The U.S. Environmental Protection Agency (USEPA) and Canada's Pest Management Regulatory Agency (PMRA) released the Pesticide Root Zone Model for Groundwater (PRZM-GW) in 2012 to estimate potential groundwater concentrations following agricultural applications of crop protection products. PRZM-GW assumes that soil sorption is linear and constant over time. However, crop protection products often demonstrate soil sorption characteristics are non-linear and increase over time (both characteristics which can reduce mobility potential in soil significantly). The objective of the study is to present model-data comparisons and to demonstrate that the use of Freundlich-type non-linear sorption and time-dependent sorption processes in leaching modeling is necessary to better describe compound movement under field conditions. Comparisons support the conclusion that predicted groundwater concentrations are more appropriate and realistic when modeling includes these processes. This outcome highlights the need for refinement options in the current regulatory groundwater modeling which does not include non-linear and time-dependent sorption behavior.

Evaluation of Freundlich sorption and time-dependent sorption of pesticide in soil with field data

248th National Meeting (2014)

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