MODELING EQUILIBRIUM CONCENTRATIONS OF MICROCONTAMINANTS IN ORGANISMSOF THE RHINE DELTA - CAN AVERAGE FIELD RESIDUES IN THE AQUATIC FOODCHAIN BE PREDICTED FROM LABORATORY ACCUMULATION

To explore the validity of extrapolation of laboratory bioaccumulation ratios to field conditions, we collected values from experiments and compared these to ratios observed in the field surveys carried out in the Rhine delta. For some major chemical groups and taxa, we concluded that: (1) Fat weight corrected concentrations of more persistent orga nics in (a) organic suspended solids, freshwater plants and pelagic in vertebrates tended to be similar, both in laboratory experiments and f ield surveys, (b) fish from the Rhine delta were about twice as high a s those in the invertebrates and those expected from laboratory studie s, and (c) birds were one order of magnitude or more above those in th eir invertebrate and fish prey, whereas accumulation in laboratory exp eriments with common birds and mammals did not exceed their food level by more than 10; (2) Fat weight corrected concentrations of less pers istent organics can be substantially lower than those of more persiste nt isolipophilic compounds; for instance, accumulation of some polycyc lic aromatic hydrocarbons in short-term laboratory experiments was sim ilar to that of more persistent compounds but held levels were 30 (in invertebrates) to more than 1000 (in fish) times lower than expected; (3) Dry weight corrected concentrations of cadmium, copper, mercury an d zinc in (a) freshwater plants and invertebrates from the Rhine delta were 0.2 to 0.3 times the concentrations in suspended solids, as more or less expected from literature, (b) fish were lower than for invert ebrates both for literature and Rhine delta data, and (c) kidneys and livers of laboratory and field birds or laboratory mammals are at most 10 times those in their food. The pattern of bioaccumulation of mercu ry is similar to that of extremely persistent organics.