Enhancement of microbial reductive dechlorination of polychlorinated biphenyls in a marine sediment by nanoscale zerovalent iron particles

Zerovalent iron is known to effectively dechlorinate many halogenated aliphatic and aromatic hydrocarbons via direct reductive reaction, as well as to be oxidized by water with the production of hydrogen gas, i.e., the preferential electron donor for many dehalorespiring bacteria. In this work, we evaluated the effect of nanoscale zerovalent iron (NZVI) particles on the reductive dechlorination of polychlorinated biphenyls (Aroclor 1254) in anaerobic slurry microcosms of a marine sediment suspended in the site water, i.e., under in situ-like biogeochemical conditions. No abiotic dechlorination and a four-fold increase in the extent and rate of the microbial reductive dechlorination process was observed in the presence of NZVI particles. NZVI also influenced the sulfate-reduction and methanogenic processes, which were both partially inhibited, and the composition of the indigenous bacterial community, leading to the enrichment of the PCB-dechlorinating bacterium Dehalobium chlorocoercia DF-1.