College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China.
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China; Hubei Provincial Academy of Eco-Environmental Sciences, Wuhan 430072, China.
Sci Total Environ. 2022 Mar 1;810:152189. doi: 10.1016/j.scitotenv.2021.152189. Epub 2021 Dec 7.
It is challenging to reduce the cadmium (Cd) and arsenic (As) contents of brown rice simultaneously due to their converse chemical behaviors in the paddy soil. Clay minerals, such as sepiolite (SEP), have significant advantages in remediating Cd-contaminated soil. Moreover, iron or manganese oxide loaded SEP can improve the As adsorption efficiency. Herein, ferric nitrate modified sepiolite (NIMS) and iron‑manganese modified sepiolite (FMS) were prepared to study their effects on Cd and As accumulation in rice using pot experiments. The results showed that NIMS and FMS had a larger specific surface area than SEP. The application of SEP only decreased Cd content (by 45%), while NIMS and FMS treatments reduced both Cd (by 57% and 87%) and As (by 30% and 25%) contents in brown rice compared with the control. The X-ray photoelectron spectroscopy (XPS) analysis results indicated that MnO and MnOOH in FMS enhanced the adsorption and co-precipitation of Cd as well as the oxidation of As(III) to As(V). The NIMS, as well as the FMS application, increased soil pH, decreased the exchangeable Cd and non-specifically and specifically adsorbed As fractions in soil, and reduced the level of Cd in the pore water. Moreover, NIMS and FMS addition limited the transfer of As from the soil to the roots by enhancing its sequestration in the iron plaque. On the other hand, FMS treatment significantly promoted the uptake of Mn by rice (P < 0.05). The results suggested that both NIMS and FMS were promising materials for simultaneous reduction of Cd and As accumulation in rice. Notably, FMS had better performance in reducing the Cd content in rice than that of NIMS.
由于在稻田土壤中它们的化学行为相反，因此同时降低糙米中的镉（Cd）和砷（As）含量具有挑战性。粘土矿物，如海泡石（SEP），在修复镉污染土壤方面具有重要优势。此外，负载铁或锰氧化物的 SEP 可以提高 As 的吸附效率。本文制备了硝酸铁改性海泡石（NIMS）和铁锰改性海泡石（FMS），通过盆栽试验研究它们对水稻中 Cd 和 As 积累的影响。结果表明，NIMS 和 FMS 的比表面积大于 SEP。SEP 的应用仅降低了 Cd 含量（降低了 45%），而 NIMS 和 FMS 处理与对照相比，降低了糙米中的 Cd（降低了 57%和 87%）和 As（降低了 30%和 25%）含量。X 射线光电子能谱（XPS）分析结果表明，FMS 中的 MnO 和 MnOOH 增强了 Cd 的吸附和共沉淀以及 As(III)的氧化为 As(V)。NIMS 和 FMS 的应用增加了土壤 pH 值，降低了土壤中可交换 Cd 和非特异性和特异性吸附 As 分数，并降低了孔水中的 Cd 水平。此外，NIMS 和 FMS 的添加通过增强铁斑中的螯合作用限制了 As 从土壤向根系的转移。另一方面，FMS 处理显著促进了水稻对 Mn 的吸收（P < 0.05）。结果表明，NIMS 和 FMS 都是同时降低水稻中 Cd 和 As 积累的有前途的材料。值得注意的是，FMS 在降低稻米中 Cd 含量方面的性能优于 NIMS。
