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PostersCrop Protection2017

Using Population Models to Gain Insights into Direct and Indirect Effects of Pesticides on Listed Fish Populations

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Abstract:

The current approach of assessing risks to fish from exposure to pesticides relies on effects data on individuals. However, the effect of a single stressor on populations may depend on multiple factors including a species’ life history, which life-history traits are impacted by the stressor and to what degree, the duration and frequency of stress occurrence, and variability in population dynamics. Population models can combine effects of stressors observed on organisms with species-specific life histories and variability in population dynamics, and project population-level outcomes over extended time periods. In this study, we used an existing matrix population model of the Slackwater darter (Etheostoma boschungi), a species listed as threatened under the U.S. Endangered Species Act, to assess stress levels that may cause population decline. We represented direct effects as changes in survival and fecundity, and indirect effects as decreased food availability. From the scientific literature, we used information on the relationships between reduced food availability, body size and survival and fecundity in fish, and incorporated these relationships in the Slackwater darter model. We analyzed exposure-effects relationships of a pesticide with the model to estimate exposure levels that could cause long-term impacts on population abundance and persistence. Further, we assessed the applicability of the modeling approach to a range of species by analyzing model predictions for potential pesticide impacts on survival and reproductive rates for related fish species with similar life histories. By combining information on life history and direct and indirect effects, population models can provide a valuable tool to assess potential risks of pesticides to populations of listed and other non-target species over ecologically relevant time periods.

Amelie Schmolke, Brian Kearns, Matthew Kern, Katherine Kapo, Colleen Moloney (Waterborne Environmental), Valery Forbes ( University of Minnesota), Aldos Barefoot (DuPont Crop Protection), Hugo Ochoa-Acuna. Using Population Models to Gain Insights into Direct and Indirect Effects of Pesticides on Listed Fish Populations. Poster ACS 2017. Washington DC.

PostersCrop Protection2017

Vegetative Filter Strip (VFS) Modeling in Risk Assessment

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Abstract:

Growers have been mandated to use 10-ft maintained vegetative filter strips (VFS) on all PWG pyrethroid agricultural labels for several decades. Since the ability of VFS to trap sediment is known with greater certainty than any other performance aspect and was used for calibrating the VFSMOD model, uncertainty in predicted pyrethroid removal by VFS will be less than for other compounds due to the pyrethroid’s extreme hydrophobicity. Essentially 100% of pyrethroid being transported by runoff/erosion will be adsorbed to sediment as it leaves the treated field; consequently, the trapping efficiency of pyrethroids should be very similar to the trapping efficiency of sediment. The impact of the mandatory VFS on total loads of eroded sediment and pyrethroid entering receiving waters was modeled using VFSMOD with a 10-ft VFS linked with EFED’s PWC model across a range of 10 crop scenarios and 8 pyrethroids. The fractions of the pyrethroid mass loading entering receiving waters after the VFS in the dissolved or absorbed states were examined. The impact of running VFSMOD with and without assuming carryover of residues in the VFS from one event to the next was also explored. The magnitude of VFSMOD’s effect on EECs is highly scenario dependent due to weather and soil properties, resulting in a wide range of EEC and sediment load reductions. Importantly, since some scenarios are dominated by aerial drift entry, the impact of VFS on water column EECs can be lower than expected; however, their impact on reducing sediment loading to receiving waters is vital. Moreover, VFS responses are often non-linear since they can be less effective during extreme rainfall events and therefore, their effect needs to be examined across the entire period as well as for the year corresponding to the 1-in-10 EECs since this mitigation is so important for reducing pyrethroid mass loading in all years.

Amy Ritter, Mark Cheplick, Dean Desmarteau (Waterborne Environmental), Paul Hendley (Phasera Ltd). Using Models to Evaluate Exposure to Non-target Plants Through Runoff and Drift From Agricultural Fields. Poster ACS 2017. Washington DC.

PostersCrop Protection2017

Using Models to Evaluate Exposure to Non-target Plants Through Runoff and Drift From Agricultural Fields

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Abstract:

The U.S. EPA uses the screening model, TerrPlant, to estimate exposure to non-target terrestrial plants from a single application of pesticide. Audrey III is a higher tier exposure model that has been developed by U.S. EPA to estimate exposure to plants in a Plant Exposure Zone (PEZ). The objective of this study was to investigate the magnitude and likelihood of exposure of non-target plants to pesticide residues through runoff from agricultural field to an adjacent PEZ. TerrPlant and AUDREYIII will be compared to two vegetative filter models: VFSMOD and PRZM-Buffer. VFSMOD is a vegetative filter strip (VFS) model designed to simulate VFS processes to remove sediment and pesticides from field runoff/erosion. PRZM-Buffer is a modified version of the Pesticide Root Zone Model (PRZM), a rainfall-runoff simulation model, to simulate pesticide fate and transport in a PEZ. Current EPA Tier II scenarios for PRZM were used to represent main field simulations. Movement of pesticide through the PEZ and the concentrations for the segments were modeled with the PRZM-Buffer model and VFSMOD. Results from these two models will be compared to each other and to U.S. EPA models TerrPlant and AUDREYIII. PRZM-Buffer can model metabolites formation and degradation in the VFS. The total residues from the PRZM-Buffer model will be compared to total residues calculated with AUDREYIII. Multiple widths of buffers were assessed to determine distance required for soil concentrations to drop below level of concern for non-target crop.

Amy Ritter, Mark Cheplick, Dean Desmarteau, Megan Guevara. Using Models to Evaluate Exposure to Non-target Plants Through Runoff and Drift From Agricultural Fields. Poster ACS 2017. Washington DC.

PresentationsCrop Protection2017

Using Web-Based Technologies to Inform Stakeholders – CoPST

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Abstract:

Increasingly the Internet is a means to relay complex information to stakeholders. Underlying GIS-based technologies now allow organizations to serve up complex information is meaningful manners and provide additional information in an interactive environment. CoPST is an integrated GIS-modeling framework that incorporates 40 high-risk pesticides and 12 aquatic endangered species presence to identify areas and timing of greatest risk in the Sacramento and San Joaquin river watersheds of California.. The framework uses data from the California Pesticide Use and Reporting database in combination with PRZM, RICEWQ models to estimate pesticide loadings to surface water at the public land survey system section level. Results are combined with species distribution maps to determine co-occurrence. Results are depicted as a series of maps was generated for the study area. These maps include several pesticide heat maps that depict pesticide use intensity. Included are a Total heat map, an Agricultural heat map and pesticide specific heat maps. Tied in with this these maps are the option to retrieve relevant monitoring information for each pesticides of interest. Heat map series include temporal information that allows the users to stepwise walk through each month of the year to see which areas are potentially of concern.

Cornelis Hoogeweg (Waterborne Environmental),  Rich Breuer (California Water Control Board), Debra Denton (USEPA), W Williams (Waterborne Environmental). Using Web-Based Technologies to Inform Stakeholders – CoPST. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Soil Sustainability: The Reality of Erosion Reduction Practices by Farmers and the Impact to Estimated Environmental Concentrations in a Risk Assessment

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Abstract:

Since 1985, USDA National Resources Conservation Service (NRCS) has had joint responsibility to carry out the Highly Erodible Land (HEL) and Wetland conservation provisions of the Food Security Act that helps farmers by delivering technical and financial assistance for conservation. HEL is identified as a field that contains soils which have an erodibility index of ≥8. If a farmer has a field that is identified as HEL, they are required to maintain a system of conservation practices to substantially reduce erosion rates to long-term sustainable levels. If the conservation practices are not adequate to reduce erosion, the farmer may be ineligible for certain USDA payments. Conservation practices that are recommended include grassed waterways, grade stabilization structures, terraces, and tillage management. A field is considered to be sustainable if the soil erosion loss is less than 5 tons/acre per year (on average). However, some US EPA Tier II modeling scenarios used in regulatory screening assessments are parameterized for the PRZM model to have a 30-year average of greater than 30 tons/acre per year; a level which would not be sustainable for continued agricultural production. These Tier II PRZM scenarios do not reflect that growing crops as parameterized is not an option open to the grower expecting program payments. For pyrethroids, which are exceptionally hydrophobic; and therefore, almost exclusively bound to soil, modeling such unsustainable soil erosion leads to predictions of very high pyrethroid loads entering receiving water bodies. This presentation will explore the impact on the estimated water and sediment environmental concentrations for pyrethroids by adjusting input parameters in standard EPA model crop-specific scenarios to match USDA recommended practices for cultivating the crops concerned on HEL land.

Amy Ritter, Dean Desmarteau (Waterborne Environmental), Paul Hendley (Phasera Ltd). Soil Sustainability: The Reality of Erosion Reduction Practices by Farmers and the Impact to Estimated Environmental Concentrations in a Risk Assessment. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Spatial Re-Allocation of Pesticide Use Data in Agricultural and Urban Settings

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Abstract:

California’s Pesticide Use and Registration (PUR) database provides detailed information regarding application timing, rates, crops and location. The public version of the PUR provides location information at the public land survey system level (PLSS) for agricultural uses. A typical PLSS unit is roughly 1 x 1 mile or 640 acres. For urban uses, the PUR provides data at the county-level. Using land use information from diverse data sources such as the National Land Cover Dataset (NLCD), California Farm Mapping and Monitoring Program (FMMP), it is feasible to re-allocate PUR data for both agricultural and urban settings. Within a GIS, it can be determined which fraction of a PLSS unit is agricultural and which is urban. Urban information can further be refined in low, medium, high density and industrial. All these land use classes can be used to demine the more likely locations of pesticide applications. Because several of the datasets are updated frequently, potential use areas were also updated, thereby introducing a refined spatial-temporal component of pesticides applications across the landscape. This re-allocation process was implemented to assess the location and number of pesticide applications to support an assessment of co-occurrence of pesticides and endangered species in California’s Central Valley. Results shows that agricultural areas can be refined and that county-level use data can be distributed using a weighting schema across the county. This spatial re-allocation resulted in more realistic use patterns that were used in the assessment.

Cornelis Hoogeweg, Raghu Vamshi, W. Williams, Mark Cheplick (Waterborne Environmental). Spatial Re-Allocation of Pesticide Use Data in Agricultural and Urban Settings. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Estimating Outdoor Residential and Urban Pesticide Use from the California Pesticide Use Reporting Database

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Abstract:

Estimating outdoor use of pesticides in urban settings requires the consideration of factors that are not typically addressed in agricultural settings. Urban/residential pesticides are used in home gardens, landscape aesthetics, vector control, preservation of wooden structures, and otherwise to erradicate or deter pests in residential and urban premises. California is unique relative to other states in reporting requirements for pesticide applications. Howver, urban use records are not as precise as agricultural records that report the day of application and at a PublicLand Survey System (PLSS) spatial resolution. Urban applications are reported only by licensed Pest Corol Operators at much coarser monthly and county-level resolutions. Homeowner use is not contained in the PUR. A method for estimating non-agricultural outdoor applications of pesticides by professional and homeowners at a daily and PLSS resolution was developed using the county-level PUR database, homeowner sales data, land use records, statistics derived from surveys, and other available sources. The results have been used to predict potential pesticide runoff from urban and residential areas.

W. Williams, Cornelis Hoogeweg (Waterborne Environmental), Yuzhou Luo (California Dept of Pesticide Regulation), Kelly Moran (TDC Environmental). Estimating Outdoor Residential and Urban Pesticide Use from the California Pesticide Use Reporting Database. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Tracer Studies in Headwater Watersheds in the Midwestern U.S. to Characterize Stream Flow Dynamics

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Abstract:

Stream flow dynamics influences agrochemical exposure timing, duration, and frequency. Tracer studies were conducted in headwater watersheds in Iowa and Missouri to characterize stream hydrological properties to better understand drivers behind the magnitude and duration of crop protection chemical concentrations in stream water and watershed model parameterization. We used chemical tracer chemographs to calculate travel time and stream volume for stream reaches under low-flow conditions. Florescent dye was injected at strategic stream locations and continuously monitored with in-situ fluorometers. Accurate travel times of the chemical tracer were calculated from injection points to corresponding, downstream monitoring points along stream reaches, and were then combined with stream discharge data to estimate stream reach flow volume. Assessing tracer data with observed runoff events indicated that the ratio of rainfall-driven stream flow to initial stream flow volume influenced duration of chemical exposure at the headwater outlet. Results also illustrate that flow in small headwater streams is significantly different from that predicted by NHD+ indicating stream characteristics at this scale require higher resolution data. Finally, tracer study results are being used to inform stream flow numerical simulations toward a better representation of stream hydrodynamic properties at the headwater watershed scale.

Greg Goodwin, Daniel Perkins, Megan Cox, Les Carver, Jennifer Trask (Waterborne Environmental), Sun Mao Chen (Syngenta Crop Protection). Tracer Studies in Headwater Watersheds in the Midwestern U.S. to Characterize Stream Flow Dynamics. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Field Study to Determine Runoff and Deposition of an Herbicide in Pasture Conditions

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Abstract:

A field-scale runoff study was conducted to evaluate the fate of herbicide residues when applied under field conditions typical to pasture production. The study monitored movement from treated areas through runoff and possible deposition in untreated down gradient areas in Texas and North Carolina. The study included a novel two-part design: 1) a Small Scale Runoff study to verify model parameters following treatment to three different cover conditions and 2) a Large Scale Runoff study to determine the residue pattern and runoff from treated to untreated areas of typical pasture following a significant rainfall event. This study was conducted in accordance with EPA FIFRA Good Laboratory Practice Standards (GLP), 40 CFR 160. The presentation will focus on the complex study goals and novel field study implementation approach including sampling methods, simulated rainfall equipment and monitoring techniques. A general discussion of results including regional differences observed and variations in impact of residue profile based on cover conditions. Discussion of unique sampling methods related to quantifying grass, thatch and soil residues will be included. The complex study provided data for both quantifying movement in the pasture environment as well as parameters useful for environmental fate modeling under different cover conditions.

Les Carver, Jennifer Trask, Nathan Snyder (Waterborne Environmental), Cecilia Mucha Hirata, Aldos Barefoot ( DuPont Crop Protection). Field Study to Determine Runoff and Deposition of an Herbicide in Pasture Conditions. Presentation ACS 2017. Washington DC.

PresentationsCrop Protection2017

Vegetated Ditches as a Best Management Practice to Filter Pesticides, Sediment, and other Constituents from Agricultural and Urban Runoff Water

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Abstract:

Vegetated ditches and bioswales have been promoted and incorporated into the agricultural and urban landscape to reduce the transport of pesticides, nutrients, sediment, and other water quality consitituents in runoff water. Research studies over the past 12 years have examined their utility as best management practices (BMPs) across a range of applications. These results are compiled and compared to predictions from the Vegetated Filter Ditch Model (VFDM) that was developed to design vegated agricultural drainage ditches at a farm level. At the time of development, very little data was available to evaluate the accuracy of model predictions. Now, approximately 10 years later, additional research has become available to verify the applicability of the model to evaluate the water quality benefits of vegetated ditches and swales in both agricultural and urban settings.

Marty Williams, Jennifer Trask (Waterborne Environmental), Debra Denton (EPA). Vegetated Ditches as a Best Management Practice to Filter Pesticides, Sediment, and other Constituents from Agricultural and Urban Runoff Water. Presentation ACS 2017. Washington DC.