SEDIMENT TRAP FLUXES AND BENTHIC RECYCLING OF ORGANIC-CARBON, POLYCYCLIC AROMATIC-HYDROCARBONS, AND POLYCHLOROBIPHENYL CONGENERS IN LAKE-SUPERIOR

Sediment trap fluxes of solids, organic carbon, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were measured in Lake Superior in 1984 and 1985. Mass fluxes from surface waters ranged from 0.14 to 1.1 g/m2.day and increased near the lake floor due to resuspension of surficial sediment and horizontal transport in the benthic nepheloid layer. Organic matter fluxes from surface waters ranged from 60 to 90 mg of C/m2.day, with approximately 5% of organic carbon settling from surface waters accumulating in bottom sediments. Concentrations of PCBs and PAHs are enriched 10-100 times on settling particles relative to those on suspended particles. Resultant settling fluxes are 10-100 times greater for several PCB and PAH compounds than net accumulation rates in bottom sediments, indicating the effective and rapid recycling in the benthic region. Biological packaging of organic pollutants into rapidly settling particles is an efficient pathway for the transport of contaminants from surface waters to benthic regions of large lakes.