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Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment
Citation:
Schmidt, S., A. Wang, P. Gidley, A. Wooley, G. Lotufo, R. Burgess, U. Ghosh, L. Fernandez, AND P. Mayer. Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 51(17):9996-10004, (2017).
Impact/Purpose:
In order to measure the bioavailable concentrations of contaminants in polluted sediments and use that information to make environmental management decisions like "Should we clean-up this contaminated site", it's critical to insure the methods used to make the measurements are accurate. This study compared two passive sampling-based approaches for measuring the bioavailable concentrations (Cfree) of polychlorinated biphenyls (PCBs) in contaminated sediments. PCBs are amongst the most common sediment contaminants and can travel through the food chain to humans. The study demonstrated that the two methods generated similar results. This is useful information and provides environmental managers with the ability to select between these two methods depending on the circumstances and know that the results will be comparable.
Description:
The Gold Standard for determining freely dissolved concentrations (Cfree) of hydrophobic organic compounds in sediment interstitial water would be in situ deployment combined with equilibrium sampling, which is generally difficult to achieve. In the present study, ex situ equilibrium sampling with multiple thicknesses of silicone and in situ pre-equilibrium sampling with low density polyethylene (LDPE) loaded with performance reference compounds were applied independently to measure polychlorinated biphenyls (PCBs) in mesocosms with (1) New Bedford Harbor sediment (MA, U.S.A.), (2) sediment and biota, and (3) activated carbon amended sediment and biota. The aim was to cross validate the two different sampling approaches. Around 100 PCB congeners were quantified in the two sampling polymers, and the results confirmed the good precision of both methods and were in overall good agreement with recently published LDPE to silicone partition ratios. Further, the methods yielded Cfree in good agreement for all three experiments. The average ratio between Cfree determined by the two methods was factor 1.4 ± 0.3 (range: 0.6−2.0), and the results thus cross-validated the two sampling approaches. For future investigations, specific aims and requirements in terms of application, data treatment, and data quality requirements should dictate the selection of the most appropriate partitioning-based sampling approach.
