The deethylatrazine/atrazine ratio as an indicator of the onset of the spring flush of herbicides into surface water of the Midwestern United States

E.M. Thurman; J. D. Fallon

doi:10.1080/03067319608045555

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The deethylatrazine/atrazine ratio as an indicator of the onset of the spring flush of herbicides into surface water of the Midwestern United States

E.M. Thurman·J. D. Fallon

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Abstract

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 (∼ 50% 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.

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E.M. Thurman, J. D. Fallon. 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. https://doi.org/10.1080/03067319608045555

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