为探索不同材料(纳米铁、猪骨炭和牛骨炭)对砷污染土壤的钝化效果,从中筛选有效的砷污染土壤钝化剂,采用室内模拟培养的方法,研究了三种物质对两种不同砷含量红壤中砷化学形态及其有效性的影响。结果表明:添加纳米铁显著(P〈0.05)降低了两种红壤有效态砷含量,同时土壤pH显著降低,当培养试验结束时(84 d),在板页岩红壤和石灰岩红壤中有效态砷含量分别降低了10.5%、11.43%,pH则比同期对照各降低了0.18、0.23个单位,纳米铁对红壤砷的钝化作用与土壤非专性吸附态砷向残渣态砷等转化过程有关;猪骨炭的加入导致两种不同砷含量红壤中有效砷含量均不同程度的提高,板页岩红壤和石灰岩红壤增幅分别为16.21%、1.36%;牛骨炭的加入对中度污染(113.3 mg·kg^-1)的石灰岩红壤表现出一定的固定性能,也可降低pH而改良碱性土壤,促进了该土壤中活性砷向残渣态砷的转化。将纳米铁用于钝化污染土壤中的活性砷,牛骨炭用于固定中度污染石灰岩发育的红壤中的砷,均具有一定的应用前景。
Chemical stabilization is an option of in situ remediation of heavy metal contaminated soils. The effectiveness of this technique is dependent on the chemical stabilizers. A laboratory incubation experiment was conducted to examine the effects of three materials, including nano-iron, pig bone char and cow bone char on chemical forms and availability of arsenic in two different red soils(slate and limestone red soil)with different arsenic contents. After 84 days of incubation, addition of nano-iron significantly reduced soil available arsenic contents by 10.5% and 11.43%, and pH value by 0.18 and 0.23 unit, respectively, in slate red soil and limestone red soil, and the stabilization of arsenic by nano-iron may be connected with the transformation from non-specifically sorbed phase to residual one. However, the addition of pig bone char led to an increase of available arsenic by 16.21% in slate red soil and 1.36% in limestone soil. Applying cow bone char to limestone red soil showed stabilizing effect on arsenic by promoting the transformation of soil arsenic from available to residual form, improving soil quality. The results suggest that nano-iron material shows great prospect in stabilizing arsenic in soils and that cow bone char could be used for immobilization of arsenic in limestone red soil.