Environmental Impact Partition Of Yangjiazhangzi Mining Area And Migration Reaserch Of Mo In Water And Soil

Yangjiazhangzi was a large mining area of molybdenum ore which has nearsly 100 years of exploit history. The local environment of water and soil were already obviously destroyed by exploiting, even seriously threaten the local people’s life and health. In order to make a comprehensive understanding of the ecological entironment pollution’s characteristics and laws in Yangjiazhangzi mining, this paper has done the following research:1. Using the single factor index method,comprehensive index method and fuzzy comprehensive evaluation method to clear the water, soil, vegetation in the study area environment quality present situation, the characteristics of pollution distribution and their corresponding pollution components. And evaluate the soil heavy metal potential ecological harm.The results show that:Surface water environment quality is good, andthepollution components are Mo, SO42-, Hardness.The excellent districts environment quality of groundwater locate in the northeast and southeast mountains and Baiyangmugou mountains; The worst districts are: Lianhua mountain, Yushugou, Shangheiyugou and the tailings lake. The pollution components are Mo, SO42-, Hardness, NH4+ and NO2-. The soil environment quality are almost exceed middle level pollution. The soil environment quality in northwestand the north are seriously polluted.The main heavy metal pollutants is Mo. The soil heavy metals’ potential ecological risk assessment results showed that most district have stronger potential ecological risk of soil heavy metals.Most of the vegetation environment are cleaning, except Heiyugou which is seriously polluted, and the exceeds component is Hg.2. Based on the characteristics of surface water, groundwater, soil?s environmental quality, select the characteristic pollution components and construct the comprehensive evaluation index system of environmental quality in the study area. Make theevaluation and partitions comprehensive environmental quality of the study area to analyze the main influence factors of comprehensive environmental quality in different partitions and proposes the corresponding countermeasures of environmental governance.Comprehensive environment quality in the study area shows that:The comprehensive environment quality of the Ⅰ level districts are mainly locate at the northeast and the southeast, which have nice environment quality of water and soil;The Ⅱ level districts are maily locate at the south of Baiyangmugou and Yejiatun, the exceeds components are NH4+, NO3-, NO2-; The Ⅲ level districts are largely locate at Yangjiazhangzi town, shangchangmao and xiachangmao. Among, the soil’s metal pollution components of Yangjiazhangzi town are Mo, Pb, Zn, the groundwater’s pollution components are SO42-, Hardness and Mo, the surface water’s main pollution component is NO3-. The main pollution component in surface water of Shangchangmao is NO3-, and in groundwater are NH4+, NO3-, NO2-; The Ⅳ level districts are: the north of Heiyugou, Lianhua mountain and Yushugou. The pollution components in water environment are Mo, Fe, SO42- and Hardness. The pollution components in soil environment are Mo, Pb, Zn and Fe.3. Based on the field investigation, collected soil samples in different locations of the study area. And based on the mineralogical and geochemical analysis results, the paper do the static adsorption and dynamic adsorption experiments on the condition of “p H=3, temperature=25℃” and got typical component?s(Mo6+) key migration parameters of different soil in the study area.The static adsorption experiment results’ show that, different location of soils on the static adsorption of Mo6+ accord with Langmiur isothermal adsorption equation.The calculation results show: The maximum value of soil static adsorption capacity is 86.96mg/kg and the minimum value is 19.57mg/kg, which locate in Shangchangmao and Heiyugou. The maximum value of soil-water partition coefficient is 2.73L/kg, and the minimum value is 0.56L/kg, which lacate in Heiyugou and the tailings lake.The dynamic adsorption experiment results’ show that, the maximum value of soil dynamic adsorption capacity is 57.66mg/kg and the minimum value is 12.79mg/kg. The maximum value of soil-water partition coefficient is 1.44L/kg, and the minimum value is 0.54L/kg. The position of dynamic adsorption capacity and soil-water partition coefficient are same to the static adsorption experiment results.4. Based on the migration parameters of pollution component Mo?s experiment in the study area, build numerical simulation model of Mo?s vertical migration in tail ore of source area and horizontal migration in hyporheic zone under the tailings dam.Using the numerical simulation technology, analysis and predict the migration characteristics of vertical and horizontal migration and of Mo6+.From the simulation results of vertical migration in tailing sand, the paper get the time of start migrating out and completely migrating out of Mo6+. The results show that the time of Mo’s complete leaching will be longer as the depth’s increasing. And the paper build the Mo’s leaching time model of different depth, basing on the simulation results.The simulation results of horizontal migration in hyporheic zone show that, Mo6+ migrate and adsorb in the source area at a distance of 1.2km(in Shangheiyugou). So that the main source of Mo in Heiyugou and other south places is the infiltration supply of Baisha river. At the same time, using darcy’s law to analyze the rationality of simulation results. The results show that, the migration distance(1.2km) of Mo6+ in simulation is less than the distance(1.6km) of groundwater particle. It conforms to the objective reality that Mo6+ has been impact with adsorption when migrating.The research achievements provide the favorable basis and important reference to control the environmental pollution of the study area.