| Heavy metal pollution of vegetable soil will affect the quality and edible safety of agricultural products and endanger human health.At present,there are few sduty on heavy metal pollution in soil-vegetable system of vegetable field in Guilin.Therefore,it is of great significance to study the distribution and risk assessment of heavy metal pollution in the soil-vegetable system of vegetable fields in Guilin.In this paper,through field investigation and sampling,the distribution and pollution characteristics of Pb,Zn,Cd,As,Sb,Hg,Cr and Cu content in vegetable soil and vegetables in main areas of Guilin City were studied,and pollution assessment was made,and source analysis of heavy metals in vegetable soil and vegetables system was conducted.Based on the correlation analysis between vegetable soil and roots,stems and leaves,the law of heavy metal migration and accumulation between soil and vegetables was expounded.In view of the current situation of heavy metal pollution in vegetable soil in Guilin,the prevention and control suggestions were put forward.The main progress and understanding of this paper are as follows:(1)Compared with the background value of Guangxi soil,the concentration coefficient from high to low was Sb(2.91)>Cd(2.67)& gt;Pb(1.32)& gt;Zinc(1.09)& gt;Hg(1.02)& gt;Cu(0.84)& gt;Cr(0.45)& gt;As(0.36).The mean contents of Pb,Cd,As,Hg and Cr in edible parts(stems and leaves)of vegetables were 0.088mg/kg,0.023mg/kg,0.015mg/kg,0.009mg/kg and 0.355mg/kg,respectively,which were not exceeded compared with the national standard limit value.(2)Cluster analysis and factor analysis showed that the combinations of heavy metals in soil and vegetables were similar,which were Pb,Zn,Cd,As,Sb and Hg.Cr and Cu,two groups of elements representing different sources.(3)The spatial distribution of heavy metal content in vegetable soil and vegetables is similar.The high concentrations of Pb,Zn,Cd,As,Sb and Hg were located in Pengjialing and northeast Qixing Park,and the spatial distribution characteristics were higher in the city center and lower in the suburbs,showing a unipeak distribution.The high concentrations of Cr and Cu are found in the Reed Dizi Rock and the southern part of the mountain.The spatial distribution features are high in the west and low in the east,and high in the south and low in the north,showing a bimodal distribution.(4)The analysis of the representative heavy metal elements showed that Zn,As and Hg accounted for the highest residual state;The proportion of Pb reducible state is the highest.Cd has the highest proportion of weak acid.Among them,Pb and Cd have higher potential harm.(5)According to the enrichment coefficient and transport coefficient,there were differences in the accumulation ability of vegetable plants to different heavy metals,among which,the accumulation ability of Sb and Cd was stronger.The enrichment degree of heavy metals in vegetable plants was in the order of root > leaf > stem.The transport coefficients of heavy metals from different parts of vegetables were as follows: leaves > stems.(6)According to the national standard evaluation method and ground accumulation index method,Cd,Zn,Pb,Sb and Cu in vegetable soil all show pollution.Among them,Cd and Sb pollution is relatively serious;According to the potential ecological risk assessment,there are strong risk samples of soil Cd and Sb,but the proportion of samples is less than10%,which are mainly distributed in Pengjialing and northeast Qixing Park.(7)According to the evaluation of single factor pollution index and Nemerow pollution index,the pollution degree of different parts of vegetables mainly concentrated in no-light pollution,and the pollution degree of each part was in the order of root > leaf > stem from high to low.There were heavy pollution spots of vegetables,but the proportion was relatively small,mainly distributed in the northeast of Qixing Park,Pengjialing and the north of Chuanshan. |
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