Characteristics And Quality Assessment Of Heavy Metal Content In Soil-Kiwi

Pollution-free agricultural products and a variety of green food have become more and more popular with the public.Excessive heavy metal content will cause soil pollution,reducing fruit quality,what's more,being harmful to human health.In recent years,the planting scale of kiwi fruit in Guizhou Province expands unceasingly.But the basic work such as the monitoring of heavy metal content in the soil is relatively backward.Therefore,In this paper,the heav-y metal content of the soil in the typical planting base of Guizhou Province was determined.Then,this paper carries out the assessment of heavy metal pollution in the soil,analyzes the potential risk of soil heavy metal pollution and explores the enrichment ability of heavy metals in the plants and fruits of kiwi fruit,in order to provide basic data and scientific basis for the production of h-igh quality kiwi fruit.Through field investigation,sampling and experimental analysis,this paper tests the content of heavy metals such as Ni,Cu,Zn,Pb,Cd,Cr,Hg and As,and uses SPSS 19.0's analysis functions——the Principal component analysis,Multidimensional Scaling analysis,and Pearson correlation analysis to analyze and process data.The main results were as follows:(1)The content of heavy metals in the soil of the planting base of the kiwi is mainly influenced by the"exogenous factors".The accumulative contribution rate of these three principal components of Xiuwen base's heavy metals in the soil reach 77.3%,the first,second and third principal component variance contribution ratio respectively 33.3%,29.6%,14.476%.Taking PCl as "external factors",mainly due t-o human interference control,Zn/Pb/As in a larger load,Cr,Ni,Cu in the second principal component has a higher load level,taking PC2 as "natural source factor"with the background values of soil are related and Cd in the third principal component positive load maximum.In the process of production and management,should pay attention to reduce the heavy metal elements Cr,Cu,Zn input,especially heavy metals Zn.Shuicheng base of heavy metals in the soil of three principal components of the accumulative contribution rate reached 86.1%,the first,second and third principal component variance contribution ratio respectively 39.5%,30.7%,15.9%.The first principal component as "natural source factor",and local soil background value relations,Cd,Pb and As in a larger load,Cr,Ni,Zn in the second principal component has a higher load level,as "external factors",subject to the control of human activities,Cu in the third principal component positive load maximum.In the production management process should pay attention to prevent the input of heavy metals Cr,Cu,Zn,Duge kiwifruit planting base to prevent Ni input.Xiuwen and Shuicheng kiwifruit planting base content of heavy metals in soil and general characteristics:three principal components of the accumulative contribution rate reached 76.2%,rate of the variance contribution of the first principal component for 46.0%,Cd,Pb,Ni,Cu in the first principal component had bigger load and four heavy metal elements content at the 0.01 level showed significant positive correlation,Cr in the second principal component have a higher load level,the second principal component's contribution to the variance of rate to 16.9%and the variance contribution of the third principal component was 13.3%.The first principal component as the "natural source factor",and the soil background value is related,the second principal component as "exogenous factor",by the human activity control.The background value of heavy metal content in the soil of the planting base of the kiwi fruit is high,and its environmental capacity is limited,so it is necessary to control the amount of exogenous heavy metals in the soil.(2)The environment of heavy metals in soil is basically safe in kiwi pla-nting bases.In the national soil environment quality secondary standard evaluation results showed that Xiuwen base of the heavy metal elements of single factor pollution index are below the warning line;Nemerow pollution index size show that Cr/Cu/Zn/Pb/Hg at a safe level.Ni/Cd/As is in the level of light pollution;ecological risk index of single pollution and potential ecological risk index(RI)were lower,the soil is low risk of injury level.Shuicheng kiwi fruit base soil Cd,Cu and Ni have varying degrees of pollution and other elements are in below the warning line;except CD for heavier risk grade,the remaining 7 kinds of heavy metals are in low level of risk.The evaluation results of the soil background values of Guizhou province showed that the Cd pollution was relatively light,and the other 7 kinds of heavy metal elements showed different degrees of pollution.The accumulation of evaluation index method,Xiuwen base soil based on the national secondary standard of soil environment of Cu,Pb,Hg in clean level;individual points of Cr,Zn,as,Ni in the level of light pollution.Based on the soil background value of Guizhou Province,the accumulation index of Cd was less than 1,which was not affected by pollution.With the integrated Application of these 4 methods,the results show that:i-n the background value of soil in Guizhou province,the content of Cd is high,but not reaching the pollution level.However,the other 7 kinds of heavy metal in Xiuwen and Shuicheng bases are both proved to reach the pollution level.So In order to protect the quality of kiwi fruit,the amount of exogenous heavy metals which is inputted to the soil should be controlled.(3)Different parts of the kiwi has significant differences in the ability of enriching heavy metals,the sequence of heavy metals enrichment coefficient is "stem>leaf>fruit".The heavy metal contents of kiwi fruit are lower than the allowable value of national standard.Different varieties of kiwi fruit stem and leaf of heavy metal enrichment coefficients is less than 1,the enrichment coefficient of stem size followed by Chuanmi>Guichang>Miliang>wild Guichang,the enrichment coefficient of leaf by Chuanmi>Miliang>Guichang>Hongxin>wild Guichang;Five kinds of heavy metal enrichment of the kiwi fruit coefficients is less than 0.05,the enrichment coefficient values for:Guichang>Hongxin>Wild Guichang>Chuanmi>Miliang.