Abstract: A large scale mud deposit associated with the Changjiang (Yangtze River) has been formed over the inner shelf waters of the East China Sea. It serves as both source and sink for finegrained sediment and organic matter. Three scientific problems in regional sediment dynamics have been identified, i.e., the processproduct relationships of the mud deposit, the role played by the mud in ecosystem dynamics, and the potential of future magnitude of the carbon reservoir contained in the sedimentary system. The research topics include the future evolution of the Changjiang mud deposit, the generation of sediment gravity flows, organic matter content in the deposit in relation to water column primary production and hypoxia, wave energy attenuation over the mud bed, the decay of particulate organic matter in response to resuspension, and the carbon reservoir pattern in relation to the evolution of the mud deposit. Such research requires an enhanced ability to collect longterm, continuous, highresolution data associated with the benthic boundary layer, the water column and some new sources (e.g., data derived from in situ imagery analysis). The bottom boundary layer data are useful to the studies on sediment gravity flow, wave energy dissipation over the mud area, and the turbulenceinfluenced sediment initiation conditions. The water column data will help to establish the delay curves of organic matter, which is critical to deal with the organic matter burial rate, the formation of shallow gas, and the carbon reservoir issues. Furthermore, there is a demand to collect innovative types of data, to obtain additional information on material source and mud deposit evolution, which awaits technological breakthroughs from the observation systems.

Key words: Ocean Observation Systems, finegrain sediment, benthic boundary layer, sourcesink relationship, carbon budgeting, ecosystems, Changjiang (Yangtze River) Estuarinecoastal waters