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Transport of terrigenous organic matter (TerOM) in marginal seas plays an important role in marine carbon cycle which is closely related to global climate change. Suspended particulates in East China Sea (ECS) inner shelf are subject to strong influence of seasonally varied Zhe-Min Coastal Current (ZMCC) and Taiwan Warm Current (TWC). Transport of TerOM attached to the mineral particulates is therefore largely dependent on these hydrodynamic conditions. To address the transport pattern of TerOM in highly dynamic marginal seas and its implication, sediment samples were collected from ECS inner shelf and fractionated by water elutriation to simulate the hydrodynamic sorting process. Lignin phenols were determined for each fraction. The abundance of C phenols preferentially concentrated in the finer fractions, which is believed as a collective effect of hydrodynamic sorting, diagenetic reactivity and association preference of C phenols with finer sediments. In contrast to the expectation, sediments at the southernmost site did not have the highest mass percentage for the finest fraction, the lowest lignin abundance and the highest degradation status. Combining the results of lignin parameters with seawater temperature and salinity profiles, it is proposed that sediments are transported along the inner shelf southward in winter and northward in summer to some extent with the influence of seasonally varied ZMCC and TWC, induced by the seasonality of East Asia Monsoon (EAM). Finer grained sediments are more susceptible to this process. This transport pattern, which was only reported previously in ocean modeling, was firstly supported by the observation of lignin biomarkers. It is suggested that cross-shelf transport of sediments in ECS seems to be possible, but is complicated and is also affected by the seasonal variation of EAM. This study improved the understanding of hydrodynamic sorting on the transport of TerOM and carbon cycling in the marine system. Unlabelled Image • Hydrodynamic sorting affects the partitioning of C lignin phenols in sediments. • This nature of C lignin phenols hampers identification of vegetation type. • Along shelf transport of sediments has seasonal variations. • Cross shelf transport of sediments is complicated. [ABSTRACT FROM AUTHOR]

Congener profiles, distribution and sources of parent and alkyl-polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Southern Yellow Sea (SYS), China were investigated. The ecological risk of parent-PAHs to aquatic organisms were evaluated based on sediment quality guidelines (SQGs), risk quotient (RQ), organic carbon (OC)-normalized analysis and mean effects range-median quotient (M-ERM-Q). The concentrations of 33 PAHs were analyzed, including 14 parent PAHs (without naphthalene and acenaphthylene), 16 alkyl-PAHs (7 methylphenanthrenes, 3 methylanthracenes, 3 methylfluoranthenes, and 3 methylpyrenes), dibenzothiophene, retene and perylene. Total concentrations of PAHs (TPAHs) ranged from 200.8 to 3629.0 ng/g dry weight (d.w.), with a mean value of 1035.4 ng/g d.w., and mainly contributed by fluorene, phenanthrene, methylphenanthrene, retene, fluoranthene and pyrene. Analysis of a broad variety of diagnostic ratios suggested that combustion was the key source of PAHs. Principal component analysis-multiple linear regression (PCA-MLR) indicated that combustion of coal, softwood and nature gas, coke oven, petroleum and vehicle emission were the main sources of PAHs in sediments of SYS, contributing 41.5%, 30.6%, 18.8%, and 9.0% to TPAHs, respectively. Ecological risk assessment of individual parent-PAHs suggested that fluorene, phenanthrene and fluoranthene may cause some risk to aquatic organisms in some stations. OC-normalized analysis and M-ERM-Q indicated that risk of multiple parent-PAHs was quite low in the studied area. [ABSTRACT FROM AUTHOR]

Dechlorane Plus (DP) is a highly chlorinated flame retardant and found to be ubiquitously present in the environment. We reported here the first record of DP in sediments from the coastal East China Sea (ECS). DP was detected in most of the surface sediments, and the concentrations ranged from 14.8 to 198 pg/g dry weight (dw) with a mean value of 64.4 pg/g dw. Overall, DP levels exhibited a seaward decreasing trend from the inshore toward outer sea. The fractional abundance of anti -DP ( f anti ) showed regional discrepancies, attributing to different environmental behaviors of DP isomers. Depth profiles of DP in a sediment core from estuarine environment showed distinct fluctuation, and the core in open sea had stable deposition environment with two peak values of DP in ~ 1978 and 2000. The f anti exhibited downward decreasing trend prior to mid-1950s, indicating a preferential degradation of anti -DP and/or a greater adsorption capacity of syn -DP after its burial. Lignin and lipid biomarkers (∑ C 27 + C 29 + C 31 n -alkanes) of terrestrial organic matters were introduced to identify region-specific sources of DP, and the results showed that DP in the northern inner shelf, southern inner shelf of 29 °N and mud area southwest of Cheju Island was mainly come from Yangtze River (YR) input, surface runoffs after discharge of local sources close to the Taizhou-Wenzhou Region and the atmospheric deposition from the North China and East Asia, respectively. The coastal ECS was an important reservoir of DP in the world, with mass inventory of approximately 310.7 kg in the surface sediments (0–5 cm). [ABSTRACT FROM AUTHOR]

Abstract: The Yangtze River estuary (YRE) and the adjacent East China Sea (ECS) inner shelf is an important sink of pollutants originated from mainland China. In this work, we studied the spatial and temporal variations and sources of polychlorinated biphenyls (PCBs) in sediments from the YRE and the ECS inner shelf. Total concentration of 23 PCBs (Σ23PCB) ranged between 24.3 and 343.3pg/g (with a mean value of 126.7pg/g), and higher values occurred in the estuarine region. The homolog profile was dominated by 3–5Cl CBs, accounting for 76.1% of Σ23PCB. The Cl proportion ranged from 45.1% to 58.8% (with a mean value of 49.9%); the lowest level appeared in the estuarine region, and it increased with distance from the YRE. Lower chlorinated congeners were carried mainly by the YR into the ocean, to be finally buried in sediments of the estuary region and vicinity. However, higher chlorinated ones were imported mainly via direct emission from local sources, to be finally buried in sediments farther away from the estuary. Of the PCBs in surface sediments, 40.1% came from the YR, 37.9% from the local sources and the rest 22.0% from atmospheric deposition. In a sediment core, we found that 81% of PCBs were technically produced and 19% unintentionally produced in the last century. Before the 1970s, PCB levels were influenced predominantly by the production and consumption of technical PCBs. While in recent decades, the effect of human activities on PCB levels has been increasing continuously. [Copyright &y& Elsevier]