富铁土氧化铁铝取代效应及其影响铁还原的生物化学机制

富铁土纲分布广泛，富含游离氧化铁，脱硅富铁铝化成土过程中氧化铁晶格中的铁原子被铝取代，显著影响氧化铁结构与性质、土壤微生物群落结构，从而影响土壤铁循环等物质循环过程。本申请以华南不同母质发育的富铁土为研究对象，以铁还原为模型土壤过程，研究土壤氧化铁的铝取代效应对氧化铁晶体结构、表面性质、土壤理化性质的影响，探讨风化程度与氧化铁铝取代效应的关系；阐明土壤铁还原与铝取代效应、风化程度的关系，从而阐明铝取代效应影响土壤铁还原过程的化学机制。采用富集培养、高通量测序等技术，研究铝取代效应与土壤铁还原菌群落间的关系，阐明铝取代效应影响土壤铁还原过程的微生物学机制。采用数理统计方法深入分析土壤铁还原过程、铝取代效应与土壤理化性质、铁还原微生物群落间的关系，深入阐明铝取代效应影响土壤铁还原过程的生物化学机制。预期成果可为深入理解成土过程对土壤典型物质循环过程影响的生物地球化学机制提供科学依据。

Ferrosols is a special soil orders in Chinese Soil Taxonomic Classification, and LAC-ferric horizon is its unique diagnostic horizon. Ferrosols contains a large amount of free iron oxides and is widely distributed in China, especially in tropical and subtropical zones. Al-substituted iron oxides is one of the most important feature under the effect of soil desilicification and allitization; the isomorphous substitution of Al for Fe in the iron oxide crystal structures may influence soil genesis, properties, the characteristics of microbial community, soil iron biogeochemical cycles as well as the transformation of contaminants in soils. This proposal will choose Ferrosols developing from different parent materials in South China as the research object, soil iron(III) reduction as the model reaction. Experiments are designed and conducted to investigate the biotic-abiotic mechanisms of iron(III) reduction in Ferrosols under the influence of Al-substituted iron oxides. The research tasks were detailed below: (1) to study the impact of Al-substitution effect on iron oxide crystal structures, surface properties, soil properties, to analyze the correlations between soil weathering degree and Al-substitution effect; (2) to investigate Al-substitution effect on soil iron(III) reduction, to study the relationship among soil iron(III) reduction, Al-substitution effect and soil weathering degree, and to reveal the chemical mechanisms of iron(III) reduction under the effect of Al-substituted iron oxides in Ferrosols; (3) using enrichment culture, high-throughtput sequencing technology and other microbiological research methods to study soil iron-reducing bacteria communities, to investigate the correlations between Al-substitution effect and soil iron-reducing bacteria communities, and to reveal the microbiology mechanisms of iron(III) reduction under Al-substitution effect in Ferrosols; (4) using statistical methods to analyze the relationship among soil iron(III) reduction, Al-substitution effect, soil properties, and soil iron-reducing bacteria communities, to disclose the biotic-abiotic mechanisms of soil iron(III) reducibility in Ferrosols under the Al-subsitution effect. Results of this proposal will improve our general understanding in soil pedogenesis and its biogeochemical impacts on typical elements' cycling processes; meanwhile, it will provide valuable information on soil iron redox chemistry as well as soil iron biogeochemical cycles researches.