硅酸-铁（氢）氧化物的复合作用及其缓解水稻镉胁迫的机制

我国土壤镉点位超标率高达7%，有2.786×105km2的农用土壤受到镉污染，已经威胁到农产品安全生产。研究表明，硅促进酸性土壤对镉的吸附，加剧镉解吸的滞后效应，降低镉生物有效性，但其微观机制尚不明确。为此，提出硅同铁（氢）氧化物复合改变其表面性质，促进镉的吸附及铁（氢）氧化物-硅酸-镉配合物形成，减少植物吸收镉的假设。拟通过生物试验、化学分析、模型预测与谱学验证相结合的方法研究硅酸-铁（氢）氧化物的复合作用及其缓解水稻镉胁迫的效应，利用CD-MUSIC模型预测硅酸对镉在铁（氢）氧化物表面的存在形态及分布影响，运用X射线衍射、拉曼光谱、红外光谱和X射线光电子能谱技术确认铁（氢）氧化物-硅酸-镉三者间化学键的形成；结合水稻逆境生理反应、细胞微结构变化阐明硅-铁（氢）氧化物的复合作用及其缓解水稻镉胁迫作用的原因，对于明确土壤中硅、镉相互作用及揭示硅降低镉生物有效性的土壤化学机制具有重要意义。

The over-standard rate of cadmium in soils in China is as high as 7%. About an area of 2.786×105km2 agricultural soils is polluted by cadmium, which has threatened the safety of agricultural production. Results showed that silicon promoted the adsorption of cadmium in acidic soils, aggravated the lag effect of cadmium desorption, and reduced the bioavailability of cadmium. However, the micro-mechanism is still unclear. Therefore, the hypothesis is that the complex of silicon and iron (hydrogen) oxides can change their surface properties, promote the adsorption of cadmium and the formation of iron (hydrogen) oxides-silicate-cadmium complex, and reduce the uptake of cadmium by plants. The complex effect of silicon-iron (hydrogen) oxides and its mitigation effect on rice cadmium stress were studied by combining biological experiments, chemical analysis, model prediction and spectroscopic verification. The morphology and distribution of cadmium on the surface of ferrosilicon (hydrogen) oxides were predicted by CD-MUSIC model. X-ray diffraction, Raman spectroscopy, infrared spectroscopy and X-ray photoelectron spectroscopy were used. Confirming the formation of chemical bonds between iron (hydrogen) oxides, silicate and cadmium, clarifying the complex action of silicon-iron (hydrogen) oxides and the reasons for alleviating cadmium stress in Rice by combining the physiological response to stress and the changes of cell microstructures are of great significance for clarifying the interaction between silicon and cadmium in soil and revealing the soil chemical mechanism of silicon reducing cadmium bioavailability.