Species distribution and geochemical modeling of antimony in the Qinlong antimony mining area
The speciation of antimony(Sb)in the soils of a smelter and the surrounding areas in the antimony mining area of Qinglong,Guizhou Province was investigated.It was found that the smelter soils were severely contaminated by Sb,with the highest content reaching 31265 mg·kg-1,while the Sb contents in the downstream soil decreased rapidly to less than 100 mg·kg-1 with increasing distance.The main Sb-bearing compounds were identified by XRD and XPS to be pentavalent calcium antimonate(Ca2Sb2O7),potassium antimonate(K3Sb5O14)and antimony oxide(Sb2O5).Sequential extraction experiments showed that besides the residue fraction,the co-precipitation with carbonate and ferric oxides was the main species of Sb in soils at the smelter area,while the strongly adsorbed fractions were significantly higher in the downstream soils,indicating that the Sb mobility increased in the transport process.A geochemical multi-surface speciation model(MSM)for Sb in soil was developed with HFO and goethite as the main active surfaces.When Sb extracted with 1 mol·L-1 Na2HPO4 was used as the total available Sb in the model,the model could successfully predict the dissolved Sb in soils with different properties and contamination levels(RMSE=0.29),indicating that the model offers a promising tool for assessing the ecological and leaching risks of Sb in contaminated soils around Sb smelters.
Sbantimony mining soilspeciationavailable speciesmulti-surface speciation model
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