Contaminants and environmental quality in biota along the Bohus Coast 1992–2001− trends, load and relationships

Investigations of environmentally harmful substances carried out on biota between 1992 and 2001 havebeen evaluated from areas along the Bohus Coast bordering the Skagerrak Sea on behalf of the Bohus CoastWater Conservation Association. Biological samples were collected five years apart at static sites. The biotainvestigated were blue mussel (Mytilus edulis), bladder wrack (Fucus vesiculosus), eel-pout (Zoarces viviparus)and cod (Gadus morhua); at two stations crab (Cancer pagurus) were also sampled. The different media wereanalysed for 11 metals, DBT, TBT, 16 PAHs, methylnaphtalenes, 7 PCBs, non-ortho-PCBs, 7 PBDEs, DecaBDE, HCB, lindan, toxaphene and PCCDs/PCDFs. The evaluations were conducted to record dispersion ofchemicals, changes over time, existing concentration relationships between various investigated media andenvironmental quality according to the Swedish criteria for coast and sea.The results show that a number of elements and compounds are dispersed along the Swedish Bohus Coast,but that the concentrations of the different elements and compounds vary between different media and sites.Metals, PCBs and PBDEs were found in all media at all sites, while in general only a few PAHs seemed to beaccumulated in biota., Toxaphene, TBT (not in bladder wrack), HCB, lindane and PCCDs/PCDFs were alsofound at all sites in those media analysed for these substances. The environmental quality (EQ) with respectto metals in biota along the coast varied from sites with good to sites with very bad conditions. The figuresevidently showed an excess of harmful substances in the urbanized/industrialized areas for all studied mediacategories. The Kosterfjord area is in this respect least strained. The relationship between the concentrationof the compounds in two different media was tested. Out of the 192 selected tests, relationships with P>95%were found in one third of the cases.The trend analyses showed that the major trends are concordant between different media in the biologicalmatrix studied, and with more than 90% probability they generally show decreasing average metal concentrations between 1992/93 and 2001. The only exceptions are tin (Sn) which increased during the period, as wasthe case of tributhyltin (TBT) and PCB in blue mussel and in the latter case also in eel-pout. In cod liver theaverage PCB concentrations have decreased. In summary, the conditions regarding environmentally harmfulsubstances in biota, with a few exceptions, improved along the Bohus Coast during the 1990s