根瘤菌对紫花苜蓿修复钼污染土壤的强化作用研究

Rhizobia strengthening phytoremediation of molybdenum-contaminated soil by alfalfa

采用温室盆栽试验方法,通过设置4个处理组(M:紫花苜蓿; R_1:根瘤菌(土壤质量的4%); MR_1:根瘤菌R_1+紫花苜蓿; MR_2:根瘤菌R_2(土壤质量的10%)+紫花苜蓿)和一个土壤对照组(CK)对比研究了根瘤菌对紫花苜蓿富集土壤中钼(Mo)的强化作用.结果表明, Mo污染下(500 mg·kg^(-1))根瘤菌促进了紫花苜蓿的生长及其钼富集能力,土壤钼转运系数(TA)和富集因子(BCF)与对照组相比分别提高了30.54%～38.94%及17.45%～19.16%.与对照组相比,各处理组均降低了土壤中钼的含量(0.23%～2.35%),其中根瘤菌紫花苜蓿组合系统修复后的土壤中.钼剩余含量较对照组降低了1.89%～2.35%.根瘤菌一方面促进了重金属钼由水溶态向中间过渡态的转变(0.07%～0.43%),有利于紫花苜蓿对钼的生物富集,同时增大了土壤残渣态钼的比例(0.06%～1.60%),降低了钼对紫花苜蓿的生物毒性.各处理组均提高了钼胁迫下土壤微生物的数量,增强了土壤酶活性.根瘤菌与紫花苜蓿组合修复系统不仅能有效降低土壤重金属钼含量,而且还可以促进土壤微生物生态功能的多样性.因此,该修复技术在重金属钼污染土壤修复工程中具有一定的应用潜力.

Through comparison of four treatment groups(M: alfalfa;R1: rhizobia(4% of soil quality);MR1: rhizobia R1 + alfalfa;MR2: rhizobia R2(10% of soil quality)+ alfalfa) and one soil control group(CK), the uptake of molybdenum(Mo) from soil by alfalfa inoculated with rhizobia was investigated utilizing a greenhouse experiment. The results show that the growth of alfalfa and the accumulation of Mo in plant were enhanced by rhizobia inoculation under Mo pollution(500 mg·kg^-1). Moreover, the transport ability(TA) and the bio-concentration factor(BCF) increased by 30.54%~38.94% and 17.45%~19.16%, respectively. Compared with the control group, Mo contents in soil reduced by 0.23%~2.35% for the treatment groups, particularly in the combined system of rhizobia and alfalfa, reduced by 1.89%~2.35%. Rhizobia, on the one hand, promoted the transition of the molybdenum from the water-soluble state to the intermediate transition state(0.07%~0.43%), which is beneficial to the bioaccumulation of molybdenum by alfalfa. on the other hand, Rhizobia increased the proportion of molybdenum residue state in the soil(0.06%~1.60%), which reduces the biological toxicity of molybdenum to alfalfa. Each treatment group increased the amount of soil microorganisms and enhanced soil enzyme activity under molybdenum stress. The combined repair system of rhizobia and alfalfa can not only effectively reduce the molybdenum content in soil, but also promote the diversity of soil microbial ecological functions. Therefore, this remediation technology has a certain application potential in molybdenum contaminated soil remediation project.