Assessment of PCB contamination in a well delimited population of Chamelea gallina clams in the Adriatic Sea

The Adriatic Sea region is intensively developed with agriculture, manufacturing, shipping and tourism. These activities have introduced a range of pollutants into the sea, including polychlorinated biphenyls (PCBs), a class... [ view full abstract ]

The Adriatic Sea region is intensively developed with agriculture, manufacturing, shipping and tourism. These activities have introduced a range of pollutants into the sea, including polychlorinated biphenyls (PCBs), a class of anthropogenic contaminants of long-standing environmental concern, also deposited by long-range transport in air and water.

PCBs show a high octanol-water partition coefficient enabling fish and invertebrates to concentrate them in fatty tissue. Based on the results of a six year long monitoring program of a population of clams (Chamelea gallina) near San Benedetto del Tronto (Adriatic Sea, Italy), this study aims to assess the trend of PCB concentration, investigate the individual PCB markers accumulation profile, compare results with other available data and with a study about PCBs mass balance on the Adriatic Sea. Our main findings:

• No significant trend is  recognizable regarding the overall PCB concentration and there is no evidence that the observed negative trend in lipid concentration is affecting PCB accumulation levels;

• Most PCB markers’concentration shows a significant positive trend and a significant negative correlation with lipid content: the unexpected PCB 138 negative trend needs further investigations;
• PCB marker's’ pattern shows that the most important contribution comes from congeners with  greater hydrophobic properties;
• Comparison with other available data shows that bivalves of the Adriatic Sea aren't a significant source of PCBs for humans;
• Our results essentially match the outcome of a PCB mass balance study, predicting an increase of highly chlorinated PCBs in the case of elevated  temperatures due to global warming.