土壤中氧化锰形态转化对Cd和Sb生物有效性影响

Manganese oxides significantly affect the migration and transformation of heavy meals in soils because of their high surface area and high reactive activity. There are many kinds of manganese oxide in soil, and the physicochemical properties of manganese oxide are different with each other, which result in different sorption capacity of heavy metal. In this proposal, Cd and Sb are selected as the typical cationic and anionic heavy metals. The mainline of the research is "Manganese Oxide – Cd/Sb - Adsorption Mechanism – Oxidation/Reduction Dissolution - Risk Assessment". Combined with macroscopic adsorption and absorption processes and micro-molecular mechanism studies, adsorption mechanism of Cd and Sb on manganese oxides will be explored by in-situ EXAFS, XPS technique and DFT simulation, and the effect of pH, dissolved oxygen, Mn(II) and organic matter on the adsorption of Cd and Sb on manganese oxides will be also studied. Based on the indoor culture experiment, the effect of oxidation and reduction of manganese on the adsorption of heavy metals by manganese oxides will be conducted. The effects mechanism of exogenous manganese oxide on the uptake of heavy metals by rice will be performed by greenhouse pot experiment employing μ-XANES, μ-XRF and μ-XRD techniques. Finally, The mechanism of the effect of transformation of manganese oxide on the bioavailability and mobility of Cd and Sb in soils will be elucidated. This research will deepen the understanding of the environmental behaviors of Cd and Sb in soils, which provide the theoretical and technical supports for the environmental soil chemical process research and remediation strategies for soil Cd and Sb pollution.

土壤氧化锰具有较大的比表面积和反应活性，显著影响重金属在土壤中的迁移转化过程。土壤中氧化锰种类多，不同构型的氧化锰性质相差较大，其固持重金属的能力差异较大。本项目拟以Cd和Sb为典型的阳离子型和阴离子型重金属，以“氧化锰－Cd/Sb－吸附机制－氧化还原溶解－风险评价”为研究主线，宏观吸附与吸收过程与微观分子机制研究相结合，应用原位EXAFS、DFT等分子手段揭示Cd/Sb在不同形态氧化锰表面的吸附固定分子机制，同时考察pH、溶解氧、Mn(II)和有机质对氧化锰吸附Cd/Sb的影响；基于室内培养实验，研究土壤Mn氧化还原过程对氧化锰固定吸附重金属的影响；基于盆栽实验，结合μ-XANES、μ-XRF、μ-XRD等方法研究外源氧化锰对水稻吸收重金属影响的分子机制，最终阐明土壤中氧化锰形态转化对Cd/Sb形态和生物有效性的影响规律，为土壤Cd/Sb污染过程研究与化学修复等提供理论、方法和途径。

土壤氧化锰具有较大的比表面积和反应活性，显著影响重金属在土壤中的迁移转化过程。土壤中氧化锰种类多，不同构型的氧化锰性质相差较大，其固持重金属的能力差异较大。项目以Cd和Sb为典型的阳离子型和阴离子型重金属，以“氧化锰－Cd/Sb－吸附机制－氧化还原溶解－风险评价”为研究主线，宏观吸附与吸收过程与微观分子机制研究相结合，应用原位EXAFS、DFT等分子手段揭示Cd/Sb在不同形态氧化锰表面的吸附固定分子机制，同时考察pH、溶解氧、Mn(II)和有机质对氧化锰吸附Cd/Sb的影响；基于室内培养实验，揭示了土壤Mn氧化还原过程对氧化锰固定吸附重金属的影响机制；基于盆栽实验，结合多表面模型成功预测了水稻对重金属的吸收，最终阐明了土壤中氧化锰形态转化对Cd/Sb形态和生物有效性的影响规律，结果为土壤Cd/Sb污染过程研究与化学修复等提供理论、方法和途径。项目执行期间发表论文17篇，其中SCI论文15篇，培养博士生2名。