Pollution Assessement And Prediction Of Heavy Metals In Soil Based On Geostatistics And GIS

The heavy metals pollution is the most important factor that breaks the soil environment. Besides, it endangers human health directly or indirectly. Based on Geostatistic method and GIS, this paper carried out a series of studies on Hg, Pb, Cd, As, Zn, Cu, Ni and Cr in soil of a developed city in south of China. First, the spatial distribution of heavy metals in the soil was studied; Second, a series of pollution assessment on the heavy metals were performed; Third, quantitative analyses on the factors influencing the pollution were provided; Last, the heavy metals concentration of studied area in 2020 were predicted. The main work are as following:(1) The spatial distribution characteristics of heavy metals were quantitatively described using geostatistical methods. The testing variograms of the eight elements completely matched theoretical structure. The Semivariogram of the heavy metals exhibited obvious nugget effects and isotropy. The study suggests that the spatial distribution of Hg, Cd and As might be affected by anthropogenic activities, while others affected mainly by parent soil materials in their ranges and anthropogenic activities out of the ranges.(2) Index of Nemero, Index of Geoaccumulation, Pollution Load Index and Potential Ecological Risk Index were used to study the anthropogenic pollution comprehensively. Conclusion shows that there is anthropogenic pollution in different levels on the metals, of which Hg, Cd, Pb, As are the primary elements causing the pollution. Besides, there is potential ecological hazard with Hg, Cd, Pb, As, of which Hg and Cd are the highest. The location and scope of pollution area can be showed visually on interpolation maps finished through geostatistic method and GIS software.(3) Based on statistical method and spatial analysis of GIS, The quantitative analysis on the factors of pollution impact suggests that the pollution of Hg, Pb, Cd and As is mainly caused by enterprises which also are connected with the locations seriously polluted.Meanwhile, the study indicates that water as a large carrier of pollution is one of the reasons for large-scale pollution.(4)Based on the Heavy Metals Cumulated Prediction Model, the heavy metals concentration of studied area in 2020 were predicted in three scene(optimistic scene, unmutation scene and pessimistic scene). The results show that the concentration will decrease in optimistic scene; However, both the concentration and over-standard area in Hg, Pb, Cd, As will significantly increase in 2020, which will increase more quickly in pessimistic scene than in unmutation scene.