"Natural Attenuation" as a possible strategy for the sustainable management of costal areas contaminated by PCBs: evidences from the Brentella Canal (Venice Lagoon)

This paper refers about the detection and characterization of the occurrence of reductive dechlorination processes towards weathered PCBs in contaminated marine sediments of Porto Marghera area (Venice lagoon, Italy) in slurry microcosms of sediments suspended in the water coming from the same contaminated site. The detected processes exhibited meta- and para-specificity and were not significantly “primed” after spiking with exogenous PCBs, that were rapidly and extensively dechlorinated. PCB dechlorination was apparently mediated by sulfate-reducing bacteria, that started to use PCBs as electron acceptors during sulfate reduction but in particular when sulfate was completely depleted. Such activities were detected under biogeochemical conditions that closely mimic those occurring in situ, and this allows to speculate that similar processes might also be in progress in situ.