Levels, persistence and bioavailability of organic contaminants present in marine harbor sediments impacted by raw sewage

As part of a program to investigate the levels, fate and bioaccumulation of organic contaminants in a polluted marine harbor, organochlorine compounds including the polychlorinated biphenyls (PCBs), dichloro diphenyltrichloroethane and metabolites (DDTs), chlordanes, dibenzo-p-dioxins (Ds) and dibenzofurans (Fs), polycyclic aromatic hydrocarbons (PAHs) and sulphur hetero cycles were analysed in sediments spiked with St. John's Harbor sludge. Winter flounder (Pseudopleuronectes americanus) were exposed to these sediments containing six levels of harbor sludge during four winter months. Following exposure, sediments were reanalysed to investigate the persistence of the contaminants. The primary contaminants detected were PAHs (approximately 5000 ng/g), predominantly alkylated phenanthrenes, fluoranthene and pyrene; PCBs with a predominance of Aroclor 1260 signature (approximately 64 ng/g), DDTs (approximately 5 ng/g), hepta and octachloro dioxins and furans (approximately 0.5 ng/g) with very low levels of less chlorinated congeners. The PAHs degraded with an estimated half life of 2 to 3 months, while no significant degradation could be attributed to the other compounds. Bioaccumulation to muscle showed the potential uptake of contaminants in biota inhabiting the harbor. A dose-response relationship was observed between spiked sediments and the concentrations of PCB congener 153 and unresolved congeners 138/163/164 in muscle. Of the dioxins and furans, only 2, 3, 7, 8-tetrachlorofuran was detectable in muscle and at a similar concentration in all exposures indicating a similar bioavailability independent of the fraction of sludge in sediments. Of the PAHs, only naphthalene and methyl naphthalenes were detected in muscle, but did not display a dose-response. One bile metabolite of pyrene was quantified and demonstrates metabolism. Biota-sediment accumulation factors were of 0.2 to 7 indicating that equilibrium was approached, with the exception of the hepta and octachloro dioxins and furans which were not significantly bioaccumulated.