Abstract: In order to ensure long-term and stable operation of the Yanlong Lake project and regional water supply safety, the change trends of 4 key water quality factors such as DO, NH3-N, CODMn and TP were analyzed, according to the monitoring data of water quality in 5 drinking water source areas (Longgang, Yancheng New, Dazong Lake, Dagang, Gu Dianbao ) from 2009 to 2016, in the Lixiahe River network region in northern Jiangsu province. Meanwhile, combined with the corresponding water quality factors and Chl-a index changes in different purification function areas of the Yanlong Lake Project, the water quality purification effect and existing problems of the ecological engineering in the source area were evaluated. The results indicate that the water quality in 5 water source areas is greatly diverse in different water periods. In high and flat water periods, the standard-exceeding rates of water quality are obviously higher than that in dry periods, especially for the factors of DO and CODMn in high periods, with the higher standard- exceeding rates. The Yanlong Lake Project generally has a better purification effect on the water quality of the source area of Mangshe River, but the purification effect of different water quality factors is different in different water periods and different functional areas. On the whole, the project has the best effect to enhance DO, but the reduction rate of CODMn is low, meanwhile, the concentration of Chl-a is high in spring and summer.

Key words: environmental engineering, river network region, drinking water source area, ecological project

摘要： 为保障盐龙湖工程长效稳定运行及区域供水安全，依据2009—2016年江苏省里下河腹部河网区河道型饮用水源地龙冈、盐城新、大纵湖、大冈和古殿堡等 5个水功能区站点的监测资料，分析了DO、NH3-N、CODMn和TP等 4个主要水质因子浓度变化趋势；结合盐龙湖工程不同净化功能区的对应水质因子以及Chl-a指标 变化，评估了水源地生态工程的水质净化效果以及存在问题。结果表明：不同水期河道型水源地水质差异较大，丰、平水期水质超标率明显高于枯水期，尤以丰 水期DO及CODMn浓度超标率偏高；监测期间盐龙湖工程对蟒蛇河水源地水质总体有较好的净化效果，但在不同水期工程不同功能区对不同水质因子的净化效果存在 较大差异；整体上工程对提升DO效果最好，但对CODMn的削减率偏低，同时，春、夏季出水Chl-a浓度偏高。

关键词: 环境工程, 河网地区, 水源地, 生态工程