The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static clos...The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.展开更多
The data of 16o national meteorological observatory （NMO） stations with long-term monthly temperature data for China were analyzed in this study to show the basin-centered summer temperature decrease against global ...The data of 16o national meteorological observatory （NMO） stations with long-term monthly temperature data for China were analyzed in this study to show the basin-centered summer temperature decrease against global warming in the past half century. The summer and winter isotherm structures of 1950s and 1990s worked out by interpolation show the isotherm structure variations： the isotherm structure generally moves northward in winter, but in summer it is characterized with separate high-temperature and low-temperature centers and the isotherm structure moves inward the centers with global warming, indicating that the temperature in the highland areas increases but that in the lowland areas decreases in the summer of the duration. The possible mechanism of the basin-centered temperature decrease in summer is discussed in this paper.展开更多
The Mediterranean climate of the Sidi Bel Abbes city in northwestern Algeria has not been the subject of many investigations except some sporadic syntheses reports. However, climate change studying its most important ...The Mediterranean climate of the Sidi Bel Abbes city in northwestern Algeria has not been the subject of many investigations except some sporadic syntheses reports. However, climate change studying its most important parameters has not, at our knowledge, been the subject of a rigorous study. For this purpose this work intends to gather several temperatures ranging between 1980 and 2006 and find a mathematical model that tells us climate changes following changes in temperature during this time interval. Consequently and undesirably, the results confirm firmly the global greenhouse effect affecting our planet, but what seems rather puzzling is the fact that this warming trend has accelerated over time resulting in a changing climate toward warmer periods, for that reason a likely shift in the region of a semi-arid to tropical or arid regime overall, depending mainly on the evolution of the Azores anticyclone.展开更多
The energy crisis and global warming become severe issues. Solar-driven CO2 reduction provides a promising route to confront the predicaments, which has received much attention. The photoelectrochemical（PEC） process...The energy crisis and global warming become severe issues. Solar-driven CO2 reduction provides a promising route to confront the predicaments, which has received much attention. The photoelectrochemical（PEC） process,which can integrate the merits of both photocatalysis and electrocatalysis, boosts splendid talent for CO2 reduction with high efficiency and excellent selectivity. Recent several decades have witnessed the overwhelming development of PEC CO2 reduction. In this review, we attempt to systematically summarize the recent advanced design for PEC CO2 reduction. On account of basic principles and evaluation parameters, we firstly highlight the subtle construction for photocathodes to enhance the efficiency and selectivity of CO2 reduction, which includes the strategies for improving light utilization, supplying catalytic active sites and steering reaction pathway.Furthermore, diversiform novel PEC setups are also outlined.These exploited setups endow a bright window to surmount the intrinsic disadvantages of photocathode, showing promising potentials for future applications. Finally, we underline the challenges and key factors for the further development of PEC CO2 reduction that would enable more efficient designs for setups and deepen systematic understanding for mechanisms.展开更多
基金This research was supported by National Natural Science Foundation of China (Grant No. 40171092).
文摘The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.
基金The work is supported by NKBRSF, PR China, No. 2oo2CBII1507 The National Key of Science and Technology, No. 2oo4BAso8B22 the Chinese National Natural Science Foundation （90302006, 90511026）；the Hundred Talents Program （2004401, KZCX3-SW-339） of the Chinese Academy of Sciences and the Project for 0utstanding Scientists （40121101） of the National Natural Science Foundation of China.
文摘The data of 16o national meteorological observatory （NMO） stations with long-term monthly temperature data for China were analyzed in this study to show the basin-centered summer temperature decrease against global warming in the past half century. The summer and winter isotherm structures of 1950s and 1990s worked out by interpolation show the isotherm structure variations： the isotherm structure generally moves northward in winter, but in summer it is characterized with separate high-temperature and low-temperature centers and the isotherm structure moves inward the centers with global warming, indicating that the temperature in the highland areas increases but that in the lowland areas decreases in the summer of the duration. The possible mechanism of the basin-centered temperature decrease in summer is discussed in this paper.
文摘The Mediterranean climate of the Sidi Bel Abbes city in northwestern Algeria has not been the subject of many investigations except some sporadic syntheses reports. However, climate change studying its most important parameters has not, at our knowledge, been the subject of a rigorous study. For this purpose this work intends to gather several temperatures ranging between 1980 and 2006 and find a mathematical model that tells us climate changes following changes in temperature during this time interval. Consequently and undesirably, the results confirm firmly the global greenhouse effect affecting our planet, but what seems rather puzzling is the fact that this warming trend has accelerated over time resulting in a changing climate toward warmer periods, for that reason a likely shift in the region of a semi-arid to tropical or arid regime overall, depending mainly on the evolution of the Azores anticyclone.
基金financially supported in part by the National Key R&D Program of China (2017YFA0207301)the National Basic Research Program of China (973 Program, 2014CB848900)+5 种基金the National Natural Science Foundation of China (21471141 and U1532135)the CAS Key Research Program of Frontier Sciences (QYZDB-SSW-SLH018)the CAS Interdisciplinary Innovation Team, the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology (2016FXCX003)the Recruitment Program of Global Experts, the CAS Hundred Talent Program, Anhui Provincial Natural Science Foundation (1708085QB26)China Postdoctoral Science Foundation (BH2060000034)the Fundamental Research Funds for the Central Universities (WK2060190064)
文摘The energy crisis and global warming become severe issues. Solar-driven CO2 reduction provides a promising route to confront the predicaments, which has received much attention. The photoelectrochemical（PEC） process,which can integrate the merits of both photocatalysis and electrocatalysis, boosts splendid talent for CO2 reduction with high efficiency and excellent selectivity. Recent several decades have witnessed the overwhelming development of PEC CO2 reduction. In this review, we attempt to systematically summarize the recent advanced design for PEC CO2 reduction. On account of basic principles and evaluation parameters, we firstly highlight the subtle construction for photocathodes to enhance the efficiency and selectivity of CO2 reduction, which includes the strategies for improving light utilization, supplying catalytic active sites and steering reaction pathway.Furthermore, diversiform novel PEC setups are also outlined.These exploited setups endow a bright window to surmount the intrinsic disadvantages of photocathode, showing promising potentials for future applications. Finally, we underline the challenges and key factors for the further development of PEC CO2 reduction that would enable more efficient designs for setups and deepen systematic understanding for mechanisms.
