Study On Special Vulnerability Of Three Nitrogen In Qing Baijiang Area

With the rapid development of industry and agriculture in recent years, the groundwater pollution in China is increasing, the groundwater pollution will lead to the groundwater resource decrease, the ecological environment and human health hazards. At the same time, with the rapid development of city urbanization, people’s requirements of a better groundwater quality and quantity makes the protection of groundwater resources and scientific prevention of groundwater pollution particularly importantly.Qingbaijiang area is located in the eastern edge of Chengdu Plain, is an important chemical and metallurgical bases in southwest area as well. Grorundwater serves as an alternate water source for city supply and main water source for some urban residents and enterprises. However, as a typical plain agricultural and industrial region, the situation of groundwater pollution in Qingbaijiang is not optimistic, groundwater pollution problems,typically three nitrogen pollution, restricted the economic development of the region. Therefore, specific vulnerability assessment of three nitrogen in groundwater of Qingbaijiang area can provide scientific guidance for the future sustainable utilization of water resources and the prevention of groundwater pollution, it has theoretical and practical significance on the sustainable utilization of groundwater resources in Qingbaijiang area.This paper use the hydrogeology survey method, mathematical statistics analysis, superimposed index evaluation method, through the analysis of three nitrogen distribution characteristics of groundwater in Qingbaijiang area in recent 30 years, discuss the controlling factors of three nitrogen distribution in the area, establish the three nitrogen vulnerability assessment index, and eventually establish the three nitrogen specific vulnerability assessment system for Qingbaijiang area. This paper mainly obtain the following understanding:(1) Within the study area three nitrogen in the groundwater mainly exists in the form of nitrate nitrogen, and a small amount of ammonium nitrogen. The concentration of three nitrogen content in each of the high value area are not identical. There are some high value area of nitrate nitrogen such as LongHu town surface high value area in Xindu district, point high value area in upstream of Mimu town, chuanhua industrial area and southern part of Datong town, as well as downstream of Chengxiang town, the rest of the area have low content of nitrate nitrogen.The distribution of nitrate nitrogen mainly located in north part of LongHu town in Xindu District, center of Chuanhua and northwest of Fuxiang town. but did not exceed the standard range.Ammonium nitrogen high value area mainly located in chuanhua Industrial area and LongHu town in Xindu district. By the analysis of the groundwater quality of Qingbaijiang district in recent 30 years, we found that the content of nitrate nitrogen and ammonium nitrogen increased, the high value area increased.(2)Through the study on the distribution characteristics of three nitrogen in groundwater,we found that the amount and distribution of three nitrogen is combined affect by the water yield property of aquifer, groundwater depth, groundwater runoff conditions and groundwater chemical characteristics. Qingbaijiang district belonged to the typical industrial district, the main source of three nitrogen in groundwater is industrial pollution, followed by agricultural pollution and domestic pollution.(3) The study uses natural factors and human factors as the main evaluation factors, choosen groundwater depth(D), infiltration coefficient of precipitation(C), water yield property of aquifer(A), groundwater runoff conditions(R), three nitrogen pollution situation of groundwater(N), the application amount of nitrogen fertilizer(F), industrial discharge capacity(I), population distribution(P) to establish the evaluation index system and evaluation standard, evaluate the three nitrogen specific vulnerability in Qingbaijiang areat by using the superimposed index evaluation method which based on Analytic Hierachy Process and entropy weight method. A comparative evaluation of the results shows that the three nitrogen in groundwater special vulnerability evaluation based on the entropy weight method is more suitable for Qingbaijiang area.(4)Three nitrogen special vulnerability of Qingbaijiang district is mainly moderate vulnerability area. Low-extremely vulnerability area is scattered in the Xiangfu town and Chengxiang town. Low area vulnerability is distributed from Xiangyang town to Dawan town,Mimou town and the north area of Xingfu and Chengxiang town. High- extremely and high vulnerability area is located in the industrial area and its vicinity. Combined with the specific circumstances of the study area, offer recommendations for three nitrogen pollution prevention in Qingbaijiang.