Sedimentary geochemistry of the Yangtze River： Sediment source-to-sink tracing implication

The Yangtze （Changjiang） River as the largest fiver originating from eastern Tibetan Plateau, has increasingly attracted considerable attention of many researchers for almost one hundred years. The fiver linking the Tibetan Plateau with the West Pacific Marginal Sea, encompasses variable source rocks and complicated drainage patterns and spans across distinct climate zones. The increasing human activities in the last 2000 years have significantly changed the weathering process and sediment source-to-sink pattern in the fiver basins. In terms of this, the Yangtze drainage basin as well as the deltaic and coastal areas can be regarded as one of the best regions in the world to investigate the source-to-sink process of continental sediments into the marginal sea. In the past ten years we systematically measured elemental and Sr-Nd-Pb isotopic compositions of the Yangtze riverine sediments which were collected from the mainstream and main tributaries. Analytical results clearly showed that the Yangtze sediments yield geochemical compositions different from those of other fiver sediments due to the very complicated source rock types and variable chemical weathering regimes in the large drainage basin. REE and Sr-Nd isotopic compositions suggest that the sediment source-to-sink pattern in the modern Yantze River basins varies considerably from the upper basin to the lower valley. Different chemical compositions among the main tributaries and the mainstream are responsible for the compositional variations of the Yangtze River sediments. It is a piece of quite challenging work to establish a sediment source-to-sink model to quantifying the contributions of the main tributaries to the mainstream.

Isolation of natural organic matter from fresh waters using reverse osmosis and electrodialysis