Accumulation of extractable organic halogens (EOX) in different organs of the freshwater mussel, Anodonta cygnea L., exposed in situ to chlorine bleached pulp and paper mill effluents

Freshwater mussels, Anodonta cygnea L., were collected at a reference site and transferred to three monitoring stations located upstream (one station) and downstream (two stations) of a chlorine bleaching pulp and paper mill. During the 91 days of the experiment, water and mussels were sampled regul arly at the three stations and halogenated organic micropollutants were det ermined using the sum-parameters AOX and EOX. The general water quality dec reased downstream of the effluent release and shows a chronic AOX contamina tion; the mean AOX concentrations increased by 9 to 16 compared to the upst ream station. The mussels exposed at the upstream station showed no signifi cant variation in EOX concentrations. In contrast, a progressive EOX accumu lation was observed in the gills, digestive glands and gonads of the mussel s exposed at the two downstream sites. The accumulation factors, calculated as the ratio between the final and the initial EOX concentrations varied b etween 3.5 and 7.4 according to the considered organ and station.