| The tailings pond of Jiapigou gold mine has been in service for many years.At present,some land resources have been destroyed,airborne dust,soil and water pollution,and the tailings pond has a certain degree of impact on the local ecological environment.Existing research in the study area focuses on geological stratigraphic research and metallogenic prediction.There are few studies on the spatial distribution characteristics of heavy metals in tailings ponds and environmental pollution assessment,and the research on the cumulative effect of heavy metals carried by atmospheric dust is also blank.This study takes tailings pond of Jiapigou gold mine as research object,discusses the spatial distribution characteristics and environmental effects of heavy metals in tailings ponds in the study area,and conducts pollution assessment and impact prediction,so as to provide a theoretical basis and technical support for the pollution control and repair of heavy metal pollution in tailings pond.The tailings pond in the study area is basically an alkaline environment,the p H of tailings falls within the range of 7.00-9.00,and the p H of water and soil samples is slightly lower than that of tailings.The spatial distribution of heavy metal content in soil and water samples is affected by distance.The closer the sampling point is to the tailings pond,the higher the heavy metal content in the sample.The spatial distribution characteristics of heavy metals(Cu,Pb,Zn,As,Hg,Ni,Cr,Cd)in tailings pond are obvious.The content of heavy metals in tailings shows an upward trend in the SN direction,and first decreases and then increases in the EW direction.The changes of heavy metal content in the samples were obviously affected by human activities and the topography of the tailings pond.The content of As in the whole tailings pond is similar,and the change is not obvious.The vertical distribution characteristics of heavy metals in tailings are as follows: the content of heavy metals Ni,Hg and Cd does not change significantly but slightly decreases with the increase of sampling depth,the content of Pb gradually decreases,and Zn,Cu and As appear peaks in the 30-50 cm layer,The Cr content first increased slightly and then decreased gradually.In general,the heavy metal content of surface tailings is slightly higher than that of deep layers.The evaluation of water pollution shows that the content of As and Hg in the surface water of the study area exceeded the standard of Class III water bodies in the "Environmental Quality Standard for Surface Water"(GB3838-2002);The cyanide content in the water sample of the catchment exceeded the standard,the main reason was the accumulation of a large amount of tailings leaching solution.The content of heavy metals As,Hg and Pb in the water samples from the monitoring wells exceeded the water standards of Class III in the "Quality Standards for Groundwater"(GB/T 14848-2017).The results of soil quality pollution assessment show that soil environment is moderately heavily polluted,average value of Nemerow pollution index is 2.92,and elemental mercury is the main pollution factor.The soil is at a strong ecological risk level,and the main risk elements include mercury,cadmium,copper,and arsenic.The sources of heavy metals were divided into three categories,heavy metals zinc,arsenic,mercury and cadmium are comprehensive pollution sources caused by atmospheric deposition and mechanical wear in pond.Copper,chromium and lead are the sources of atmospheric deposition,and nickel is the main natural source.The soil around the tailings pond is polluted by tailings dust.The longer the service life of the tailings pond and the closer the receiving soil is to the tailings pond,the higher the pollution.Under normal operation,the tailings pond will not cause pollution to the water environment.Countermeasures for the prevention and control of pollution from tailings pond are proposed,which can reduce the impact of tailings pond on the surrounding environment. |
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