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A large portion of polychlorinated biphenyls (PCBs) from e-waste released into the coastal areas may be the potential source of PCBs to the global oceans. The paper presents data of PCBs concentrations in fifty surface sediment samples and a dated sediment core in Yangtze River Delta (YRE) and adjacent East China Sea (ECS). The total PCBs levels varied from 5.08 to 19.64 ng/g dry weight, with the highest concentrations situate within the river-sea boundary zone which is so-called “marginal filter”. Concurrent with the operation of e-waste recycling over the last two decades, PCB fluxes started to rise again after 1980s and reached a maximum in this century. The full data set was used to estimate the burden of PCBs in YRE and adjacent ECS. A total sediment burdens were 192.8 tons, with the spatial density of 364 ng/cm2 which accounts for 1.9% of all the PCBs in China. [Copyright &y& Elsevier]

Residual levels and enantiomeric signatures of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in surface sediments from Xiangshan Bay, East China Sea were investigated. The concentrations of ∑HCHs (sums of α-, β-, γ-, and δ-HCH) and ∑DDTs (sums of p, p'-DDT, p, p'-DDD,p, p'-DDE, o, p'-DDT, and o, p'-DDD) ranged from 0.14 to 0.67 ng g-1 and 0.61 to 22.38 ng g-1, respectively. A slight potential health risk to the organism was then indicated for the residual levels of DDTs according to the ERL/ERM guidelines. Moreover, the predominant β-HCH implied that the technical HCH contamination was mainly due to the historical usage. But the high ratio of DDT/∑DDTs depicted a cocktail input pattern of fresh and weathered DDTs. The enantiomeric fractions (EFs) of α-HCH, o, p'-DDT, and o, p'-DDD were also determined. The degradation of α-HCH was enantioselective in all sediments samples, resulting in an enrichment of (-)-enantiomers. However, the racemic residues of o, p'-DDT and o, p'-DDD were observed in all sediments samples. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distributions and chiral signals of organochlorine pesticides (OCPs) in surface sediments from Yueqing Bay and Sanmen Bay, East China Sea were investigated. The total OCPs concentrations ranged from 2.11 to 18.15ngg−1 dry weight for all the sampling stations. HCHs and DDTs were dominant, although trans-chlorodane/cis-chlorodane were also observed in some sites. The predominant β-HCH and the α-HCH/γ-HCH ratios indicated that the residues of HCHs in these places mainly originated from the historical usage of technical HCH. However, the ratios of (DDE+DDD)/DDT reflected a cocktail input pattern of fresh and weathered DDTs. Based on ERL/ERM guidelines, p,p′-DDT and ΣDDT posed a small risk to the bottom-dwelling consumers, while p,p′-DDD, p,p′-DDE and Σchlorodane were not found at concentrations expected to adversely affect sediment biota. Enantiomeric analysis showed that the degradation of chiral OCPs was enantioselective, resulting in enrichment of (−)-enantiomers for α-HCH, o,p′-DDT and o,p′-DDD in all samples. These results implied that the sediment quality guidelines of chiral OCPs should be reassessed using concentrations of their individual enantiomers. [Copyright &y& Elsevier]

Abstract: Grain-size distributions, total organic carbon (TOC) and total nitrogen (TN) concentrations, and TOC/TN ratios (C/N) were analysed for surface sediments from the Lower Yangtze River-East China Sea (ECS) shelf system. Hierarchical cluster analysis of grain-size parameters (mode, mean, sorting, skewness and kurtosis) has been employed to characterize grain-size compositions. The results suggest there are five grain-size compositional types (type-I–V) that fingerprint distinct depositional conditions. In areas with high sedimentation rates, hydrological sorting preferentially enriches the fraction coarser than 6.4ø (12μm) in shallow seafloor sediments (water depth<30m) by transporting the finer fraction to the deeper seafloor (water depth>30m), and thus forms grain-size compositional type-I (shallow) and type-II (deep). In the open shelf, where modern sediment supply is very limited, grain-size types-III–V are identified according to different winnowing intensity. Overall TOC contents significantly correlate with mud proportions, suggesting muddy sediments are the primary control on OM accumulation. However, de-association of terrestrial OM from fine sediments in the Estuary and the occurrence of presumably relict OM in the open shelf exert additional controls on OM dispersal and carbon cycling in the ECS. By considering geography, oceanography, sediment source, and the relation between sedimentation conditions and sedimentary OM distributions, we define six depositional settings: the lower river, the estuary, the coast, the offshore upwelling area, the erosional area, and the open shelf. These settings describe the sediment dispersal and associated organic matter cycling in the Lower Yangtze River-ECS shelf system. [Copyright &y& Elsevier]