2-chlorobiphenyl and 2-5-dichlorobiphenyl

Increased polychlorinated biphenyl (PCB) loadings from sediment to the water column under low-flow conditions during late spring and summer months have been observed in the Grasse River (Massena, NY) and other PCB-contaminated rivers in the United States. Temperature appears to be an important factor affecting this phenomenon, as increased sediment temperature leads to increased microbial and bioturbator activity as well as increased rates of diffusion and desorption. Laboratory-scale sediment microcosms were developed and used to study with fine-scale resolution the effects of temperature and microbial activity on PCB transport in river sediment. Over the time course of these experiments, with the extraction procedures used, irreversible sorption of each congener to sediment was observed and increased with aging of the sediment. Temperature-dependent transport was observed for PCB congeners 2,4,5-trichlorobiphenyl (BZ29), 2,5-dichlorobiphenyl (BZ9), and 2-chlorobiphenyl (BZ1) in Grasse River sediment and a synthetic sediment system. The fastesttransport of the congeners occurred in biologically active Grasse River sediment followed by biologically inactive (autoclaved) Grasse River sediment, and synthetic sediment. The increased transport in biologically active sediment demonstrated the importance of microbial activity, in particular gas bubble generation, in PCB transport in near-surface sediments.

Topics: Anaerobiosis; Biphenyl Compounds; Chlorine; Environmental Monitoring; Fresh Water; Geologic Sediments; Polychlorinated Biphenyls; Soil Microbiology; Temperature; United States; Water Pollutants, Chemical

Pseudomonas sp. strain UCR2 was isolated from a multi-chemostat mating experiment between a chlorobenzoate-degrader, Pseudomonas aeruginosa strain JB2, and a chlorobiphenyl-degrader, Arthrobacter sp. strain B1Barc. Strain UCR2 differed from either of the parental organisms in that it grew on both 2-chloro- and 2,5-dichlorobiphenyl with concomitant release of chloride. Phenotypic typing by the Biolog system indicated that strain UCR2 shared greater similarity with strain JB2 (88%) than strain B1Barc (3%). In DNA:DNA hybridization experiments, genomic DNA from strain UCR2 hybridized with both strain JB2 and strain B1Barc, with the former pairing yielding a much stronger signal than the latter. In contrast, no hybridization whatsoever was observed when the parental organisms strains JB2 and B1Barc were probed against each other.

Topics: Biodegradation, Environmental; Biphenyl Compounds; DNA, Bacterial; Minerals; Nucleic Acid Hybridization; Oxygen Consumption; Polychlorinated Biphenyls; Pseudomonas; Sequence Homology, Nucleic Acid; Species Specificity