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Updated: Jan 27, 2026

Characterization and Application of Passive Samplers for Monitoring of Pesticides in Water
Published on: August 3, 2016
Spatial assessment of pesticide leaching risk to groundwater: sub-national decision making and model output
Thomas Pf Dowling1, Sabine Beulke2, James Garratt2
1Department of Geography, King's College London, London, UK.
Background:
This study compares standard regulatory methodology (fixed scenarios and models) to spatial modelling at a 1 km landscape resolution for the evaluation of predicted environmental concentrations of pesticides in groundwater. The use of spatial modelling in the decision-making processes is discussed and three options for the sub-national evaluation and restriction of substances based on spatial environmental fate modelling are examined. Wheat and sugar beet are tested with two modified FOCUS substances (A and D) in the PEARL and GeoPEARL models. The 80th percentile value in time and space, aggregated to three different sub-national divisions of interest to a regulator, is used as a regulatory relevant output.
Results:
Means and medians of predicted environmental concentrations at the national level are not useful summary statistics in the age of extensive and freely available geospatial data. A better statistic to use is the P80 (or other desired threshold/percentile combination) in time and space of predicted environmental concentration, combined with flexible and adaptable sub-divisions of the country based on the desired protective target.
Conclusion:
Tier 3b modelling is shown to provide an increase in localism and regulatory nuance over Tier 1 scenarios when combined with soil and aquifer type sub-national units. © 2019 Society of Chemical Industry.
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