生物炭对设施栽培土壤重金属Cd形态变化的影响

Effect of Biochar on Heavy Metal Cd Morphologic Change in Greenhouse Field

设施栽培土壤重金属Cd污染问题备受关注,为阐明生物炭对设施栽培土壤重金属Cd污染的修复效果,试验设置B0（0 t/hm2）、B10（10 t/hm2）和B20（20 t/hm2）3个生物炭水平,研究施用生物炭对土壤Cd形态、生物有效性以及含量的影响。结果表明：生物炭施用显著增加土壤p H和有机质含量,改变了土壤Cd的形态分布,氧化态、有机结合态和残渣态含量增加,交换态Cd含量显著降低。随着生物炭施用量的增加,土壤固定Cd的速率会增加,土壤中有效态Cd的含量发生变化,与对照相比,B10降低土壤有效态Cd 45%~62%,而B20可降低66%~89%。另外,试验还表明,生物炭对Cd污染较轻的大棚土壤有效态Cd的固定效果要好于Cd污染严重的大棚土壤。因此,生物炭可以改变大棚土壤Cd形态,降低土壤Cd的生物有效性,但对受Cd污染严重的设施栽培土壤的修复效果不好。

Heavy metal Cd pollution in greenhouse soil is of great concern.In order to study the remediationeffect of biochar on heavy metal Cd in greenhouse soil,three levels of biochar application amount B0（0 t/hm2）,B10（10 t/hm2） and B20（20 t/hm2） were designed,the effects of biochar on Cd form,bioavailability and contentwere studied.The results showed that the application of biochar significantly increased soil p H and soil organicmatter,changed Cd form distribution,and increased the oxidation state,organic-bound state and residual formCd content,decreased exchangeable Cd content significantly.The rates of Cd immobilization in soil increasedwith the increase of biochar application amount,the effective state Cd content changed,compared with that ofCK,effective state Cd content of B10 decreased by 45%-62% and that of B20 decreased by 66%-89%.Inaddition,the immobilization effect of biochar in low heavy-metal-contaminated greenhouse soil was betterthan that of high heavy-metal-contaminated greenhouse soil.Therefore,the application of biochar couldchange Cd form in greenhouse soil,reduce Cd bioavailability,but had little effect on high heavy-metal-contaminated soil.