Toxicity characterization of surface sediments from a Mediterranean coastal lagoon

The occurrence of bioactive compounds and contaminant-associated effects was assessed by means of in vivo and in vitro assays using different extractable fractions of surface sediments from a contaminated coastal lagoon (Mar Menor, SE Spain). Sediment elutriates and clean seawater, previously exposed to whole sediment, were used for assessing the in vivo toxicity on embryo development of the sea urchin Paracentrotus lividus. Agonist and antagonist activities relating to estrogen and androgen receptors and agonist activities on aryl hydrocarbon receptor (expressed as ethoxyresorufin-O-deethylase (EROD) activities) were investigated in sediment extracts by using HER-Luc, AR-EcoScreenTM and fibroblast-like RTG-2 cell lines. Embryotoxicity effects were greater for sediment elutriates than those incubated in sediment-water interphase, implying that diffusion of bioactive chemicals can occur from sediments to sea water column, favoured by sediment disturbance events. In vitro results show the occurrence in extracts of compounds with estrogen antagonism, androgen antagonism and dioxin-like activities. Multidimensional scaling analysis classified the sampling sites into four sub-clusters according to their chemical-physical and biological similarities, relating in vitro bioactivity with the total organic carbon and known organic chemical load, with particular reference to total sum of PAHs, PCB 180, p,p-DDE and terbuthylazine. Overall, results pointed to the presence of unknown or unanalyzed biologically-active compounds in the sediments, mostly associated with the extracted polar fraction of the Mar Menor lagoon sediments. Our findings provide relevant information to be considered for the environmental management of contaminated coastal lagoons.

Toxicity profiling of marine surface sediments: A case study using rapid screening bioassays of exhaustive total extracts, elutriates and passive sampler extracts

This study was carried out in the framework of the ICON project (Integrated Assessment of Contaminant Impacts on the North Sea) (Hylland et al., 2015) and aimed (1) to evaluate the toxicity of marine sediments using a battery of rapid toxicity bioassays, and; (2) to explore the applicability and data interpretation of in vitro toxicity profiling of sediment extracts obtained from ex situ passive sampling. Sediment samples were collected at 12 selected (estuarine, coastal, offshore) sites in the North Sea, Icelandic waters (as reference sites), south-western Baltic Sea and western Mediterranean during autumn 2008. Organic extracts using a mild non-destructive clean-up procedure were prepared from total sediment and silicone passive samplers and tested with five in vitro bioassays: DR-Luc bioassay, ER-Luc bioassay, AR-EcoScreen bioassay, transthyretin (TTR) binding assay, and Vibrio fischeri bioluminescence bioassay. In vitro toxicity profiling of total sediment and silicone passive sampler extracts showed the presence of multiple organic contaminations by arylhydrocarbon receptor agonists (e.g. polycyclic aromatic hydrocarbons) and endocrine-active compounds, as well as non-specific toxicity caused by organic contaminants, at virtually all sampling sites. In vitro responses to total sediment extracts from coastal/estuarine sites were significantly different from those in offshore sites (p < 0.05). Several bioassays of passive sampler extracts showed highest activity in some offshore sediment samples. Impact on embryogenesis success and larval growth in undiluted sediment elutriates was shown at some sites using the in vivo sea urchin embryo test. The observed toxicity profiles could only partially be explained by the chemical target analysis, indicating the presence of unknown or unanalysed biologically-active compounds in the sediments. In vitro bioassay testing with silicone passive sampler extracts of sediments is a promising tool to assess the toxic potency of the bioavailable fraction of hydrophobic sediment contaminants, but further work will be needed before it can be routinely applied for sediment quality assessment.