Determinations of mercury in various compartments of a coastal marine ecosystem

Accurate determinations of mercury in the different compartments of the ecosystem are a basic requirement for the study of its circulation. Sampling and analyzing techniques have been examined for the waterclumn, analyzing techniques for the sediments and the biological compartment. Two seawater sampling techniques (Niskin bottle and peristaltic pump) are compared; they give statistically no different results. For the preconcentration of dissolved mercury a self-synthesized resin seems to satisfy very well. In three different sediment samples mercury has been assessed after total, strong and weak attacks. The most reproductible results are obtained with HF/HNO3 (total attack) and HNO3/KMnO4 (strong attack). Several mineralisation -digestion techniques for analysis of mercury in plants have been tested. HF/HNO3, /KMnO4/ H2SO4/HNO3, and H2SO4/HNO3/V2O5, KMnO4 provided the best results.The spatial patterns of total and particulate mercury in the Belgian coastal zone confirm the earlier observed concentration gradients. In addition, the absorption capacity studies on particulate matter of the Scheldt estuary suggest that for mercury the particulate, solid phase is more important than the dissolved phase