This paper comments and analyses the research progress of the estuary sediment and ecological environment, including saltwater intrusion phenomenon and laws, sediment and ecological environment. The physical context, sediment and ecological environmental problems of the tributary bay of TGR are analyzed comparatively with those in ocean estuary. Based on the existing research and achievements, this paper puts forward that the research ideas and methods of the ocean estuary should be drawn from, and outlooks the future research works on the dynamic and ecological environmental problems in tributary bays of TGR.

The phytoplankton blooms in the tributary bays have become the most serious environmental problem in Three Gorge Reservoir (TGR), China. In order to understand the mechanism of those phytoplankton blooms, the factors to affect the eutrophication and Phytoplankton blooms have been summarized. Generally, in lakes eutrophication is a natural evolutionary process, which is affected by light, temperature, nutrients, predation, migration and stratification. Recent decade's human activities played a role to promote this evolution but not to change the evolutionary direction. However, in the TGR, the changed hydrodynamics caused by the TGD are considered to be the most important triggers to the phytoplankton blooms, especially the longer residence time, thermal density currents and stratification.

This study focuses on the analysis of algae growth when nitrogen is enough and phosphorus is different though the method of enclosure experiments. and to determine the influence of phosphorus for algae population structure. The results showed that the optimum value for algae grew isρp=0.14mg·L-1in the different phosphorus concentrations, and algae grew better at phosphorus concentration more than 0.14mg·L-1than less than it. Community structure of phytoplankton has a little change between the experiments.The dominance of diatom is much larger than that of other phylum.The phosphorus can influence algae growth but has little effect on phytoplankton succession.A further research about the reason of phytoplankton succession in Xiangxi bay is needed.

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