PCB trends and patterns in the plankton of the river Meuse (Belgium).

PCB concentrations were monitored in the river Meuse (Belgium) from 1993 to 1998; compartments sampled were water, suspended matter (mainly phytoplankton), zooplankton and sediment. The PCB patterns were compared to those of Aroclors and found to best match a mixture of 30 to 40% of Aroclor 1254 and 60 to 70% of Aroclor 1260 for all compartments with the exception of suspended matter where the proportions were of 50% of both Aroclor 1254 and 1260. These patterns together with the average total concentrations did not show any trends throughout the monitoring period nor did they show any particular seasonal pattern variations. Mean total PCBs concentrations were of 0.029 ng/g in the water, 3408 ng/g D.W. in suspended matter, 862 ng/g D.W. in zooplankton and 387 ng/g D.W. in the sediment. Bioconcentration factors for phytoplankton (suspended matter) and zooplankton were respectively of 118 000 and 30 000 indicating there is no biomagnification between these two trophic levels. These results will be commented on the basis of in vitro contamination experiments with planktonic organisms.