三仙湖氮磷污染现状与问题诊断

 三仙湖湖区水质好坏及水量多寡关乎湖南南县及周边地区的战略饮用水安全。三仙湖流域水质与底质的调查结果表明：三仙湖湖体水中总磷平均质量浓度为0.18 mg/L，总氮平均质量浓度为1.26 mg/L，总体水质为V类，总磷超标严重，对比国内重要湖泊水质总氮均值依次表现为三仙湖 < 洞庭湖 < 鄱阳湖 < 太湖，总磷均值为鄱阳湖 < 洞庭湖 < 三仙湖 < 太湖。沉积物中总氮污染较重，总磷生态效应较总氮低，对比国内重要湖泊底质总氮均值表现为洞庭湖 < 三仙湖 < 鄱阳湖 < 太湖，总磷均值表现为三仙湖 < 鄱阳湖 < 洞庭湖 < 太湖。分析表明，目前存在农业面源污染严重、湖内底泥淤积、内源污染释放风险较大、散养牲畜进入湖区放养现象突出、受精养塘等渔业污染严重等问题。

Water environment status and diagnosis of Sanxian Lake

Sanxianhu Lake's water quality and quantity relates to the drinking water in Nanxian County of Hunan province and the surrounding area's strategic security. For the watershed protection planning and policy making, surveys have been carried out to analyze Sanxianhu Lake water environment situation and diagnose its ecological environment problems. Results show that Sanxianhu Lake average concentration of total phosphorus is 0.18 mg/L and average concentration of total nitrogen is 1.26 mg/L, both meeting the V class of water quality. Compared with other major domestic lakes, it follows that Sanxianhu lake < Dongtinghu Lake < Poyanghu Lake < Taihu Lake in terms of total nitrogen, and Poyanghu Lake < Dongtinghu Lake < Sanxianhu Lake < Taihu Lake in terms of total phosphorus. Moreover, the polluted effect in sediments caused by total nitrogen is higher than that by total phosphorus. Compared with major domestic lakes in sediments, Dongtinghu Lake < Sanxianhu Lake < Poyanghu Lake < Taihu Lake in total nitrogen values, and Sanxianhu Lake < Poyanghu Lake < Dongtinghu Lake < Taihu Lake in phosphorus values. Sanxianhu lake is suffering from pollution problems including agricultural nonpoint source pollution, sediment deposition, internal pollution release risk, free range livestock and the fertilized pond fisheries.