No abstract

The concentration of heavy metals (cadmium, copper, lead, mercury and zinc) found in muscle, gills and liver of eel, bream and pike-perch living in Lake Balaton (Hungary) varied significantly between fish species and organs. The toxic metals in the muscle of fish, except for cadmium in bream, were below the maximum permissible level for human consumption. Cadmium concentrations above the maximum permissible level occurred in autumn in a few small individuals of bream, which, because they have poor culinary value and are seldom consumed, does not represent a risk for humans. Cadmium, copper, lead and zinc levels proved to be higher in eel and bream compared to pike-perch, while high mercury concentrations were found in the predator fish, pike-perch. Mercury accumulated most in the muscle in each species, while other metals were found in higher levels in the gills and liver. Seasonal differences were found for cadmium in each species and for lead in eel; the concentrations being elevated in autumn compared to spring. The fish species studied as bio-monitors demonstrated that the overall heavy metal pollution of Lake Balaton is not significant, although, during summer an increase of cadmium and lead loading could occur at the catchment area and in the lake. Studies on the size (age) dependency of heavy metal concentrations showed that, in most cases, none or a negative relationship exists for each organ and metal in all species studied, and a positive regression coefficient was characteristic only on some occasions for mercury, cadmium and lead.

No abstract

No abstract