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Publications: 2013

PostersCrop Protection20132014

Spatial Approaches to Refine Agricultural Chemical Use Areas for Endangered Species Assessments: Study With California Tiger Salamander

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The geospatial analysis of a threatened and endangered species risk assessment will be presented by highlighting a tiered approach to characterizing the potential exposure of the California Tiger Salamander (CTS) to an herbicide use. The studied herbicide use was recorded in 35 California counties from 2001 to 2010 (Pesticide Use Reporting Database, California Department of Pesticide Regulation), while CTS critical habitats defined by the U.S. Fish and Wildlife Service were located in 21 counties. Using herbicide applications to orchards as an example for refining species/pesticide co-occurrence beyond the county-level screening, multiple approaches to characterizing spatial relationships between potential herbicide use sites and species habitats were performed. Best available geospatial data for species habitat, crop, vegetation, hydrology, wetlands, topography, and more were incorporated step-wise to represent realistic spatial relationships while documenting the impact (and uncertainty) each refinement made. Pesticide transport modeling was used to determine the distance that potential exposure may affect the species or its habitat. Refinements to this modeling further reduced the geographic extent of potential exposure. The tiered approach offers a step-wise refinement to quantify the potential overlap of pesticide usage with widely distributed species locations from the state-wide scale to the field scale. This was performed in a programmatic, documented and transparent way, allowing for full retrieval of all details.

Spatial approaches to refine agricultural chemical use areas for endangered species assessments: Study with California Tiger Salamander. Raghu Vamshi, Joshua Amos, Christopher Holmes, JiSu Bang. SETAC North America 34th Annual Meeting. Nashville, TN. November 17-21, 2013

PostersCrop Protection2013

Development of EuroPEARL 2012 to Support Large-Scale Exposure Assessments and Monitoring Programs

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Modelling of pesticides is integral to the fate assessment of agrochemicals in the European Union (EU). Changes to the modelling framework for groundwater e.g., EFSA (2007) mean that it is more difficult for agrochemicals to rely upon modelling alone to gain registration within the EU. Consequently, registrations are increasingly dependent upon monitoring to demonstrate compliance in the context of concentration limits imposed by authorities.

A challenge with conducting monitoring studies in the EU is that often there is no network of wells established that can be placed in a known context of groundwater vulnerability. Therefore suitable locations for monitoring well installation must be identified before monitoring can begin. The lack of appropriate high-resolution GIS data at the EU-level places restrictions on the scale at which candidate monitoring sites can be identified. Similarly, basic datasets, such as depth to shallow groundwater are not available at an EU level.

Gerco Hoogeweg, Paul Sweeney, Shelby Zelonis, Lucy Fish, Sue Hayes, Paul Hendley. Presentation by Paul Sweeney, Syngenta. Pesticide Behaviour in Soils, Water and Air. York, UK. September 2-4, 2013.

PostersAgriculture and Food2013

A Geospatial Toolbox for Higher-Tier Endangered Species Exposure Assessments During Pesticide Registration Review

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Going beyond the screening-level proximity assessment, several challenges are faced in higher-tier analyses for a threatened and endangered species risk assessment conducted as part of USEPA’s registration review of pesticides. Presented here is a toolbox for spatial analysis that offers a suite of approaches depending on the species being studied and the mode of chemical transport in order to characterize and refine the possible interaction between endangered species habitats and pesticide use areas.

Potential pesticide use areas can be spatially located using best available agricultural land cover data from USDA and state-level sources. However, aspects such as classification accuracy and the temporal nature of cropping need to be taken into account when defining the final data layer.

Opportunities exist to spatially refine endangered species habitats after the screening level assessment. Examples of higher tier refinements to species location data include distinguishing the specific aquatic or terrestrial habitat suitable for breeding based on life history information, distinguishing the habitat types preferred by adults that are within a specific migratory distance from spawning sites, and using elevation data to limit species range.

In addition to refining species habitats and pesticide use sites, the spatial relationships between them can be characterized using novel approaches. For instance, vegetation between crops and species location can be characterized in order to identify features that may impede pesticide runoff or drift; the magnitude of co-occurrence can be quantified by calculating the proportion of species habitat potentially exposed; pesticide application timing can be assessed in relation to sensitive species life stages; and other landscape factors affecting pesticide transport such as intervening slope (when erosion is the concern) or wind speed/direction (when drift is the concern) can be examined.

The approaches utilized from this toolbox will depend on the specific aspects of exposure being examined and provide a useful mechanism to refine the scope of potential pesticide exposure to protected species, and focus energies on those specific areas in which mitigation or stewardship are of greatest value.


A geospatial toolbox for higher-tier endangered species exposure assessments during pesticide registration review. Joshua Amos, Raghu Vamshi, Christopher Holmes, and Vivienne Seed. SETAC North America 34th Annual Meeting. Nashville, TN. November 17-21, 2013