The Spatial Distribution Characteristics Of Heavy Metals In Soil And Evaluation Of Pollution In Shijiazhuang

Soil, an important safeguard for agricultural production, the repository ofbiological and chemical substances circulating in the earth, is one of the necessaryresources for human survival and development, which is sensitive to environmentalchanges extremely.With the development of China’s industrialization and urbanization,the increasing strength of environmental exploitation year by year, the amount ofoutside pollution in soil has also increased year by year, especially in industrialproduction, transportation, a lot of contaminants from human life falling into the soil,which cause numerous environmental pollution incidents and the consequences havean irreversible trend. The concerns about accumulation of soil heavy metal pollution andhazards should be important works in environmental protection.Taking Shijiazhuang City as the research object, I select10kinds of heavy metalelements including As, Cd, Co, Cr, Mn, Cu, Ni, Pb, V and Zn to make an analysis andtest. I use single factor index and Nemerow index to analyze the condition of heavymetal pollution and then I use potential ecological risk index to evaluate the potentialecological hazards of heavy metals and reveal the spatial distribution of soil heavymetals in Shijiazhuang City, which are expected to provide scientific basis for thespatial distribution pattern of soil heavy metals, the soil environmental qualityassessment and sustainable development of urban ecological environment,environmental management, land use planning and soil heavy metal pollutionprevention in Shijiazhuang City. The main results are as follows:(1) The spatial distribution characteristics of surface soil heavy metals shows thathigh values of Cd, Cr, As, Cu, Pb and Zn are point-like or multi-island distribution,which is disturbed by human strongly; high values of Cu and Pb elements appear inthe southern freight yard of Shijiazhuang nearby, which is disturbed by humanrelatively strong; high values of Ni, V, Mn and Co are all point-like distribution,which is also disturbed by human factors. From the point of spatial distributionpattern view, I can come to the conclusion that the content of heavy metals inindustrial enterprise nearby regions especially near the Development Zone and the Second Ring Road of Northeast Zone are generally higher than other regions.(2) The distribution characteristics of heavy metals in the soil profiles overallshows that the content of each element decreases with the increase of depth. In thedevelopment zone, the elements of Cd, Cr, Pb and Zn all show large distance ofvertical migration; the elements of As, Mn, Ni and V migrating in the soil profile arenot obvious and the content of each soil profiles is lower than background values; themigration distance of Cu element soil profile in the park is relatively large; themaximum value of Co element soil profile presents on15-30cm level.(3) Comprehensive evaluation of soil contamination shows that the soil is in aclean level when pollution index is less than0.7by the minimum value assessment;the soil is in serious pollution level when pollution index P>3by the maximum valueassessment;the soil is light pollution level when pollution index in1<P≤2range bythe average assessment.(4) Single factor ecological risk assessment results that the situation of Cdpollution is not optimistic, which presents that the observation points basically aremore moderate ecological hazard areas and only few scattered mild ecological hazardareas; Cu, Cr, Co, Pb, Zn, As, V, Mn and Ni elements are slightly ecological hazardlevel, the differences between these factors distribution are that Cu, Cr and Co havethe diffusion trend from point to planar areas; the part areas of Pb, Zn and As haveplanar polluted areas; the pollution situations of V, Mn and Ni are available controland human disturbance factor is small.(5) Comprehensive ecological risk assessment concludes that the integratedpotential ecological risk index of soil is larger in the second Ring Northeast roads anddevelopment zone in the study areas where have appeared150≤RI <300moderateecological hazard areas and other regions are minor ecological hazard areas, whilemore than50%of these areas are near the moderate ecological hazard areas that cannot be ignored.The distribution pattern of ecological risk assessment has a goodconsistency with the spatial distribution of heavy metals.