新近研究表明，大量存在于稻田土壤表层的周丛生物是磷素在土水之间发生交换、分配、迁移及形态转化等行为过程的重要微界面，但其对磷的调控机制尚不清楚。因此，本项目拟以稻田“土壤-周丛生物-水”三相界面为研究对象，通过野外调查和室内模拟实验，结合31P核磁共振、同位素δ18O法、磷的近边同步辐射、宏基因组等先进化学解析和分子生物学技术，解析周丛生物表面磷素形态及其影响因素对磷在土水两相之间分配的影响，研究周丛生物群落特征与表面属性对磷行为的调控机制，阐明周丛生物与土水界面典型环境因子的相互影响及对磷调控的耦合机制。项目成功实施，将阐明周丛生物对稻田土水界面磷的生物地球化学调控机制及其影响因素，为从土水界面提高磷的生物有效性，减少磷流失提供科学依据和新的思路。

Periphyton exists ubiquitously in wetland system, which is an important interface for phosphorus exchange, allocation, migration, and transformation between sediment and water interfaces. However, the regulation mechanism of periphyton on phosphorus behaviors between soil and water interfaces in paddy fields is still unclear. In this application, this study will be conducted in both mesocosm and in situ experiments, based on three interfaces of soil, periphyton and floodwater in six areas in China. Using the advanced technologies such as 32P isotopic tracing, 31P-NMR, δ18O, and synchrotron-based XANES, we will study i) the phosphorus species on the periphyton surface and the effects of periphyton on phosphorus distribution between soil and floodwater interfaces, ii) the regulation mechanisms of phosphorus behavior (including phosphorus transferring and transportation) by periphyton community and surface property, and iii) the coupling regulation of phosphorus behaviors by periphyton and environmental factors of soil-water interfaces. This project is expected to clarify the role of periphyton in distributing phosphorus, and reveal the phosphorus species in molecular level on periphyton surfaces. Th revealed coupling mechanism of regulating phosphorus behaviors by periphyton community, surface property and environmental factors will give an insight into understanding the phosphorus cycle in soil-water interface. This contributes not only to understand the phosphorus behavior in paddy fields, but also to promote phosphorus utilization efficiency and reduce phosphorus loss.