Herbicide Transport in Goodwater Creek ExperimentalWatershed: I. Long-Term Research on Atrazine

Atrazine continues to be the herbicide of greatest concern relative to contamination of surface waters in the United States (U.S.). The objectives of this study were to analyze trends in atrazine concentration and load in Goodwater Creek Experimental Watershed (GCEW) from 1992 to 2006, and to conduc...

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Bibliographic Details
Published in:Journal of the American Water Resources Association 2011-04, Vol.47 (2), p.209-223
Main Authors: Lerch, R.N., Sadler, E.J., Sudduth, K.A., Baffaut, C., Kitchen, N.R.
Format: Article
Language:English
Subjects:
Aquatic ecosystems
atrazine transport
Contamination
correlation analysis
Creeks & streams
critical transport period
cumulative frequency distributions
cumulative vulnerability index
Herbicides
monitoring
regression analysis
Series & special reports
Studies
Surface water
watershed
watershed regression for pesticides model
Watersheds
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Summary:Atrazine continues to be the herbicide of greatest concern relative to contamination of surface waters in the United States (U.S.). The objectives of this study were to analyze trends in atrazine concentration and load in Goodwater Creek Experimental Watershed (GCEW) from 1992 to 2006, and to conduct a retrospective assessment of the potential aquatic ecosystem impacts caused by atrazine contamination. Located within the Central Claypan Region of northeastern Missouri, GCEW encompasses 72.5 km... of predominantly agricultural land uses, with an average of 21% of the watershed in corn and sorghum. Flow-weighted runoff and weekly base-flow grab samples were collected at the outlet to GCEW and analyzed for atrazine. Cumulative frequency diagrams and linear regression analyses generally showed no significant time trends for atrazine concentration or load. Relative annual loads varied from 0.56 to 14% of the applied atrazine, with a median of 5.9%. A cumulative vulnerability index, which takes into account the interactions between herbicide application, surface runoff events, and atrazine dissipation kinetics, explained 63% of the variation in annual atrazine loads. Based on criteria established by the U.S. Environmental Protection Agency, atrazine reached concentrations considered harmful to aquatic ecosystems in 10 of 15 years. Because of its vulnerability, atrazine registrants will be required to work with farmers in GCEW to implement practices that reduce atrazine transport. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:1093-474X
1752-1688
DOI:10.1111/j.1752-1688.2010.00503.x