Bacillus halotolerans G20联合生物炭及钾长石对生菜吸收镉和改良土壤的影响

Synergistic effect of Bacillus halotolerans G20 and biochar and K-feldspar on Cd uptake of lettuce and remediation in Cd-contaminated soils

[目的]本文旨在探究细菌与不同钝化剂联合阻控生菜吸收重金属、修复重金属污染土壤的作用。[方法]采集南京市某矿区镉污染土壤为盆栽试验土壤,选用生物炭(B)和钾长石(K)作为钝化剂与镉抗性细菌Bacillus halotolerans G20菌株联合,探究不同处理对生菜(Lactuca sativa L.var.ramosa Hort.)地上部干质量、Cd含量、营养品质和根际土壤pH值、有机质含量、Cd形态变化的影响。[结果]与对照相比,菌株G20、生物炭、钾长石及其固体菌剂均能增加生菜地上部干质量,降低生菜Cd含量。其中,菌株G20与生物炭制备的固体菌剂(G20L+B)使生菜地上部Cd含量显著降低53.1%,降至0.15 mg·kg^-1,低于国家食品安全生产限量标准。该固体菌剂处理还能显著提高生菜根际土壤细菌数量(16.5%)、pH值(0.3)和有机质含量(44.6%),降低根际土壤有效态Cd含量(45.4%),显著增加生菜中维生素C含量(32.9%),降低亚硝酸盐含量(38.8%),减轻Cd对生菜的毒害,提高生菜品质。[结论]B.halotolerans G20与生物炭制备的固体菌剂具有修复中度Cd污染土壤,保障蔬菜安全生产的潜力。

[Objectives]The objective of this study was to explore the role of bacteria and different passivation agents in reducing the heavy metals uptake of vegetables and remediating heavy metal contaminated soil.[Methods]The cadmium-contaminated soil in a mining area in Nanjing was collected as potting test soil.In this pot experiment,biochar(B)and K-feldspar(K)were used as passivators in combination with the cadmium-resistant bacteria Bacillus halotolerans G20 strain to explore the effects of different treatments on the growth,Cd content and quality of lettuce(Lactuca sativa L.var.ramosa Hort.)in Cd-contaminated soil,as well as pH,organic matter content and Cd morphological changes of lettuce rhizosphere soils.[Results]Compared with the control,strain G20,biochar,K-feldspar and their combined bacteria agents could increase the above-ground dry weight and reduce the Cd content of lettuce.Among them,the Cd content in the above-ground tissue of lettuce treated with biochar combined bacteria agent(G20L+B)was significantly reduced by 53.1%to 0.15 mg·kg^-1,which was lower than the national food safety limit.G20+B agent could increase the bacterial count(16.5%),pH value(0.3)and organic matter content of the lettuce rhizosphere soil(44.6%),reduce the effective Cd content(45.4%),reduce the toxicity of Cd to the lettuce,significantly increase the vitamin C content in the lettuce(32.9%),and reduce nitrite content(38.8%).[Conclusions]The biochar combined B.halotolerans G20 bacteria agent had the potential to repair moderately Cd-contaminated soil and to ensure the safe production of vegetables.