| Southwest China,including Yunnan,Guizhou,Sichuan,Chongqing,Tibet,five provincial-level administrative region,in 2015 the resident population of 199 million,accounting for land area of 1/4.1950s,the new China’s mining technology backward,lax management,the foundation is very weak;After 60s,the mining industry has been greatly developed,after 80s,the rapid development of mining economy,gradually occupy an important position in the national economy.However,the large-scale development of mineral resources in the protection of national economic development needs and create huge economic benefits at the same time,caused by the mine environmental problems are also very prominent.The production and operation process of the mining,mining and smelting of the mine not only causes the destruction of the equilibrium condition of the groundwater in the region,but also discharges a large amount of solid and liquid waste,which causes serious groundwater pollution.Groundwater pollution has the characteristics of concealment,long-term and complexity,and heavy metal has been paid more and more attention by scholars both at home and abroad because of its high toxicity,persistence and difficult to degrade.At the same time,the southwest region is located in the one or two step geomorphic units in our country,the large gap,is the main river in China and the upper reaches of the river recharge area distribution area,its unique topography,complex geological conditions determine the characteristics of the ecological environment in the region.Based on the characteristics of hydrogeological structure in Southwest China,this paper makes a study on the heavy metal pollution of groundwater in a lead-zinc mining area and its surrounding areas:(1)Based on the analysis of the characteristics of heavy metal pollutants in the soil and groundwater system,migration law,combined with the pollution characteristics of heavy metal pollution sources.Analysis of influence factors of heavy metal pollution of groundwater and the inherent characteristics of heavy metal pollution,vulnerability,special vulnerability and groundwater level in four aspects of value,principles and methods of constructing index system from the selection of heavy metal pollutant toxicity index of 15,according to the actual characteristics of the formation of the southwest area of heavy metals in groundwater pollution risk assessment index system.And determine the weight of each index value.(2)This paper introduces two methods for risk assessment of heavy metal pollution in groundwater by triangular fuzzy number method and catastrophe progression method.The triangular fuzzy number method is simple and quick,and the applicability is strong.The catastrophe progression method does not involve the weight of the index,and to some extent,it reduces the subjectivity of the evaluation results.(3)To the southwest of a lead-zinc mining area as an example,the application of triangular fuzzy number method and catastrophe progression method of heavy metals in groundwater pollution risk assessment of the lead-zinc mine and the surrounding area,and two kinds of evaluation methods are compared and analyzed.The evaluation result showed that the lead-zinc mining area and its surrounding areas affected by heavy metal contamination risks are low to moderate levels,indicating that the area of groundwater by the heavy metal pollution is slight,but also verified the applicability evaluation method. |
