Geochemical Characteristicsand Environmental Impact Assessment Of Heavy Metalsin Lead Zinc Mine

People in the production and life,on the surrounding environment caused great influence.This paper is in a large number of field investigation and indoor data collection and indoor experiment on the basis of the human activities on the environmental impact of the most direct and most damaging environmental pollution problems caused by mining development and utilization of research.This paper is based on “the southwest area of groundwater heavy metal pollution source identification and pollution risk assessment project”,according to the geochemical characteristics of heavy metals in Hanyuan Tang lead-zinc mine hometown in the surrounding environment,migration of elements in the mine environment,and the development and utilization of mine on the surrounding environment in soil and plants,as well as the influence of atmospheric dust water and impact assessment.The previous research on heavy metal pollution in Hanyuan Tang Jia Xiang lead-zinc mine are unilateral for soil or plant,for the full range of Hanyuan Tang Jia Xiang lead-zinc mine in the surrounding environment,this thesis not only studies the plants and soil,is also preparing to study Chinese source Tang Jia Xiang lead-zinc mine on the basis of the surrounding atmospheric dust and water and other factors,to a more comprehensive understanding of elements migration in the mine environment,as well as the influence of lead zinc ore on the surrounding environment,and make relevant environmental impact assessment.The research shows that the development and utilization of mine caused a slight influence to the water in the study area,the groundwater in the studied area of heavy metals did not exceed the standard,but the surface runoff is only HYSY04 in the content of Pb is higher than the national standard,other metals in the sample content did not exceed the standard;and the study area in the plant and soil by mining influence Zn,As,Pb,Cd,Hg,and other heavy metals in surface soil was more than the background value even several times,and heavy metals by tailing pond effect of downward migration and enrichment process of plants affected by degree of mining area is large,the content of Pb exceeded the food safety standards in all plant samples,the corresponding root although the content of Pb in soil is not very high,but the existing form of Pb,Zn and other elements of instability,bio available and potential biological availability With the state,to the plant absorption and transformation;influence of atmospheric dust is also affected by the mining area,atmospheric dust has a certain degree of pollution in the study area,the average Pb content is 1208.6mg/kg,and the average content of Zn element is reached 3154mg/kg,and the effect of exhaust gas by mining tailings weathered seriously.Experimental results show that the leaching,leaching regularity of heavy metal elements in liquid has some similarities,most of the elements are with the passage of time the leaching quantity decreased and stabilized,while the Pb element is increased with the passage of time,presumably due to insufficient leaching time led to the two elements of the law is different from other elements;when reached a certain time after leaching,leaching column chemical reaction changes by neutralization reaction between leachate and sulfide into the reaction at the same time,the release of heavy metal ion,leaching experiment continues,then the sulfur reacts with water is basically completed,the chemical reaction in column leaching to the neutralization reaction of heavy metals leaching amount tends to be stable.The formation of heavy metals through the mining wastewater generated by weathering and leaching of AMD into the water,but because the study area dominated by carbonate rock,heavy metal ions formed by hydrolysis precipitation and precipitation,did not cause a big impact to the environment of mine tailings;heavy metal elements in the formation of AMD by Fenghua eluviations,elevated heavy metal the active elements,the adsorption desorption effect of colloid into the soil,because of heavy metals in biological availability and biological potential available,so it is easy to be absorbed by plants,thus entering the food chain,causing harm to human health;heavy metals by mining the waste gas and the tailings dry naturally formed dust into the atmosphere,the formation of atmospheric dust on human health become harmful.Based on the analytic hierarchy process(AHP),the fuzzy comprehensive evaluation of the ecological environment in the study area was carried out to establish the risk assessment model suitable for this kind of ecological environment,and the two evaluation factors included the soil,the medium and the plant.The results showed that there were three kinds of evaluation factors.The next level of evaluation factors including soil heavy metal elements content and form elements,the first class evaluation factor of transmission media including mining wastewater,groundwater,surface water and atmospheric dust,22 comparison of various factors weights,different ecological environment from different membership,get various factors weights and membership degree vector matrix multiplication the risk assessment,ecological risk assessment results will be divided into low,medium and high grade,four.The probability of risk study area is 13%,the probability of risk as low as 19.9%,moderate risk probability is 25.8%,the probability of risk as high as 41.3%,so the study area is high risk level,shows the influence of Tang lead-zinc on Hanyuan hometown surrounding ecological environment caused serious.