River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-...River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.展开更多
Electrocatalysis is deemed as a promising approach for sustainable energy conversion and chemical production.Although a variety of cathode reactions(e.g.,hydrogen evolution and CO_(2)/N_(2)reduction)produce valuable f...Electrocatalysis is deemed as a promising approach for sustainable energy conversion and chemical production.Although a variety of cathode reactions(e.g.,hydrogen evolution and CO_(2)/N_(2)reduction)produce valuable fuels and chemicals,the extensively studied oxygen evolution reaction(OER)at anode only generates O_(2),which is not a high-value product.Substituting the OER with thermodynamically more favorable biomass derivative oxidation reactions(BDORs)not only enables energy-saving electrocatalysis,but also provides value-added anode products.Recent achievements have demonstrated that non-noble electrocatalysts are promising for BDORs.Herein,we provide a comprehensive review on recent achievements in the field of electrochemical BDORs catalyzed by non-noble catalysts.We start by summarizing the electrocatalytic oxidation of different types of biomass-derived substrates,aiming to show the advantages of the electrocatalytic pathway and to introduce the state-of-the-art non-noble catalysts.The reaction mechanisms of non-noble-material-catalyzed BDORs are then summarized and classified into three types according to the acceptor of hydrogen species during the dehydrogenation of biomass derivatives.Subsequently,discussions are devoted to the strategies for promoting the performances of non-noble electrocatalysts.Finally,we propose our opinions regarding future trends and major challenges in this field.展开更多
基金Under the auspices of Key Program of Chinese Academy of Sciences(No.KJZD-EW-TZ-G10)National Key Research and Development Program of China(No.2016YFA0602704)Breeding Project of Institute of Geographic Sciences and Natural Resources Research,CAS(No.TSYJS04)
文摘River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.
基金supported by the National Natural Science Foundation of China (21978147 and 21935001)Haihe Laboratory of Sustainable Chemical Transformationssupported by the Shuimu Tsinghua Scholar Program (2021SM072)
文摘Electrocatalysis is deemed as a promising approach for sustainable energy conversion and chemical production.Although a variety of cathode reactions(e.g.,hydrogen evolution and CO_(2)/N_(2)reduction)produce valuable fuels and chemicals,the extensively studied oxygen evolution reaction(OER)at anode only generates O_(2),which is not a high-value product.Substituting the OER with thermodynamically more favorable biomass derivative oxidation reactions(BDORs)not only enables energy-saving electrocatalysis,but also provides value-added anode products.Recent achievements have demonstrated that non-noble electrocatalysts are promising for BDORs.Herein,we provide a comprehensive review on recent achievements in the field of electrochemical BDORs catalyzed by non-noble catalysts.We start by summarizing the electrocatalytic oxidation of different types of biomass-derived substrates,aiming to show the advantages of the electrocatalytic pathway and to introduce the state-of-the-art non-noble catalysts.The reaction mechanisms of non-noble-material-catalyzed BDORs are then summarized and classified into three types according to the acceptor of hydrogen species during the dehydrogenation of biomass derivatives.Subsequently,discussions are devoted to the strategies for promoting the performances of non-noble electrocatalysts.Finally,we propose our opinions regarding future trends and major challenges in this field.
