PESTICIDES IN WATER AND FISH FROM RIVERS FLOWING INTO LAKE BIWA (II)

Surveys of pesticides (diazinon , IBP, malathion and MEP) were performed for water and fish samples obtained from seven rivers flowing into Lake Biwa in 1990 . The field data on accumulation of pesticides by pale chub (Zacco playtpus) and ayu sweetfish (Plecoglossus altivelis) were compared with the laboratory experimental data on willow shiner (Gnathopogon caerulencense) and topmouth gudgeon (Pseudorasbora parva) . The bioconcentration factors (BCF) of pesticides in the field could not be satisfactorily estimated from the experimental data. This is not only due to the difference of fish species but also the reason that the concentrations of these pesticides in the river water are changeable and those in the fish body do not reach plateaus instantly.