Phytoplankton play a crucial role in maintaining the health of river ecosystems,and their communities are closely linked to river hydrodynamics.In inland waterways,disturbances generated by ship propellers alter flow ...Phytoplankton play a crucial role in maintaining the health of river ecosystems,and their communities are closely linked to river hydrodynamics.In inland waterways,disturbances generated by ship propellers alter flow dynamics and may affect phytoplankton communities.To clarify it,phytoplankton communities in the Zhenjiang section of the Beijing-Hangzhou Grand Canal(BHGC)in China,the world's longest canal,were studied and compared them with its undisturbed tributaries.The results revealed major alternations in seasonal patterns of phytoplankton communities in the BHGC,shifting the peak of phytoplankton density from spring to autumn and the lowest diversity from summer to autumn.Ship disturbances increased water turbidity and created optimal N/P ratios,which provided Cyanobacteria with a competitive advantage in autumn.The proliferation of Cyanobacteria resulted in a phytoplankton density in the BHGC,exceeding that in the tributaries by more than tenfold,accompanied by a decrease in diversity to its lowest level.Due to habitat alterations,functional groups emerged that are resilient to strong disturbances and high turbidity.The findings add to the understanding of the impact of ship traffic on river ecosystems.展开更多
As nitrogen removal requires anaerobic conditions for denitrification,which facilitates the production of methane(CH_(4)),a potent greenhouse gas,it is a challenge to achieve nitrogen removal with minimal CH_(4) emiss...As nitrogen removal requires anaerobic conditions for denitrification,which facilitates the production of methane(CH_(4)),a potent greenhouse gas,it is a challenge to achieve nitrogen removal with minimal CH_(4) emissions in constructed wetlands(CWs).This study proposed a solution for mitigating CH_(4) emissions while achieving nitrogen removal using porous fillers in CWs.We found that active denitrification occurred in the interior pores of these fillers in an oxygen-rich environment.The microbial analysis indicated that the internal pores of porous fillers created anaerobic habitats for denitrifiers as they had a higher nosZ/amoA ratio than on the surface.The anaerobic decomposition of organic matter was inhibited,yielding significantly lower CH_(4)/CO_(2) ratios(<1.0×10^(-5))than those of traditional CWs(0.07).The methanogen proliferation and CH_(4) production efficiency also remained at low levels(<1.1×10^(-3) and 0.045%,respectively),which was significantly lower than in traditional CWs(2.3×10^(6) and 38%,respectively).Overall,this study proposed a strategy for mitigating the greenhouse effect of carbon emissions from CWs in the future.展开更多
基金Jiangsu Provincial Carbon-peak and Carbonneutralization Technology Innovation Project,Grant/Award Number:BK20220041National Natural Science Foundation of China,Grant/Award Numbers:42477073,42277060。
文摘Phytoplankton play a crucial role in maintaining the health of river ecosystems,and their communities are closely linked to river hydrodynamics.In inland waterways,disturbances generated by ship propellers alter flow dynamics and may affect phytoplankton communities.To clarify it,phytoplankton communities in the Zhenjiang section of the Beijing-Hangzhou Grand Canal(BHGC)in China,the world's longest canal,were studied and compared them with its undisturbed tributaries.The results revealed major alternations in seasonal patterns of phytoplankton communities in the BHGC,shifting the peak of phytoplankton density from spring to autumn and the lowest diversity from summer to autumn.Ship disturbances increased water turbidity and created optimal N/P ratios,which provided Cyanobacteria with a competitive advantage in autumn.The proliferation of Cyanobacteria resulted in a phytoplankton density in the BHGC,exceeding that in the tributaries by more than tenfold,accompanied by a decrease in diversity to its lowest level.Due to habitat alterations,functional groups emerged that are resilient to strong disturbances and high turbidity.The findings add to the understanding of the impact of ship traffic on river ecosystems.
基金supported by National Natural Science Foundation of China(No.42422605,42277060,42477073)National Key Research and Development Program of China(No.2024YFC3214500)Natural Science Foundation of Jiangsu Province(BK20240142).
文摘As nitrogen removal requires anaerobic conditions for denitrification,which facilitates the production of methane(CH_(4)),a potent greenhouse gas,it is a challenge to achieve nitrogen removal with minimal CH_(4) emissions in constructed wetlands(CWs).This study proposed a solution for mitigating CH_(4) emissions while achieving nitrogen removal using porous fillers in CWs.We found that active denitrification occurred in the interior pores of these fillers in an oxygen-rich environment.The microbial analysis indicated that the internal pores of porous fillers created anaerobic habitats for denitrifiers as they had a higher nosZ/amoA ratio than on the surface.The anaerobic decomposition of organic matter was inhibited,yielding significantly lower CH_(4)/CO_(2) ratios(<1.0×10^(-5))than those of traditional CWs(0.07).The methanogen proliferation and CH_(4) production efficiency also remained at low levels(<1.1×10^(-3) and 0.045%,respectively),which was significantly lower than in traditional CWs(2.3×10^(6) and 38%,respectively).Overall,this study proposed a strategy for mitigating the greenhouse effect of carbon emissions from CWs in the future.
