Comprehensive Assessment Of Seawater Quality By Using Fuzzy Mathematical Model In Shanghai Adjacent Sea Area And Trend Prediction

Coast zone is the most active contact zone of interactions between the land,the sea and the atmosphere,where environment and ecosystem are influenced by both the land and the sea. It is extremely sensitive to the disturbances caused by nature and human being because of its vulnerable ecosystem. Shanghai as the mega city of economic rapid development,Red tide occur frequently, the marine environment and fishery resources are threatened by kinds of polluting sources from the Changjiang River estuary. In order to protect marine environment and construct ecological Shanghai, identification of seawater quality and marine pollution is very necessary. It also can be considered as a reference when the government constitutes the precepts of marine economy, resource development and environment protection.Based on the investigation data from 1986 to 2006 in Shanghai adjacent sea area,the fuzzy comprehensive evaluation method is used to evaluating the seawater quality and analyze the variation of seawater quality since last 21 years. ARIMA model is used to simulating and predicting the seawater quality in 2010.The results show that: (1) DIN and PO4-P reachâ…£type water quality based on China's seawater quality part; The heavy metals, Pb and Hg are betweenâ… andâ…¡type seawater quality. Pollution degree of overall seawater quality decreases from west part to east part in Shanghai sea area. (2) The seawater quality was good comparatively in 1980s, and the main pollutant are heavy metals; The seawater quality deteriorated rapidly in 1990s, reaching allâ…£type seawater quality. The main pollutants were changed from the heavy metals to DIN. The overall seawater quality shows a"fast deterioration-slow deterioration"trend. (3) According to the seawater quality prediction from 2007 to 2010, pollution degree of DIN and PO4-P will increase rapidly; pollution degree of oil will decrease slowly; pollution degree of Hg and Cu will increase slowly; pollution degree of Pb and Cd will fluctuate slightly and keep stable. The overall seawater quality will continue to deteriorate slowly.