生物炭对城郊农业土壤镉有效性及镉形态的影响

Effects of Biochar on Availability and Speciation of Cadmium(Ⅱ) in Suburb Agricultural Soil

为探索生物炭对镉污染土壤的钝化效果,采用室内培养的方法,研究了低镉(镉含量1.86 mg/kg)及高镉(镉含量6.55mg/kg)土壤条件下生物炭对土壤有效态镉及不同形态镉分布的影响。研究结果表明:至培养末期,添加生物炭显著降低了2种镉条件下土壤有效态镉含量,低镉及高镉条件下降幅分别达到4.31%和6.82%。生物炭添加对短期及较长期内不同形态镉含量均会产生影响。在培养初期,2种镉条件下添加生物炭均使可交换态镉含量显著下降(P<0.05),铁锰氧化物结合态镉及残渣态镉含量上升,且后者上升显著(P<0.05)。在培养末期,生物炭的添加减少了2种镉条件下可交换态和有机物及硫化物结合态镉含量,提高了碳酸盐结合态及残渣态镉含量,且低镉条件下各形态镉含量的变化均有显著差异。该实验数据表明,生物炭与土壤的有效结合降低了重金属镉的有效态含量,其迁移性和生物有效性得以控制,生物炭对土壤重金属镉具有显著的钝化作用,在土壤重金属镉污染治理方面有着巨大潜力。

Effects of biochar added to soil contaminated by Cd in order to immobilize Cd ions in soil were studied,so that a laboratory cultivation experiment was conducted to examine the content of available Cd and the its speciation and distribution by adding biochar to soil samples with two levels of cadmium content respectively,i.e.,low cadmium content 1.864 mg/kg;high cadmium 6.551 mg/kg. Findings of the experiment showed that the available Cd content was significantly reduced at the end of the cultivation under the condition of both levels of cadmium content,and biochar could impact Cd speciation and distribution in terms of both of short term and long term;in the initial cultivation,compared with non-biochar treatment,biochar treatment notably reduced exchangeable Cd（P〈0.05）, while Fe-Mn oxides-bound Cd and residual Cd was increased,and residual Cd is notably increased（P0.05）under the condition of both high and low levels of Cd content. On the other hand,at the end of the cultivation biochar reduced exchangeable Cd and organic-bound Cd,and increased carbonate-bound Cd and residual Cd. In general,effective combination of biochar and soil could decrease the available content of cadmium,and its mobility and bioavailability could be brought under control.