Identification And Migration Simulation Of Groundwater Pollution Factors In The Affected Area By Typical Metal Mine Tailings Ponds

In order to study the impact of non-ferrous metal mine tailings ponds on the groundwater environment,the Xinxing Copper Mine Concentrator in Wulate Houqi and the Lituo Lead-Zinc Mine Tailings Dam in Linxi County were selected as the research objects.Groundwater and surface water were collected in the high-low season of 2020.A total of 63 water samples were used to determine the content of heavy metals Cu,Pb,Zn,Cd and As,as well as conventional chemical indicators.Field geophysical testing and groundwater level measurement were performed to obtain the aquifer structure and groundwater flow field.Piper three-line diagram method,Gibbs diagram,correlation analysis,ion ratio method are used to realize the source analysis of groundwater chemical components.Combining Arc Gis to analyze the temporal and spatial distribution characteristics of heavy metals,the single factor index method and Nemerow comprehensive pollution index method are used to evaluate water quality and judge characteristic pollutants.Finally,a numerical model is established to predict the migration and change characteristics of major heavy metal pollutants,and to provide decision-making basis and technical support for tailings pond management and groundwater environmental restoration.The main results of the thesis are as follows:(1)The source analysis of conventional water chemistry components in the two study areas was carried out:the water chemistry type in the study area of Wulate Houqi is SO₄·CL-Ca·Na·Mg type water dominant type;evaporation and concentration determine the groundwater in the study area The important mechanism of the main ion.The water chemistry type in the Linxi County study area is dominated by SO₄·HCO₃-Ca·Na·Mg type water;rock weathering is an important mechanism that determines the main ions of groundwater in the study area.The Cl^-content of some sampling points in the two study areas is relatively high,indicating that there may be human pollution in the two study areas.(2)On the basis of exploring the chemical characteristics of groundwater and the evolution of chemical components in the two study areas,conduct groundwater quality evaluation in the two study areas:During the high water period in Wulate Houqi study area,the average pollution index of As and Pb exceeded the standard,and the watershed All groundwaters have As exceeded the standard;only Pb in the groundwater of the entire study area exceeded the standard during the dry season,with a maximum exceeding 6.3times.In general,the pollution was serious during the wet season,and the pollution was reduced during the dry season.The change in the content of most metal elements had significant seasonal pollution.In the Linxi County study area,the pollution content in the study area in the wet season is higher than that in the dry season,and the pollutant concentration changes have a significant period.Through the comprehensive evaluation of heavy metal Nemero:the sampling points of the groundwater quality in the high and low water period of the Wulate Houqi study area in the pollution range accounted for 66.7%and 46.1%of the total sampling points respectively;the sampling of the groundwater quality in the high and low water period of the Linxi County study area in the pollution range The points account for 25%and 8.3%of the total sampling points respectively,and the overall water quality is relatively safe.(3)Based on the numerical models of groundwater in the two places,use the MT3DMS module in GMS to establish a groundwater quality model.According to the water quality evaluation,the representative and widespread pollutant As in the two study areas was selected as the pollutant evaluation factor in the two study areas.Through simulation calculation,the diffusion range and distance of pollutant As in the study area of Wulate Houqi and Linxi County in 50d,100d,1000d,and 3650d were obtained respectively.At 3650d,pollution plumes with a length of about 1400m from north to south,a width of about 450m from east to west,a length of about 1100m from north to south,and a width of about 1100m from east to west were formed in the two study areas respectively.Both water quality models show that over time,pollutants not controlled by intervention will continue to accumulate and diffuse in the downstream area,and continue to cause catastrophic impacts on the downstream groundwater environment and the surrounding ecological environment.