Comparing Polychaete and Polyethylene Uptake to Assess Sediment Resuspension Effects on PCB Bioavailability

Abstract

Polyethylene sampler uptake was compared to polychaete uptake to assess bioavailability of polychlorinated biphenyls (PCBs) from resuspended sediments. New Bedford Harbor (MA, U.S.) sediment contaminated with PCBs, was resuspended under four different water column oxidation conditions: resuspension alone, resuspension under aeration, resuspension under helium, and no resuspension (control). Residuals were tested for differences in PCB availability to the marine polychaete Nereis virens and to polyethylene (PE) passive samplers. Few significant differences between the four resuspension treatments were observed: under aeration, three of 23 PCBs analyzed showed significant increases in polychaete accumulation, while resuspension alone showed increased concentrations in PE samplers for nine of 23 PCBs. Otherwise, no differences were observed and overall we concluded that resuspension had no effect on residual PCB availability. The relationship between disequilibrium-corrected PE and lipid-normalized polychaete PCB concentrations was nearly 1:1 with a strong linear correlation (r2 = 0.877), demonstrating PCBs are taken up similarly into PE and lipid. On average, PE samplers suggested dissolved PCB concentrations 3.6 times greater than those calculated with lipid-water partitioning, though on a congener-specific basis this was only observed for lower chlorinated PCBs; for higher chlorinated PCBs, PE-water partitioning suggested lower dissolved concentrations than those based on lipid. Organic carbon (OC)-water and OC and black carbon combined (OC+BC)-water partitioning suggested average dissolved concentrations 29 and 10 times greater, respectively, than those estimated with lipid-water partitioning. This demonstrates that PE-measured porewater concentrations can provide a more reliable estimate of bioavailability than sediment geochemistry.

Sorption of PBDE in low‐density polyethylene film: Implications for bioavailability of BDE‐209

“…Polymer-coated (such as poly(dimethyl)siloxane [PDMS]) glass fibers [10] and low-density polyethylene (LDPE) films [11] have been used as biomimic probes, because they behave similarly to biological lipid. In such applications, the key step is to accurately determine the partition coefficients between the sorbent phase and water.…”

Passive sampling techniques for sensing freely dissolved hydrophobic organic chemicals in sediment porewater

“…Available information [2,3,9] shows that, so far, harbors have been selected most widely for sediment porewater sampling, so the partitioning of target analytes between sediment porewater and the sorbent phase could be impacted by dissolved salt. Adams et al [24] found that the partition coefficients of phenanthrene and pyrene between LDPE and freshwater were approximately 94% of those obtained with 0.1 M NaCl solution instead of freshwater, but the deviation could be corrected with the Setschenow constant [25].…”

“…It has been shown to be able to accumulate HOCs with high partition coefficients, and developed into the sorbent phase used in polyethylene devices (PEDs). These PEDs have been used to measure dissolved HOC levels in sediment porewater [3,8,9] and to assess the effects of sediment resuspension on the bioavailability of PCBs [9] (Table 1). Thin LDPE sheets are cheap (US$0.40/m 2 ) [34], firm, easily deployable in sediment, and scalable to various sensitivity needs, so they are ideal for monitoring dissolved HOC levels in sediment porewater.…”

“…However, possible sequestration of HOCs in black carbon embedded in sediment and uncertainty in partition coefficients may affect the accuracy of such estimates [6][7][8]. Besides, although benthic species can often sense the bioavailability of HOCs in sediment [9], freely dissolved concentrations of HOCs estimated from organism lipid loading could be overestimated as both bound and freely dissolved HOCs in porewater may be accumulated by benthic species. Furthermore, benthic species have natural biological variability (e.g., lipid content and composition), and there is no single species that can be used to monitor freely dissolved HOCs in sediment porewater around the world.…”

“…Passive sampling techniques [e.g., based on the principles of solid-phase microextraction (SPME) and employing low density polyethylene (LDPE) and other polymer materials as the sorbent phases] have commonly been used for sensing HOCs in sediment porewater [2,9]. In the non-equilibrium sampling mode, the molecular diffusion of the freely dissolved analytes onto the sorbent phase, a critical step in the process, can be rapid and used to determine time-weighted average (TWA) concentrations of HOCs.…”