西宁市不同功能区土壤重金属铬和镍的形态研究

Chemical Forms of Heavy Metals Cr and Ni in Soils from Different Functional Zones of Xining City

采取Tessier连续提取法对西宁市6个功能区城市土壤中重金属Cr和Ni的形态进行研究。结果表明,西宁市各功能区土壤中Cr和Ni的全量分别是全国土壤几何平均值的2.6～3.2,1.3～2.1倍。各功能区Cr的含量均无显著差异(P>0.05);Ni的含量表现出矿冶区与风景区和开发区差异显著(P<0.05),但与其他功能区差异不显著(P>0.05),并且除矿冶区外其他功能区间也均无显著差异(P>0.05)。Cr的各形态分布趋势为:残渣态>铁锰氧化物结合态>有机结合态>可交换态>碳酸盐结合态;Ni的各形态分布趋势为:残渣态>铁锰氧化物结合态>有机结合态>碳酸盐结合态>可交换态。重金属Cr为:不可利用态>潜在可利用态>可利用态;重金属Ni为:潜在可利用态>不可利用态>可利用态。研究表明土壤中重金属Cr和Ni的生物有效性和潜在生态危害性较大。

Chemical forms of Cr and Ni in soils from 6 kinds of functional zones in Xining city were characterized using Tessier sequential extraction procedure. Results showed that mean total content of Cr and Ni in the soils were 2.6 to 3.2, 1.3 to 2.1 times of the mean value of their national background respectively. The content of Cr in 6 kinds functional zones had no significant difference（P〉0.05）; and the content of Ni in metallurgy zone was significantly different from that of scenic zone and newly developed zone（P〈O.05）, but was not significantly different from other functional areas（P〉O.05）; and that between other functional areas had no significant difference（P〉O.05） except metallurgy zone. Distribution trend for forms of Cr was residual form〉Fe-Mn oxide form〉organic form〉exchangeable form〉carbonate bound form, and distribution trend for forms Ni was residual form〉Fe-Mn oxide form〉organic form〉carbonate bound form〉exchangeable form. Bioavailability of Cr was unavail- able form〉 potential available form 〉 available form, and of Ni was potential available form 〉 unavailable form 〉 available form. Heavy metal Cr and Ni in the soils had high bioavailability and potential ecological risks.