C‐18‐coated silica particles as a surrogate for benthic uptake of hydrophobic compounds from bedded sediment

Environmental Toxicology and Chemistry (Impact Factor: 3.23). 12/1996; 15(12):2284 - 2289. DOI: 10.1002/etc.5620151224


To simulate the bioaccumulation of neutral organic contaminants by infaunal benthos, the partitioning of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) between a contaminated estuarine sediment and admixed C-18-coated silica particles was measured. The concentrations of lower chlorinated PCB congeners (less than five chlorine atoms per molecule) on the C-18-coated silica particles reached apparent steady state within 300 h while congeners with greater numbers of chlorine atoms required much greater time periods (greater than 1 year) to reach apparent steady state. Polycyclic aromatic hydrocarbons showed less partitioning from sediment to the C-18 particles than PCB congeners, although the log Kow ranges of the compounds in these comparisons were similar. The biota sediment accumulation factors, defined as the lipid-normalized contaminant concentration in an exposed organism divided by the organic carbon-normalized contaminant concentration of the sediment, were calculated for these exposures using the C-18 of the particles as the lipid. The results from these exposures agreed closely with those measured in studies where living benthic organisms were exposed to contaminated sediment.

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    ABSTRACT: Semipermeable membrane devices (SPMDs), Tenax TA, and a polyethylene tube dialysis (PTD) methods were used to estimate the “available” fraction of PAH in marine sediment slurries. The polyethylene membrane used in the SPMD and PTD methods mimics a biomembrane. The PAH must diffuse through the membrane into triolein or pentane, respectively. The Tenax TA scavenges PAH from the water phase and is separated from the sediment, thus particle-associated PAH are excluded from all three methods. Spiked PAH were more readily available than endogenous (unspiked) PAH, and the presence of sediment organic matter decreased desorption and thus availability of the PAH. All three methods could aid in bioremediation feasibility assessments and predictions on the potential toxicity of sediments or soils. The SPMD method has the advantage of being available commercially, and the use of such a standard method allows comparison with other samples from the literature. The Tenax method gave similar results with the exception of the larger compounds that were recovered more efficiently, and it was less expensive. The PTD method was the most stringent assay for availability and could be useful in assessing the risk associated with exposure to a contaminated sample.
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