Current Situation Analysis And Evaluation On Heavy Metal Pollution For The Soil Around Chang-an Landfill Site

The municipal solid waste (MSW) is mainly disposed through sanitary landfill, incineration, compost and many other ways, among which the Sanitary landfill is the uppermost one in China. It is true that sanitary landfill has destroyed the environment and brought a series of environment problems and potential risks, which however, has rarely been reported. Given this, this paper takes the soils around Chang-an Landfill site as study samples and get a preliminary understanding of the content level and spatial distribution of Cu, Pb, Zn and Cr in the soils around Chang-an Landfill site by setting and analyzing these samples. It also made a systematic evaluation of the heavy metal pollution for the soils around Chang-an Landfill site by the means of Single Pollution Index, Nemerow Composite Pollution Index and Potential Ecological Risk Index. The main conclusions are as follows.(1) The pH value of the surface soil ranges from7.574to8.490and the average value is8.003, which belongs to basic soil. The average level of Cu, Pb, Zn and Cr takes up354%,287%,200%and104%of the soil environmental quality standards value respectively;(2) The levels of Cu, Pb, Zn and Cr reduced with the increasing of the distance away from landfill site in horizontal direction and the deepening of soil-extracting in vertical direction. Thus there are correlations between the distance and each level of Cu, Pb and Zn, and the coefficients are-0.524**,-0.554**and-0.654**respectively, while the distance and the level of Cr are not significantly related. And when it comes to direction, the level of the heavy metals around Chang-an landfill site keeps higher in northeast than that in northwest.(3) The levels of Cu, Pb, Zn and Cr are closely related to the land use types and the levels of other heavy metals. As far as land use types, the level of the4heavy metals reduces in the turn of Bare land> Road>Artificial grassland>Natural grassland. As for the level of other heavy metals, there are positive correlations between each level of Cu, Pb and Zn.(4) By the means of Single Pollution Index, it showed that8.33%of the samples were slightly polluted by Cu,10%were slightly polluted by Pb,6.67%were moderately polluted by Zn and28.33%were slightly polluted by Zn as well. It was also found that25%of the samples were polluted by heavy metal through Nemerow Composite Pollution Index.(5) Tested by Potential Ecological Risk Index, we found that the Single Pollution Potential Ecological Risk Index of Cu, Pb, Zn and Cr kept in the soils around Chang-an Landfill site were level I, which means a low degree of hazard; And the total Potential Ecological Risk Index (RI) was level I that stands for a low degree of hazard.(6) According to the analysis of the soil pollution around Chang-an Landfill site, we preliminary judged that the heavy metal pollution in this area is not caused by Chang-an Landfill site, but very likely for the human activities around it. So given this, we put forward3eco-countermeasures namely establishing the standardization process of refuse transportation and loading and unloading, planting roadside shelterbelt and perfecting phytoremediation measures.