Key Processes and Mechanisms of Nitrogen and Phosphorus Cycling in Lakes

WU Zhen, WU Sifeng, LIU Yong†, ZHANG Yuyu, XIE Shuguang, GUO Huaicheng

Key Laboratory of Water and Sediment Sciences (MOE), College of Environmental Science and Engineering, Peking University, Beijing 100871; † Corresponding author, E-mail: yongliu@pku.edu.cn

Abstract Special attention has been paid to three types of processes, that is, source process, removal process and internal cycling. Through the summary of literatures, the mechanisms of typical cycling processes, such as sediment release and denitrification, were discussed. The comparison of contributions of different cycling processes was listed as well. Moreover, the main research approaches of experiment and modeling in this field were well summarized and compared, raising a general framework for the study of nutrients cycling in lakes. With the purpose of looking into the cycling of nutrients, different approaches should be combined together. For example, mechanism models and observation for the mass balance of nutrients, then the microcosmic experiments for the impact factors of cycling processes. It is an efficient way to explore the cycling of nutrients in lakes. Key words lake eutrophication; nitrogen and phosphorus cycling; internal loading; denitrification; nitrogen and phosphorus coupling

湖泊富营养化问题是水环境领域面临的突出挑[1–4]战 。对受损湖泊进行生态修复和污染控制, 有效地预防湖泊生态退化, 是国内外相关研究的核心

[5–7]问题, 也是目前我国环境治理的重要任务 。氮和磷是湖泊生态系统中不可或缺的营养元素, 其循环主要指湖泊中氮磷物质在水体、底泥和生物体中的迁移和转化过程, 主要包括源过程(如点源、面源及大气沉降、固氮等)、去除过程(如湖体出流、反硝化等)以及湖体内的迁移和转化过程(如生物吸

收和排泄、微生物分解、硝化作用等)[8–10]。湖泊内正常的氮磷循环是维持生态健康的必要条件, 而大量氮磷的进入会导致湖体内营养物质循环过程的变化, 增加富营养化的风险。因此, 开展相关研究对湖泊生态修复和预防湖泊生态退化有重要的指导作用[11–13]。湖泊氮磷循环在湖泊管理方面的意义表现在3个方面。1) 对于尚未富营养化的湖泊, 需特别关注主要的氮磷循环过程, 了解主要驱动因子, 增强有