Soil characteristics and agrichemicals in groundwater of the Midwestern United States
A comprehensive set of soil characteristics were examined to determine the effect of soil on the transport of agrichemicals to groundwater. This paper examines the relation of soil characteristics to concentrations and occurrence nitrate, atrazine, and atrazine residue from 99 wells completed in unconsolidated aquifers across the Midwestern United States. Soil characteristics that determine the rate of water movement were directly related to the occurrence and concentrations of nitrate and atrazine in groundwater. The substantial differences in the relations found among soil characteristics and nitrate and atrazine in groundwater suggest that different processes affect the transformation, adsorption, and transport of these contaminants. A multi-variable analysis determined that the soil characteristics examined explained the amount of variability in concentrations for nitrate (19%), atrazine (33%), and atrazine residue (29%). These results document that, although soils do affect the transport of agrichemicals to groundwater, other factors such as hydrology, land use, and climate must also be considered to understand the occurrence of agrichemicals in groundwater.