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...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 N_(2) and Ar concentrations through N_(2):Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities 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 nitrogenfixing 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,suggesting that controlling nitrogen in such lakes is feasible if the growth of cyanobacteria is limited by nitrogen.展开更多
基金jointly supported by the National Natural Science Foundation of China(Nos.41830757,41573076 and 41671494)。
文摘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 N_(2) and Ar concentrations through N_(2):Ar method using a membrane inlet mass spectrometer to quantify the nitrogen fixation capacities 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 nitrogenfixing 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,suggesting that controlling nitrogen in such lakes is feasible if the growth of cyanobacteria is limited by nitrogen.
