Study On Spatial Distribution And Pollution Evaluation Of Heavy Metals In Soil Around Gold Tailing Ponds In Pinggu District

The tailings pond is an important product of metal mining activities,which is likely to cause serious heavy metals pollution to surrounding environment.Pinggu District,as an important ecological conservation area and drinking water source in Beijing,has a long history of gold mining.And there are seven gold tailing ponds distributed in Jinhaihu Town,Pinggu District.it is of great significance to acquaint the status of heavy metals pollution in the surrounding environment of these gold tailing ponds.So this paper takes the seven gold tailing ponds as the research objects,which distributed in six study areas,and uses various evaluation methods to study the concentration distribution characteristic and pollution situation of cyanide and seven heavy metals(Sb,As,Cd,Cu,Pb,Zn,Hg)in surface soil of each study area.The main research work and achievements are as follows:(1)In every study area,the concentrations of elements were high and positively skewness distribution,and the spatial variability was great.The spatial distribution maps showed that the concentration is higher in the soil near tailing ponds and lower in the soil farther,indicating that the cyanide and heavy metals mainly comes from the gold tailings.(2)The Geoaccumulation index and local background values were used to evaluate the accumulated pollution level of each element.The results showed that Cd is strongly polluted in each study area.By comparion,the pollution level of each element in the soil around Yanzhuang and Heishuiwan tailing ponds is higher.(3)The single pollution index and screening value were used to evaluate the over-standard pollution level of each element.The result showed that in every study area,cyanide,As and Cd were seriously polluted.And according to the comprehensive pollution assessment by Nemerow pollution index,the soil was serious pollution in the study areas of Yanzhuang,Heishuiwan tailing ponds,as the heavily polluted areas are large in these areas.(4)The ecological environment risk of each study area was evaluated by the potential ecological risk index.The results showed that the ecological risks of Cd and As are a little higher in each study area.And the high ecological risk ranges are larger and the ecological risks are higher in Yanzhuang and Heishuiwan areas,while the other study areas only have a certain degree of ecological risk in a small area near the tailing ponds.