Bioanalytical and instrumental screening of the uptake of sediment-borne, dioxin-like compounds in roach (Rutilus rutilus)

Abstract

To examine the uptake of dioxin-like compounds (DLCs), common roaches (Rutilus rutilus) were exposed for 28 days to differently contaminated sediments from two major European rivers in a purpose-built facility. Dietary transfer of DLCs was investigated by exposing fish to sediments inoculated or non-inoculated with black worms (Lumbriculus variegatus). Dioxin-like polychlorinated biphenyls (DL-PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), measured via high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) in sediments and whole fish, were used to calculate toxicity equivalent quotients (TEQs). TEQs were compared with biological toxicity equivalent quotients (BEQs) determined via the 7-ethoxyresorufin-O-deethylase (EROD) assay, performed with mammalian (H4IIE) and fish (RTL-W1) liver cell lines. TEQs and BEQs indicated an uptake of sediment-borne DLCs by roach, which was independent of sediment contamination levels, but rather reflected sediment-specific characteristics. For most sediment treatments, DLC uptake did not increase with time. Highest congener-specific uptake (DL-PCB 123) was 10-fold compared to control. Exposure to worm-inoculated sediment of highest overall DLC contamination caused a 2-fold (TEQ and H4IIE BEQ) greater uptake of DLCs by fish compared to the respective non-inoculated treatment. H4IIE cells showed the greatest sensitivity (0.37 ± 0.25 pM TCDD) and the strongest correlation with TEQs (r (2) = 0.79), hence, they seem to be best suited for DLC screening of sediments and biota, amended by compound-specific instrumental analysis if required.

Toward Streamlined Identification of Dioxin-like Compounds in Environmental Samples through Integration of Suspension Bioassay

“…Additionally, to compare the results of chemical analysis for DLCs with the results of our HT-EDA method, two wellstudied sediment samples collected in Germany were also investigated. Two sampling sites, one at the Rhine River at the harbor Ehrenbreitstein (EBR), and one from the cutoff meander Zollelbe (ZE) in the city of Magdeburg, Elbe River, 30 were chosen. Sediment preparation and extraction were comparable to the method described above, while the cleanup involved acidic silica gel to remove acid-labile compounds including many PAHs, according to US-EPA method 8290, 31 with modifications as described in Eichbaum et al 30 This is one of the most common cleanup schemes for analysis of dl-PCBs and PCDD/Fs in sediment extracts.…”

“…Two sampling sites, one at the Rhine River at the harbor Ehrenbreitstein (EBR), and one from the cutoff meander Zollelbe (ZE) in the city of Magdeburg, Elbe River, 30 were chosen. Sediment preparation and extraction were comparable to the method described above, while the cleanup involved acidic silica gel to remove acid-labile compounds including many PAHs, according to US-EPA method 8290, 31 with modifications as described in Eichbaum et al 30 This is one of the most common cleanup schemes for analysis of dl-PCBs and PCDD/Fs in sediment extracts. The concentrations of these compounds, as well as the dioxin-like effects of unfractionated extracts in the micro-EROD assay, were determined in the context of previous studies (Supplementary Table S3).…”

“…The concentrations of these compounds, as well as the dioxin-like effects of unfractionated extracts in the micro-EROD assay, were determined in the context of previous studies (Supplementary Table S3). 30 2.3. Fractionation Method.…”

“…Additionally, the results of our EDA approach indicated that PCDD/Fs were found to be responsible for the majority of the dioxin-like activity measured in sediment ZE, while no significant contribution of PCDD/Fs were observed in sediment EBR, which were identical with the conclusions drawn from DLCs analysis in multilayer silica column-treated sediment extracts from the rivers Rhine and Elbe, Germany. 30 In previous studies, monitoring strategies may have failed to identify pollutants of concern because the measurement of environmental concentrations of priority pollutants does not necessarily allow for identification of the causative pollutants. In this context, EDA is a particularly useful tool but limited through its laborious, costly, and time-consuming nature which requires interdisciplinary knowledge of the researchers.…”

An assessment of the concentrations of PCDDs/Fs in contaminated bottom sediments and their sources and ecological risk

“…However, other experimental results suggest that the concentrations of PCDDs/Fs in sediments are not all dependent on TOC (Ikenaka et al 2005;Lee et al 2006;Pan et al 2010;Nunes et al 2011;Li et al 2012;Eichbaum et al 2016). Li et al (2012) report a poor correlation between PCDDs/Fs and TOC in bottom sediments, indicating that they are influenced by seasonal changes, while Vẚcha et al 2011note a weak correlation between POP concentration and the content and quality of organic matter in sediment.…”