Eutrophication and harmful cyanobacterial blooms threaten water resources all over the world.There is a great controversy about controlling only phosphorus or controlling both nitrogen and phosphorus in the management of lake eutrophication.The primary argument against the dual nutrients control of eutrophication is that nitrogen fixation can compensate the nitrogen deficits.Thus,it is of great necessary to study the factors that can significantly affect the nitrogen fixation.Due to the difference of climate and human influence,the water quality of different lakes (such as water temperature,N:P ratio and water residence time) is also quite different.Numerous studies have reported that the low N:P ratio can intensify the nitrogen fixation capacities.However,the effects of temperature and water residence time on the nitrogen fixation remain unclear.Thus,30 shallows freshwater lakes in the eastern plain of China were selected to measure dissolved N2 and Ar concentrations through N2:Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capac-ities and investigate whether the temperature and water residence time have a great impact on nitrogen fixation.The results have shown that the short lake water residence time can severely inhibit the nitrogen fixation capacities through inhibiting the growth of nitrogen-fixing cyanobacteria,changing the N:P ratio and resuspending the solids from sediments.Similarly,lakes with low water temperature also have a low nitrogen fixation capacity,sug-gesting that controlling nitrogen in such lakes is feasible if the growth of cyanobacteria is limited by nitrogen.

Feng Zhao;Xu Zhan;Hai Xu;Guangwei Zhu;Wei Zou;Mengyuan Zhu;Lijuan Kang;Yulong Guo;Xingchen Zhao;Zicong Wang;Wei Tang

State Key Laboratory of Lake and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;School of Environmental and Civil Engineering,Jiangnan University,Wuxi 214122,China;University of Chinese Academy of Sciences,Beijing 100049,China

环境科学学报（英文版）

[1]Feng Zhao;Xu Zhan;Hai Xu;Guangwei Zhu;Wei Zou;Mengyuan Zhu;Lijuan Kang;Yulong Guo;Xingchen Zhao;Zicong Wang;Wei Tang-.New insights into eutrophication management:Importance of temperature and water residence time)[J].环境科学学报（英文版）,2022(01):229-239

shallows,resuspending

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