Shicun Village Mine Gangue Leaching Filtrate Of Heavy Metal Migration In Groundwater Characteristics Research

During the process of industrialization, human activities have a more and more strong impact on groundwater environment. Sewage, industrial wastewater and solid waste produced through human activity caused a regional pollution of water environment. Gangue filtrated into the aquifer via the leachate produced by rainfall and then spread to the entire aquifer along with the groundwater movement. That leaded to the pollution of groundwater and it would do harm to human health if there is a consumption of contaminated groundwater. This paper conducted a heavy metal ion detection on the leach solution produced by gangue leaching test, and the results showed that: the zinc ion concentration is 11.3 mg/L, the lead ion concentration is 0.167 mg/L, the arsenic ion concentration is 0.109 mg/L, the nickel ion concentration is 0.134 mg/L. All the 4 concentrations are higher than the national drinking water quality standards. The Infiltration into the groundwater of the high salinity gangue leachate would cause deterioration of water quality. The test results of groundwater water samples collected from coal gangue accumulation zone showed that: heavy metal ions had spreaded to the surrounding groundwater and caused the groundwater pollution.Through field investigation, test analysis, numerical simulation and indoor data comprehensively research, based on the hydrogeological conditions and the analysis of the existing engineering data.This paper firstly collected samples around the coal gangue accumulation zone to get a better understanding of the heavy metal ions pollution in local groundwater. Then analyze the heavy metal ions' migration patterns in the groundwater with taking the deteriorating water dynamic conditions into account. Then use Modflow to simulate the groundwater seepage field in the study area, MT3 D predict the migration process of heavy metal ions, analyzes its migration characteristics. The main conclusions are as follows:1. On the basis of the predecessors' research results and the author field investigation, the aquifer system is divided into: quaternary loose accumulation-water-rich of not water?weak perched aquifer,, the Triassic North Si Group pure limestone- water-rich of heavy shallow aquifer, luo Lou Zu limestone of clastic rocks in the upper- water-rich of weak?medium perched aquifer, the lower shale of Triassic Luolou group and the tuff of Permian Dalong group- relatively impermeable laye, the Flint limestone of Permian Heshan group- water-rich of weak?medium perched aquifer.2. According to the test results of water samples, the study area groundwater is neutral water, high salinity, total hardness is medium- hard water, this type of groundwater is HCO₃ ? SO₄—Ca type.3. Gangue Leachate for heavy metal pollution on the surrounding groundwater.Specialized water samples tested, according to the test results of heavy metals,since manganese ion, cadmium ion, chromium ion, copper ion concentration is low,so it is not detected; the closer the coal gangue stack area, the more ions are detected, the greater the ion concentration; the zinc ion in most of the water samples detected the highest concentration of 0.783 mg/L, exceeding the national Grade II standard 0.5mg/L.4. Quaternary loose deposits in the study area based on different soil layers are divided into two categories: the surrounding coal gangue stack area within 200 m is silty clay containing gravel, its permeation coefficient is 0.0021 cm/s; other areas is silty clay, its permeation coefficient is 0.000727 cm/s.5. leaching test, the solution was slightly acidic now, the initial leaching, As3 + concentration is relatively high, after little change in concentration; Pb²⁺, Ni²⁺ concentration is low start, but with the continuation of the leaching time of their concentrations continue increase, then gradually stabilized; leach solution in each of the heavy metal ions are faster initial dissolution rate, then slow down; Zn²⁺ is leaching test up to the dissolution of heavy metal ions, exceeding 11.3 times, Pb²⁺ exceeded 16.7 times, Ni²⁺ exceeded 6.7 times, As³⁺ exceeded 10.9 times, Cr⁶⁺ exceeded 2.4 times. Throughout the leaching process, Zn²⁺ of dissolution and dissolution rate than any other heavy metal ions, is most likely to affect the heavy metal elements in the environment. Heavy metal Pb, As, Ni biological toxicity, and the dissolution rate is high, they has a greater impact on the environment.6. heavy metal ion transport simulation and analysis:?1? heavy metal ion transport directions: the migration of ions is mainly affected by the direction of groundwater flow, groundwater is affected by diffusion, the study area is karst formations, groundwater flow faster, to the west of the main gangue leaching of heavy metal ions in the filtrate, the southwest side of migration.?2? heavy metal ion mobility range: heavy metal ion mobility range oval shape, with an area contaminated simulation time increases gradually expanded, becoming circular migration range; runoff due to the impact on the migration rate is greater than the lateral longitudinal range significantly greater than the longitudinal scope of the migration, in the direction of groundwater flow, downstream ion range greater upstream small, basically unchanged. Prediction longer time scales, the affected farm runoff, heavy metals eventually migrate to groundwater discharge zones- Red River.?3? heavy metal ion diffusion in the vertical direction: Different concentrations of heavy metal ions increases over time at a depth gradually increases, the nearer from the ground, the peak concentration of heavy metal ions occurs sooner, the higher the concentration.