Study On The Distribution And Pollution Of Heavy Metal Content In Soil Of Chang'an Shaoling

Soil heavy metal pollution cause many serious problem on human health,this investigation have practically significant.In order to find out content and spatial distribution of heavy metal and the level of soil pollution,this paper choose two loess-palesol profiles,which are 3 metres deep,(Contains the top of the first layer of the loess)and 15 surface soil sample sites,we collected 220 soil samples.The content of heavy metal elements and major elements in soil is analyzed by the X-Ray Fluorescence Spectrometry,the soil granularity is analyzed by Laser Particle Size Analyzer,the pH values,electrical conductivity(EC),magnetic susceptibility are measured by other related instruments.According to the experiment information,we deeply studied temporal variations of soil heavy metal content in Shaoling tableland,the source of heavy metals and influence factor.We assess the strength of the soil heavy metal pollution by using single factor index evaluation method,Nemerow multi-factor index method and potential ecological risk index.The main conclusion gained are as follows:(1)The average value of pH of surface soil in Shaoling tableland is 7.89,the range of pH is 5.9?8.9,it belong to the partial alkaline soil.The particle size distribution of two profile is characterized by generally the content of coarse silt is most,followed by clay,fine silt and very fine sand,fine sand with the least content.(2)Ki,CIA,Na/K present varied regular change in the profile of Sifu and West Yangwarn,we determine the weakest regolith(2.5?3m)by chemical weathering coefficient.(3)The content of heavy metals element present varied regular change with stratification of loess-palesol.The content of heavy metals are higher in the Holocene paleosol S0 than The Holocene loess L0 and Malan loess Li.(4)Using ArcGIS as the tool of data processing,the spatial distribution of heavy metals are investigated in surface soil of Shaoling tableland.The spatial distribution of Cu,Ni and Zn is similar with many points of plaque and uneven distribution.The spatial distribution of Cr,Mn and Pb is similar with Cu,which show high content in the southeast,low content in northwest.The spatial distribution of As and Co is much more dispersed.(5)Based on Shaanxi soil background values as reference value,the assessment results of single factor index show that single factor index of As,Cu and Mn are the highest,followed by Pb,Ni,Co and Cr,Zn with the least.Except for Zn,all of heavy metals are light pollution appearances.The results of Nemerow Pollution Index(Pn)and Potential Ecological Risk Index(RI)show that among all the sampling sites are Light pollution and low-pollution level,respectively.Based on the content of heavy metals in the weakest regolith as reference value,the assessment results of single factor index showed that single factor index of Pb is the highest,followed by Cu,Co and Mn,Ni,As and Cr is lower,Zn with the least.The Pn and RI show that among all the sampling sites are Light pollution and low-pollution level,respectively.(6)Eight kinds of heavy metal elements in soil of Shaoling tableland can be divided into three categories.The first part is the As,Ni and Zn,mainly comes from natural factors,followed by human activities,including atmospheric deposition,agricultural and industrial pollution.The second part is Co,Mn and Cr,which comes from natural factors,followed by human activities.The third part is Cu and Pb,which main source affected by Traffic pollution.The main reason caused different distribution in the content of heavy meals is orchard and agricultural fertilization.The main reason caused different content of heavy meals between two profiles is the depth of argillic horizon.(7)Most of heavy metal element enriched in the Holocene paleosol because paleosol developed argillic horizon,the content of clay is high and the clay can be used to adsorb heavy mental element.