Distribution of trace elements from industrial discharges in the Hardangerfjord, Norway: A multivariate data analysis of saithe, flounder and blue mussel as sentinel organisms

Arsenic, copper, zinc, cadmium, lead and mercury were determined in the muscle and liver of two species of fish, saithe (Gadus virens) and flounder (Platichthys flesus), and in the soft tissues of blue mussels (Mytilus edulis). These were sampled from eight locations along the Hardangerfjord up to 100 km from the source of the pollution at the head of the fjord. Both relative and absolute amounts of the six elements differed between the two species of fish, and, more so, between the two tissues. The mussel contained higher amounts of the elements than the fish. The pattern of the elements was also very different in the mussel. Differences and similarities among the various types of samples from the eight locations were evaluated by principal component analysis. Correlation between the six elements was also tested by this method. A concentration gradient away from the source of pollution was only found for arsenic in the saithe tissues, while the only gradient detected in flounder was for mercury in the liver tissue. In mussels the gradient for arsenic was marginal, while gradients were detected in varying degrees for the other elements. Cadmium did not correlate with the other elements in mussels. The mussel was found to be a much better sentinel organism for these elements, except arsenic, than the two fish species.