Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environme...Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environmental problems. With the increasing global demand for environmental protection and sustainable development, it is much necessary to develop novel and clean methods for the synthesis of urea.Electrocatalysis provides an efficient and renewable synthesis route that can directly produce urea at room temperature and atmospheric pressure by the coupling of CO_(2) and nitrogenous molecules. In this review, we summarized the most recent advances in electrochemical synthesis of urea via CAN coupling systematically, focusing on the coupling of CO_(2) and different nitrogen sources. And the associated coupling mechanism, catalysts optimization, and electrolyzer design are well discussed. Moreover, the challenges and future directions for electrocatalytic CAN coupling are prospected. This review will provide timely and valuable guidance for others and attract more interests to promote the development of electrochemical synthesis of urea or other valuable chemicals containing CAN bond.展开更多
Yunnan and Guizhou are two provinces in Southwest China where in recent years drought disasters have occurred due to natural and human factors. This paper reviewed literature and summarized the related achievements of...Yunnan and Guizhou are two provinces in Southwest China where in recent years drought disasters have occurred due to natural and human factors. This paper reviewed literature and summarized the related achievements of water resources utilization and protection in Yunnan and Guizhou provinces. rivers, and karst ground water in the two provinces, and also This included characters and utilization of precipitation, the various explanations of drought （climate and human factors） and strategies for coping with droughts. Our concluding remarks highlight three lines of future studies： inequalities and equitable use of water distribution, better evaluation systems, and raising awareness through conservation practices.展开更多
The Third Plenary Session of the 18 th Central Committee of the Communist Party of China has proposed an important national strategic decision: to explore and establish the balance sheet of natural resources, to imple...The Third Plenary Session of the 18 th Central Committee of the Communist Party of China has proposed an important national strategic decision: to explore and establish the balance sheet of natural resources, to implement leaders’ of-office auditing system about natural resources assets. Water is one of the most essential nature resources of human beings; water resources accounting, as an important water resources management tool, is an essential part of compiling the natural resources balance sheet. In this paper, we provide a summary of the historic evolution of water resources accounting and analyze its application in some typical countries. Although water resources accounting and water resources balance sheet reflect different implications and focus, both require water resources accounts as the basis in system establishment.展开更多
Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes...Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes and raypaths by a shooting technique based upon the IASP91 Earth model,and it can calculate the traveltimes and raypaths for not only the seismic phases in the traditional traveltime tables such as IASP91,AK135,but also some phases such as pPcP,pPKIKP,and PPPPP.It is not necessary for this method to mesh the Earth model,and the results from the numerical modeling and its application show that the absolute differences between the calculated and theoretical traveltimes from the ISAP91 tables are less than 0.1 s.Thus,it is simple in manipulation and fast in computation,and can provide a reliable theoretical prediction for the identification of a seismic phase within the acquired earthquake data.展开更多
Photocatalytic technology harnesses solar energy to facilitate chemical transformations,presenting significant potential in energy generation and environmental remediation.However,the conventional O_(2)evolution proce...Photocatalytic technology harnesses solar energy to facilitate chemical transformations,presenting significant potential in energy generation and environmental remediation.However,the conventional O_(2)evolution process is hindered by high reaction barriers and inefficiencies,which limit its widespread application.Therefore,exploring novel photocatalytic coupling strategies to replace water oxidation has become a key route to enhance the efficiency of H_(2)production.In this review,organic pollutants removal and the valorization of organics as substitutes for water oxidation coupling strategies for photocatalytic H_(2)production are comprehensively summarized.These strategies not only circumvent the high reaction barriers associated with O_(2)evolution to enhance the H_(2)production but also aid in the removing of organic pollutants or synthesis of value-added chemicals.We also present future research directions and underscore the significance of advanced catalyst design,in-depth analysis of reaction mechanisms,and systematic optimization strategies in realizing an efficient and sustainable photocatalytic process.This guidance is anticipated to provide theoretical and practical new insights for the future development of photocatalytic coupling reactions,fostering further explorations in the realm of renewable energy and environmental governance.展开更多
Background Although phytoplankton are important primary producers in food webs,they are relatively less studied in large rivers compared to other types of systems.To fill this research gap,we studied phytoplankton tax...Background Although phytoplankton are important primary producers in food webs,they are relatively less studied in large rivers compared to other types of systems.To fill this research gap,we studied phytoplankton taxonomic and functional composition and their relationships with water quality,habitat,climate,and land use across 30 river sections in the middle and lower reaches of the Yangtze River during 2017–2018.Results Major observed phytoplankton groups were cyanobacteria,bacillariophyta,and chlorophyta.Phytoplankton total abundance,total biomass,and species richness significantly decreased in the dry season compared to the wet season,with the species and functional composition differing significantly between seasons.Phytoplankton species differences between seasons were mainly contributed by Oscillatoria sp.,Pseudanabaena sp.,and Melosira granulata.The dfferences in phytoplankton functional groups between seasons were mainly contributed by P(including Closterium sp.,Melosira sp.),Lo(including Merismopedia sp.,Peridinium sp.,Ceratium sp.,and Gymnodinium sp.),and J(including Pediastrum sp.,Tetraedron sp.,Crucigenia sp.,Scenedesmus sp.,and Coelastrum sp.).The variance partitioning showed that water quality(NO_(3)-N,total suspended solids,turbidity)and habitat(water flow,river bank and river channel conditions)were critical factors in shaping phytoplankton patterns,followed by climate and land use.Conclusions Results indicated that there was significant seasonal variation of phytoplankton in the Yangtze River,with water quality and habitat primarily driving phytoplankton patterns.Our study contributes to the understanding of natural and anthropogenic factors that drive seasonal successional processes of phytoplankton in the Yangtze River.These findings have important implications for environmental management as well as towards the ecological restoration of large rivers.展开更多
Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,a...Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,and are therefore,infrequently applied to large rivers.To that end,phytoplankton communities and environmental variables were monitored in 30 sampling segments of the middle and lower reaches of the Yangtze River,China during the wet(July-August)and dry(November-December)seasons in 2017-2018.We developed a phytoplankton-based index of biotic integrity(P-IBI)and used the index to assess the ecological health of the Yangtze River.Relationships among P-IBI,its component metrics,and environmental factors were analyzed across different seasons.Results Results obtained from the P-IBI indicated that the phytoplankton-based ecological health of the Yangtze River was rated as“good”during both seasons,with an overall better condition in the dry season.During the wet season,there were scattered river segments with P-IBI ratings of“fair”or below.Water quality and land use appeared to shape the patterns of P-IBI.In the wet season,P-IBI negatively correlated with total phosphorus,nitrate,total suspended solids,turbidity,conductivity,and dissolved oxygen.In the dry season,P-IBI positively correlated with total nitrogen,ammonium,and nitrite,and negatively correlated with water temperature.Conclusions The ecological health of the Yangtze River as reflected by the P-IBI exhibited spatial and temporal variability,with the effect of water quality being greater than that of local land use.This study indicated the importance of considering seasonal effects in detecting large river ecological health.These findings enhanced our understanding of the ecological health and characterized potential benchmarks for management of the Yangtze River.These findings also may be applicable to other large rivers elsewhere.展开更多
基金National Natural Science Foundation of China (No. 22202065, 22075092 and U21A20500)。
文摘Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environmental problems. With the increasing global demand for environmental protection and sustainable development, it is much necessary to develop novel and clean methods for the synthesis of urea.Electrocatalysis provides an efficient and renewable synthesis route that can directly produce urea at room temperature and atmospheric pressure by the coupling of CO_(2) and nitrogenous molecules. In this review, we summarized the most recent advances in electrochemical synthesis of urea via CAN coupling systematically, focusing on the coupling of CO_(2) and different nitrogen sources. And the associated coupling mechanism, catalysts optimization, and electrolyzer design are well discussed. Moreover, the challenges and future directions for electrocatalytic CAN coupling are prospected. This review will provide timely and valuable guidance for others and attract more interests to promote the development of electrochemical synthesis of urea or other valuable chemicals containing CAN bond.
基金funded by the National Social Science Foundation of China (No. 10CGL050)
文摘Yunnan and Guizhou are two provinces in Southwest China where in recent years drought disasters have occurred due to natural and human factors. This paper reviewed literature and summarized the related achievements of water resources utilization and protection in Yunnan and Guizhou provinces. rivers, and karst ground water in the two provinces, and also This included characters and utilization of precipitation, the various explanations of drought （climate and human factors） and strategies for coping with droughts. Our concluding remarks highlight three lines of future studies： inequalities and equitable use of water distribution, better evaluation systems, and raising awareness through conservation practices.
基金supported by the Chinese Science Academy STS Program: Natural Resources Balance Sheet Research and Application (KFJ-EW-STS-001)National Natural Science Funds Key Project (Grant No. 91125019)National Natural Science Youth Foundation (Grant No. 41401645)
文摘The Third Plenary Session of the 18 th Central Committee of the Communist Party of China has proposed an important national strategic decision: to explore and establish the balance sheet of natural resources, to implement leaders’ of-office auditing system about natural resources assets. Water is one of the most essential nature resources of human beings; water resources accounting, as an important water resources management tool, is an essential part of compiling the natural resources balance sheet. In this paper, we provide a summary of the historic evolution of water resources accounting and analyze its application in some typical countries. Although water resources accounting and water resources balance sheet reflect different implications and focus, both require water resources accounts as the basis in system establishment.
文摘Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes and raypaths by a shooting technique based upon the IASP91 Earth model,and it can calculate the traveltimes and raypaths for not only the seismic phases in the traditional traveltime tables such as IASP91,AK135,but also some phases such as pPcP,pPKIKP,and PPPPP.It is not necessary for this method to mesh the Earth model,and the results from the numerical modeling and its application show that the absolute differences between the calculated and theoretical traveltimes from the ISAP91 tables are less than 0.1 s.Thus,it is simple in manipulation and fast in computation,and can provide a reliable theoretical prediction for the identification of a seismic phase within the acquired earthquake data.
基金financially supported by the National Natural Science Foundation of China(No.22202065)。
文摘Photocatalytic technology harnesses solar energy to facilitate chemical transformations,presenting significant potential in energy generation and environmental remediation.However,the conventional O_(2)evolution process is hindered by high reaction barriers and inefficiencies,which limit its widespread application.Therefore,exploring novel photocatalytic coupling strategies to replace water oxidation has become a key route to enhance the efficiency of H_(2)production.In this review,organic pollutants removal and the valorization of organics as substitutes for water oxidation coupling strategies for photocatalytic H_(2)production are comprehensively summarized.These strategies not only circumvent the high reaction barriers associated with O_(2)evolution to enhance the H_(2)production but also aid in the removing of organic pollutants or synthesis of value-added chemicals.We also present future research directions and underscore the significance of advanced catalyst design,in-depth analysis of reaction mechanisms,and systematic optimization strategies in realizing an efficient and sustainable photocatalytic process.This guidance is anticipated to provide theoretical and practical new insights for the future development of photocatalytic coupling reactions,fostering further explorations in the realm of renewable energy and environmental governance.
基金supported by National Key Research and Development Program of China(2023YFC3209002,2019YFD0901203)Chinese Academy of Sciences(ZDRW-ZS-2017-3-2)supported by the Innovative and Entrepreneurial Talents Project of Jiangxi Province(JXSQ2020102109)
文摘Background Although phytoplankton are important primary producers in food webs,they are relatively less studied in large rivers compared to other types of systems.To fill this research gap,we studied phytoplankton taxonomic and functional composition and their relationships with water quality,habitat,climate,and land use across 30 river sections in the middle and lower reaches of the Yangtze River during 2017–2018.Results Major observed phytoplankton groups were cyanobacteria,bacillariophyta,and chlorophyta.Phytoplankton total abundance,total biomass,and species richness significantly decreased in the dry season compared to the wet season,with the species and functional composition differing significantly between seasons.Phytoplankton species differences between seasons were mainly contributed by Oscillatoria sp.,Pseudanabaena sp.,and Melosira granulata.The dfferences in phytoplankton functional groups between seasons were mainly contributed by P(including Closterium sp.,Melosira sp.),Lo(including Merismopedia sp.,Peridinium sp.,Ceratium sp.,and Gymnodinium sp.),and J(including Pediastrum sp.,Tetraedron sp.,Crucigenia sp.,Scenedesmus sp.,and Coelastrum sp.).The variance partitioning showed that water quality(NO_(3)-N,total suspended solids,turbidity)and habitat(water flow,river bank and river channel conditions)were critical factors in shaping phytoplankton patterns,followed by climate and land use.Conclusions Results indicated that there was significant seasonal variation of phytoplankton in the Yangtze River,with water quality and habitat primarily driving phytoplankton patterns.Our study contributes to the understanding of natural and anthropogenic factors that drive seasonal successional processes of phytoplankton in the Yangtze River.These findings have important implications for environmental management as well as towards the ecological restoration of large rivers.
基金supported by National Key R&D Program of China(2019YFD0901203)Chinese Academy of Sciences(ZDRW-ZS-2017-3-2).
文摘Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,and are therefore,infrequently applied to large rivers.To that end,phytoplankton communities and environmental variables were monitored in 30 sampling segments of the middle and lower reaches of the Yangtze River,China during the wet(July-August)and dry(November-December)seasons in 2017-2018.We developed a phytoplankton-based index of biotic integrity(P-IBI)and used the index to assess the ecological health of the Yangtze River.Relationships among P-IBI,its component metrics,and environmental factors were analyzed across different seasons.Results Results obtained from the P-IBI indicated that the phytoplankton-based ecological health of the Yangtze River was rated as“good”during both seasons,with an overall better condition in the dry season.During the wet season,there were scattered river segments with P-IBI ratings of“fair”or below.Water quality and land use appeared to shape the patterns of P-IBI.In the wet season,P-IBI negatively correlated with total phosphorus,nitrate,total suspended solids,turbidity,conductivity,and dissolved oxygen.In the dry season,P-IBI positively correlated with total nitrogen,ammonium,and nitrite,and negatively correlated with water temperature.Conclusions The ecological health of the Yangtze River as reflected by the P-IBI exhibited spatial and temporal variability,with the effect of water quality being greater than that of local land use.This study indicated the importance of considering seasonal effects in detecting large river ecological health.These findings enhanced our understanding of the ecological health and characterized potential benchmarks for management of the Yangtze River.These findings also may be applicable to other large rivers elsewhere.
