Collecting a water sample (grab sample) for the reconnaissance of herbicide concentrations in streams.

USGS scientists collecting large-volume water samples off of a bridge across the San Joaquin River near Vernalis, Calif., in support of a study of pesticides in runoff from agricultural fields in the watershed (circa 2000).

The analysis of pesticides sometimes requires large-volume water samples to detect pesticides that are toxic at low concentrations. This is a view of a pump used to collect samples from the San Joaquin River near Vernalis, Calif. (circa 2000).

Collecting water-quality samples for pesticide analysis off of a bridge over the San Joaquin River near Vernalis, Calif. (site ID 11303500, circa 2000). Safety plans for work on bridges includes the use of safety cones and signs, lane blockage, and traffic control.

Packing in supplies as part of a study of herbicides transported by rain to Isle Royale National Park, Mich. USGS scientists detected trace concentrations of herbicides in the remote island's lakes and streams.

USGS scientists studied the transport of herbicides by rain to the pristine waters of Isle Royale National Park, Mich., located in Lake Superior on the United States-Canadian border. Results of the study showed that herbicides can be transported to pristine areas and result in detectable concentrations in streams and lakes.

The supplies for the analysis of pesticides by enzyme-linked immunosorbent assay (ELISA). ELISA is a cost effective way to conduct studies on the occurrence of pesticides, such as atrizine, in water resources that involve the collection of large numbers of samples.

USGS scientists used gas chromatography/mass spectrometry (GC/MS) to analyze water-quality samples during a reconnaissance study of herbicides and their metabolites in surface water of the Midwestern United States. The study also compared the results of immunoassay and GC/MS analysis.

USGS scientist using an autotrace to extract pesticides from water samples in preparation for gas chromatography/mass spectrometry (GC/MS) analysis. The autotrace automates the processing of large numbers of samples.

A liquid chromatography/mass spectrometry (LC/MS) instrument with an on-line solid phase extraction (SPE) system used for the analysis of pesticides in water. SPE provides for shorter total analysis times, the ability to automate analysis procedures, and much smaller sample volumes for analysis.

USGS scientist preparing a sediment sample for the analysis of herbicides. USGS scientists developed an analytical method for the ultratrace analysis of herbicides in soil that combined solid-phase extraction (SPE) and enzyme-linked immunosorbent assay (ELISA).

Incorporating an encapsulated herbicide (atrazine) into the soil as part of an experiment to determine if encapsulating herbicides reduces runoff. The white pipes are suction cup lysimeters used to sample water from the unsaturated zone.