中文摘要：

东平湖位于淮海经济区北部，是国家南水北调东线工程的关键调蓄湖，其水环境状况对于调水水质安全具有重要意义．硅藻是指示湖泊水环境的敏感指标，在湖泊水质监测中有着广泛应用．为了解东平湖的水环境状况，2011年分季节对东平湖硅藻样品和水样进行了采集分析．研究表明：东平湖硅藻有16属43种，主要以部分附生和浮游种为主；优势属种有 Achnanthes minutissima ，Aulacoseira ambigua ，Aulacoseira granulata ，Fragilariacapuci-na v ．vaucheriea ，Synedra tenera ，Synedra ulna v ．acus等．冗余分析（RDA）结果共解释物种数据累计方差的28.1％；Monte Carlo检验表明，东平湖水体中COD ，pH值、总P和深度是影响底栖动物群落分布最关键的环境因子（ F＝2.04～2.85， p＜0.05）．总体来看，目前东平湖整体水质处于中营养及中营养向富营养方向转化之中，今后要特别注意湖区人类活动增强后对湖泊的污染，以确保南水北调输水水质的安全．

英文摘要：

As the key storage lake of South-to-North Water Diversion Project in China ,Dongping Lake ,which locate in the north of Huaihai Economic Zone ,is great important to the regulation of water environment security .For the most sensitive and effective bio-indicator ,diatom is widely used in most of the lake water quality monitoring .In or-der to explain the water environment in Dongping Lake ,surveys on diatom in surface sediment and water of the lake were carried out seasonally in 2011 .Result shows that a total of 43 diatom species belonging to 16 genera are identi-fied ,and the main species are Achnanthes minutissima ,Aulacoseira ambigua ,Aulacoseira granulata ,Fragilaria capucina v .vaucheriea ,Synedra tener and Synedra ulna v .acus .The result of redundancy analysis accountes for 28.1% of diatom community variance ,and Monte Carlo＇s test shows that COD ,total phosphorus ,depth and pH（F=2.04-2.85 ,p〈0.05） are the key factors that significantly influence the distribution and community structure of diatom .Overall ,Dongping Lake is now in nutritional status and even from mesotrophic to eutrophic .We should pay more attention to the pollution which produced by the increasing human activities to ensure the quality of South-to-North water .