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United States Department of Agriculture

Agricultural Research Service

Title: The Occurence and Distribution of Diuron in Riparian Areas Adjacent to a Grass Seed Field

Authors
item Field, Jennifer - OSU ENVT & MOLECULAR TOX
item Reed, Ralph - OSU ENVT & MOLECULAR TOX
item Sawyer, Thomas - OSU ENVT & MOLECULAR TOX
item Griffith, Stephen
item Wigington, P - USEPA CORVALLIS OR

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 31, 2002
Publication Date: February 28, 2003
Citation: FIELD, J.A., REED, R.L., SAWYER, T.E., GRIFFITH, S.M., WIGINGTON, P.J. THE OCCURENCE AND DISTRIBUTION OF DIURON IN RIPARIAN AREAS ADJACENT TO A GRASS SEED FIELD. JOURNAL OF ENVIRONMENTAL QUALITY. 2003. v. 32(1). p. 171-179.

Interpretive Summary: Diuron (Karmex) is the principal herbicide used in grass seed production. The occurrence and distribution of diuron in surface and groundwater was investigated for two years at a site located in the southern Willamette Valley of Oregon. The experimental sites consisted of an agricultural field under grass seed production with a farmed riparian zone and a second site was part of the same grass field but had a non-cultivated riparian zone. Diuron and its breakdown products were determined in samples of surface water, shallow and deep groundwater, and soil collected from the two study sites. Concentrations of diuron and one of its breakdown products in surface water declined from a maximum immediately following application to low levels that persisted as long as flow was present. Diuron and one of its breakdown product concentrations in shallow groundwater were highest in the zone immediately adjacent to Lake Creek, which indicates the influence bank infiltration on shallow groundwater quality. Diuron distributions in shallow groundwater obtained from these two field sites supports the hypothesis that groundwater at this site bypasses the rooting zone of the riparian areas. The combined concentrations of diuron and one of its byproducts in soil were found to be equal to or greater than the diuron application rate, which indicates that these residues persist in soil. Surface runoff during the rainy season removes very little of the applied herbicide.

Technical Abstract: Diuron (3-(3,4-dichlorophenyl)-1,1-dimethyl urea) is the principal herbicide used in grass seed production. The occurrence and distribution of diuron was investigated at a poorly drained field site located along an intermittent tributary of Lake Creek in the southern Willamette Valley of Oregon. The experimental sites consisted of a field under grass seed production with a cultivated riparian zone and a second site was part of the same grass seed field but had a non-cultivated riparian zone. Diuron and its metabolites were determined in samples of surface water, shallow and deep groundwater, and soil collected from the two study sites. Diuron and its metabolite DCPMU were the only significant residues detected in this study, while DCPU, DCA, and its dechlorination products were not detected. Concentrations of diuron and DCPMU in surface water declined from a maximum immediately following application to low levels that persisted as long as flow was present. Diuron and DCPMU concentrations in shallow groundwater were highest in the zone immediately adjacent to Lake Creek, which indicates the influence of bank infiltration on shallow groundwater quality. Diuron distributions in shallow groundwater obtained from these two field sites supports the hypothesis that groundwater at this site bypasses the rooting zone of the riparian areas. The combined concentrations of diuron and DCPMU in soil were found to be equal to or greater than the diuron application rate, which indicates that these residues persist in soil. Surface runoff during the rainy season removes very little of the applied herbicide.

Last Modified: 9/10/2014
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