You are here:
REDUCTIVE DEHALOGENATION OF HALOMETHANES IN NATURAL AND MODEL SYSTEMS: QSAR ANALYSIS
Citation:
Kenneke, J F. AND E J. Weber. REDUCTIVE DEHALOGENATION OF HALOMETHANES IN NATURAL AND MODEL SYSTEMS: QSAR ANALYSIS. Presented at 220th American Chemical Society National Meeting, Washington, DC, August 20-24, 2000.
Impact/Purpose:
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Description:
Reductive dehalogenation is a dominant reaction pathway for halogenated organics in anoxic environments. Towards the goal of developing predictive tools for this reaction process, the reduction kinetics for a series of halomethanes were measured in batch studies with both natural sediments (iron-reducing/methanogenic and sulfate-reducing) and chemical model systems (Fe(II)/goethite, FeS and Fe(O)) to elucidate key system and molecular properties controlling the mechanism and rate of halomethane reduction. The facile reduction of the
halomethanes in the model systems indicates that chemical reduction is a dominant process controlling the loss of these chemicals in the natural sediments. Correlation analysis indicates, however, that the chemical model systems have limited value for predicting rates of reduction for the halomethanes in natural sediments. A significant decrease in the first-order reduction rate constant with increasing substrate concentration in the iron-reducing/methanogenic
sediment suggests that the microbially-mediated regeneration of chemical reductants and/or diffusion to reactive sites becomes the rate controlling process at higher substrate concentrations.