Based On Gis And Statistical Interpolation Of Spatial Distribution Of Soil Heavy Metals And Pollution Evaluation Research

The soil plays the significant role in the ecological system, because it is the place where mineral, water, air and living beings react to each other. The problem of heavy metal accumulating in the soil has arise public’s attention, because it may create food safety problems which causes potential health risks, and damages land ecological system. This paper takes Zhehai town Huizhe county of Yunnan province which covers about99square kilometers soil areas as the research object. It uses GIS, Geostatistics and statistics to investigate lead, zinc, copper, arsenic, cadmium, chromium, six kinds of heavy metal spatial distribution. At the basic of that, it refers soil environmental quality assessment methods using single factor index method and nemerow comprehensive pollution index method to evaluate heavy metal pollution in the soil. After that, it expresses the result by visualization and analyzes the possible reasons. Main contents are as follows:(1) It found high spatial correlation between Pb and Zn by using statistical method, while it has no correlation between Cr, Cu and other heavy metal elements. Six kinds of heavy metal are divided into four classes through principal component analysis. Classification becomes more clearly using clustering analysis:lead, zinc is the first class, copper as the second class, arsenic and cadmium as the third class, chromium as the fourth class.(2) Analyzing six kind’s heavy metal ratio of nugget and sill using Geostatistical methods, it discovers the ratio of zinc, lead, copper are higher than75%, so random factors plays dominant role in spatial variability, that means anthropogenic activities generate bigger effect in the soil pollution. The ratio of Chromium is between25%and75%, so both the random factors and structural variation cause the spatial variability, that means anthropogenic activities and natural weathering factor together influence the soil, the ratio of Arsenic, cadmium are lower than25%, so structural variation plays dominant role in spatial variability, that means natural weathering factor generates bigger effect in the soil pollution. The lag class distance interval of zinc, lead is close to range, while Copper and Chromium’s lag class distance interval are shorter than range. The anisotropic of Zinc, lead, Chromium are northeast to southwest. The anisotropic of Arsenic, cadmium, copper are east to west. (3) According to the different heavy metal analysis data, it uses ordinary kriging interpolation method to lead, zinc, copper, chromium and inverse distance weight interpolation method to arsenic, cadmium. It uses single pollution index method and nemerow comprehensive pollution index method to evaluate the interpolation of soil heavy metal. From the interpolation diagram of all kinds of heavy metal content, it can see that lead and zinc have all levels contamination. It includes not small severe pollution area, mainly concentrated in the central area; it may have relationship with local lead-zinc mining enterprise which originates in1950s. As to copper and chromium, it is basically no contamination, only few areas are light polluted. As to arsenic and cadmium, it has moderate pollution and few of heavy pollution, which mainly concentrated in the central region.