| Along with agricultural economic develops rapidly in Jiangsu, environmental pollution and ecological demage are controlled satisfactory in the urban, but the environment are more seriously damaged in the rural region, which is called urban-rural dual structure phenomenon. The rural environment deterioration will be a direct threat to Jiangsu’s rivers and lakes. Agricultural non-point source pollution (ANSP) has gradually become the main tasks of water environment treatment in Jiangsu in present and future.The study based on the background of the negative effects of ANSP to Jiangsu sustainable development. Meanwhile, it has also has explored the ANSP’s property, source and formation mechanism from the theoretical view. Using the comprehensive investigation and assessment method upon every unit composed with fertilizer, livestock farming, aquiculture, farmland solid waste and domestic waste. Taking into account the chemical oxygen demand (COD), total.nitrogen (TN), and total phosphorus (TP) are the main limiting factor of eutrophication of water bodies, so these three indicators are used to measure the ANSP. The study caculated the discharge amount, density, variation and contribution of COD, TN, and TP from1990to2009in Jiangsu and other13cities. The degree and different distribution of agricultural non-point source pollution was analysised from1990to2009in Jiangsu. In addition, DEA method was used to estimate the variation of input and output efficiencies of the agricultural production and the agricultural non-point source pollution since1990, and the ANSP reduction programs were also put forward from the macro and micro levels. The main conclusions are as follows:First, the results indicated that the discharge amount of COD, TN, and TP were increased from64.20,54.29, and4.78to96.88,72.87, and8.33ten thousand tons, respectively, and the average growth rates were2.54%,1.71%, and3.72%. Meanwhile, the densities of COD, TN, and TP were increased from20.97,17.74and1.56mg/L to31.65,23.81and2.72mg/L in Jiangsu from year1990to2009. From the dynamic decomposition analysis, the variation of TN and TP mainly derived from fertilizer and livestock farming in Jiangsu from1990to2009.Second, there were significant differences in the13cities in Jiangsu. For example, the discharge amount of COD, TN, and TP were2.46～17.26,1.62～14.40and0.177～1.757ten thousand tons, and the densities of COD, TN, and TP were11.26～105.6,6.14～90.01and0.81-9.24mg/L separately.Third, the features of agricultural industry in Jiangsu during1990～2009are:(1) the proportion of agricultural output in national economy every year;(2) agricultural labor force transfers quickly, while capital dependence agriculture develops rapidly;(3) agricultural crop structure trends to high income and high capital dependence;(4) the food consumption structure transfers obviously, and aquaculture develops rapidly;(5) the rural infrastructure construction is lagged, environmental protection facilities are lacked and rural environmental protection laws and regulations are missed. These characteristics are the most important reasons for the formation and aggravating of ANSP problems in Jiangsu.Fourth, the characteristics of ANSP in Jiangsu were obviously different in southern, central, and north. It was showed that the total and density was increased from southern to north. The reasons are:(1) in southern areas (Suzhou, Wuxi, Changzhou, Zhenjiang, Nanjing) of Jiangsu there’s smaller proportion, higher industrialization and the abundant water resource, so the ANSP is relatively lower than central and north of Jiangsu;(2) in central areas (Taizhou, Yangzhou, Nantong), industry develops rapidly, and the pollution level is between south and north;(3) in northern areas (Xuzhou, Yancheng, Suqian, Huaian, Lianyungang) of Jiangsu, there’s higher proportion agriculture, relatively slower industrialization and scarcest water resource, and the ANSP is relatively more serious than the southern and central of Jiangsu..Fifth, technical efficiency reached1only in the last2008and in2009in Jiangsu during1990-2009, the remaining years were between0.6and1, the lowest was0.639in2003. Agricultural production technology is effective in Suzhou, Zhenjiang and Lianyungang in the13cities, and they were also quite different. For example, it was only0.196in Yancheng, and less than0.5in Nantong, Changzhou, Huaian, Xuzhou and Suqian. In Wuxi, Yangzhou, Taizhou and Nanjing, it was between0.6and1. Finally, under the situation of crop yields not being decreased, fertilizer nitrogen application rate could be reduced by20%in Jiangsu province, and the numbers of the cattle, pigs, sheep, poultry, and aquaculture should be reduced by61.60%,27.00%,24.80%,42.30%and28.20%, respectively. Denitrification, phosphorus removal, and reduction of COD content could be achieved by constructing the ecological agro-ditch. Meanwhile, demestic wastewater could be handled by building artificial wetlands in rural areas. |
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