Remediation of heavy metal polluted agricultural soil is essential for human health and ecological safety and remediation mechanisms at the microscopic level are vital for their large-scale utilization. In this study, natural sepiolite was employed as an immobilization agent for in situ field-scale remediation of Cd-contaminated paddy soil and the remediation mechanisms were investigated in terms of soil chemistry and plant physiology. Natural sepiolite had a significant immobilization effect for bioavailable Cd contents in paddy soil, and consequently could lower the Cd concentrations of brown rice, husk, straw, and roots of rice plants by 54.7–73.7%, 44.0–62.5%, 26.5–67.2%, and 36.7–46.7%, respectively. Regarding soil chemistry, natural sepiolite increased the soil pH values and shifted the zeta potentials of soil particles to be more negative, enhancing the fixation or sorption of Cd on soil particles, and resulted in the reduction of HCl and DTPA extractable Cd concentrations in paddy soil. Natural sepiolite neither enhanced nor inhibited iron plaques on the rice root surface, but did change the chemical environments of Fe and S in rice root. Natural sepiolite improved the activities of antioxidant enzymes and enhanced the total antioxidant capacity to alleviate the stress of Cd. It also promotes the synthesis of GSH and NPT to complete the detoxification. In general, the remediation mechanisms of natural sepiolite for the Cd pollutant in paddy soil could be summarized as the collective effects of soil chemistry and plant physiology.

中文翻译：

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天然海泡石对镉污染土壤的田间修复机制

污染重金属污染的农业土壤的修复对人类健康和生态安全至关重要，微观层面的修复机制对其大规模利用至关重要。在这项研究中，天然海泡石被用作原位固定剂从土壤化学和植物生理学的角度研究了镉污染的水稻土的田间修复及修复机理。天然海泡石对水稻土中可利用的Cd含量具有显着的固定作用，因此可以使糙米，稻壳，稻草和稻草根部的Cd浓度降低54.7–73.7％，44.0–62.5％，26.5–67.2％ ，分别为36.7–46.7％。在土壤化学方面，天然海泡石提高了土壤的pH值并使土壤颗粒的zeta电位更负，从而增强了Cd在土壤颗粒上的固定或吸附，并降低了水稻土中HCl和DTPA可提取Cd的浓度。 。天然海泡石既不增强也不抑制稻根表面的铁斑，但是确实改变了水稻根中铁和硫的化学环境。天然海泡石提高了抗氧化酶的活性，增强了总抗氧化能力，从而减轻了镉的胁迫。它还促进了GSH和NPT的合成以完成排毒。总体而言，天然海泡石对水稻土中Cd污染物的修复机理可以归结为土壤化学和植物生理的共同作用。