The Study On The Spatial Distribution And Pollution Assessment Of Heavy Metal Elements In Soil Of Tongling Area Based On GIS

The heavy metal elements pollution is the important factor that breaks the soil environment and endanger to the human body health directly or indirectly. Tongling is the main mineral industry city in China, and the environmental pollution is very serious in Tongling. The exploitation and smelting of metals deposit such as copper, gold and so on, have become the important heavy metals pollution source of the soil in Tongling area.This paper studies the spatial distribution of heavy metal elements based on GIS in the soil of Tongling area where the heavy metal pollution is more serious, and assesses the pollution degree. First, the background content of heavy metal elements in soil are calculated based on Hazen probability curve in Tongling area. The calculations are consistent with the actual situation, the meaning of the causes of the parameters is clear and in line with the objective reality.The pollution degree of heavy metal elements in soil is assessed by Index of Geoaccumulation, Potential Ecological Risk Index, Sediment Enrichment Factor, Fuzzy theory and Pollution Load Index. Assessment identifies Cd, Pb, As are the primary heavy metal elements that cause the pollution. The pollution of Zn, Cu, Mn is close to the deposits. Hg and T1 content in the soil is not high, but the pollution is also existent because of its high biological toxicity.The spatial distribution characteristics of heavy metal elements in the soil of Tongling area are studied using geostatistics method and MAPGIS software. The calculations of variogram commendably explain the spatial structures of the heavy metal elements distribution. The location and scope of pollution area can be showed visually on isopleth map plotted by GIS software. Content distribution isopleth map and assessement isopleth map show that the location of pollution area is basically the same, but assessment isopleth map describes the pollution area more elaborately.The spatial characteristics of relative environmental capacity of the soil are reflected visually using MAPGIS software and a mathematical model. The research shows that the relative environmental capacity of the soil in Tongling area is at the middle level, the quality of environmental geochemistry general is common. The relative environmental capacity of As and Pb elements is high, but the relative environmental capacity of Cd elements is very low. The results show that the main cause of the spatial characteristics of relative environmental capacity of elements is the natural separation of elements, moreoverthe impact of human factors is exist.The factors of pollution impact are analysed based on the study of the spatial distribution characteristics of heavy metal elements in the soil of Tongling area. The pollution of As, Cd, Pb, Zn elements is mainly caused by deposits, and the pollution of Hg is mainly caused by enterprises and towns. The study indicates that water as a large carrier of pollution is one of the reasons for large-scale pollution. In addition, the efficiency of different methods of assessment is validated based on the factor analysis of pollution impact. The applicability of assessment methods to different elements has been found.