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Comparing Polychaete Bioaccumulation and Passive Sampler Uptake to Assess the Effect of Sediment Resuspension on Contaminant Bioavailability
Citation:
Friedman, C., R. M. BURGESS, M. PERRON, K. T. HO, M. G. CANTWELL, S. A. RYBA, R. A. MCKINNEY, AND R. Lohmann. Comparing Polychaete Bioaccumulation and Passive Sampler Uptake to Assess the Effect of Sediment Resuspension on Contaminant Bioavailability. Presented at SETAC North American 29th Annual Meeting, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
The bioavailability of PCBs from resuspended, resettled sediments to the benthic polychaete Nereis virens was compared to the PCB uptake by polyethylene passive samplers in a standard 28-day bioaccumulation study.
Description:
Increased bioavailability of polychlorinated biphenyls (PCBs) from resettled sediments following remedial dredging is suspected of contributing to elevated organism tissue concentrations at contaminated sites. However, little data exists to evaluate whether increases in bioavailability actually occur. To address the effects of resuspension on bioavailability, sediment samples from the New Bedford Harbor (MA) Superfund site were resuspended for approximately 18 hours under four different water column oxidation conditions: resuspension alone, resuspension with air, resuspension with helium, and no resuspension. Following a four day settling period, the marine polychaete Nereis virens was exposed to the residuals in a standard 28-day bioaccumulation study. In addition to N. virens, polyethylene (PE) samplers were included in the bioaccumulation study to assess whether PE has potential for use as an organism surrogate in routine bioaccumulation tests. PE samplers were deployed in both the water column and sediment of individual bioaccumulation exposure chambers. Sediment, tissue, and PE samples were analyzed for 23 PCB congeners. Resuspension did not statistically alter PCB concentrations in the sediment. Bioaccumulation by N. virens was greater in the “resuspended with air” treatment for nearly all PCB congeners analyzed, implying that aeration of sediment particles could increase the bioavailability of particle-associated PCBs. Equilibrium PCB concentrations in PEs deployed in the sediment were found to correlate linearly with lipid-normalized polychaete PCB concentrations with r2 of 0.89 to 0.94. Dissolved (i.e., bioavailable) PCB concentrations in pore water were calculated based on PE accumulation and were found to correlate with dissolved concentrations calculated using N. virens accumulations with r2 ranging from 0.76 to 0.84. On average, PE PCB concentrations accounted for 97% (range 33% to 204%) of lipid-normalized N. virens concentrations. Our results suggest that using PE to estimate bioavailability to benthic organisms is a viable option.