Pesticide uses over impervious surfaces like concrete and subsequent washoff and offsite transport significantly contribute to pesticide detection and aquatic toxicity in urban watersheds. Existing modeling approaches include exponential and power-law functions, both of which have a limited ability to describe experimental washoff data. A novel modeling approach was designed to characterize the time-dependence of the washoff potential after application and the dynamics of pesticide washoff during a runoff event. The model satisfactorily captured washoff mass loads and their temporal variations for pesticides examined with a wide range of chemical properties (logKOW =0.6-6.9) under both single and repeated (1-7 times) rainfall events after varying set times (1.5 h-238 days after application). Results of this study suggested that, in addition to commonly reported physicochemical properties for the active ingredient of a pesticide product, additional parameters determined from washoff experiments are required for risk assessments of urban pesticides.

Pesticide washoff from impervious surfaces: Characterization and prediction

248th National Meeting (2014)

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