Contaminant levels in sediments and asteroids (Asterias rubens L., Echinodermata) from the Belgian coast and Scheldt estuary: polychlorinated biphenyls and heavy metals.

The Southern Bight of the North Sea is particularly exposed to anthropogenic contamination, due to heavy urbanisation and industrialisation of its catchment area. The present work focuses on polychlorinated biphenyl (PCB) and metal contamination of the marine environment along and off the Belgian coast. Its objectives were to compare the concentrations of seven PCB congeners and four heavy metals in the sediments (a repository for anthropogenic contaminants) and in the asteroid Asterias rubens (a recognized bioindicator species). Nineteen sampling stations were considered between the mouth of the Scheldt Estuary and the southern limit of the Belgian coast (asteroids were found in 10 out of the 19 stations). PCB and metal concentrations measured in sediments and asteroids were in the range of values reported in previous studies. Stations under direct influence of the Scheldt were the most impacted by the considered contaminants. Metal concentrations varied according to the grain-size fraction considered. In asteroids, PCBs and metals were found to be selectively distributed among body compartments, and pyloric caeca were found to most efficiently discriminate between sampling stations contamination levels. PCB and metal analysis of sediments provided a physicochemical evaluation of the contamination, whereas analysis of asteroids introduced a biological dimension to the approach by taking into account bioavailability of the contaminants.