in the home?
Start time: 8:00 AM
Ganser, L¹, Brown, A², ¹ Marine-Estuarine Environmental Science, University of Maryland, College Park, MD, US² Department of Entomology, University of Maryland, College Park, MD, US
Pesticide use is extensive in US agricultural as pesticides aid workers by increasing yields and farming efficiency. While pesticides are an aid to workers, they may also pose a risk to workers' health and the environment. As many farm homes are close to the pesticide application sites, opportunity for track-in and indirect exposure to pesticides exists. Previous studies have detected pesticide residues in homes located in agricultural and non-agricultural areas. This project examined the recommended practice of placing doormats in home entryways to reduce indirect pesticide exposure by decreasing track-in. For this project, five types of doormats with different fiber content were chosen with multiple samples taken for each mat type. The mats were contaminated with an indicator pesticide and then laundered to determine the extent of pesticide residue removed by laundering. Laundering is typically used to remove pesticide residues from clothing. So that any residues do not continue to be tracked in, laundering is also recommended for doormats. The indicator pesticide was removed to varying degrees in the various doormats. After determining the differences in pesticide decontamination through laundering among doormats, recommendations on use and laundering of doormats were established. The recommended procedures will be provided to agricultural workers through pesticide safety conferences and Extension publications.

P038 (FAL-1117-727513) Organochlorine pesticides in store bought vegetables grown organically and traditionally.
Start time: 8:00 AM
Wolensky, B.¹, Falconer, R.¹, ¹ Chatham College, Pittsburgh, PA, USA
The demand for organically grown foods has increased dramatically in recent years. Organically grown foods are thought to be a safer choice because of low or no pesticide residues. However, regulations for organic products do not control past-use pesticides sprayed decades ago. Since most of the organochlorine pesticides used from the 1960's to the 1980's have half lives in soils on the order of decades, many soils still contain measurable residues. Vegetables grown in contaminated soil, in particular root vegetables, can be exposed to these residues and organic farming practices are unlikely to lessen this exposure. This survey looked at the differences in pesticide levels in vegetables purchased from local grocery and natural food stores labeled as either traditionally or organically grown. Samples were washed as a typical consumer would do. The skin and flesh were analyzed separately to determine the location of any pesticides. Samples were analyzed for a variety of organochlorine pesticides/metabolites including DDTs, chlordanes, oxychlordane, heptachlor, heptachlor epoxide, dieldrin and hexachlorocyclohexanes. Pesticides were found at measurable, albeit low, levels in the vegetables. The skins typically had higher levels than the flesh. On average, no difference in levels was seen between organically and traditionally grown vegetables for these past use chemicals.

P039 (HAL-1117-712231) Effects of Dissolved Organic Material on the Fate of Selected Pesticides.
Start time: 8:00 AM
Haley, M¹, Davis, E¹, Anthony, J¹, Wershaw, R², Leenheer, J², Cox, L², ¹ U.S. Army, Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA² U.S. Geological Survey, National Research Program, Denver, CO, 80225
The persistence of Dicrotophos, Dichlorvos and Mevinphos in natural water is documented, however the effects on hydrolysis rates from potential catalysts in natural water, and the identification of subsequently generated degradation products are limited. Open literature suggests that dissolved organic carbon (DOC) substantially influence the degradation rates of pesticides. Many half-life determinations for organophosphorous compounds have been conducted in river and pond waters, however those waters were not well characterized. Thus the effects from DOC cannot be fully determined without additional water analysis. In this study, the half-life of selected pesticides was determined in distilled water, and a natural water from the Neversink Reservoir which is part of the New York City water supply. In addition to natural Neversink water, we treated subsamples with granular activated carbon (GAC) to reduced the DOC by 60%. These waters were used in fate studies to determine the effects of DOC on the degradation rates of the pesticides Dicrotophos, Dichlorvos, and Mevinphos. All the studies were conducted in darkness at room temperature. The initial concentration of pesticides was 100 mg/L, and the waters were analyzed using an Agilent 1100 Series HPLC. It was shown that in all waters tested, Dichlorvos degraded the quickest, followed by Mevinphos, and then Dicrotophos. The degradation rates of pesticides were determined both in buffered non-buffered (none added) water, and those maintained at a pH of 6.2 were degraded substantially faster than in non-buffered waters. The 60% reduction in DOC did not affect the degradation rates of the pesticides.

P040 (JAN-1117-830306) Kinetics and Mechanism of the Reaction of Organophosphorus Insecticides with Reduced Sulfur Species.
Start time: 8:00 AM
Wu, Tong¹, Guo, Xiaofen¹, Jans, Urs¹, ¹ City College of CUNY, New York, NY, USA
High concentrations of reduced sulfur species can occur in porewater of sediments and in anoxic subregions of estuaries. The kinetics of the reactions of organophosphorus insecticides (e.g., chlorpyrifos-methyl, chlorpyrifos, parathion-methyl) with reduced sulfur nucleophiles (e.g., bisulfide, thiosulfate, thiophenolate, polysulfide) is determined using well-defined aqueous solutions over a pH range from 5 to 9. The resulting pseudo-first-order rate constants yielded a second-order rate constant for the different pesticides and sulfur nucleophiles. The second-order rate constant for bisulfide is more than 50 times larger than for hydrogen sulfide, while polysulfide reacts 20 times faster than bisulfide. The reactivity for thiophenolate is similar to bisulfide, while thiophenolate is a little less reactive than polysulfides. Product studies clearly indicate that the nucleophilic attack of the sulfur nucleophile occurs primarily at the carbon of the methoxy/ethoxy groups of the organophosphorus insecticide and not at the phosphorus atom. The effect of natural organic matter (NOM) and reduced sulfur species on the fate of organophosphorus insecticides has also been investigated. The results show that NOM is increasing the rate of reaction of some of the investigated pesticides in the presence of bisulfide. It was found that in the presence of NOM different degradation products can be formed. The results indicate that reduced sulfur species (bisulfide, polysulfides) present at environmentally relevant concentrations may represent an important sink for organophosphorus insecticides in a coastal marine environment.

P041 (STR-1117-829987) Occurrence of current-use pesticides in surface waters of Ontario, Canada.
Start time: 8:00 AM
Struger, J.¹, Sverko, E.¹, Marvin, C.¹, Dove, A.¹, Backus, S.¹, Muir, D.¹, Martin, P.¹, Hewitt, M.¹, Thompson, D.², Palace, V.³, ¹ Environment Canada, Burlington, ON, Canada² Natural Resources Canada, Sault Ste. Marie, ON, Canada³ DFO, Winnipeg, MA, Canada
There are limited data on the occurrence, distribution and fate of current-use pesticides in surface waters of watersheds in Ontario. As part of the Environment Canada National Project on Water Quality Surveillance (Pesticide Science Fund) samples were collected over a three year period starting in 2003. Surface water samples were collected from approximately 30 sites located in the Great Lakes Basin including small agricultural and urban watersheds distributed throughout Ontario. The survey design incorporated spatial and seasonal components to determine the distribution and fate of current-use pesticides in relation to use and application. Surface water samples were collected monthly or bi-monthly from April-November and were analyzed for a suite of pesticides including neutral herbicides (e.g. atrazine and metolachlor), phenoxy acid herbicides (e.g. 2,4-D, dicamba and mecoprop) and organophosphorous insecticides (e.g. diazinon and chlorpyrifos). Additional pesticides analyzed included pyrethroid insecticides, glyphosate, imidacloprid, methoprene and metabolites and sulfonyl urea herbicides. Maximum concentrations in surface waters of commonly detected pesticides included atrazine (1590 ng/L), desethyl atrazine ( 472 ng/L), metolachlor (1560 ng/L), 2,4-D (6940 ng/L), mecoprop (6580 ng/L) and dicamba (7100 ng/L). Several orgnophosphorous insecticides were occasionally detected including diazinon (maximum 5490 ng/L), azinphos methyl (6140 ng/L), chlorpyrifos (205 ng/L) and dimethoate (175 ng/L). Glyphosate was also detected occasionally in water. The applicability of immunoassay screening techniques was also evaluated for atrazine, metolachlor and diazinon. Pesticide concentrations were assessed against applicable water quality criteria. In addition, the effects of pesticides on biological responses of wild fish populations (golden shiner) and amphibian populations (leopard and green frogs) in selected drainage systems were measured.

P042 (SMA-1117-819482) Input of dissolved and sediment-associated pesticides to the Yolo Bypass, California.
Start time: 8:00 AM
Smalling, K¹, Orlando, J¹, Kuivila, K¹, ¹ U.S. Geological Survey, Sacramento, CA, 95819
Current-use pesticides are transported into the Yolo Bypass, a leveed flood-control basin in northern California. The objective of this study was to compare the relative distribution of pesticides in waters and sediments transported from five source watersheds to the Bypass. Water and suspended sediments were collected during two high-flow runoff events (February 2004 and January 2005), while bed sediments were collected during the dry season in late September 2004. Dissolved pesticides were analyzed using solid-phase extraction and gas chromatography/mass spectrometry (GC/MS). Sediments were extracted using microwave-assisted extraction, cleaned with carbon and alumina followed by gel-permeation chromatography, and analyzed by GC/MS. The more hydrophilic pesticides (hexazinone, simazine and diazinon) were detected most frequently and at the highest concentrations in the water samples. Pesticides with high use and ranging in log K_oc from 2 to 5 were detected in the water and the sediments. Suspended sediments generally had more pesticides and higher concentrations, compared to bed sediments. Equilibrium partitioning between the water and the suspended sediments was modeled for six pesticides varying in K_oc values and application amounts. Two pesticides, metolachlor and oxyfluorfen, appeared to be in equilibrium between the water and the sediment. In contrast, the other four pesticides (molinate, thiobencarb, trifluralin, and pedimethalin) were not in equilibrium, with higher-than-predicted pesticide concentrations associated with the sediment. Although the current-use pesticides are hydrophilic, a significant percentage of the total amount of each pesticide is associated with the suspended sediments. Differentiating the partioning between the dissolved and sediment-bound fractions is important in understanding the fate and transport of current-use pesticides in the environment.

P043 (ROB-1117-816116) Multi-residue method for the determination of five synthetic pyrethroids in environmental water samples using SPME with negative ion chemical ionisation mass spectrometry detection.
Start time: 8:00 AM
Robinson, N J¹, Olberding, E², Lam, C³, Chen, A⁴, Sharma, A K⁵, ¹ Syngenta, Bracknell, Berkshire, UK² Dow Agrosciences, Indianapolis, IN, USA³ Bayer CropScience, USA⁴ FMC Corporation, Princeton, NJ, USA⁵ DuPont Crop Protection, USA
A multi-residue analytical method has been developed for the analysis of five synthetic pyrethroid insecticides (lambda-cyhalothrin, esfenvalerate, cyfluthrin, cypermethrin and bifenthrin) in environmental water samples. The method utilises solid phase microextraction (SPME) of the water sample followed by gas chromatography with negative ion chemical ionisation mass spectrometry (GC-NICI) detection. The sensitivity of the SPME sampling technique coupled with the high sensitivity and selectivity of the GC-NICI detector allow low part per trillion amounts of pyrethroid insecticides to be measured by direct analysis of the water sample without the need for sample pre-concentration. The poster will describe the analytical method and compare the sensitivity of SPME versus conventional liquid/liquid partition methods. Analyte concentrations determined by the two methods will be compared to assess differences between truly aqueous concentrations and total water concentrations, i.e. aqueous plus that associated with particulate and dissolved organic carbon. This approach is relevant to the evaluation of bioavailable fractions in aqueous systems.

P044 (WON-1126-036713) A Retrospective Assessment of 2-4D Concentrations in Suncook Lake: Implications for Risk Assessment.
Start time:
Wongsearaya, E¹, ¹ New Hampshire Department of Environmental Services
Analysis of previously collected water samples from Lower Suncook Lake were used as a part of an investigation to determine how closely an analysis of degradation rates of herbicide 2-4D butoxyethyl ester formulation (Aqua-Kleen) matched a theoretical consideration conducted in advance of the herbicide application for risk assessment purposes. Time and depth-specific samples were taken at two sites in the lake (Sites A and B). Aqua-Kleen water concentration data were measured at depths of 1m, 2.5m, and 2.75m for day 7 and 0.5m, 2.5m, and 2.75m for day 14 with n=6 for both data sets. The _day7 = 90.5 ppb with a 95% C.I. ± 15.15. _day14 = 110.5 ppb with 95% C.I. ± 7.90. The analysis suggests 2-4D concentrations do not comport with the half-life degradation patterns assumed to occur over a 7 to 28 day period. Instead, 2-4D concentrations tended to rise over a twenty-one day period then precipitously dropped by day twenty-eight. The derived theoretical 2-4D concentrations appear to overestimate the observed concentrations strongly pointing to the need for more extensive chemical environmental fate and transport data for purposes of conceivably more precise assessments of exposure and risk.