Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment

Abstract

The Gold Standard for determining freely dissolved concentrations (C) 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 C in good agreement for all three experiments. The average ratio between C 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.

Can Tenax Extraction Be Used as a Surrogate Exposure Metric for Laboratory‐Based Bioaccumulation Tests Using Marine Sediments?

“…However, lower lipid levels were found in amphipods (ANOVA; p < 0.001) exposed to New Bedford Harbor and Gould Island sediments compared with those exposed to control sediment (Supplemental Data, Figure S6). This finding suggests that PCBs and other contaminants (e.g., metals and non-HOCs) in the sediment likely contributed to the observed effect (Naval Facilities Engineering Command 2014;Schmidt et al 2017;US Environmental Protection Agency 2018c). For example, PAHs were recently detected in New Bedford Harbor sediment samples at a total concentration of 10 mg/kg dry weight (Schmidt et al 2017).…”

“…This finding suggests that PCBs and other contaminants (e.g., metals and non-HOCs) in the sediment likely contributed to the observed effect (Naval Facilities Engineering Command 2014;Schmidt et al 2017;US Environmental Protection Agency 2018c). For example, PAHs were recently detected in New Bedford Harbor sediment samples at a total concentration of 10 mg/kg dry weight (Schmidt et al 2017). Also, nutrients and sewage discharges have been reported in New Bedford's coastal waters (Voyer et al 2000).…”

Equilibrium sampling reveals increasing thermodynamic potential of polycyclic aromatic hydrocarbons during sewage sludge digestion

“…Equilibrium sampling using jars coated with multiple thicknesses of silicone has successfully been applied for studying HOCs in soil (Reichenberg et al, 2008;Määenpää et al, 2011), marine (Jahnke et al, 2012;Schmidt et al, 2017), lake (Jahnke et al, 2014), and river sediments (Schäfer et al, 2015).…”

In Situ Investigation of Performance Reference Compound‐Based Estimates of PCB Equilibrated Passive Sampler Concentrations and Cfree in the Marine Water Column

“…Uncertainty in C free can arise from either the K PEW estimates used or from the value measured or calculated from the deployment. Cross‐validation experiments have shown that C free values derived using different passive sampling mediums like silicone rubber, semipermeable membrane devices, and polyethylene often perform similarly and yield C free estimates that are within a factor of 2 (Fernandez et al 2012; Jacquet et al 2014; Schmidt et al 2017). These studies provide confidence in the partitioning coefficients ( K PEW ) that are available for polyethylene.…”

“…Using PRCs introduces additional measurements and estimates that contribute to the uncertainty of estimates. Often in situ, PRC‐based estimates of are validated by comparing equilibrium‐estimated C free values with synonymous ex situ deployments where equilibrium had been confirmed (Gschwend et al 2011; Fernandez et al 2014; Apell and Gschwend 2016; Schmidt et al 2017). In general, the estimated C free values when equilibrium had been achieved or when it had been modeled using PRC data agreed within a factor of 2.…”