The Study Of Heavy Metal Pollution Of Articultural Soils And Crops Of Tongguan Shaanxi Province

Tongguan， Shaanxi Province was found to suffer the influence of mining activity.Mining brought not only economic benefit but also heavy metal contamination. For the sakeof the remediation of the polluted farmland soils and crops in Tongguan， The contaminationstatus of Hg， Cd， Pb， Cu， Zn and As in both farmland and main crops wheat and cornwas investigated in this article. Besides， Hg， Cd and Pb concentrations in the wild superiorplants in Tongguan were also measured. The results were as followed.(1)Heavy metal concentration in the tail slag were very high.Hg， Cd， Pb， Cu and Znexceeded the standards to different extent，which indicated that farmland soils， water and airin Tongguan were very likely to be polluted by heavy metals in the tail slag.(2)83.6%of farmland soils were polluted to different extent， mainly by Hg， Cd andPb，30.6%of which were severely polluted. The potential ecological risk factor potentialecological risk factor of Hg was largest，followed by the potential ecological risk factor Cdand Pb. The soils with moderate， high or very high values of potential ecological risk indexwere55.1%， the soils with low values of potential ecological risk index were44.9%.Overall， the farmland of Tongguan were severely polluted， of which the pollution of Hg ismost serious.(3)The soils with low values of potential ecological risk index mainly occurred innorthwest and east， the soils with moderate values of potential ecological risk index weremainly distributed in the middle and south and the soils with high and very high values ofpotential ecological risk index were primarily located in the south.(4)Crops were also mainly polluted by Hg， Cd and Pb， which exceeded the standardby39.1%，39.1%and47.8%in wheat and44.4%，33.3%and33.3%in corn， respectively.(5)Oil crops were also polluted by Hg， Cd and Pb， which exceeded the standard by60.0%，20.0%and60.0%in oil sunflower. Hg and Pb exceeded the standard by66.7%and100%in rapeseed， while Cd in rapeseed was within the standard.(6)The correlation analysis between metal concentration in farmland soils and crops wasconducted and a significant correlation between the Hg in wheat and corn and the Hg in soilwas revealed. And a significant correlation between the Cd in rapeseed and the Cd in soil was revealed as well.(7)The spatial distribution of the Hg， Cd and Pb in wheat and corn indicated that thearea where Hg and Pb in wheat were higher was overlapped partially with the area where Hgand Pb in soils were higher.(8)The pollution status of other crops indicated that the pollution status of leaf vegetablescrops was most severe， followed by the pollution status of seasoner crops. Medicinal cropswere only polluted by Hg. Rhizome crops， fruit vegetable crops， legume crops， fruit andoil crops were barely polluted.(9)The Hg， Cd and Pb concentrations in wild superior plants in Tongguan indicated thatenrichment factors of Hg and Pb of Conyz Canadensis were largest and it was likely to beused in phytoremediation. Further study was needed to ensure that.