Herbicide persistence and mobility in recharge lake watershed in York, Nebraska

Elevated levels of herbicides in surface and groundwater are a concern in the Cornbelt in the USA. This study was conducted to interpret the herbicide behavior in a watershed system using data collected from runoff, Recharge Lake, and groundwater influenced by agriculture and lake seepage. The York...

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Bibliographic Details
Published in:Journal of environmental quality 1997-01, Vol.26 (1), p.115-125
Main Authors: Ma, L. (Univ. of Nebraska-Lincoln, Lincoln, NE.), Spalding, R.F
Format: Article
Language:English
Subjects:
Applied sciences
BASSIN VERSANT
CUENCAS HIDROGRAFICAS
Exact sciences and technology
Freshwater
HERBICIDAS
HERBICIDE
LAC
LAGOS
Natural water pollution
NEBRASKA
Pollution
Water treatment and pollution
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Summary:Elevated levels of herbicides in surface and groundwater are a concern in the Cornbelt in the USA. This study was conducted to interpret the herbicide behavior in a watershed system using data collected from runoff, Recharge Lake, and groundwater influenced by agriculture and lake seepage. The York Ground Water Recharge Project was constructed on a tributary of Beaver Creek, which drains a 3327-ha watershed of primarily row-cropped heavily irrigated farmland. The estimated average runoff is 1.48 X 10(6) m3 yr-1 under a precipitation norm of 635 mm yr-1. Maximum atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) inputs to Recharge Lake occurred in May and June runoff events and resulted in average lake concentrations of 36 and 17 micrograms L-1 in 1993 and 1994, respectively. Only about 0.28 and 0.19% of total applied atrazine was lost to runoff in 1993 and 1994, respectively. The deethylatrazine (DEA) to atrazine molar ratio (DAR) decreased rapidly over a period of several hours in runoff samples, which is consistent with inputs from recently atrazine-treated soil. After the spring runoff, herbicide levels in Recharge Lake rose rapidly in response to the runoff event, then diminished gradually over a period of months. Atrazine concentrations in Recharge Lake decreased exponentially with time. Degradation half-lives were 237 d (r = 0.93) in 1993 and 209 d (r = 0.91) in 1994. Adjusted DEA concentrations in Recharge Lake remained relatively constant, indicating little evidence for biotic degradation and suggesting that abiotic degradation of atrazine to hydroxyatrazine (2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine) was the most likely major degradative pathway in Recharge Lake
ISSN:0047-2425
1537-2537
DOI:10.2134/jeq1997.00472425002600010018x