Analysis On Characteristics,Risks,and Management Countermeasures Of Soil Contamination By Heavy Metals In Mining Area,Oasis,and Their Ecotone Of Baiyin

Because of the huge health and ecological risks,more and more attentions have been paid to soil heavy metal pollution in the past few years,people also begin to focus on the researches about the domain,in such a case,comprehensively analyzing the pollution is fairly crucial.Research zone which consists of oasis,mine zone and their ecotone was to the east of Dongdagou in Baiyin.Analyzing the pollution of soil and crop,assessing the ecological and health risk of the pollution and making a doable plan to control the risk is the theme of this research,here are some remarkable conclusions:(1)The sequence of pollution extent in research zones is: oasis > ecotone > mine zone.Among the four heavy metals researched,the sequence of pollution extent is:Cd > Pb > Cu > Zn.According to China’s risk control standard for soil contamination of agricultural land,the research zone is not suitable for agriculture anymore,its utilization is needed to be switched.(2)There is huge differences between fractions’ ratio of Cd and Pb.But there are considerable amount of Fe-Mn oxide form of Cd and Pb.When soil physicochemical properties change,it’s highly possible that the Fe-Mn oxide form will transform to more exchangeable forms,which should be paid adequate attention.(3)Ecological risk and health risk in the research zone is very high.Potential ecological risk of the soil in research zone is 16146.86,which is of very high ecological risk.Among the heavy metals,Cd has the biggest ecological risk,followed by Pb,while Cu and Zn has low ecological risks.For health risk,both the carcinogenic and non-carcinogenic risks of the soil in the study area exceeded the acceptable range,Cd has the biggest carcinogenic risk while Pb has the biggest non-carcinogenic risks of soil.For the crop in the zone,it also has health risk which threatens children more than adults.(4)Ecotone and mine zone can be transformed to second development land with strict control on the emission of trace metal.While oasis is not suitable for human-being anymore,control and remediation are needed to reduce the risk.(5)Given the reality of this region,phytomanagement is chosen to control the risk of oasis soil.According to the research of native plants,nitraria and elm were found suitable to survive in oasis with the ability to remediate the trace metal in soil.To sum up,the research zone is highly polluted by trace metal,soil and crop in the zone have high levels of ecological risk and health risk;main source of the trace is the irrigation by wasted-water which needs to be strictly controlled in future;and elm can be essential when remediating the trace metal polluted soil.Hope this research can be helpful to the further planning and development of this region.