Changes Of Agricultural Non-point Source Pollution In Chongqing Three Gorges Reservoir Area In Recent Ten Years

With the economic growth and the further development of society, the agricultural non-point source pollution has exceeded the point source pollution that has become the main reason for the deterioration of water environment, causing global concern. The ecological environment of Three Gorges reservoir area is fragile and sensitive. In recent years, because of the unreasonable agricultural economic activities, it has caused serious agricultural non-point source pollution, leading to the gradual deterioration of water quality in the reservoir area, which seriously restricted the sustainable development of economy and society in the reservoir area.The Agricultural non-point source pollution is affected by many complex factors, in addition to the natural factors, a series of changes in social and economic development also have an important impact on it. Along this train of thought, the paper from a perspective of economic development changes, to analyze its effects on agricultural nonpoint source pollution in the reservoir area, and explore the variation between agricultural non-point source pollution and economic development in reservoir area, understand changes in economic development to produce what kind of influence and effect size to the agricultural non-point source pollution. Using the inventory analysis method to account the total number emissions of total nitrogen and total phosphorus from chemical fertilizer, livestock and poultry, rural life the three agricultural non-point sources as well as their contribution. Then using the software of Geographic Information System analyzed the spatial and temporal variation characteristics of agricultural non-point source pollution. Theoretically analyzing the relationship between economic development and the agricultural non-point source pollution, then based on the Environmental Kuznets Curve theory, build the model to verify if the variation of the agricultural non-point source pollution with economic growth is in line with the EKC hypothesis. If meet, then judge the turning point when to appear. Then based on the factor decomposition theory in environmental economics subject, the economic development effects are decomposited into scale effect, structure effect and technology effect. Through theoretical analysis, the impact of economic development on agricultural non-point source pollution was discussed. Finally through the measurement model to empirically study the influence of various factors in the economic development on the agricultural non-point source pollution. The main research conclusions are as follows:(1) The total emissions of total nitrogen and total phosphorus showed a trend of increase year by year in Three Gorges Reservoir area of Chongqing from 2003 to 2013. The emissions of chemical fertilizer pollution and the livestock and poultry pollution all showed a trend of increase year by year, while emissions of rural life pollution presented a decreasing trend year by year. In addition, from the view of contributions to agricultural non-point source pollution, the livestock and poultry pollution is the biggest source of pollution, and its proportion of accounted for TN, TP ratio is 64.45%, 80.73%; The chemical fertilizer pollution is the second biggest source of pollution, and its proportion of accounted for TN, TP ratio is 35.05%, 18.98%.(2) From the view of spatial distribution characteristics of agricultural non-point source pollution, there are three regional centers of the most serious agricultural non-point source pollution in the Three Gorges Reservoir area: the three regions that Wanzhou, Kaixian and Yunyang as the center in the hinterland, Fuling is the center in the central area, and at the tail of the reservoir it is the Jiangjin as the center. The area of lowest agricultural non-point source pollution emissions is mainly the area in the metropolitan at the tail of the reservoir.(3)From the space distribution characteristics of total nitrogen and total phosphorus emission intensity, the higher emissions intensity areas of total nitrogen are mainly concentrated the regions of Wanzhou, Kaixian and Zhongxian in the hinterland. In the central reservoir it’s the region of Fuling and Changshou. At the tail of reservoir it’s the region of periphery of urban function core area and Jiangjin. The lower emission intensity areas of total nitrogen in Three Gorges Reservoir area are mainly concentrated the regions of Wushan, Wuxi and Fengjie that in the hinterland, in the central reservoir area it’s the region of Shizhu, Fengdu and Wulong that as the center, and at the tail of the reservoir is mainly the three regions of Yubei, Nanan and Jiulongpo. While the total phosphorus emission intensity of the Three Gorges Reservoir area, except for Wushan, Wuxi and Fengjie in the hinterland and the Shizhu, Wulong in the central reservoir area that are relatively low, the other areas are generally high.(4) The relationship of agricultural non-point source pollution and the economic growth in Three Gorges reservoir area is in accordance with the Environmental Kuznets Curve hypothesis, and the curve shape is "inverted U". The environmental kuznets curve’s turning point of the total nitrogen and total phosphorus emission intensity with the economic growth appeared in the farmer per capita net income of 6421 yuan, 7620 yuan. Currently the Counties of Wushan and Wuxi in the hinterland of the Three Gorges Reservoir area haven’t exceeded the total nitrogen environment kuznets curve’s inflection point. They are still in the left of the curve, which means the two Counties of Wushan and Wuxi in the process of economic development will still be faced with the increasing pressure of the total nitrogen pollution. In addition, the five counties of Wushan, Wuxi, Kaixian, Yunyang and Fengjie that in the hinterland of the Three Gorges Reservoir area have not exceeded the total phosphorus environmental kuznets curve’s turning point. They are still in the left of the curve, while other sixteen counties have exceeded the inflection point in different time. It means with the economic development in the reservoir area, the total phosphorus pollution of the five counties will further aggravate. Because of the difference in the level of economic development, the time of the inflection point is also different. Therefore, the management of agricultural non-point source pollution in reservoir should be adapted to the local conditions.(5) Effect of changes in the development of economy on agricultural non-point source pollution can be decomposed into scale effect, structure effect and technology effect. Specifically be refined as the total output value of agriculture, the proportion of planting industry, the proportion of grain crops to economic crops, and the land productivity of the five indicators. The econometric model results show that the total agriculture output, the rural population and the planting industry proportion to emission intensity of total nitrogen and total phosphorus has a positive effect, while the grain crop to economic crop and land productivity to emission intensity of total nitrogen and total phosphorus has negative effect. This suggests that with the further expansion of the agricultural economy, increase of the rural population scale, agricultural planting proportion rising and increase of economic crop planting area, it will cause the emission intensity of agricultural non-point source pollution be further deteriorated, while the land productivity(indirectly represent the technology progress effect) can reduce the emissions intensity of agricultural non-point source pollution. With economic development, in the process of transforming model of agricultural economic development, promoting the adjustment of agricultural structure, it will be very necessary to fully understand the impact of changes of various factors in the economic development on agricultural nonpoint source pollution. By increasing the environmental investment, strengthening science and technology innovation, popularizing the application of environmental technology, developing green agriculture, ecological agriculture and other means to achieve the coordinated development between economic growth and environmental quality.