Hydropower reservoirs on the upper Mekong River modify nutrient bioavailability downstream  

作　　者：Qiuwen Chen Wenqing Shi Jef Huisman Stephen C.Maberly Jianyun Zhang Juhua Yu Yuchen Chen Daniele Tonina Qitao Yi 

机构地区：[1]State Key Laboratory of Hydrology-Water Resources&Hydraulic Engineering,Nanjing Hydraulic Research lnstitute,Nanjing 210029,China [2]Center for Eco-Environment Research,Nanjing Hydraulic Research Institute,Nanjing 210098,China [3]Department of Freshwater and Mae Ecology,Insttute for Biodiversity and Ecosystem Dynamics,University of Amsterdam,Amsterdam 1090 GE,the Netherlands [4]Lake Ecosystems Group,UK Centre for Ecology&Hydrology,Lancaster LA 14AP,UK [5]Department of Eco-Environment Conservation,Yangtze lnstrtute for Conservation and Development,Nanjng 210029,China [6]Center for Ecohydraulics Research,University of ldaho,Bolse,ID 83702,USA

出　　处：《National Science Review》2020年第9期1449-1457,共9页国家科学评论（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(91547206,S1425902,51979171 and s1709181);the Ministry of Science and Technology of China(2016YFCO502205);the UKNatural Environment Research Council;We thank the four anonymous reviewers and the editor for their insightful comments.

摘　　要：Hydropower development is the key strategy in many developing countries for energy supply,climate-change mitigation and economic development.However,it is commonly assumed that river dams retain nutrients and therefore reduce downstream primary productivity and fishery catches,compromising food security and causing trans-boundary disputes.Contrary to expectation,here we found that a cascade of reservoirs along the upper Mekong River increased downstream bioavailability of nitrogen andphosphorus.The dams caused phytoplankton density to increase with hydraulic residence time and stratification of the stagnant reservoirs caused hypoxia at depth.This allowed the release of bioavailable phosphorus from the sediment and an increase in dissolved inorganic nitrogen as well as a shift in nitrogen species from nitrate to ammonium,which were transported downstream by the discharge of water from the base of the dam.Our findings provide a new perspective on the environmental impacts of river dams on nutrient cycling and ecosystem functioning,with potential implications for sustainable development of hydropower worldwide.

关 键 词：Mekong River cascade reservoirs downstream nutrient bioavailability nitrogen PHOSPHORUS 

分 类 号：X17[环境科学与工程—环境科学] TV72[水利工程—水利水电工程]