| Zhoushan sea area, a part of the East China Sea, is located in the south of the Yangtze River estuary. This sea area has been being polluted by terrigenous pollutants(outside) from the Yangtze River, Qiantang River and other rivers, in the meanwhile, polluted by regional contaminant(inside) due to regional marine economy development. therefore, under duel stress from outside and inside contaminant, Zhoushan sea area has become one of the most seriously polluted areas in our Chinese coastal waters, and the main contaminant is nutrients. To effectively improve the Zhoushan marine environmental conditions, we need excavate the existing multi-source data, analyze the space-time distribution characteristics of nutrient content in Zhoushan coastal waters and its change, and explore the interaction effect and changing trend between terrigenous input source from rivers and regional marine and point source input, in order to make clear the direction and location of the marine environment management.This paper, from the perspective of historical change,has synthesized the nutrients survey data during the period of 1990, "11th five-year plan" and the "twelfth five-year plan" of Zhoushan sea area. On the other hand, it systematically and comprehensively analyzes the space-time distribution characteristics of nutrient by using GIS spatial analysis technology, and discusses the relative change situation and the impact on the marine environment between exogenous pollutants input from rivers and marine emission and endogenous input from regional point source pollution. Besides, this paper puts forward Zhoushan marine nutrient pollution prediction model under the joint action of internal and external source. In the end, on the basis of regional social and economic development planning, this paper analyzes the change trend of nutrient pollution in different development scenarios in the future. Paper main research conclusions are as follows:(1)Waters spatial distribution characteristics of nutrient pollution: On the whole it presents the regularity of west is high but east is low and inshore is high but infralittoral is low. But in the later stages, under the action of endogenous, some local sources of pollution appears, which results in the distribution characteristics of west is high but east is low in local area is no longer obvious. As a whole, in the later stages, difference between west and east phase in nutrient distribution is similar to 1990, which showed that exogenous pollution on sea nutrient distribution is the main effect.(2)Waters temporal change characteristics of nutrient pollution: During the period of "11th five-year plan", the concentration of active phosphate and inorganic nitrogen in Zhoushan coastal waters is higher than 1990.Compared to the "11th five-year plan", during the period of "12th five-year plan", pollution degree of active phosphate and inorganic nitrogen is slightly better.(3)The space-time distribution characteristics of nutrient pollution shows that, on the whole, exogenous pollution is still the main effect, but the endogenous impact on nutrient content in local waters is growing. According to the change of both, this paper builds the nutrient pollution prediction model based on internal and external changes in the source waters, besides, it predicts the nutrient pollution of waters in the coming "13th five-year plan".(4)Pollution control countermeasure: during the period of "13th five-year plan", In these two possible development mode that it only considers the economic growth achieved goals and the economic growth, the main pollutant emission reductions achieved the anticipated target, the nutrient pollution of Zhoushan sea area presents aggravating trend, exogenous pollution is still the main effect, therefore, for some time to come, Zhoushan sea nutrient pollution treatment should still give priority to exogenous control(the Yangtze river basin pollution control), at the same time, endogenous growth cannot be ignored. |
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