长江流域重点湖泊的富营养化及防治

 近几十年，湖泊富营养化问题严峻，限制了流域社会经济可持续发展。为实施长江大保护，修复长江生态环境，推动长江经济带可持续发展，沿程湖泊富营养化问题亟需解决。本文以长江水系沿程6个重点湖泊为对象，探讨其富营养化历史演变特征、成因及控制对策。结果表明，长江流域6个主要湖泊的富营养化指数在近几年基本呈逐渐降低趋势，富营养化程度得到进一步改善。富营养化成因复杂，外源输入与内源释放是其主要原因，湖泊形态与水文条件也起了辅助作用：6个湖泊都是浅水湖泊，且多为封闭或半封闭状态，利于营养物质积累与藻类生长。对于外源中工业和生活源输入，其控制措施相对成熟，通过扩建污水处理厂、提高污水处理率及完善配套管网建设等措施，可大大减少入湖营养物含量；而外源中的面源污染则需通过种植结构调整、平衡施肥、生态工程（湿地、塘等）防治。对于内源释放，其治理过程相对复杂，目前主要有底泥疏浚、沉积物氧化、化学沉淀、底泥覆盖、微生物制剂、生物浮床等多种物理化学生物方法。但不同湖泊因其物理化学条件差异，适用方法也不同，故各湖采取的内源控制技术有待进一步论证。控制湖泊内外源营养盐输入的同时，进行流域生态修复并保障治理与管理并重，才能确保湖泊富营养化治理的长期有效性。

Eutrophication and control measures of key lakes in the Yangtze River Basin

In recent decades, lake eutrophication has severely limited the economic and social sustainable development in the lake basin. To repair the ecological environment and promote the development of the Yangtze river economic belt, solutions to the lake’s eutrophication problem are urgently needed. The six key lakes along the Yangtze river are taken as the research objects, and their historical changes, characteristics, cause analysis and control measures for eutrophication are discussed. It is shown that the eutrophication indexs of the six lakes have been gradually reduced in recent years and the state of lake eutrophication has a tendency of getting better. Causes of lake eutrophication are complex, the main influence factors include exogenous input and endogenous release. In terms of of lake forms and hydrological conditions, the six lakes are shallow lakes and mostly are closed or semi-closed state, which is advantageous to the accumulation of nutrients and algae growth. The control measures of exogenous input are relatively mature and can greatly reduce the nutrients discharged into the lake, such as the expansion of the sewage treatment plant, improvement of sewage treatment and supporting pipe network construction. But for internal release, the governance process is relatively complicated. At present there are mainly physical and chemical methods and technologies such as dredging, sediment oxidation, chemical precipitation, sediment cover, microbial agents, biological floating bed, and so on. Due to the differences of physical and chemical conditions, the applicable method to each lake is also different, so the appropriate lake endogenous control technology remains to be demonstrated. Controlling nutrients input from inside and outside sources, executing river ecological restoration and security governance, and management together could ensure the long-term effectiveness of eutrophic lakes governance.