Study On The Spatial And Temporal Variations Of Surface Water, Air And Soil Environmental Quality During Rapid Urbanization In Shanghai

Shanghai has experienced an extensive urban expansion since the reform and opening policy of China. After 1990s, the city is in the process of suburbanization. The research results show that urbanization level increases with economic growth. According to the urbanization level of districts or country in Shanghai, this study divided Shanghai into three types: urban, suburban and rural areas. Three spatial areas indicate that the process of urbanization arose from the urban areas expanding to the suburban and rural areas gradually. Then monitored data of surface water, atmospheric, and soil environment were used to calculate the integrated pollution index in urban, suburban and rural areas (The larger the integrated pollution index is, the worse the surface water quality). Based on the spatial and temporal variations of the integrated pollution index in three spatial areas, the paper studied the variations of environmental quality in Shanghai.Main results of this research are as followed:â‘  For urban areas, KN, BOD₅, TN and so on are the main pollutants, but VP became the first pollutant in 2005. These pollutants are from industrial wastewater and integrated domestic wastewater. The important pollutants of atmospheric environment are dustfall, SO₂, NO_X, TSP and so on, which are from fuel burning, industrial production, vehicles let and so on.For suburban areas, KN, BOD₅, COD_mn, Hg, KN, TN and so on are the main pollutants for surface water quality, dustfall, acid rain and TSP and so on are the main pollutants for atmospheric environment, Cd, Hg, Zn and so on are the main pollutants for soil environment in past 20 years.For rural areas, main pollutants for surface water environment are COD_mn, BOD₅, Hg and so on; dustfall, acid rain, NO_x and so on are for atmospheric environment; Cd, Hg, Zn and so on are for soil environment.â‘¡ On the spatial scale, the environment quality of surface water and air spatially showed that pollution in urban areas was the most severe, followed by suburban areas, and with rural areas relatively better. The spatial variations of the level of urbanization were consistent with the variations of integrated pollution index. The higher the urbanization level, the worse the environmental quality was. In the periods of 1986-2001, the differences of three spatial areas were the biggest for surface water, because the urban pollution was more serious. And after 2002, the differences of three spatial areas were reduced gradually. For air quality, the differences of three spatial areas were on the small sides because of the serious air pollution in suburban areas, and it was reduced more after 2002. For soil environment, the soil pollution of Shanghai was worse than nation. Except for the eighth "Five-Year-Plan" period, the soil quality of suburban areas was better than rural areas in the other programming periods. Based on the national Environmental quality standard for soil, the differences of spatial areas were the biggest in the sixth "Five-Year-Plan" period, the other three programming period were not obvious. Based on the Environment background value of soils in Shanghai, the spatial differences were the biggest in eight "Five-Year-Plan" period, it was the smallest in the ninth "Five-Year-Plan" period.â‘¢ On the temporal scale, The annual variations of surface water and air environment in urban areas showed an inverted-U-shaped curve which reflects a developing phase of "pollution first, treatment after", and the critical turning point showed a tendency for the integrated pollution index to decrease in the 1990s. The surface water and soil quality were improved in the middle-1990s, but the contaminative index of air environment increased again after 2000 in suburban areas. In rural areas, the air and soil environment were improved more in 1990s, but the integrated pollution index of surface water had undulated in its range and risen significantly in recent years.â‘£ Surface water quality ran down with the increase of GDP per capita and urbanization level during 1982-1990, and it improved after 1990, which showed an inverted-U-shaped curve. However, air quality worsened quickly during 1982-1990, then improved gradually in the period of 1991-2000, after 2000 it appeared the trend to exasperate again. In a word, the temporal variations were N-shaped curve. With the development of GDP per capita and urbanization level, soil quality improved gradually after "Eight Five" programming period (from 1991 to 1995).⑤ In the rapid urbanization of Shanghai, the increase of population density, population redistribution, adjustment of industrial structure, enterprise redistribution, foundation construction, agriculture activity, economical development and environmental policies are the dominate factors on the surface water, air and soil environment.As the representation of the urbanization in China and other developing countries, the spatial and temporal variations are theory and data materials for the Shanghai Municipal Government and environmental protection department. And this paper also put forward some environmental protection and management suggestions for the construction of ecological city and Shanghai World Expo in 2010.