Distribution of organic matter in the Changjiang (Yangtze River) Estuary and their stable carbon and nitrogen isotopic ratios: Implications for source discrimination and sedimentary dynamics

Organic carbon and total nitrogen as well as stable carbon (δ¹³C_org) and nitrogen (δ¹⁵N) isotopic ratios were determined on suspended matter, settling particles and bottom sediments collected from the Changjiang (Yangtze River) Estuary during the summer flood period in 2001. From the results, three sources of suspended matter, riverine, deltaic (salt marshes) and marine (East China Sea - ECS) were distinguished. The resuspended particulate organic matter contents in the water column increased with the amount of total suspended matter (TSM) indicating the role of dispersive and/or turbulent mixing and its control over the high TSM concentration in the Changjiang Estuary. This and an active resuspension/deposition in the estuary determine the nature of organic matter in suspended materials reaching the East China Sea.