Distribution of persistent toxic substances in benthic bivalves from the inshore areas of the Yellow Sea

Abstract

A baseline survey of trace metals and organic pollutants in bivalves from the coastal areas of the Yellow Sea (China) showed the the concentrations of Cd and Pb in the bivalves from more than 85 and 73%, respectively, of the total sites (30 sites in all) exceeded the low limits of the national quality standards for marine organisms. At three sites, the contents of Cd in three species were even higher than the median limit, and a similar case with Pb occurred at another site. The tissue concentrations of As at four sites and of Hg at one site were above the low and the median limits, respectively, of the quality standards. At 43% of all sites, the levels of petroleum hydrocarbons were higher than the low limit of the quality standards, and the tissue concentrations at two sites even went beyond the median limit at one site and the high limit at the other. The concentrations of phthalate esters and polycyclic aromatic hydrocarbons (PAHs) in the collected bivalves were not high, as shown by peak values of 305 and 302 ng/g, respectively. The contents of polychlorinated biphenyls for all the species were much lower than the low limit of the quality standards. The compositional properties and isomeric ratios of PAHs indicated various pyrolytic procedures as the dominant origins. The sites with higher tissue contents of DDT and its metabolites (DDTs) over the low or the median quality limit were located mainly in the South Yellow Sea. The fractions and specific ratios of DDTs suggested that new inputs of DDT existed at two sites in the North Yellow Sea, and the potential sources involved technical DDT, technical dicofol, and their mixture.