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Abstract: This paper reports the initial result of the flux of submarine groundwater discharge (SGD) into the Changjiang effluent plume (CEP). A radium mass balance model and a 224Ra/223Ra activity ratio (AR) apparent age model were applied to estimate the residence time of water above the pycnocline in the CEP. These two approaches gave similar results, yielding residence times of 5.4d and 7.0d, respectively, in the inner and outer plume zones. The nonconservative inventory of 226Ra was established in the CEP, and converted to a 226Ra flux by dividing by the water residence time and assuming steady state conditions. After subtracting the desorption of 226Ra from suspended sediment and the diffusion from the bottom sediment, the 226Ra flux from SGD was converted to a total SGD flux by dividing by the measured activity of 226Ra in local groundwater. The SGD flux in the CEP is estimated to be 0.2–1.0×109 m3 d−1, which is equivalent to 6–30% of the Changjiang water discharge during flood season. This large flux indicates that SGD may be another important nutrient source to the East China Sea. [Copyright &y& Elsevier]

Abstract: X-ray diffraction (XRD) mineralogical and grain-size analyses indicate that inner continental shelf sediments in the East China Sea (ECS) represent a unique mixing of clays derived from the Yangtze River and silts/sands from small western Taiwanese rivers. Taiwanese (e.g., Choshui) clays (<2μm) display no smectite but the best illite crystallinity and are only distributed along southeastern Taiwan Strait. Both Yangtze and Taiwanese river clays are illite-dominated, but the poor illite crystallinity and the presence of smectite and kaolinite indicate that Taiwan Strait clays are mainly Yangtze-dominated. In contrast, medium silts (20–35μm) and very fine sands (63–90μm) in the Taiwan Strait are characterized by low feldspar/quartz, low K-feldspar/plagioclase and high kaolinite/quartz, indicating their provenance from Taiwanese rivers. Taiwanese silts and sands are introduced primarily by the way of typhoon-derived floods and transported northward by the Taiwan Warm Current during summer–fall months. Yangtze clays, in contrast, are widely dispersed southward about 1000km to the western Taiwan Strait, transported by the China Coastal Current during winter–spring months. Since most Taiwan Strait samples were collected in May 2006, clay results in this paper might only represent the winter–spring pattern of the dispersal of Yangtze sediments. [Copyright &y& Elsevier]