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Reductive dechlorination of aroclor 1242 in anaerobic sediments: Pattern, rate and concentration dependence
Ist Teil von
Environmental toxicology and chemistry, 1993-06, Vol.12 (6), p.1025-1032
Ort / Verlag
Hoboken: Wiley Periodicals, Inc
Erscheinungsjahr
1993
Link zum Volltext
Beschreibungen/Notizen
Anaerobic biotransformation of polychlorinated biphenyls of Hudson River sediment microorganisms was investigated using the commercial mixture Aroclor 1242 in the laboratory at six different concentrations: 120, 300, 500, 800, 1,000, and 1,500 μg/g (on a sediment dry‐weight basis). Dechlorination was concentration dependent. No change in congener composition was found at 1,000 and 1,500 μg/g during seven months of incubation, but significant shifts were observed in sediments with concentrations below 800 μg/g. A mass balance of the transformation indicated that, despite the shifts, the total molar concentration remained the same. An optimum concentration, based on the decrease of Cl per biphenyl, was 500 μg/g, but based on Cl removed per gram sediment it had a range from 500 to 800 μg/g. Dechlorination (total Cl removed per biphenyl) at 300 and 500 μg/g appeared to be first order, with rate constants of —0.039 and —0.059 per month, respectively. The rate also varied with the substitution position; it was faster for m‐Cl, followed by p‐Cl, but no o‐Cl was removed. However, the faster rate of m‐dechlorination in Aroclor 1242 was probably due to a high concentration of congeners in the Aroclor with Cl substitution patterns favoring its removal, rather than the meta‐position itself.