Wavelength-Dependent Photoreactivity of Mirex in Lake Ontario

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• 作者：Kelly L. Lambrych and John P. Hassett
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：February 1, 2006
• 年：2006
• 卷：40
• 期：3
• 页码：858 - 863
• 全文大小：150K
• 年卷期：v.40,no.3(February 1, 2006)
• ISSN：1520-5851

文摘

Mirex is a toxic, hydrophobic pollutant in Lake Ontariothat undergoes an indirect photoreaction mediated by naturaldissolved organic matter. The monohydro productphotomirex further photolyzes to form a dihydro product.The efficiency of mirex photolysis was determined aswavelength-dependent reaction quantum yield coefficients.Quantum yield coefficients were determined for 14 lakesamples collected from multiple locations and over the courseof several weeks from one location. Values declinedwith increasing wavelength, with reactivity extending above436 nm. Individual samples showed no seasonal trend.Pooled quantum yield coefficients and 95% confidenceintervals were calculated by combining the results for allsamples. Using the quantum yield coefficients withinthis confidence interval, mirex photolysis rates wereaccurately predicted during a sunlight exposure study foran independently collected water sample. In a relativerate experiment, the rate constants for mirex photolysis andsubsequent photomirex photolysis were not significantlydifferent from each other at the 95% confidence level, andthis finding was further supported by the sunlight exposureresults. Using the results from this study, it was estimatedthat, on a cloudless June day, the photolysis half-life of mirexin the epilimnion of Lake Ontario is 19 days.