Integr Environ Assess Manag. 2022 Sep 22. doi: 10.1002/ieam.4688. Online ahead of print.
Pesticide surface water monitoring data have rarely been used as the only quantitative measure of exposure because the available monitoring data for most pesticides has not been considered robust enough for direct use in pesticide exposure assessments due to infrequent sampling. The cost of daily sample collection and analysis prohibits high sampling frequency for most monitoring programs. In this context, a common question raised in assessments is how likely peak concentrations (i.e., annual maximums) may be missed if sampling intervals are greater than daily. The US Geological Survey developed the statistical model ‘seasonal wave with streamflow adjustment and extended capability’ (SEAWAVE-QEX) to address the need to estimate infrequently occurring pesticide concentrations, such as annual maximum daily concentrations, for sites with non-daily monitoring data. This study compares the results of two post-processing methods and evaluates the capability of SEAWAVE-QEX to estimate annual maximum concentrations of three commonly used herbicides and one metabolite in a catchment in Belgium. The study concludes that the appropriateness of using SEAWAVE-QEX to estimate annual maximum concentrations is dependent on pesticide characteristics and usage and that the model can be particularly sensitive to non-flow correlated exposure events (e.g., point source contributions or drift). This article is protected by copyright. All rights reserved. © 2022 SETAC.