E.M. Thurman
P. J. Squillace
1992
<div id="yui_3_14_1_1_1457731641111_1474" data-canvas-width="60.43028543586828">Alachlor, atrazine, cyanazine, metolachlor, and metribuzin were measured at six sites during 1984 and 1985 in large subbasins within the Cedar River, IA. A computer model separated the Cedar River discharge hydrograph into groundwater and overland-flow components. The concentration of herbicides in the river when groundwater was the major flow component was less than 1.0 <span>μ</span>g/L and averaged 0.2 <span>μ</span>g/L. The maximum concentrations of herbicides occurred when overland flow was the major component of river discharge, exceeding 50 pg/L for total herbicides. About 6% of the annual river load of atrazine was transported with the groundwater component, while 94% was transported with overland flow. From 1.5 to 5% of the atrazine applied during the year was transported from the basin. Atrazine concentrations in the river in- creased according to the discharge divided by the drainage area. This correlation indicates that rivers with large normalized 2-year peak flows have the potential to transport large concentrations of herbicides. A diagrammatic model of nonpoint-source transport of herbicides was developed that suggests that sorbed transport from fields occurs during episodes of overland flow with rapid dissolution of herbicides downstream. </div>
application/pdf
10.1021/es00027a015
en
American Chemical Society
Herbicide transport in rivers: Importance of hydrology and geochemistry in nonpoint-source contamination
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