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Research Abstracts Online
January 2010 - March 2011

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University of Minnesota Twin Cities
College of Science and Engineering
Department of Civil Engineering

PI: William A. Arnold, Associate Fellow

Kinetic Isotope Effects in Contaminant Transformations

Isotopic enrichment of a substrate occurs during the reaction of organic pollutants if the rate-limiting step involves bond cleavage. Recent work has used this enrichment to verify that transformation of organic pollutants is occurring (rather than dilution, which does not result in degradation or enrichment) in the field. If the kinetic isotope effects responsible for the isotopic fractionation of different possible process are known, it should be possible to determine not only if degradation is occurring, but also the specific process responsible (hydrolysis, reduction, biodegradation). Recently, several research groups have determined kinetic isotope effects/enrichment factors for a variety of transformations centered on carbon atoms. Many environmental pollutants, such as herbicides, explosives, insecticides, and pharmaceuticals, contain nitrogen, and in some cases, environmental reactions involve the breakage of nitrogen-carbon or nitrogen-oxygen bonds. Thus, studying nitrogen kinetic isotope effects is a means to evaluate the transformation mechanisms of such compounds. MSI resources are used to calculate kinetic isotope effects to compare with experiments.