西宁市不同功能区土壤重金属含量及形态研究

采取化学分析和Tessier连续提取法,对西宁市6个功能区城市土壤重金属Cu、Zn、Pb和Cd的含量及形态进行研究。结果表明:西宁市各功能区土壤的Cu、Zn、Pb和Cd的全量分别是全国土壤相应重金属几何平均值的1.9~5.2,1.9~6.9,0.8~4.0,7.4~11.1倍,4种重金属污染比较严重。6个功能区的重金属Cu、Zn、Pb和Cd含量进行差异显著性分析,结果是广场区Cu的含量与风景区的差异不显著(P>0.05),但与其他4个功能区差异显著(P<0.05);风景区与开发区差异显著(P<0.05),但与其他4个功能区差异不显著(P>0.05);开发区Zn的含量与商业区和居民区的差异显著(P<0.05),而其他各功能区间差异均不显著(P>0.05);各功能区Pb和Cd的含量均无显著差异(P>0.05)。研究土壤中重金属的化学形态有较大的差异,Cu以残渣态和有机结合态为主;Zn以残渣态和铁锰氧化物结合态为主;Pb和Cd以残渣态为主。Cu活性相对较高的土壤出现在风景区、矿冶区和居民区,Zn活性相对较高的土壤出现在风景区和广场区,Pb活性相对较高的土壤出现在风景区和居民区,Cd活性相对较高的土壤出现在矿冶区和开发区,研究土壤中4种重金属均具有一定的生物有效性和潜在的生态危害性。

Contents and Chemical Forms of Heavy Metals in Soils From Different Functional Zones of Xining City

The contents and chemical forms of Cu,Zn,Pb and Cd in soils from 6 kinds functional zones of Xining city were characterized using Tessier sequential extraction procedure.Results showed that mean total contents of Cu,Zn,Pb and Cd in the soils were 1.9-5.2,1.9-6.9,0.8-4.0,7.4-11.1 times of the mean values of their national background,respectively.The soils had seriously been polluted by Cu,Zn,Pb and Cd.The contents of Cu,Zn,Pb and Cd in 6 kinds functional zones have been analyzed the significant difference.Results showed that mean the contents of Cu in square zone and scenic zone had no significant difference(P> 0.05),but had significant difference(P<0.05) with the other functional areas.And the contents of Cu in scenic zone and newly developed zone had significant difference(P<0.05),but had no significant difference(P>0.05) with the other functional areas.The contents of Zn in newly developed zone with business zone and residential zone had significant difference(P<0.05),but between each functional area had no significant difference(P> 0.05).The contents of Pb and Cd in 6 kinds functional zones had no significant difference(P>0.05).There was considerable difference in distribution of different forms of heavy metals in soils.Cu existed mainly in organic state and residual state.Zn existed mainly in residual state and Fe-Mn oxide form.Pb and Cd existed mainly in residual state.Cu activity was relatively high in the soils from scenic,metallurgy and residential zones.Zn activity was relatively high in the soils from scenic and square zones.Pb activity was relatively high in the soils from scenic and residential zones.Cd activity was relatively high in the soils from metallurgy and newly developed zones.The results above indicated that Cu,Zn,Pb and Cd in the soils had high bioavailability and potential ecological risks.