|茅东水库、长荡湖、滆湖、太湖竺山湾是洮滆水系从上游到下游排列的4大典型湖库， 2008年的监测分析表明，氮、磷是该水系湖库富营养化的主要污染因子，并沿流域呈加剧趋势，上下游TP质量浓度为0.081 ~0.296mg/L，差异小，而TN质量浓度为0.314 ~5.67 mg/L，差异大，长荡湖到滆湖是洮滆水系首要污染物TN快速增加的关键区域。水系自上而下4个湖库综合营养状况指数分别为45.3，63.0，68.3，69.5，富营养化呈加重趋势，后二者已接近重度富营养化并呈北重南轻的态势，并且4—9月重于其他月份，其生态风险较大。自上而下流域内农田及建设用地的比例均呈增加趋势，表明农业面源污染、城镇生活污染及工业污染的负荷也呈增加趋势，它们的总比例与综合营养状况指数呈正相关（P＜0.05）。从藻类种类构成来看，下游竺山湖以铜绿微囊藻（Microcystis aeruginosa）为绝对优势种，有大量表面水华爆发且有黑臭发生，上游滆湖和长荡湖以点状平裂藻（Merismopedia punctata）为绝对优势种，几乎无表面水华爆发，这与鲢、鳙鱼的养殖规模密切相关。
|关键词: 湖库 富营养化 生态风险 洮滆水系 太湖
|Feature Analysis and Comparison on Ecological Risk of Eutrophication in Lakes and Reservoir in Taoge River
|Maodong reservoir, Changdang lake, Gehu lake and Zhushan bay were the four representative lakes of Taoge river system. Eutrophication in these four water bodies was studied in 2008 and nitrogen and phosphorus were demonstrated as the main factors of pollution, which was getting more serious along the flow direction of Taoge river. The concentration of total phosphorus varied from 0.081 mg/L to 0.296 mg/L, while the concentration of total nitrogen varied dramatically, ranging from 0.314 mg/L to 5.67 mg/L, especially in the key area between Changdang lake and Gehu lake. Comprehensive trophic status index (TLIc) of these four water bodies was 45.3, 63.0, 68.0 and 69.5, respectively which showed Gehu lake and Zhushan bay almost reached severe eutrophication. TLIc of the north part was higher than the south. From the time point of view, the highest TLIc of the two lakes appeared from April to September. The phenomenon implied high ecological risk in Gehu lake and Zhushan bay. According to the changes of land use type, the increased ratio of farmland and building land along the flow direction indicated that agriculture non-point source pollution, industrial pollution and domestic pollution in market town were getting worse, which had positive correlation to TSI of lakes（P ＜0.05）. Composition of algae species in these lakes was different, the dominant species of Zhushan bay was Microcystis aeruginosa causing water bloom and the black smelly. The disappearance of water bloom in Changdang lake and Gehu lake in which Merismopedia punctata was the dominant species caused by large scale breeding of Hypophthalmichthys molitrix and Aristichthys mobilis.
|Key words: lakes and reservoir eutrophication ecological risk Taoge river Taihu lake