Integrated biological effects assessment of the discharge water into the Sunndals fjord from an aluminium smelter

Summary

The following study describes an integrated biological effects monitoring programme using field transplanted mussels to determine the potential biological effects of the effluent discharge from the aluminium smelter operated by Hydro AS in the Sunndals fjord in Norway. Chemical body burden (PAH and metals) and a suite of biological effects markers were measured in mussels positioned at known distances (1, 2, 5, 10 and 20 km) from the aluminium smelter for 6 weeks. Overall, the biological responses observed where greater in the mussels positioned closest to the smelters discharge (1 – 5 km), although the chemical concentrations measured in mussel tissues were low and below the expected threshold levels where biological responses would be expected. The lowest chemical accumulation and biomarker responses were observed in mussels positioned 10 km from the smelters effluent and could be considered as the reference field population. Mussels located furthest from the smelter (20 km) exhibited significant biomarker responses, probably associated with a different contaminant source within the fjord. The integrated biological response index (IBR) reflected the expected level of exposure to the smelters discharge and the Principal component analysis (PCA) differentiated between the mussel groups, with the most impacted located closest to the smelters discharge. Not one chemical factor explained the biological responses in mussels, but the presence of PAH16, PAH41 and metals Mn, Ni and Cr were the main contributors to the higher stress seen in the mussels from the 1 and 5 km groups.