| Renewable copper industry can make up for the shortage of copper resources in China.However,the pollutants in the production process will cause potential pollution and harm to the soil,groundwater and other ecological environment.The weathering fissure water which is well developed in the mountainous areas of southern Shaanxi is controlled by various factors such as topography,geological lithology,stratigraphic structure,fissures,and valley cutting density.Therefore,it is particularly important and urgent to study groundwater pollution assessing models and methods.Luonan Huanyayuan Copper Co.,Ltd.intends to construct an annual research and development project for the treatment of 200,000 tons of copper-containing wastes and technologies in Weidong Industrial Concentration Zone,Luonan County,Shaanxi Province.It is located in the upstream of the recharge runoff area of Luonan County's water source area,where Luohui Channel passes through the factory area and the hydrogeological conditions are complex.On the basis of field hydrogeology and environmental investigation,MODFLOW groundwater pollution model was established and environmental impact assessment of construction projects was carried out.The following results were achieved:(1)Groundwater in the project area can be divided into fissure water in bedrock and pore water in loose rock.The weathering pore and fissure diving of bedrock composed of limestone and phyllite occupies most of the hilly and mountainous areas,creating conditions for groundwater storage.The lower part of the weathering zone has good rock integrity,relatively less developed fissures,good sealing,poor water-rich and conductivity,constituting the aquifer floor.Through hydrogeological tests of five boreholes,the permeability coefficients of porous and fractured phreatic aquifers are calculated to be 4.16-67.86 cm/d.(2)Based on field experiments and borehole data,DEM elevation data are extracted,and a generalized model of hydrogeology in mountainous areas is established by using Modflow software.The model is identified and validated,and a numerical model which can basically reflect the actual conditions of hydrogeology in the study area is obtained.(3)It is determined that the polluted wastewater comes from the initial rainwater collection tank and septic tank.The main influencing factors are COD,ammonia nitrogen and heavy metal ions such as Pb and Cu.The sensitive targets of groundwater environment in this area are mainly Luohui Channel,Luohe River,Gulouhe Reservoir and downstream wells.(4)The initial rainwater pool simulation scenario was predicted by short-term injection of tracer for 30 days.The results showed that the Pollution Plume reached its maximum in 30 days when short time tracer mode was predicted.Furthermore,after cutting off the pollution source,the exceeded pollution range of plumbum would decrease at once until disappeared,while the detected pollution range of copper would firstly increase,and then decreased gradually.The exceeded pollution range of COD would decreased gradually.the detected pollution range of COD would firstly increase,and then decreased gradually.The pollution range moved downstream.The simulation scenario of septic tank was predicted by tracer continuous injection model.The results showed that the exceeded pollution range would continuous increase.The contaminants in the channel transported mainly along the flow direction,which distributed in a narrow-pinnate condition,and the pollution degree declined as the distance from the point source pollution increased. |
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