漫湾电站建成后澜沧江下游水质变化

随着澜沧江流域水电资源的开发，其水质变化及其跨境影响，越来越受到下湄公河流域国家及许多国际组织的关注。以漫湾电站为例，利用澜沧江下游1988～2002年6个断面、21个项目的水质监测资料，采取对比分析法，评价分析了漫湾电站建设和运行15年来，整个下游干流的水质状况和主要污染物变化趋势。结果表明，漫湾电站的建设和运行，目前对澜沧江下游干流水质总体还没有明显影响，但漫湾水库受重金属等污染物的污染，水库水质趋于下降。主要污染物M\-nO\+-\-4指数、NH\+-\-4 N、Hg、Pb和Cd的污染呈下降趋势；TP的污染有所加重。重金属Pb、Cd的污染主要集中于嘎旧（漫湾）断面和景临桥断面；M\-nO\+-\-4指数、TP和NH\+-\-4 N产生的有机污染主要集中在版纳水文站断面和勐罕渡口断面；澜沧江出境断面关累水质良好，基本达到该断面水环境功能要求。

CHANGES IN WATER QUALITY IN THE DOWNSTREAM OF LANCANGJIANG RIVER AFTER THE CONSTRUCTION OF MANWAN HYDROPOWER STATION

With the development of hydroelectric power source in Lancangjiang River valley, the water quality change and the cross-boundary effect are concerned more and more by the downstream countries and many international organizations. This paper takes Manwan hydroelectric station as an example, using water quality monitoring materials of 6 sections and 21 items in the downstream of Lancangjiang River from 1988 to 2002, adopting contrast analysis method, evaluates the water quality status and trend of main pollutants of the whole mainstream of Lancangjiang River downstream since the construction and running of Manwan hydroelectric station for 15 years. The results indicate that the construction and running of Manwan hydroelectric station has not produced obvious impacts on water quality of mainstream of Lan- cangjiang River downstream currently. But Manwan reservoir was polluted by heavy metal and other pollu- tants, and its water quality tends to go down. Pollution of the main pollutants such as MnO4-index, NH4- -N, Hg, Pb and Cd tend to decrease, and pollution of TP was heavier. Pollution of Pb and Cd heavy metal was mainly concentrated at Gajiu (Manwan) section and Jinglinqiao bridge section, and organic pol- lution produced by MnO4-index, TP and NH4--N mainly concentrated at Xishuangbanna hydrology sta- tion section and Menghan ferry section. Water quality of Lancangjiang River at leave-boundary section was good and basically meet the requirement of water environmental function.