围涂开垦为缓解人口压力和保证粮食安全等方面作出了重要贡献，然而目前对微观尺度下滩涂围垦稻田土壤结构的演化过程及其微生物学机制还知之甚少。本研究以我国东部沿海未垦滩涂和不同围垦年限的水稻土所组成的时间序列为研究对象，采用现代光谱学技术(XPS、NEXAFS、NanoSIMS)、同位素示踪技术、分子生物学方法和微生物代谢物提取等手段，系统研究：(1) 滩涂围垦稻田土壤发生过程不同粒径团聚体中有机碳、氧化铁和微生物群落结构及其代谢物赋存的动态变化规律和耦合关系；(2) 不同粒径团聚体中有机碳、氧化铁和微生物空间分布特征；(3) 滩涂围垦稻田不同发育阶段团聚体的生物/化学稳定性的差异及其影响机制。通过阐明碳-铁-微生物及其代谢物参与下滩涂围垦土壤团聚体形成和稳定机制，构建滩涂围垦稻田土壤发育过程中团聚体周转的动态概念模型，将为深入了解稻田生态系统碳铁循环过程以及保证土地可持续利用提供科学依据。

Reclamation has made important contributions to alleviating the pressure of population growth and ensuring food security. However, the evolution process of paddy soil structure and its related biological mechanism at micro-scale after tideland reclamation still remain unclear. The paddy soil chronosequence consisting of six ages with approximately 10, 20, 50, 100, 300, 700 years of rice cultivation history and an uncultivated tidal marsh representing the original soil were selected. Using the modern spectroscopy technologies (e.g. XPS, NEXAFS, NanoSIMS), isotope tracer technique, molecular biology method and microbial metabolites extraction technology, this proposal will focus on (1) dynamics and coupling relationships of organic carbon, iron oxides, microbial community structure and their metabolites in different size aggregates during paddy soil occurrence after reclamation; (2) spatial distribution characteristics of organic carbon, iron oxides and microorganisms in different size aggregates; (3) differences in biology/chemical stability of aggregates at different paddy development stages and its regulation mechanisms. Finally, we will clarify the mechanism of carbon-iron-microbes participating in the soil aggregates formation and stabilization after reclamation, and establish a dynamic conceptual model of aggregates turnover during paddy soil development. This work will provide an important scientific basis for further understanding the biogeochemical cycling process of paddy ecosystem and ensuring the sustainable utilization of land resources.