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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

Papers & ReportsAgriculture and Food2012

TFA From HFO-1234yf: Accumulation and Aquatic Risk in Terminal Water Bodies

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A next-generation mobile automobile air-conditioning (MAC) refrigerant, HFO-1234yf (CF3CF = CH2), is being developed with improved environmental characteristics. In the atmosphere, it ultimately forms trifluoroacetic acid (TFA(A); CF3COOH), which is subsequently scavenged by precipitation and deposited on land and water as trifluoroacetate (TFA; CF3COO-). Trifluoroacetate is environmentally stable and has the potential to accumulate in terminal water bodies, that is, aquatic systems receiving inflow but with little or no outflow and with high rates of evaporation. Previous studies have estimated the emission rates of HFO-1234yf and have modeled the deposition concentrations and rates of TFA across North America. The present study uses multimedia modeling and geographic information system (GIS)-based modeling to assess the potential concentrations of TFA in terminal water bodies over extended periods. After 10 years of emissions, predicted concentrations of TFA in terminal water bodies across North America are estimated to range between current background levels (i.e., 0.01–0.22 µg/L) and 1 to 6 µg/L. After 50 years of continuous emissions, aquatic concentrations of 1 to 15 µg/L are predicted, with extreme concentrations of up to 50 to 200 µg/L in settings such as the Sonoran Desert along the California/Arizona (USA) border. Based on the relative insensitivity of aquatic organisms to TFA, predicted concentrations of TFA in terminal water bodies are not expected to impair aquatic systems, even considering potential emissions over extended periods. Environ. Toxicol. Chem. 2012; 31: 1957–1965. © 2012 SETAC

Russell, M.H., C.G. Hoogeweg, E.M. Webster, D.A. Ellis, R.L. Waterland, and R.A Hoke.. 2012. TFA from HFO-1234yf: Accumulation and aquatic risk in terminal water bodies. Environmental Toxicology and Chemistry. doi: 10.1002/etc.1925.