Pesticide Risk Assessment in the Pampa Region of Argentina: Framework for exposure characterization

JULIE C BRODEUR; MARISOL SANCHEZ; LUCIANA CASTRO; DANTE E. ROJAS; DIEGO CRISTOS; MARIA JIMENA DAMONTE; MARIA BELEN POLISERPI; MARIA FLORENCIA D´ANDREA; ADRIAN ANDRIULO

Congreso; SETAC LatinAmerican 12th annual meeting; 2017

The estimation of the Predicted Environmental Concentrations (PEC) of a pesticide is an essential first step when performing an ecotoxicological risk assessment for aquatic environments. In the past, the lack of readily available databases, scenarios and tools to define PEC have limited the development and use of pesticide risk assessment practices in the Pampa region of Argentina. The Pesticide Water Concentration (PWC) is a free computer model developed by the U.S. Environmental Protection Agency, which allows to estimate probable concentrations of pesticide in surface water for use in risk assessment. The objectives of the current project are (1) to develop climate and soil databases necessary for using PWC in the Pampa region, (2) to realize a sensitivity analysis of PWC to detect the sensitive parameters of the model, and (3) to define exposure scenarios describing the various subregions of the Pampa region. For soil data, a soil map with a resolution of 1:2.500.000 and which includes values for the various soil horizons was selected. In this soil database, the Pampa region is divided in 82 cartographic units. On this basis, we proceeded to generate one weather file per soil cartographic unit for the period 1984-2014 by ordinary kriging using data from 30 meteorological stations. To detect the presence of temporal variations in the climatic variables used, trend analysis was performed using the Mann-Kendall Test. This test demonstrated the presence of significant upward trends in maximum temperatures over the region that were sometimes, but not always, accompanied by upward trends in evapotranspiration. As pan evaporation data were not continuous for the entire time period, these values were calculated from pan coefficients obtained by relating evapotranspiration to pan evaporation data available in each meteorological stations. Calculated pan coefficients ranged between 0.55 and 0.68 over the territory. The sensitivity analysis of the PWC model was realized using the SENSAN section of the PEST model. The most sensitive parameters were, in decreasing order, (1) water body dimensions, (2) chemical, (3) run off, (4) erosion, (5) applications, (6) benthos, (7) water column, (8) crop. The ongoing final step of the project consists in building and comparing exposure scenarios associated to the different cartographic units so as to define a framework for pesticide exposure characterization and risk assessment in the Pampa region.