A five-year monitoring study of the chlorinated hydrocarbons in the fish of a Finnish lake ecosystem

The present study, concerning the chlorinated hydrocarbon contents, PCB- and DDT-related compounds in the Finnish inland water fish, was the biggest ever carried out in Finland. During five years 1723 specimens and twelve species were analysed, the material being obtained from Lake Päijänne, the second largest lake in Finland. The lake consists of five limnologically different areas. The results of the study were statistically tested by t-test, one way analysis of variance and regression analysis. The results showed that the average PCB concentration mg/kg on a wet weight basis was 0·056 and ΣDDT (DDT + metabolites) 0·010, respectively. The concentrations of lindane, aldrin and dieldrin were under 0·0005 mg/kg. The differences between the species were greater than those between the areas. The regression analysis showed that in the commonest fish, pike, perch and bream, mostly no statistically significant differences were observed in the concentrations between different areas and research years.