| City developments drive economic and social development, but on the other hand also cause pollution and damage to the city environment. As an important element city environment, soil is also the major pollution sink of the city. Human action bring large amount of heavy metal pollutants to the soil environment and cause them to accumulate in the soil. The pollutants threaten human health through atmosphere and water body in a direct or indirect way. Therefore, the pollution of soil heavy metal pollution becomes the core of the study of the city environmental pollution problem.Harbin is the capital city of Heilongjiang Province, it is located at east of Songnen Plain, the right bank of Songhua river, it is the political, economic, cultural and transportation center of Heilongjiang Province and the core heavy industry base of Harbin-Daqin-Qiqihar industry corridor. With the increasing speed of economic development and industrialization, the environment of the city stands out. According to 1:250,000 multi-purpose geochemistry investigation data, the heavy metal content in soil environment of Harbin is relative high, especially Cd,Hg,Pb,which have abnormally high concentration in city proper and suburb areas.The ecological geochemical study on soil heavy metal pollution is abundant abroad, but most of the study focus solely on city soil heavy metal pollution or spatial heterogeneity, neglect the internal relation of overall pollution and spatial characteristics of soil heavy metal pollution, few focus on combined research of macro-level evaluation and micro-level analysis. Currently, there is no systemic research focuses on ecological geochemical study on soil heavy metal pollution.Therefore, study on degree of city top-level soil heavy metal pollution, spatial characteristics of heterogeneity, spatial distribution pattern and the source of pollution in Harbin are carried out supported by Geochemical evaluation of regional ecology in Heilongjiang province project, according to the current status and data collected by laboratory test of heavy metal (such as Hg,Pb,Cr,Cd) pollution in soil of Harbin, following the principle of geo-statistics,theory of spatial heterogeneity and statistics, using GIS spatial analysis tools and spatial analysis technology such as GS+,SPSS, combining the method of potential ecology threatening index and pollution load index. Combining macro-level evaluation and micro-level analysis, the soil heavy metal pollution status in Harbin is collected. Following are the areas that are covered in the research:The Potential Ecology Threatening Index (PETI) and Pollution Load Index (PLI) are combined to evaluate the four heavy metal pollution comprehensively. PETI shows that the heavy metal pollution load in Harbin city proper have shown trends of deterioration; PLI shows that potential threaten level has reached medium level.Combining the results showed by PETI and PLI, the heavy metal pollution in Harbin top-level soil is serious, due to the high toxicity of Hg and Cd, the potential damage is high, and contributes a lot to the heavy metal pollution threaten in the area. Comparing the spatial distribution plot of PETI and PLI, it is clear that PETI and PLI are deteriorating in particular region of Harbin, and most of them are concentrated at south Daowai District, north Nangang District and Xiangfang District and middle and north-eastern of Daolin District, where south-west wind is dominant.The anomaly value of heavy metal pollution data was eliminated using regional recognition method. The normal distribution of data was check by K-S test and histogram in spatial statistics module in ArcMap. GS+7.0 geo-statistical software were used to converging experimental variogram and theoretical model, calculating parameters and drawing the variogram. Based on the analysis, spatial heterogeneity theory based on geo-statistics was used to analyze the characteristics of spatial structure of heavy metal concentration in top-level soil in Harbin. Results showed that Hg,Cd,Pb and Cr are medium level correlated, means that the spatial heterogeneity is the combined result of random and structural factors. The range of Hg,Cd and Pb are relative the same, all close to the sampling points, shows that they are influenced by human actions. It is probably due to the fact that Hg,Cd and Pb concentration are more liable to human actions. The conclusion here is consistent with the conclusion derived from the macro-level evaluation that the pollution load of Hg and Cd are serious and contribute a lot to the heavy metal ecological damage of Harbin.Combining the analysis of spatial structure and spatial analysis function of GIS, the distribution of heavy metal pollution are visualized using normal kriging and inverse distance kriging. The spatial distribution map generated by GIS shows that the concentration of Hg and Cd is continuous in top-level soil while that of Pb and Cr shows the pattern of arc islands.From the spatial distribution plot, areas that have high Cr concentration are mainly located in middle and ease part of Nangang District, and then in middle and south part of Xiangfang, as well as northwest part of Pingfang; areas with high Pb concentration are mainly located at middle and north part of Daowai Distribt, Xiangfang District and Nangang District; areas with high Cd concentration are mainly located at Daowai District, middle and north Daolin District, north part of Pingfang; areas with high Hg concentration are mainly located at south part of Daowai District/ north Daoli District, north Nangang District, north Xiangfang District. Analyzed with distribution of industry, it shows that the pollution pattern is highly related with industry distribution, and consistent with the visualization result that polluted areasStudy on the relationships of the four heavy metal, the result shows that Cd and Pb are highly correlated, the source of pollution is consistent; the top-level soil of Harbin have been polluted in a compound way. In view of build-up areas and environment, the source is analyzed, and counter measures are put forward. The unique feature and innovation of the research is to combine the PETI and PLI method to determine the potential threat and pollution load of heavy metal in Harbin, give play to the complementary characteristics of the two method, improved the results for heavy metal evaluation, broadened the point of view and train of thought; combined the spatial theory of heterogeneity and spatial analysis function of GIS; combined the region pollution status and soil heavy metal spatial characteristics, combined macro and micro level, to carried out study on distribution on spatial heterogeneity and pollution degree, and made precise estimation on the spatial distribution of soil heavy metal distribution.Overall, this paper combined the pollution and ecological threaten,macro and micro level to reveal the current status of heavy metal pollution in Harbin, provided visualizing of pollution distribution, carried out research on heavy metal pollution degree and spatial heterogeneity, put forward advice on how to prevent heavy metal pollution. Provided scientific foundation for decision-making departments to formulate environmental recovery and protect policy. The study is important for the recovering and protection of soil environment in Harbin, the sustainable development of social economics and stabilize human health. The research method can apply to other similar studies and applications to improve the technical progress. Therefore has important realistic and theoretical importance, and worth to further investigate. |
PDF Full Text Request