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Two northern Minnesota lakes that had been studied in detail 22 years earlier (1958) were restudied to determine the extent of alteration in ecological conditions. Approximately one year after the original investigation, a coal-fired power plant, which incremented sulfate loading by about 6 kg/ha-yr, began operation nine miles away. These lakes lie within a region judged susceptible to acidic precipitation, though each lake, based on its buffering capacity, would be judged only moderately sensitive. In spite of the influence of this plant and other anthropogenic inputs, the change in lake ecology was apparently minimal. Water clarity decreased in both lakes and some alteration in zooplankton community structure was observed. The long-term utility of lake surveys depends upon how carefully and completely conditions can be reconstructed from records and reports. Past surveys generally omit measures of variability for the data, allowing only qualitative comparisons to be drawn. In order to judge the graded responses of aquatic ecosystems, necessary to sound management, quantitative measures are needed.Deceased.  相似文献
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自2006年起,美国环保署(EPA)在美国本土开展了两次湖泊生态状况调查和评估,从营养状态、生物健康和休闲娱乐的关键指标开展评估,旨在摸清美国湖泊生态环境现状和影响湖泊生态健康的关键胁迫因子。EPA逐步形成了涵盖水文、水质、水生生物等多重指标在内的湖泊调查评估体系,该体系已成为美国湖泊环境管理系统的重要组成部分,为湖泊环境保护和水生态系统恢复提供了有力支持。本文从清单建立、重点调查湖泊清单筛选、采样布点、监测指标、评估方法等方面系统研究总结美国湖泊调查评估的关键技术方法体系,以期为我国湖泊生态环境保护和环境管理工作提供借鉴。  相似文献
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