Characterization of Surface Heavy Metal Content and Ecological Risk Evaluation of Representative Iron Tailing Ponds in Eastern Hebei Province
Eastern Hebei Province is an important distribution area of sedimentary metamorphic iron ore(BIF)in Chi-na,but the study on the content characteristics and migration pattern of heavy metals in its tailings is relatively weak.In this paper,the horizontal and vertical spatial content changes of heavy metals in tailings were investigated based on the content and variation characteristics of heavy metal elements Pb,Cr,Cd,Cu,Zn,As,Hg and Ni,using samples from the Yanshan and No.2 tailings ponds of Sijiaying Iron Mine of Hebei Iron and Steel Group,a representative BIF-type iron ore mine in China as the study object.Based on this,the heavy metal pollution characteristics and ecological risks of the tailings ponds were evaluated by using the single factor pollution index method,the Nemero integrated pollution index method and the potential ecological risk index method.The results showe that:① the content of elemental Cr,Cu,Ni and Cd in some points of Sijiaying Yanshan tail-ings pond exceeded the background value;the content of elemental Cu,Cr and Pb in some points of Sijiaying No.2 tailings pond exceeded the background value;and the heavy metal forms in the two tailings ponds were mainly Fe-Mn oxide-binding state and residue state,and the effective state of heavy metals accounted for a higher percentage.② In the vertical direction,the heavy metals in the two tailing ponds showed a trend of migration from the surface layer to the subsurface layer;in the hori-zontal direction,the total heavy metals in different areas of the two tailing ponds showed a trend of migration to the pond.③ The single-factor and Nemero pollution indices show that the pollution level of heavy metals in Sijiaying Yanshan tailings pond is ranked as Cd>Ni>Cu>Cr,which is in light pollution;the pollution level of heavy metals in Sijiaying No.2 tailings pond is ranked as Cu>Cr>Ni>Pb,with Cu as medium pollution,Cr as light pollution,Ni and Pb as alert level.The potential ecologi-cal risk index indicates that the potential ecological risk index RI of both tailings ponds is a mild ecological hazard level.Over-all,there is a certain risk of heavy metal pollution in the iron tailings in the area,and dynamic monitoring and ecological resto-ration treatment should be strengthened to stop further heavy metal pollution.
iron tailings pondheavy metalscontent characteristicsecological risk assessment
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