Kansas Water Science Center
The Deethylatrazine/Atrazine Ratio as an Indicator of the Onset of the Spring Flush of Herbicides into Surface Water of the Midwestern United States
By E.M. Thurman and J.D. Fallon
The ratio of deethylatrazine to atrazine (DAR) may be used to record the first major runoff of herbicides from non-point-source corn fields to surface water in the Midwestern United States. The DAR dramatically decreases from -0.5 to <0.1 upon application of herbicide and the first major runoff event of a basin. The DAR then gradually increases to values of approximately 0.4-0.6 during the harvest season. Furthermore, the DAR may be used in studies of surface water movement to give a temporal indicator of water moving into reservoirs for possible storage of herbicides. It is hypothesized that deethylatrazine, which accounts for only 6% of the degradation of atrazine, becomes a significant metabolite in surface water (ž50% of parent compound) because of its selective removal from soil. This removal process may be an important concept for consideration in studies of herbicide contamination of rivers and reservoirs.
KEYWORDS: atrazine, deethylatrazine, hydroxyatrazine, metabolites, surface water, and runoff
Additional information about the Organic Geochemistry Research Laboratory can be found at: http://ks.water.usgs.gov/pages/research-lab
Thurman, E.M. and Fallon, J.D., 1996, The Deethylatrazine/Atrazine Ratio as an Indicator of the Onset of the Spring Flush of Herbicides into Surface Water of the Midwestern United States [abst.]: International Journal of Environmental Analytical Chemistry, v. 65, p. 203-214.
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