The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distrib...The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distribution of heavy metals in the calcareous tufa collected from the mining laneway of the Qixiashan Pb-Zn Mine in Nanjing were investigated by using multiple mineralogical techniques.Examination by X-ray diffraction spectrum(XRD) shows that calcite is the major compo-nent of the calcareous tufa.Several heavy metals such as Mn,Zn,Mg,Fe and Pb are detected in calcite by means of electron microprobe analysis.Although the heavy metal contents in the hostrock and the formation water are significantly low,the contents of Mn,Zn,Mg,Fe and Pb in the tufa calcite are as high as 23.65 wt%,9.6 wt%,0.76 wt%,4.44 wt% and 0.66 wt%,respectively.The back-scattered electron image shows complex compositional zoning texture in the tufa,which is linked directly to varia-tions in heavy metals,particularly in Mn and Zn.In addition,we also observed floccule and helical precipitations,which may be derived from the metabolism of the microbe.It is deduced that the occurrence and high concentration of heavy metals in tufa may be controlled by the activities of microbes.The results presented in this work suggest that calcite will be an important candidate for the remediation of the heavy metal contamination in mining areas.展开更多
基金Supported by National Basic Research Program of China (Grant No.2007CB815603)National Natural Science Foundation of China (Grant No.40573001)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No.20050284044)
文摘The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distribution of heavy metals in the calcareous tufa collected from the mining laneway of the Qixiashan Pb-Zn Mine in Nanjing were investigated by using multiple mineralogical techniques.Examination by X-ray diffraction spectrum(XRD) shows that calcite is the major compo-nent of the calcareous tufa.Several heavy metals such as Mn,Zn,Mg,Fe and Pb are detected in calcite by means of electron microprobe analysis.Although the heavy metal contents in the hostrock and the formation water are significantly low,the contents of Mn,Zn,Mg,Fe and Pb in the tufa calcite are as high as 23.65 wt%,9.6 wt%,0.76 wt%,4.44 wt% and 0.66 wt%,respectively.The back-scattered electron image shows complex compositional zoning texture in the tufa,which is linked directly to varia-tions in heavy metals,particularly in Mn and Zn.In addition,we also observed floccule and helical precipitations,which may be derived from the metabolism of the microbe.It is deduced that the occurrence and high concentration of heavy metals in tufa may be controlled by the activities of microbes.The results presented in this work suggest that calcite will be an important candidate for the remediation of the heavy metal contamination in mining areas.
