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Total organic carbon (TOC), total nitrogen (TN), δ 13 C org , δ 15 N, and grain size were measured in two sediment cores from reserves adjacent to Dongshan Bay, China. The aims were to identify organic matter (OM) sources and to evaluate the combined impact of human activity and natural environmental processes over the last ∼100 yr. In a coral reserve far from the estuary of Zhangjiang River, the average sediment accumulation rate ( SAR ) was 0.51 cm/yr from ca. 1839–2015, and the values of δ 13 C org and C/N (atomic ratio of TOC to total N) ranged from −21.9‰ to −23.7‰ and from 5.7 to 8.1, respectively. In a mangrove forest reserve near the estuary, SAR averaged 0.49 cm/yr from ca. 1891–1985 and 2.41 cm/yr from ca. 1985–2015, and the δ 13 C org and C/N values ranged from −22.7‰ to −26.3‰ and from 9.3 to 21.7, respectively. By combining a comparison plot of C/N and δ 13 C org and a binary mixing model (based on δ 13 C org and N org /C org , respectively), the major OM sources were assigned and their sedimentary contributions estimated. The sedimentary OM in the coral reserve had mainly an offshore marine authigenic signature with an average terrigenous contribution of <27%. In the mangrove forest reserve, the sedimentary OM was a mixture of terrestrial and marine sources, with an average terrigenous contribution of >56%. While input from the Zhangjiang River declined from the 1980 s, urban development, deforestation and land reclamation contributed to an overall increase in the total mass accumulation rate ( MAR ). The coral was also severely damaged by the advent of poaching around the same time. These two factors collectively resulted in a rapid decrease in OM content and OC accumulation rate ( CAR org ) of the sediments until the establishment of the coral reserve in 1997. Changes in terrain and climate and the construction of water conservancy facilities were traditionally the primary factors responsible for changes in the sedimentary environment of the mangrove forest reserve. Since the 1980s, however, the expansion of the mangrove forest along with human activity has led to rapid increases in MAR and CAR org ; while, protective measures and a favorable climate have also promoted the growth of the mangrove forest. [ABSTRACT FROM AUTHOR]

The deep basin of the South China Sea (SCS) receives terrigenous materials from the surrounding continents and islands, making it an ideal region for studies on source-to-sink transport. The analysis of grain size, major and trace elements, and Sr-Nd isotopes of 130 surface sediment samples throughout the SCS deep basin has been performed for identifying the contribution of terrigenous and volcanic materials. Based on the analysis results, the SCS deep basin can be divided into three geographic areas with different provenances: the northern area of the East Subbasin (NES), the southern region of the East Subbasin (SES), and the Southwest Subbasin (SWS). The predominant provenances of sediments in the NES and SWS are Taiwan rivers and Mekong River, respectively. Sediments from the SES exhibit higher mean grain size, less radiogenic 87Sr/86Sr, and more radiogenic 143Nd/144Nd than those from the NES and SWS. Pinatubo ash input from the Luzon Island may be a predominant source in the SES. The contribution of Pinatubo ash decreased westward from 80% to 20% in the SES. The supply of Pinatubo ash could be considered insignificant to the NES and SWS. Sediments from Taiwan rivers or Mekong River were the subordinate source in the SES. The deep-water current and mesoscale eddies may play a role in transporting terrigenous materials into the SCS deep basin as well as the turbidity current. • The deep basin of SCS can be divided into three provinces with different provenances. • The predominant provenances of sediments in the NES and SWS are Taiwan rivers and Mekong River, respectively. • Sediment from the SES had less radiogenic 87Sr/86Sr but more radiogenic 143Nd/144Nd compared to those from the NES and SWS. • The proportion of contribution from Pinatubo ash decreased from 80% to 20% westward in the SES. [ABSTRACT FROM AUTHOR]

Sediment transport in estuarine systems has been of increasing interest for scientists during the past few decades. However, the mechanisms for sediment redistribution remain unclear. We characterized in detail sediment transport in the Xiaoqing River estuary using the mathematical Weibull function to partitiongrain-size components of surface sediments in the southwestern Laizhou Bay, Northeast China. Four partitioned components: finer than 4, 4.6-12.5, 23.4-63.3, and 67.1-132.6 μm were interpreted in terms of hydrodynamic conditions. During sediment transport, silt grains were suspended and moved seaward from three depositional centers, whereas fine-grained sands moved generally landward. Overall, sediments are transported clockwise in a generally NNE direction near shore and then turn eastward offshore. The mathematical partitioning method showed a great potential for future estuarine environmental studies. [ABSTRACT FROM AUTHOR]

A correction to the article "Grain size and geochemistry of surface sediments in northwestern continental shelf of the South China Sea" that was published online on the January 24, 2013 issue is presented.