Abstract:

According to data of pollution source monitoring station,part of the Monitoring System of Three Gorges Project Ecology and Environment,status in recent years and change over the years of chemical oxygen demand (CODCr) and ammonia nitrogen loads into the reservoir were analysed.Results show that pollution loads mainly come from upper reaches. During recent 5 years,the CODCr pollution load was 5286 million tons annually on average,of which CODCr load from upper reaches and that from the reservoir area were 4.432 million tons and 854, 500 tons,accounting for 838% and 162% respectively; the ammonia nitrogen pollution load was 72 800 tons annually on average,of which the load from upper reaches and that from the reservoir area were 47 500 tons and 25 300 tons, accounting for 65.2% and 348% respectively. From 1997 to 2009,especially during the period from first impoundment to completion,the total discharge of waste water into reservoir increased significantly with the rapid economic and social development of the reservoir area,but the trend of increasing emissions of the main pollutants (CODCr and ammonia) had been effectively controlled,especially the CODCr loads in sewage discharge decreased,indicating that a series of water environmental policies and measures had resulted in obvious effects. Nevertheless,water environmental protection of both the reservoir area and upper reaches can never be neglected