Study On Special Vulnerability Of Nitrogen Pollution In Bei Jing Suburbs

With the rapid economic development,the sharp expansion of population,and the acceleration of urbanization process, groundwater pollution became seriously day by day. It 1eads to decrease for water resources, which can be used, intensify water resources crisis, and influence economic development, also bring up dangers for eco-environments and human health. These problems also exist in Beijing where human activities are frequent and environments are weak. Beijing is a national key exploit region, and capital of China and center of economy and culture. The shortage of water resources and the groundwater pollution have become severe environmental problems. It is urgent to exploit rationally, manage and protect groundwater resources in the new situation. Therefore, it will be of momentous current significance to study groundwater special vulnerability in Beijing. The contents of this paper are as follow:Firstly, this paper analyze and summarize the current situation of the concept, classification, influencing factors, assessment methods on groundwater specific vulnerability at home and abroad, and point out some problems existed in groundwater specific vulnerability researches.Secondly, this paper analyze and study geology, terrane and hydro-geological condition in Beijing suburbs, and comprehensively survey the unsaturated zone state and the reason of groundwater pollution by the investigation of the field and the analysis of water samples. The result show that the pollution of nitrate in groundwater had been very severe and the target achieves by study groundwater specific vulnerability in Beijing.Thirdly, based on analyzing data home and abroad, this paper study deeply geology, hydro-geological condition and the influencing factors about the specific vulnerability of"Three Nitrogen"pollution of groundwater in this region.Fourthly, taking into account the important role of the unsaturated zone and the specific vulnerability of"Three Nitrogen"pollution of groundwater being concerned with the process of transportation and transformation about"Three Nitrogen"in the unsaturated zone, this paper design and made experiments in indoor, and study themechanism of transportation and transformation about"Three Nitrogen"in the unsaturated zone of medium sand, soil, clay.Fifthly, according to the analysis of influencing factors on specific vulnerability, regarded geology condition, the process of transport and transformation of"Three Nitrogen"in unsaturated zone and human factors as the main control factors of specific vulnerability. From these factors, we establish the assessment index system and the assessment standard on specific vulnerability of groundwater, which was made up of lithology in unsaturated zone, stratum structure in unsaturated zone, the depth to groundwater, TN decline rate constant, also contrast nitrogen pollution and reflect space change characteristics of specific vulnerability of groundwater.