Fate and effects of the triazinone herbicide metribuzin in experimental pond mesocosms

Fairchild, J. F.; Sappington, L. C.

Abstract:

Metribuzin is a triazinone herbicide that is widely used for the control of grasses and broad-leaved weeds in soybeans, sugarcane, and numerous other crops. Metribuzin is highly toxic to freshwater macrophytes and algae under laboratory conditions (median plant EC50 = 31 ??g/L; n = 11 species) but has not been studied under controlled outdoor conditions. We conducted a 6-week study to examine the aquatic fate and effects of metribuzin in 0.1-ha outdoor aquatic mesocosms. Mesocosms (n = 2 per treatment) were treated with metribuzin at one of five concentrations: 0, 9, 19, 38, or 75 ??g/L. Concentrations were selected to bracket known laboratory effect concentrations and to reflect calculated edge-of-field concentrations. The dissipation half-life of metribuzin in water was 5 days. Metribuzin had no statistically significant effects on water quality, periphyton biomass, macrophyte biomass, macrophyte species composition, fish survival, or fish growth at treatment levels ranging up to and including 75 ??g/L. Although metribuzin is highly toxic to freshwater macrophytes and algae under laboratory conditions, it poses little risk to nontarget aquatic plants due to the short aqueous dissipation half-life. The findings also demonstrate that current herbicide risk assessment procedures used in the registration process could benefit from empirical assessments of the fate of chemicals under realistic environmental conditions.

Genre:

Article

ProdID:

70024401

Citation Author:

Fairchild, J. F.; Sappington, L. C.

Citation Contributing Office:

Citation Datum:

Citation Day:

Citation Edition:

Citation Editor:

Citation End Page:

202

Citation Issue:

Citation Keywords:

Citation Language:

English

Citation Larger Work Title:

Archives of Environmental Contamination and Toxicology

Citation LatN:

Citation LatS:

Citation LonE:

Citation LonW:

Citation Month:

Citation No Pagination:

Citation Number Of Pages:

Citation Online Only Flag:

Citation Phsyical Description:

Citation Projection:

Citation Public Comments:

Citation Publisher:

Citation Series:

Citation Series Code:

Citation Series Number:

Citation Search Results Text:

Fate and effects of the triazinone herbicide metribuzin in experimental pond mesocosms; 2002; Article; Journal; Archives of Environmental Contamination and Toxicology; Fairchild, J. F.; Sappington, L. C.