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To accurately assess the risks of metal contaminants in soil,the bioavailability of the metals need to be considered.Huize country,a typical region contaminated by mining activities,was selected as a case study area.The total concentrations and chemical speciation of heavy metals in agricultural and non-agricultural soil around a Pb–Zn mine were analyzed.The pollution index of the heavy metals indices for As,Cd,Cr,Cu,Hg,Pb,and Zn of non-agricultural soil and agricultural soils in the study area,showed that the highest level of pollution is distributed near and around a Pb–Zn mine.Principal component analysis(PCA)and cluster analysis(CA)have been also applied to understand the relationships among the heavy metals responsible for pollution in the research area.The modi?ed BCR(three steps)sequential extraction method was applied to evaluate the mobility and bioavailability of the heavy metals in 68 representative samples of the study area.The mobility and bioavailability of the metals,based on the mean values of the relative abundance of the sums of the ?rst three fractions,are in the following order: Cd(57.0%)> Zn(43.1%)> Cu(42.2%)> Ni(35.7%)> Pb(33.3%)> As(25.6%)> Cr(23.2%)> Hg(6.2%).The risks of heavy metals are also evaluated by risk indexes(RI),and risk assessment code(RAC),respectively.According to RAC,Cd poses very high risk to the ecosystem due to its higher toxicity and percentage in the exchangeable and carbonate fractions.Hg and Zn pose a high risk.The overall risks levels of heavy metals are in the declining order of Cd > Hg > Zn > As > Pb > Cu > Ni > Cr.Calculated environmental risk index also reveal a considerable-high ecological risk in study area.The overall RI in agricultural and none-agricultural caused by the toxic heavy metals range from 29.3-262.5 and 113.3-959.7,respectively,indicating some sites where the mining activities are concentrated presents high degree potential ecological risk.The comparison results of risk values of heavy metals based on different methods show that there are several disagreements,because the total concentration,chemical speciation and toxic response factor of individual heavy metal were considered together in one method.Therefore,the improvement of ecological risk assessment of heavy metals in future should be carried out quickly.