Aquifer vulnerability to pesticide pollution—combining soil, land-use and aquifer properties with molecular descriptors

Abstract

This study uses an extensive survey of herbicides in groundwater across the midwest United States to predict occurrences of a range of compounds across the region from a combination of their molecular properties and the properties of the catchment of a borehole. The study covers 100 boreholes and eight pesticides. For each of the boreholes its catchment the soil, land-use and aquifer properties were characterized. Discriminating boreholes where pollution occurred from those where no pollution occurred gave a model that was 74% correct with organic carbon content, percentage sand content and depth to the water table being significant properties of the borehole catchment. Molecular topological descriptors as well as K oc, solubility and half-life were used to characterize each compound included in the study. Inclusion of molecular properties makes it possible to discriminate between occurrence and non-occurrence of each compound in each well. The best-fit model combines: organic carbon content, percentage sand content and depth to the water table with molecular descriptors representing molecular size, molecular branching and functional group composition of the herbicides.