洛阳市硒高背景区农田土壤重金属形态特征及影响因素研究OA

Speciation analysis of heavy metals was conducted on 38 farmland soil samples from the high selenium background area of the Yiluo River Basin,Luoyang City.The results show that the speciation composition of each element is basically consistent across different soil types and geological units.The residual fractions of As,Zn,Cu,Hg and Pb all account for more than 50%of the total contents.Cd has the highest proportion of mobile fractions,reaching 39.92%,indicating it is a potentially high-risk element.Pb is mainly present in the iron-manganese oxide fraction.Correlation analysis between elemental speciation and total contents shows that the humic acid-bound,iron-manganese oxide-bound,strongly organic-bound and residual fractions of all elements are significantly positively correlated with their total contents.The water-soluble,ion-exchangeable and carbonate-bound fractions of Cu and Cd,as well as the carbonate-bound fractions of Pb and Zn,are also significantly positively correlated with their total contents.Soil organic matter and pH exert significant influences on the total contents and speciation of heavy metals.Soil organic matter has no significant correlation with total As and its residual fraction,residual Cd,or carbonate-bound Pb,but is positively correlated with other fractions and total contents.Soil pH is significantly negatively correlated with the water-soluble and ion-exchangeable fractions of Pb and Zn,and negatively correlated with the water-soluble fractions of Cd and Cu.In contrast,pH is significantly positively correlated with the water-soluble,ion-exchangeable,carbonate-bound,humic acid-bound and iron-manganese oxide-bound fractions of As.