Reconnaissance data for selected herbicides, two atrazine metabolities, and nitrate in surface water of the Midwestern United States, 1989-90

Abstract

Water-quality data were collected from 147 rivers and streams during 1989-90 to determine the temporal and geographic distribution of selected preemergent herbicides, two atrazine metabolites, and nitrate in 10 Midwestern States. This report includes a description of the sampling design, data-collection techniques, laboratory and analytical methods, and a compilation of constituent concentrations and quality-assurance data. All water samples were collected by depth-integrating techniques at three to five locations across the wetted perimeter of each stream. Sites were sampled three times in 1989~before application of herbicides, during the first major runoff after application of herbicides, and in the fall during a low-flow period when most of the streamflow was derived from ground water. About 50 sites were selected by a stratified random procedure and resampled for both pre-and post-application herbicide concentrations in 1990 to verify the 1989 results. Laboratory analyses consisted of both enzyme-linked immunosorbent assay (ELISA) and confirmation by gas chromatography/mass spectrometry (GC/MS). The data have been useful in studying herbicide transport, in comparison of the spatial distribution of the post-application concentrations of 11 herbicides and 2 atrazine metabolites (deethylatrazine and deisopropylatrazine) in streams and rivers at a regional scale, in examination of the annual persistence of herbicides and two atrazine metabolites in surface water, and in assessment of atrazine metabolites as indicators of surface-and ground-water interaction.