title: Estimation of rate constants of PCB dechlorination reactions using an anaerobic dehalogenation model.
abstract: This study aims to estimate anaerobic dechlorination rate constants (km) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway kmvalues are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM. DAs published in the literature in terms of chlorine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The best fit explaining the congener pattern changes was found for pathways of Phylotype DEH10, which has the ability to remove doubly flanked chlorines in meta and para positions, para flanked chlorines in meta position. The range of estimated kmvalues is between 0.0001-0.133d-1, the median of which is found to be comparable to the few available published biologically confirmed rate constants. Compound specific modelling studies such as that performed by ADM can enable monitoring and prediction of concentration changes as well as toxicity during bioremediation.
authors.affiliation: Department of Environmental Engineering, Middle East Technical University, 06800 Ankara, Turkey.
authors.forename: Filiz
authors.initials: F
authors.lastname: Karakas
authors.affiliation: Department of Environmental Engineering, Middle East Technical University, 06800 Ankara, Turkey. Electronic address: ipeki@metu.edu.tr.
authors.forename: Ipek
authors.initials: I
authors.lastname: Imamoglu
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D059013:Microbial Consortia / Q000502:physiology*; D008962:Models, Theoretical; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Anaerobic dechlorination rate constant; Anaerobic dehalogenation model; Bioremediation; Polychlorinated biphenyls; Sediment