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为揭示赤泥条件下水稻(Oryza sativa L.)根表和根际铁膜形成及铁膜中重金属(Fe、Mn和Cd)分布与水稻镉(Cd)吸收的潜在关系,本文采用盆栽试验,即在2和5 mg·kg-1两种镉浓度条件下,试验设置0%、0.5%和1%3个梯度的赤泥施用量,利用根际袋法系统研究了赤泥对水稻(浙优12号)根表和根际铁膜的形成及重金属(Fe、Mn、Cd)分布特征,探讨了赤泥条件下水稻根际效应对水稻Cd吸收转运及生物量的影响。研究结果表明,赤泥显著增加了水稻的株高、根干重、秸秆干重和籽粒重;显著降低了供试水稻根部Cd浓度、秸秆Cd和籽粒Cd的浓度,下降幅度分别为23.6%~40.2%,20.1%~48.8%和45.5%~103%;显著提高了水稻根表和根际铁膜中Fe、Mn和Cd的浓度(P<0.05),且随赤泥施用量的增加而增加。水稻根表铁膜中Fe、Mn和Cd浓度提高幅度分别为64.5%~107%、13.9%~43.7%和20.8%~69.9%;水稻根际铁膜中Fe、Mn和Cd提高幅度分别为93.8%~206%,20.1%~42.2%和17.3%~111%。与对照处理相比,添加赤泥土壤的p H值提高程度均达到显著水平(P<0.05),DTPA提取态镉含量分别降低17.9%~47.9%和26.3%~48.6%。水稻根表和根际铁膜中Cd浓度与水稻根Cd浓度、秸秆Cd浓度、籽粒Cd浓度、根表和根际铁膜中的Fe浓度和Mn浓度呈显著正相关(P<0.05)。结论:赤泥的添加促进了水稻的生长,且其富含铁氧化物的特性还可以促进水稻根表和根际铁膜的形成,通过铁膜中的Fe和Mn对Cd富集作用来减少水稻秸秆和籽粒对Cd的吸收。因此,利用富含铁氧化物的赤泥作为钝化材料修复中低度Cd污染稻田有望达到较好的修复和利用效果。
In order to reveal the potential relationship between the formation of iron film on the surface and rhizosphere of rice (Oryza sativa L.) and the distribution of heavy metals (Fe, Mn and Cd) in the iron film and the Cd uptake in rice under red mud conditions, That is, the red mud application rates of 0%, 0.5% and 1% of 3 gradients were set at 2 and 5 mg · kg-1 cadmium concentrations. The rhizosphere bag method was used to study the effects of red mud on rice You 12), and the distribution of heavy metals (Fe, Mn and Cd) in roots and rhizosphere, and the effects of rhizospheric rice rhizosphere on the absorption and transportation of Cd and the biomass of rice under red mud conditions. The results showed that the red mud significantly increased the plant height, dry root weight, dry weight of straw and grain weight of rice, and significantly reduced the concentrations of Cd, Cd and Cd in roots of test rice, which decreased by 23.6% 40.2%, 20.1% -48.8% and 45.5% -103% respectively. The concentrations of Fe, Mn and Cd in root and rhizosphere of rice were significantly increased (P <0.05), and increased with the increase of red mud . The concentration of Fe, Mn and Cd in the root surface of rice increased by 64.5% -107%, 13.9% -43.7% and 20.8% -69.9%, respectively. The increase of Fe, Mn and Cd in the rhizosphere of rice was 93.8 % ~ 206%, 20.1% ~ 42.2% and 17.3% ~ 111%. Compared with the control, the pH value of red soil added significantly increased (P <0.05), and the Cd content in DTPA decreased by 17.9% -47.9% and 26.3% -48.6%, respectively. The concentration of Cd in root and rhizosphere of rice was significantly and positively correlated with Cd concentration in rice roots, Cd concentration in straw, Cd concentration in roots, Fe concentration in root and rhizosphere, and Mn concentration (P <0.05). CONCLUSION: The addition of red mud promoted the growth of rice, and its iron-rich characteristics also promoted the formation of iron film on rice root and rhizosphere, and decreased the accumulation of Cd by Fe and Mn in the iron film Absorption of Cd by Rice Straw and Grain. Therefore, the use of iron oxide-rich red mud as a passivation material to repair low and medium Cd contaminated rice is expected to achieve better recovery and utilization.