In order to systematically study the heavy metal pollution status,ecological risks and sources of heavy metal pollution in farmland soils in the suburbs of Luozhuang District,Linyi City.Soil samples were collected from 81 sampling units.Ten elements including Ti,Zn,Cr,Ni,Pb,Cu,As,Tl,Cd,Hg were measured and analyzed.And the spatial variation level,pollution degree and ecological risk level of soil heavy metals in the study area were evaluated by the methods of coefficient of variation,single factor index,geo-accumulation index and comprehensive potential ecological risk index,respectively.Pollution sources of soil heavy metal were analyzed by the method of principal component analysis.The results were as follows,(1)the average mass fractions of Ti,Zn,Cr,Ni,Pb,Cu,As,Tl,Cd and Hg in suburban farmland soils were 3 730,53,55,25,22,17.1,7.20,0.39,0.14,0.043 mg·kg-1,respectively.Compared to the soil background value in Linyi city,the average mass fractions of Ti,Zn,Cr,Ni,Pb,Cu and Tl were lower,the average mass fractions of As,Cd and Hg were higher.However,the average mass fractions of every metal were lower than the risk screening value.(2)The variation coefficients of Hg and Cd were both higher than 50%,indicating that they were more widely affected by external activities.But the spatial variation levels of Pb,Cu,Ti and Tl were moderate,which were less affected by external activities.(3)Overall,the pollution levels of every metal in the study area were all pollution-free.However,in some areas where Hg was severely enriched.(4)The ecological risk results showed that the comprehensive ecological risk level of all sampling points in the study area was low risk.However,the potential ecological risk of single-factor pollution of the Hg was at medium risk level,and the potential ecological risk levels of single-factor pollution of the other 9 elements were all considered as low risk.(5)The results of principal component analysis revealed three main sources of pollution:Tl,As,Zn,Cu,Ti,Cr and Ni in the farmland soil of the study area were mainly influenced by natural geological background sources.Cd and Hg were mainly derived from industrial and agricultural production emissions,and Pb was primarily derived from transportation activities emissions.
关键词
重金属污染/生态风险/农田土壤/来源
Key words
heavy metal pollution/ecological risk/farmland soil/source