生物炭和油菜幼苗对土壤重金属镉污染的钝化效应

Passivation Effect of Biochar on Soil Cadmium Pollution and Rape Growth

为探讨生物炭和油菜幼苗对南疆地区土壤重金属镉(Cd)污染的修复技术,以黄油菜、黑油菜和印度芥菜为供试材料,设置生物炭添加量的质量分数分别为0%(T0)、2%(T2)、4%(T4)、6%(T6)、8%(T8)共5个处理,分析不同处理的土壤理化性质和Cd形态、幼苗生物量和Cd在各部位富集转运,研究添加生物炭对Cd胁迫下油菜幼苗生长和Cd积累的影响。结果表明,随着生物炭添加量增加,土壤pH、有机质含量及油菜生物量(干重)均显著提升;同时活性较高的可交换态Cd的含量逐渐降低,不易被作物吸收的碳酸盐结合态Cd、铁锰氧化物结合态Cd、有机质及硫化物Cd含量逐渐上升;当土壤Cd含量一定时,Cd活性指数逐渐降低,T8处理的钝化效果最显著;生物炭有效降低油菜根部Cd的富集系数和地上部转运系数,8%的生物炭施用量效果最佳。在不同生物炭处理下,黄油菜土壤pH、有机质含量、油菜生物量及Cd的形态变化、根富集系数、地上部转运系数的响应效果最佳。总体来看,8%的生物炭施用量的钝化效果和油菜生长特性最佳,且黄油菜对生物炭处理的响应效果最好。通过添加生物炭,可有效缓解南疆地区重金属Cd对油菜幼苗生长的影响,结果为南疆地区油菜栽培提供技术理论支撑。

In order to explore the remediation technology of biochar and rape seedlings for heavy metal cadmium(Cd)contamination of soil in the southern border area,the yellow rape,black rape and Indian mustard(Brassica juncea)were used as test materials,the mass fraction of biochar addition was set as 0%(T0),2%(T2),4%(T4),6%(T6)and 8%(T8),respectively.The effects of biochar addition on the growth and Cd accumulation of rapeseed seedlings under cadmium(Cd)stress were elucidated by measuring and analyzing the soil physicochemical properties and Cd morphology,seedling biomass and enrichment transport of each site in different treatments.The results showed that the pH,organic matter content and oilseed rape biomass(dry weight)in the soil increased significantly with the increase of biochar addition;meanwhile,the content of the more active exchangeable Cd gradually decreased,and the content of carbonate-bound Cd,Fe-Mn oxide-bound Cd,organic matter and sulfide Cd,which were not easily absorbed by the crop,gradually increased.When the soil Cd content was certain,the Cd activity index decreased gradually,and the passivation effect of T8 treatment was the most significant.Biochar effectively reduced the root enrichment coefficient and above-ground transport coefficient of rapeseed,and the best effect was achieved with 8% biochar application.The best response effects of pH,organic matter content,rapeseed biomass,Cd morphology changes and root enrichment coefficient and above-ground transport coefficient in yellow rape soil were observed under different biochar treatments.Overall,the best passivation effect and growth characteristics of rapeseed were selected for 8% biochar application,and yellow rape showed the best response to biochar treatment.By adding biochar,the heavy metal Cd was effectively mitigated on the growth of rape seedlings in South Xinjiang region,which provided technical and theoretical support for oilseed rape cultivation in South Xinjiang region.