关键词: 水体富营养化, 驱动机制, 水文情势, 营养盐, 长江流域

Abstract: Eutrophication is a common and urgent problem for rivers, lakes and reservoirs in the Changjiang River Basin. Based on the monitoring data and related historical literature on water quality, nutrient concentration, hydrology process and sediment transportation as well as eutrophication assessment index, current trophic status and its evolution trends of the waters in the whole basin during the past decades were analyzed, and the eutrophication driving mechanism for typical rivers, lakes and reservoirs were further demonstrated. It was indicated that eutrophication ranking for different kinds of waters from low to high were rivers, reservoirs, lakes. Sichuan Basin in the upstream and Jianghan Plain in the middle stream were the key concentrate region for eutrophic lakes and reservoirs. During the past 10 years, proportions of the moderate eutrophic lakes to total assessed lakes continually increased from 31.3% in 2009 to 42.7% in 2018, and trophic level of the reservoirs dramatically changed from mesotrophic to slightly eutrophic. Due to nutrient discharge by anthropic activities and operations of massive dams, factors including sufficient nutrient sources, declined flow velocity, decreased runoff, slow water exchange and worsen connectivity for water bodies greatly induced the occurrence of the eutrophication. Therefore, countermeasures including monitoring the nutrient such as nitrogen and phosphorus concentrations and flux on controlled sections, strengthening the discharging management for agricultural irrigation recession water and aquaculture waste water, and implementing the coupled regulation for water, sediment and nutrient at the basin level have been recommended to control the development of eutrophication in the basin.

Key words: water eutrophication, driving mechanism;hydrological regime, eutrophication salt, Changjiang River