Cadmium, lead, copper and zinc in blue mussels (Mytilus edulis) sampled inthe Hardangerfjord, Norway

Cadmium. lead, copper and zinc were determined in the soft tissues of blue mussels (Mytilus edulis) sampled from four locations along the Hardangerfjo rd in western Norway. A source of pollution is located at the head of the f jord and the sampling was performed at various distances from this source. The results obtained in this study (1998) were compared with results from s imilar studies carried out in 1983 and 1992. The mean cadmium concentration s in blue mussels sampled at Mage (13 km from the source of pollution) were approximately 18 mg kg(-1) fresh weight in 1983, 2.4 mg kg(-1) fresh weigh t in 1992 and 1.1 mg kg(-1) fresh weight in 1998. The mean cadmium concentr ations in blue mussels sampled at Varaldsoy (105 km from the source of poll ution) were approximately 5 mg kg(-1) fresh weight in 1983, 0.5 mg kg(-1) f resh weight in. 1992 and 0.4 mg kg(-1) fresh weight in 1998. The mean lead concentration in blue mussels sampled at Mage was 140 mg kg(-1) fresh weigh t in 1983. The mean lead concentrations in 1992 and 1998 had decreased to 6 and 3 mg kg(-1) fresh weight, respectively. The mean lead concentrations i n blue mussels from Gravdal were 15 mg kg(-1) fresh weight in 1982, 1 mg kg (-1) in 1992 and less than 1 mg kg(-1) fresh weight in 1998. The mean coppe r concentrations in blue mussels were relatively constant over this period at all locations, with a variation between 0.6 and 1.2-mg kg(-1) fresh weig ht. The mean zinc concentration in blue mussels sampled at Mage decreased f rom 120 to 30 mg kg(-1) fresh weight in the period between 1983 and 1998.