Abstract
The average amounts of mercury, PCBs, and σ DDT (primarily DDE), found in macrozoobenthos, on the wet basis, in Lake Päijänne, Finland, for the time period 1972–1974, were 79 ng/g, 29 ng/g, and 8 ng/g, respectively. Lindane was found in negligible amounts in only 2% of the samples examined; aldrin was present in 10% of the samples; no dieldrin was detected. Mercury and PCB concentrations varied regionally in the lake. PCB and σ DDT concentrations were greater in the predatory bottom animals than in the herbivores or detritus feeders, and the amounts of chlorinated hydrocarbons were greater in profundal animals than in littoral animals. No significant correlation was apparent between the amount of residues found and the weight of the animal (e.g.Anodonta). A significant positive correlation was evident in the amounts of PCBs and Σ DDT in most of the taxonomical groups.Spongilla lacustris andAnodonta piscinalis were excellent species for monitoring purposes.