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Cyanazine, Atrazine, and Their Metabolites as Geochemical Indicators of Contaminant Transport in the Mississippi River

ACS Symposium Series

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Abstract

The geochemical transport of cyanazine and its metabolite cyanazine amide (CAM) was compared to atrazine and its metabolite deethylatrazine (DEA) at three sites in the Mississippi River basin during 1992 and six sites during 1993. The floods of 1993 caused an uninterrupted exponential decline in herbicide concentrations; whereas, in 1992 herbicide concentrations varied mostly in response to two discrete discharge pulses in the spring and midsummer and were stable during an extended period of summer low-flow. Concentration half-lives calculated from the 1993 data for atrazine were approximately twice those of cyanazine at all sites. The half-life for atrazine and cyanazine was shortest, 22 and 14 days, respectively at the Mississippi River at Clinton, Ill. - the farthest upstream site - and longest, 42 and 22 days, respectively, at the Baton Rouge, La. site - the farthest downstream site. The concentration of CAM exceeded the concentration of DEA through September at all sites where the mean ratio of atrazine-to-cyanazine (ACR) was less than 4.0. The ratio of CAM-to-cyanazine (CAMCR) increased from 0.2 to more than 1.0 and the ratio of DEA-to-atrazine (DAR) increased from less than 0.1 to 0.3 from application in May through early to mid-July. Temporal changes in the CAMCR were used to identify pre- and post-application "slugs" of water transported along the reaches of the Mississippi River.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Cyanazine, Atrazine, and Their Metabolites as Geochemical Indicators of Contaminant Transport in the Mississippi River
Series title:
ACS Symposium Series
Volume
630
Year Published:
1996
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
288
Last page:
302
Number of Pages:
15