Activated Carbon Immobilizes Residual Polychlorinated Biphenyls in Weathered Contaminated Soil

Activated carbon (AC) has recently been shown to be effective in sequestering persistent organic pollutants (POPs) from aquatic sediments. Most studies have demonstrated significant reductions of POP concentrations in water and in aquatic organisms; however, limited data exist on the possibility of using AC to immobilize remaining POPs at terrestrial contaminated sites. Under greenhouse conditions, pumpkin (Cucurbita pepo ssp pepo cv. Howden) were grown, and red wiggler worms (Eisenia fetida) were exposed to an industrial contaminated soil containing a mixture of polychlorinated biphenyls (PCBs), i.e., Aroclors 1254 and 1260) treated with one of four concentrations of AC (0.2, 0.8, 3.1, and 12.5%) for 2 mo. The addition of AC to contaminated soils virtually eliminated the bioavailability of PCBs to the plant and invertebrate species. There were reductions in PCB concentrations of more than 67% in C. pepo ssp pepo and 95% in E. fetida. These data suggest that AC could be included as part of comprehensive site closure strategy at PCB-contaminated sites.