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Technical Report A-98-6, US Army Corps of Engineers, Waterways Experiment Station
November 1998

Aquatic Plant Control Research Program

David G. Petty, John G. Skogerboe, Kurt D. Getsinger, Dale R. Foster, James W. Fairchild, Lars W. Anderson

ABSTRACT

The aquatic fate of the triethylamine formulation of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) was studied in closed-pond systems in California, Missouri, and Texas, as whole-pond applications. This study determined dissipation rates of triclopyr and its major metabolites, TCP (3,5,6-trichloropyridinol) and TMP (3,5,6-trichloro-methoxypyridine) in water, sediment, and finfish. Two ponds at each site containing a healthy biological community were treated at 2.5 mg/L triclopyr. Water and sediment samples were collected through 12 weeks posttreatment, and non-target animals were collected through 4 weeks posttreatment.

Dissipation rates for triclopyr, TCP, and TMP were similar at each of the study sites, despite differences in weather, water quality, biotic community, light transmission, and geographic location. Half-lives of triclopyr in water ranged from 5.9 to 7.5 days, while TCP ranged from 4.0 to 10.0 days, and TMP ranged from 4.0 to 7.7 days. Levels of triclopyr and TCP declined in sediments at half-lives ranging from 2.8 to 4.6 days, and 3.8 to 13.3 days, respectively. Levels of TMP in sediment were below limits of detection. Triclopyr and TCP cleared from fish in relation to concentrations found in the water column. TMP levels in fish were generally an order of magnitude higher than levels of triclopyr and TCP; particularly in the viscera portion of the animals.

No adverse effects on water quality or on the non-target biotic community were found following triclopyr applications. Results of this study were similar to those of triclopyr dissipation studies conducted in reservoirs, lakes, and riverine systems in Georgia, Florida, Minnesota, and Washington. Therefore, the degradation and dissipation of triclopyr and its metabolites is similar in representative systems throughout the continental U.S.

For more information:

Petty, David
NDR Research
710 Hanna St.
Plainfield, IN  46168
Email:  dpetty@ndrsite.com