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Change characteristics of DSi and nutrition structure at the Yangtze River Estuary after Three Gorges Project impounding and their ecological effect

Li L., Shen X., Jiang M.

Archives of Environmental Protection

2017

Vol. 43, no. 2

74--79

The variation law of dissolved silica (DSi), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and nutrition structure after the Three Gorges Project (TGP) impounding as well as their ecological effect were analyzed according to monitoring survey of the Yangtze River Estuary in spring (May) and summer (August) from 2004–2009. The results showed that after impounding, DSi and DIN concentration decreased and increased, respectively. During the study period, DSi decreased by about 63%, while DIN almost tripled. DIP concentration fluctuated slightly. With respect to nutrition structure, N:P increased, whereas Si:P and Si:N declined. According to chemometry standard of nutrient limits, nutrition structure tended to be imbalanced and the limiting factor of phytoplankton growth (P) was studied. Changes of nutrition structure have largely decreased diatom and caused different composition of dominant phytoplankton species. This may change ecosystem structure of the Yangtze River Estuary.

Real-time Risk Assessment for Aids to Navigation Using Fuzzy-FSA on Three-Dimensional Simulation System

Chen J., Chen T., Shi C., Jia D.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2014

Vol. 8, no. 2

197--203

The risk level of the Aids to Navigation (AtoNs) can reflect the ship navigation safety level in the channel to some extent. In order to appreciate the risk level of the aids to navigation (AtoNs) in a navigation channel and to provide some decision‐making suggestions for the AtoNs Maintenance and Management Department, the risk assessment index system of the AtoNs was built considering the advanced experience of IALA. Under the Formal Safety Assessment frame, taking the advantages of the fuzzy comprehensive evaluation method, the fuzzy‐FSA model of risk assessment for aids to navigation was established. The model was implemented for the assessment of aids to navigation in Shanghai area based on the aids to navigation three‐dimensional simulation system. The real‐time data were extracted from the existing information system of aids to navigation, and the real‐time risk assessment for aids to navigation of the chosen channel was performed on platform of the three‐dimensional simulation system, with the risk assessment software. Specifically, the deep‐water channel of the Yangtze River estuary was taken as an example to illustrate the general assessment procedure. The method proposed presents practical significance and application prospect on the maintenance and management of the aids to navigation.