Microbial reductive dechlorination of weathered and exogenous co-planar polychlorinated biphenyls (PCBs) in an anaerobic sediment of Venice Lagoon.
The occurrence of reductive dechlorination processes towards pre-existing PCBs and five exogenous coplanar PCBs were investigated in a contaminated sediment of Porto Marghera (Venice Lagoon, Italy) suspended, under strictly anaerobic conditions, in water collected from the same site. PCB dechlorination started after five months of incubation, when sulfate initially occurring in the microcosms was completely depleted and methanogenesis was in progress. It was ascribed to sulfate-reducing bacteria. Several pre-existing hexa-, penta- and tetra-chlorinated biphenyls were slowly bioconverted into tri- and di-, ortho-substituted PCBs from the 5th to the 16th month of experiment. Spiked coplanar PCBs, i.e., 3,3',4,4'-tetrachlorobiphenyl, 3,3',4,4',5- and 2,3',4,4',5-pentachlorobiphenyls, 3,3',4,4',5,5'- and 2,3,3',4,4',5-hexachlorobiphenyls, were extensively transformed (by about 90%) into lower chlorinated congeners, such as 3,3',5,5'-/2,3',4,4'-tetrachlorobiphenyl, 3,3',5-, 2,4,4'-, 2,3',4- and 2,3',5-trichlorobiphenyl, 3,4-/3,4'- and 3,3'-dichlorobiphenyl and 2-chlorobiphenyl. The reductive dechlorination of spiked PCBs did not influence significantly the biotransformation rate and extent of pre-existing PCBs.
Zanaroli
G
G
DICASM, Faculty of Engineering, University of Bologna, viale Risorgimento 2, 40136 Bologna, Italy.
Pérez-Jiménez
J R
JR
Young
L Y
LY
Marchetti
L
L
Fava
F
F
D000693:Anaerobiosis; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000378:metabolism*; D019015:Geologic Sediments; D007558:Italy; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism
D004785:Environmental Pollutants; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls