Monitoring Of Rural Soil Environmental Quality And Assessment Of Heavy Metal Pollution In Shenyang

Shenyang is a famous old industrial city in China.In recent years,the overall rural soil ecological environment is not good,resulting in the lack of agricultural land environmental quality data.Therefore,the soil pollution in rural areas of Shenyang can not be ignored.Based on the evaluation of soil pollution,40 soil sampling sites in rural areas of Shenyang were collected and analyzed,and the soil physical and chemical properties and heavy metal pollution in the sampling area were monitored,analyzed and evaluated.Physical and chemical properties including: p H,CEC,SOM.heavy metals including: Cd,Hg,As,Cu,Pb,Cr,Zn and Ni.The spatial distribution characteristics of heavy metal pollution were analyzed by Inverse Distance Weight（IDW）interpolation method in Arc GIS,and the correlation analysis,Cluster analysis and principal component analysis were carried out by SPSS 21.0.The single pollution index method,the Nemerow comprehensive pollution index method,the geoaccumulation pollution index method,the potential ecological risk assessment method and the human health risk assessment method were used to evaluate the heavy metal pollution in the sampling area,with a view to improving the rural soil environment in Shenyang.Provide basic data and technical support.Research indicates:In the sampling area,the mean value of soil p H was neutral,soil fertility was at a medium level,and soil nutrient content was at a medium level.There are not only strong correlations among the three physical and chemical properties,but also certain correlations between some physical and chemical properties and some heavy metals.The average content of the eight heavy metals in the sampling area is:Cr（92.034mg/kg）>Zn（48.293mg/kg）>Cu（20.976mg/kg）>Ni（14.108mg/kg）>Pb（12.878mg/kg）>As（6.401mg/kg）>Cd（0.0503mg/kg）>Hg（0.0395mg/kg）,the overstandard rate of the eight heavy metals background values in soil is:Cr（55%）>Cu（40%）>Zn（17.5%）>As（12.5%）=Ni（12.5%）>Hg（10%）=Pb（7.5%）>Cd（2.5%）,Cr（55%）and Cu（40%）exceed the standard of relatively serious.According to the IDW Interpolation of the eight heavy metals,the heavy metal pollution degree in the southeast of Xinmin is relatively large,and the heavy metal pollution degree in the west of Liaozhong is relatively small.Through the source analysis of heavy metal in the sampling area,the heavy metal with large correlation coefficient are Hg-Zn-As,Cu-Cr and Pb-Ni.Cluster analysis can divide heavy metals into three categories,including Cr and Zn and Cd,Hg,As,Pb,Ni,Cu.Finally,through principal component analysis,heavy metals can be divided into three principal components: PC1: Cd,Hg,As,Zn.PC2: Cu,Cr.PC3: Pb,Ni.PC1 can be considered as "chemical fertilizer,pesticide and natural source factor".PC2 can be considered as "industrial emission source factor".PC3 can be considered as "atmospheric sedimentation factor".The results of the single pollution index of heavy metal in the overall sampling area show that the order of soil pollution by eight heavy metals is:Cr（1.596）>Cu（0.854）>Zn（0.807）>Hg（0.790）>As（0.728）>Pb（0.581）>Ni（0.505）>Cd（0.314）.The Nemerow comprehensive index method shows that: The order of soil pollution degree is: Xinmin>Faku>Sujiatun>Liaozhong>Kangping.The index of geoaccumulation method showed that the average level of all heavy metals in the sampling area is 0（no pollution）,and the pollution degree of each heavy metal to soil is in the order of Cr（-0.512）>Cu（-0.963）>Hg（-0.993）>Zn（-1.043）>As（-1.137）>Pb（-1.596）>Ni（-1.899）>Cd（-4.386）.According to the potential ecological risk index method,it can be known that the pollution degree of heavy metal to soil is in the following order: Hg（31.600）> Cd（9.422）> As（7.282）> Cu（4.269）> Cr（3.192）>Pb（2.907）>Ni（2.526）>Zn（0.807）,according to the potential ecological risk index RI of each county,the order of soil pollution degree of each county is:Sujiatun>Xinmin>Faku>Kangping>Liaozhong,all counties and districts are in a state of slight ecological harm.RI values at all points are less than 150,indicating slight ecological harm on the whole.The results of human health risk assessment showed that regardless of adults or children,the main non-carcinogenic and carcinogenic exposure pathways of heavy metal are oral ingestion,and the accumulated non-carcinogenic and carcinogenic exposure pathways are oral ingestion.The size distribution of the noncarcinogenic risk index HQ of each heavy metal to human body is Cr>As>Pb>Ni>Cu>Zn>Hg>Cd,the size distribution of CR for human carcinogenic risk index of each heavy metal is Cr>Ni>As>Cd,under the same exposure pathway,the HI and TCR values of children are greater than that of adults.