Silicone passive equilibrium samplers as ‘chemometers’ in eels and sediments of a Swedish lake

Abstract

Passive equilibrium samplers deployed in two or more media of a system and allowed to come to equilibrium can be viewed as 'chemometers' that reflect the difference in chemical activities of contaminants between the media. We applied silicone-based equilibrium samplers to measure relative chemical activities of seven 'indicator' polychlorinated biphenyls (PCBs) and hexachlorobenzene in eels and sediments from a Swedish lake. Chemical concentrations in eels and sediments were also measured using exhaustive extraction methods. Lipid-normalized concentrations in eels were higher than organic carbon-normalized concentrations in sediments, with biota-sediment accumulation factors (BSAFs) of five PCBs ranging from 2.7 to 12.7. In contrast, chemical activities of the same pollutants inferred by passive sampling were 3.5 to 31.3 times lower in eels than in sediments. The apparent contradiction between BSAFs and activity ratios is consistent with the sorptive capacity of lipids exceeding that of sediment organic carbon from this ecosystem by up to 50-fold. Factors that may contribute to the elevated activity in sediments are discussed, including slower response of sediments than water to reduced emissions, sediment diagenesis and sorption to phytoplankton. The 'chemometer' approach has the potential to become a powerful tool to study the thermodynamic controls on persistent organic chemicals in the environment and should be extended to other environmental compartments.

Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota

“…This gives additional evidence that PCB levels in aquatic species residing in this Finnish ecosystem are likely below equilibrium partitioning levels relative to the sediment. These results agree with what was observed in Lake Ången, a small lake in Sweden without known sources of pollutants other than the atmosphere, where PCBs had generally a lower activity in eels than in sediment (activity ratios of 0.048 for PCB 101 up to 0.295 for PCB 118) . In the present study, the slope of the linear regression for the mussel–sediment activity ratio for different PCB congeners was 0.034 for the native mussels collected from site 2 (Supplemental Data, Figure S7B).…”

“…In conclusion, both environmental exposure phases (sediment porewater and overlying water) that differed in their C free undoubtedly have a role in bioaccumulation. The estimates of C LipÐSed were conservative, however, which is in agreement with earlier findings [2,9,25,26].…”

“…An organism may be in disequilibrium with its environment for several reasons, including slow uptake kinetics of hydrophobic organic chemicals, biomagnification, or biotransformation. Disequilibrium of organochlorines between sediment and fish was also observed in studies in the Baltic Sea and a freshwater lake . The disequilibrium was apparent whether the evaluation relied on passive sampler–derived chemical activities or the concentrations normalized to fish lipid and sediment organic carbon.…”

Coupling passive sampling with in vitro bioassays and chemical analysis to understand combined effects of bioaccumulative chemicals in blood of marine turtles

“…Recent advances in polymer-based passive sampling using polydimethylsiloxane (PDMS), for example, have opened an opportunity for rapid, quantitative extraction of neutral organic chemical mixtures from biological samples, based on equilibrium partitioning between the polymer and major sorption phases, such as lipid and proteins (Jahnke et al, 2008(Jahnke et al, , 2009(Jahnke et al, , 2011(Jahnke et al, , 2014Jahnke and Mayer, 2010;Allan et al, 2013;Mäenpää et al, 2014). Combined with high-throughput bioanalytical tools, this polymer-based extraction method facilitates our understanding of mixture effects of bioaccumulative chemicals present in lipid-rich tissues, such as dugong blubber (Jin et al, 2013(Jin et al, , 2015.…”

How to Improve Exposure Assessment

“…Experience exists with the use of PRCs and the determination of silicone-water partition coefficients (Booij et al, 2002;Smedes et al, 2009). Recently, silicone has been used for the passive sampling of hydrophobic compounds from water by e.g., Prokes et al (2012) and Jahnke et al (2014).…”