Biotransformations of Aroclor 1242 in Hudson River test tube microcosms

K. M. Fish, J. M. Principe

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


A microcosm system to physically model the fate of Aroclor 1242 in Hudson River sediment was developed. In the dark at 22 to 25°C with no amendments (nutrients, organisms, or mixing) and with overlying water being the only source of oxygen, the microcosms developed visibly distinct aerobic and anaerobic compartments in 2 to 4 weeks. Extensive polychlorinated biphenyl (PCB) biodegradation was observed in 140 days. Autoclaved controls were unchanged throughout the experiments. In the surface sediments of these microcosms, the PCBs were biologically altered by both aerobic biodegrading and reductive dechlorinating microorganisms, decreasing the total concentration from 64.8 to 18.0 μmol/kg of sediment in 140 days. This is the first laboratory demonstration of meta dechlorination plus aerobic biodegradation in stationary sediments. In contrast, the primary mechanism of microbiological attack on PCBs in anaerobic subsurface sediments was reductive dechlorination. The concentration of PCBs remained constant at 64.8 μmol/kg of sediment, but the average number of chlorines per biphenyl decreased from 3.11 to 1.84 in 140 days. The selectivities of microorganisms in these sediments were characterized by meta and para dechlorination. Our results provide persuasive evidence that naturally occurring microorganisms in the Hudson River have the potential to attack the PCBs from Aroclor 1242 releases both aerobically and anaerobically at rapid rates. These unamended microcosms represent a unique method for determining the fate of released PCBs in river sediments.

Original languageEnglish
Pages (from-to)4289-4296
Number of pages8
JournalApplied and Environmental Microbiology
Issue number12
StatePublished - 1994


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