稻田砷污染和稻米砷富集是关系人类健康的重大环境问题，氧酸型砷铁离子团簇是外源铁在根际土壤限域阻断水稻砷富集的关键因子。本项目基于水稻砷吸收富集的必然通道——水稻根际土壤限域，围绕氧酸型砷铁离子团簇的成核过程、微观结构及阻断水稻砷富集的作用机制，采用耦合化学在线提取与原位谱学表征技术，结合盆栽与根箱栽培实验，重点研究：①水稻根际土壤限域固-液相中氧酸型砷铁离子团簇的形态变化与数量分布，探究氧酸型砷铁离子团簇的物种多样性及其微观结构随根际生理活动的演变规律；②系统分析根际土壤限域中氧酸型砷铁离子团簇的物种分布和微观结构的精细谱图，明确离子团簇迁移活性及关键影响因素；③结合极化连续介质模型结构理论，从分子角度揭示氧酸型砷铁离子团簇的团聚趋势与成核关键节点，阐明水稻根际土壤限域氧酸型砷铁离子团簇协同阻断砷富集的根际反应边界条件窗口。以期为水稻土壤砷环境行为的调控及有效削减稻米砷富集提供科学依据。

Arsenic pollution in rice field and arsenic enrichment in rice are important environmental problems related to human health. The oxy-acid arsenic-ferric ion cluster is the key factor to block arsenic enrichment in rice by exogenous iron in rhizosphere soil limits. Based on the rice rhizosphere soil region, which is an inevitable channel for arsenic absorption and enrichment in rice, this project focused on the microstructure and the nucleation mechanism of blocking rice arsenic enrichment by oxy-acid arsenic-ferric ion clusters. Coupled with chemical on-line extraction and in situ spectroscopic characterization techniques, the morphological changes and quantitative distribution of oxy-acid arsenic-ferric ion clusters in the solid-liquid phase of rice rhizosphere soil are studied to explore the evolution of species diversity and microstructure of oxy-acid arsenic-ferric ion clusters with physiological activities of the rhizosphere with the help of pot culture and root box cultivation experiments. The species distribution and microstructure of oxy-acid arsenic-ferric ion clusters in the rhizosphere soil limits are systematically analyzed, and the migration activities and key influencing factors of the ion clusters are determined. In combination with the structure theory of polarized continuum model, the agglomeration trend and the key nodes of nucleation of oxy-acid arsenic-ferric ion clusters are revealed from the molecular perspective. The boundary condition window of the rhizosphere reaction that the oxy-acid arsenic-ferric ion clusters synergistically block arsenic enrichment in rice rhizosphere soil limits is clarified. It provides a scientific basis for regulating and controlling the environmental behavior of arsenic in paddy soil and effectively reducing arsenic enrichment in rice.