碳氮磷是湖泊生态系统物质和能量循环的重要组分。与碳氮相比，磷特别是有机磷环境与生物地球化学过程认识十分有限。有机磷是湖泊内源磷的重要组分，其循环过程是揭示湖泊生态环境效应的关键环节之一。项目拟在原有工作基础上，利用现代物理、化学和生物新方法，重点开展我国湖泊水环境有机磷生物化学组成、结构和效应机理研究。选择我国多个不同营养水平湖泊，建立环境多介质（水体、颗粒物、底泥、藻类和水生植物等）有机磷提取与浓缩富集新方法，采用高分辨率二维1H-31P NMR技术、生物酶水解法和氧同位素(δ18Op)技术等深入揭示不同介质有机磷生物化学组成与结构特征，系统阐述不同湖泊有机磷组分时空分布及生物有效性差异特征，并开展有机磷重要生化组分来源辨析研究。结合室内外模拟研究阐明有机磷生物地球化学循环与效应机理，深入揭示有机磷与湖泊富营养化耦合机制，为湖泊污染控制与治理提供新思路，完善生源要素环境生物地球化学理论。

Carbon (C), nitrogen (N), and phosphorus (P) are the essential elements for biogenic matter and energy cycle in the lake ecosystems. There is limited information regarding the biogeochemical processes of P, especially organic P, compared with that of C and N. Organic P is an important constituent of internal P load in lakes. The cycling processes of organic P are the key to clarify the ecological and environmental effects of lakes. The aim of present study is to investigate the biochemical composition and structures of organic phosphorus and their effects in the lake environment based on the modern physical, chemical and biological techniques. Different levels of eutrophic lakes are to be selected. The new methods for extraction and bioconcentration of organic P will be established for various environmental media, including water, suspended particles, sediments, algae, and aquatic plants. The advanced instruments and novel analytic methods, including 2D 1H-31P NMR, enzymatic hydrolysis, oxygen isotope in the phosphate (δ18Op), would be used to characterize the structures and biochemical compositions of organic P in lakes. The distributions and bioavailability of organic P would be systemically investigated and compared. The origins for different constituents of organic P are to be identified. The ultimate objectives are to elucidate the biogeochemical cycling and environmental effects of organic P and to further understand the coupling relationship between organic P and eutrophication. In summary, the project will make a great contribution to the control of lake eutrophication and improve the biogeochemical theory of biogenic elements.