Organic and trace metal contaminants in sediments, seawater and organisms from two Bermudan harbours

This paper presents the results of chemical analyses of sediments, seawater and selected organisms collected during an IOC/GEEP Workshop held in Bermuda in September 1988. The data show gradients for the trace metals Cu, Pb and Zn in sediments and for petroleum hydrocarbons in sediments and organisms related to point and nonpoint source inputs to the local harbour waters. Evidence for local sources of PAH combustion products and PCBs is presented, although no obvious point sources could be identified. Methods of the organic analyses were expanded to provide an estimate of the relative abundance of hydrocarbon oxidation products compared to the parent hydrocarbon contaminants. Water samples confirmed that the harbours receive inputs of low boiling fuel products in addition to deposition of fossil fuel combustion products. However, in the island's subtropical environment, processes of evaporation, tidal flushing and photo-degradation are rapid enough to prevent significant accumulation of light hydrocarbons in the calcareous sand sediments. Hydrocarbons in sediments were medium and high molecular weight residues, while the bivalve and holothurian “indicator” organisms concentrated the more soluble lighter hydrocarbon and PCB components. Arca zebra displayed bioaccumulation patterns for organic contaminants similar to those known for Mytilus edulis and Perna viridis. The data base was too small to determine the full potential of the benthic feeding holothurians as indicators of contamination, although they accumulated some organic contaminants. Significant proportions of the hydrocarbon residues in all samples were present as oxygenated reaction products, highlighting the need for further research on the bioaccumulation and relative bioactivities of the oxidation products.