Spatial Analysis And Pollution Evaluation Of Heavy Metals In Contaminated Flow From Soil-water Interfaces In Manganese Mine Area

In the process of industrialization, human demand for mineral resources is growing. In the development and utilization of mineral resources, not only destroyed the local ecological environment, but also caused a lot of environmental problems. The mining activities generally go through some stages such as mining, dressing and refining, each stage will produce solid, liquid or gaseous waste which contained various heavy metal elements. Due to the improper discharge of mining residue and tailings and the unreasonable emit of waste gas and water, resulted in the destruction of the ecological environment and serious heavy metal pollution problem in mining areas, which seriously threaten the health of the residents in mining areas.In the study,43contaminated flow water samples were collected from2.6km2area surround the Hongqi mining area in Xiangtan Manganese mine area in Xiangtan city, Hunan province. The pollution characteristics、spatial structure features、distributing rules and pollution assessments of six heavy metals Mn、Cu、Ni、Zn、Pb、Cd and their main influence factors were researched using geostatistics combined with GIS. The results as follows:1. The differences between the maximum and minimum values of six heavy metals concentrations were larger. The variable coefficients of six heavy metals concentrations were greater than0.7, which showed that the degree of dispersion of six heavy metals concentrations were greater. The complexity of geological environment as well as the human activities, transportation, industrial production and other factors in manganese mine area increased the regional differences in the concentrations of six heavy metals.2. The result of correlation analysis indicated that the correlation between Mn-Ni, Mn-Zn, Mn-Pb, Cu-Zn, Cu-Pb, Zn-Cd were more significant. The result of principal component analysis indicated that the first principal component have comparatively obvious positive correlation with6kinds of heavy metals. Ni has good positive correlation with three principal components, indicating that the source of Ni is very widely.3. The result of spatial structures analysis showed that in addition to Ni, the semivariogram theoretical models of Mn、Ni、Cu、Zn、Pb were well fitted. The determination coefficients of six semivariogram theoretical models ranged from0.540to0.895.The ratio of nugget and sill of six heavy metals were less than0.4, which indicated that six heavy metals all have strong spatial correlation.4. The result of spatial distribution of six heavy metals Mn、Cu、Ni、 Zn、Pb、Cd showed that tailings waste, pools which formed by leachate and smelter are the main sources of heavy metals in the contaminated flow from soil-water interfaces in the study area. Moreover, dressing plant, waste residues, abandoned private mining hole, sewage irrigation and ore spatter in transport are the important sources of heavy metals in the contaminated flow from soil-water interfaces in the study area.5. The result of pollution evaluation of six heavy metals Mn、Cu、Ni、 Zn、Pb、Cd demonstrated that Cd pollution was heavier in the contaminated flow in manganese mine area, followed by Mn and Pb pollution, and Zn, Cu, Ni pollution were lighter.