Fraction distribution and risk assessment of soil heavy metals in Anxin—Qingyuan County in Baoding of Hebei

In order to reveal chemical forms and its potential ecological risk of soil heavy metals( Cd,Cu,Pb,Zn) in Anxin-Qingyuan County in Baoding of Hebei Province,37 soil samples were collected to determine total contents and chemical speciation of heavy metals. Potential ecological risk assessment was performed based on the total amount and different forms of heavy metal in soil. The bioavailability of heavy metals,including the directly available state Cbio,the potentially available state C_(Pbio)and the non-use state CNbio,were combined with the Hakanson potential ecological risk index method to construct a comprehensive evaluation of soil heavy metal pollution risk model using different weight factors. The results show that Cbioratio of heavy metals followed the order: Cd Pb Cu Zn,C_(Pbio)ratio: Pb Cu Zn Cd,and CNbioratio: Zn Cu Pb Cd. The average values of the ecological risk index obtained by the bioavailability metal-form method were identical to those of the Hakanson method. Risk distribution map directly shows the similarity of the distribution of the evaluation results. Since the chemical speciation of the potential ecological risk index takes into account the total amount of heavy metals and the bioavailability of chemical speciation,it would be more reasonable compared to those with the Hakanson method,which only considers the total amount of heavy metals.