Organochlorine Pollutants in Western Antarctic Peninsula Sediments and Benthic Deposit Feeders

Sediments and benthic deposit feeding holothurians were collected near the Palmer Long Term Ecological Research grid during the austral winter of 2008. Polychlorinatted biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in western Antarctic Peninsula continental shelf sediments, porewater, and benthic biota. Concentrations and fluxes in sediments decreased sharply away from the tip of the peninsula toward its interior. Sedimentary PCB fluxes were an order of magnitude lower than reported elsewhere, supporting the notion of a pristiner Antarctic environment. Hexa-chlorinated biphenlys dominated (40-100%) the PCB profiles in the sediments, while trichlorinated biphenyl 28 was the most abundant PCB congener in the porewater. PCB and OCP concentrations in holothurians were comparable to concentrations in the low trophic level biota in Antarctic food web (i.e., krill). The partitioning of PCBs and OCPs between the sediments and porewater can be explained by a dual-mode model, which included both organic carbon and black carbon as partitioning media. Alternatively, a simpler one-parameter prediction assuming coal tar-like organic carbon performed equally well in explaining porewater concentrations. The majorities of PCBs (63-94%) in the Western Antarctic Peninsula sediments were bound to black carbon or recalcitrant tar-like organic carbon, thereby lowering porewater concentrations. PCBs and OCPs in the holothurians were in equilibrium with those in the porewater.