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Effects of drip and flood irrigation on carbon dioxide exchange and crop growth in the maize ecosystem in the Hetao Irrigation District,China 被引量:1
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作者 LI Chaoqun HAN Wenting PENG Manman 《Journal of Arid Land》 SCIE CSCD 2024年第2期282-297,共16页
Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation metho... Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation methods on carbon dioxide(CO_(2))exchange and crop growth in this region.The experimental site was divided into drip and flood irrigation zones.The irrigation schedules of this study aligned with the local commonly used irrigation schedule.We employed a developed chamber system to measure the diurnal CO_(2)exchange of maize plants during various growth stages under both drip and flood irrigation methods.From May to September in 2020 and 2021,two sets of repeated experiments were conducted.In each experiment,a total of nine measurements of CO_(2)exchange were performed to obtain carbon exchange data at different growth stages of maize crop.During each CO_(2)exchange measurement event,CO_(2)flux data were collected every two hours over a day-long period to capture the diurnal variations in CO_(2)exchange.During each CO_(2)exchange measurement event,the biological parameters(aboveground biomass and crop growth rate)of maize and environmental parameters(including air humidity,air temperature,precipitation,soil water content,and photosynthetically active radiation)were measured.The results indicated a V-shaped trend in net ecosystem CO_(2)exchange in daytime,reducing slowly at night,while the net assimilation rate(net primary productivity)exhibited a contrasting trend.Notably,compared with flood irrigation,drip irrigation demonstrated significantly higher average daily soil CO_(2)emission and greater average daily CO_(2)absorption by maize plants.Consequently,within the maize ecosystem,drip irrigation appeared more conducive to absorbing atmospheric CO_(2).Furthermore,drip irrigation demonstrated a faster crop growth rate and increased aboveground biomass compared with flood irrigation.A strong linear relationship existed between leaf area index and light utilization efficiency,irrespective of the irrigation method.Notably,drip irrigation displayed superior light use efficiency compared with flood irrigation.The final yield results corroborated these findings,indicating that drip irrigation yielded higher harvest index and overall yield than flood irrigation.The results of this study provide a basis for the selection of optimal irrigation methods commonly used in the Hetao Irrigation District.This research also serves as a reference for future irrigation studies that consider measurements of both carbon emissions and yield simultaneously. 展开更多
关键词 carbon dioxide exchange maize growth drip irrigation harvest index net primary productivity Hetao Irrigation District
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Enabling low-cost decentralized power reserves adopting carbon dioxide for green methane exchange in stabilized clathrate adsorbent
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作者 Lucas Hanssens Maarten Houlleberghs +7 位作者 C.Vinod Chandran Geert Watson Sambhu Radhakrishnan Pascal Van Der Voort Joeri F.M.Denayer Christine E.A.Kirschhock Johan A.Martens Eric Breynaert 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第10期438-443,I0009,共7页
1.Challenges circular methane energy systems In recent decades,methane-based energy systems have rapidly gained traction across the globe because of the increasing availability of low-cost methane production capacity.... 1.Challenges circular methane energy systems In recent decades,methane-based energy systems have rapidly gained traction across the globe because of the increasing availability of low-cost methane production capacity.However,fossil methane production and combustion lead to large greenhouse gas emissions,contributing to climate change[1]. 展开更多
关键词 Long duration energy storage Green methane carbon neutrality Confined clathrate hydrates CH_(4)/CO_(2) exchange Direct gas exchange
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Effect of NH_4^+ exchange on CuY catalyst for oxidative carbonylation of methanol 被引量:4
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作者 王玉春 郑华艳 李忠 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第8期1403-1412,共10页
NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY cata‐lysts by a high temperature anhydrous interaction between the support and copper (II) acety‐lacetonate Cu(acac)2. The... NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY cata‐lysts by a high temperature anhydrous interaction between the support and copper (II) acety‐lacetonate Cu(acac)2. The catalysts were used for the oxidative carbonylation of methanol to dime‐thyl carbonate (DMC) at atmospheric pressure. The textural and acidic properties of NaNH4Y zeolite and the CuY catalysts were investigated by X‐ray diffraction, scanning electron microscopy, N2 ad‐sorption‐desorption, temperature programmed reduction of H2, X‐ray photoelectron spectroscopy and temperature programmed desorption of NH3. With increasing NH4NO3 concentration, the NH4+exchange degree increased while the crystallinity of the zeolite remained intact. Crystalline CuO was formed when the NH4+exchange degree of NaNH4Y was low, and the corresponding CuY catalyst showed low catalytic activity. With increasing of the NH4+exchange degree of NaNH4Y, the content of surface bound Cu+active centers increased and the catalytic activity of the corresponding CuY catalyst also increased. The surface bound Cu+content reached its maximum when the NH4+ex‐change degree of NaNH4Y reached towards saturation. The CuY exhibited optimal catalytic activity with 267.3 mg/(g·h) space time yield of DMC, 6.9%conversion of methanol, 68.5%selectivity of DMC. 展开更多
关键词 High temperature anhydrous interaction NH4+exchange degree CuY catalyst Oxidative carbonylation Dimethyl carbonate
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Effects of Carbonate on Exchangeability and Bioavailability of Exogenous Neodymium in Soil 被引量:3
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作者 徐仲均 李德成 +1 位作者 杨剑虹 彭安 《Journal of Rare Earths》 SCIE EI CAS CSCD 2001年第3期233-237,共5页
The effects of carbonate on the exchangeability and the bioavailability of exogenous neodymium in soil were studied by Nd-147 isotopic tracer method. Exchangeable Nd was extracted by I mol(.)L(-1) NaAc (pH8.2) in the ... The effects of carbonate on the exchangeability and the bioavailability of exogenous neodymium in soil were studied by Nd-147 isotopic tracer method. Exchangeable Nd was extracted by I mol(.)L(-1) NaAc (pH8.2) in the experiment. The results indicate that whether carbonate exists in soil or not, beyond 99% of exogenous Nd is adsorbed by soil. Low-concentration carbonate (0.8 similar to 1.6 g(.)kg(-1)) can reduce exchangeable Nd concentration in soil, while high-concentration carbonate (4.0 g(.)kg(-1)) impacts little on the exchangeable Nd concentration. In addition, carbonate of 0.8 similar to 1.6 g(.)kg(-1) in soil can inhibit wheat seedlings to absorb Nd. However, when the carbonate concentration rises to 4.0 g(.)kg(-1) the inhibition will become indistinct. 展开更多
关键词 rare earths carbonATE NEODYMIUM exchangeABILITY BIOAVAILABILITY
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In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells(PEMFCs) 被引量:2
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作者 Sheng Sui Xiaolong Zhuo +4 位作者 Kaihua Su Xianyong Yao Junliang Zhang Shangfeng Du Kevin Kendall 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第3期477-483,共7页
An extensive study has been conducted on the proton exchange membrane fuel cells (PEMFCs) with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the ... An extensive study has been conducted on the proton exchange membrane fuel cells (PEMFCs) with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode (GCE) to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic (IV) acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm (diameter) x l0 nm (length) by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry (CV) and scanning electron microscope (SEM) as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants (oxygen or hydrogen). 展开更多
关键词 PLATINUM catalyst layer carbon powder layer proton exchange membrane fuel cells
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Interannual variations of the air-sea carbon dioxide exchange in the different regions of the Pacific Ocean 被引量:1
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作者 LI Yangchun XU Yongfu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2013年第3期71-79,共9页
Interannual variations of the air-sea CO2 exchange from 1965 to 2000 in the Pacific Ocean are studied with a Pacific Ocean model. Two numerical experiments are performed, including the control run that is forced by cl... Interannual variations of the air-sea CO2 exchange from 1965 to 2000 in the Pacific Ocean are studied with a Pacific Ocean model. Two numerical experiments are performed, including the control run that is forced by climatological monthly mean physical data and the climate-change run that is forced by interannually varying monthly mean physical data. Climatological monthly winds are used in both runs to calculate the coefficient of air-sea CO2 exchange. The analysis through the differences between the two runs shows that in the tropical Pacific the variation of export production induced by interannual variations of the physical fields is negatively correlated with that of the air-sea CO2 flux, while there is no correlation or a weak positive correlation in the subtropical North and South Pacific. It indicates that the variation of the physical fields can modulate the variation of the air-sea CO2 flux in converse ways in the tropical Pacific by changing the direct transport and biochemical process. Under the interannually varying monthly mean forcing, the simulated EOF 1 of the air-sea CO2 flux is basically consistent with that of sea surface temperature (SST) in the tropical Pacific, but contrary in the two subtropical Pacific Ocean. The correlation coefficient between the regionally integrated air-sea CO2 flux and area-mean SST shows that when the air-sea CO2 flux lags SST by about 5 months, the positive coefficient in the three regions is largest, indicating that in the tropical Pacific or on the longer time scale in the three regions, physical processes control the fiux-SST relationship. 展开更多
关键词 air-sea carbon dioxide exchange surface temperature export production interannual varia-tions Pacific Ocean
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High-performance proton exchange membrane fuel cell with ultra-low loading Pt on vertically aligned carbon nanotubes as integrated catalyst layer 被引量:3
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作者 Qing Hao Meng Chao Hao +4 位作者 Bowen Yan Bin Yang Jia Liu Pei Kang Shen Zhi Qun Tian 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第8期497-506,I0013,共11页
Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure ... Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance. 展开更多
关键词 Proton exchange membrane fuel cells Order-structured catalyst layer Vertically aligned carbon nanotubes Ultra-low Pt loading Membrane electrode assembly
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Tree-Ring Carbon Isotopic Constraints on Carbon-Water Exchanges between Atmosphere and Biosphere in Drought Regions in Northwestern China 被引量:1
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作者 WANG Shilu WAN Guojiang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2000年第2期301-305,共5页
The comparison between the carbon isotope and the index of ring width of a pine disc from the Tuomuer Peak region in Xinjiang shows that the effects of climate changes on the tree-ring growth and carbon isotopic fract... The comparison between the carbon isotope and the index of ring width of a pine disc from the Tuomuer Peak region in Xinjiang shows that the effects of climate changes on the tree-ring growth and carbon isotopic fractionation varies with time. The reason is probably relative to the characters of climate changes and adaptability of the tree-ring growth to climate changes. The relationships between the atmospheric CO2 level and the revised δ13Cair by the tree-ring carbon isotope indicate that the carbon cycle is not in a steady state, but under a stage-change condition in this area. It also can be concluded that the ratio of CO2 from the terrestrial eco-system has increased, and the flux of CO2 exchange between the atmosphere and the biosphere was gradually increasing over the past century. In addition, the results also confirm the validity and superiority of the carbon isotope to the research of the water-use efficiency. 展开更多
关键词 tree ring carbon isotope CO_(2) exchange water-use efficiency
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Direct Radiative Effect of Aerosols on Net Ecosystem Carbon Exchange in the Pearl River Delta Region 被引量:1
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作者 MAI Bo-ru DENG Xue-jiao +1 位作者 LIU Xia YIN Shu-xian 《Journal of Tropical Meteorology》 SCIE 2021年第3期272-281,共10页
The environmental impact of aerosols is currently a hot issue that has received worldwide attention. Lacking simultaneous observations of aerosols and carbon flux, the understanding of the aerosol radiative effect of ... The environmental impact of aerosols is currently a hot issue that has received worldwide attention. Lacking simultaneous observations of aerosols and carbon flux, the understanding of the aerosol radiative effect of urban agglomeration on the net ecosystem carbon exchange(NEE) is restricted. In 2009-2010, an observation of the aerosol optical property and CO_(2) flux was carried out at the Dongguan Meteorological Bureau Station(DMBS) using a sun photometer and eddy covariance systems. The different components of photosynthetically active radiation(PAR),including global PAR(GPAR), direct PAR(DPAR), and scattered PAR(FPAR), were calculated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART) model. The effects of PAR on the NEE between land-atmosphere systems were investigated. The results demonstrated that during the study period the aerosol optical depth(AOD)reduced the DPAR by 519.28±232.89 μmol photons · m^(-2)s^(-1), but increased the FPAR by 324.93±169.85μmol photons ·m^(-2)s^(-1),ultimately leading to 194.34±92.62 μmol photons · m^(-2)s^(-1);decrease in the GPAR. All the PARs(including GPAR,DPAR, and FPAR) resulted in increases in the NEE(improved carbon absorption), but the FPAR has the strongest effect with the light use efficiency(LUE) being 1.12 times the values for the DPAR. The absorption of DPAR by the vegetation exhibited photo-inhibition in the radiation intensity > 600 photons · m^(-2)s^(-1);in contrast, the absorptions of FPAR did not exhibit apparent photo-inhibition. Compared with the FPAR caused by aerosols, the DPAR was not the primary factor affecting the NEE. On the contrary, the increase in AOD significantly increased the FPAR, enhancing the LUE of vegetation ecosystems and finally promoting the photosynthetic CO_(2) absorption. 展开更多
关键词 atmospheric aerosol photosynthetically active radiation net ecosystem carbon exchange
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Elements, Structure and Electrochemical Property of Carbon Derived from La^(3+) Adulterating Polystyrene Cation Exchange Resin
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作者 WANG Shu jun 1, LIU Qing guo 2 ( 1. Department of Chemical Engineer, University of Petroleum Beijing, Beijing 102200, China 2. Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China) 《Journal of Rare Earths》 SCIE EI CAS CSCD 2000年第3期214-214,共1页
The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion... The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion cell were investigated. The test results show that comparing with the polystyrene cation exchange resin without adulterating, the contents of hydrogen, oxygen and sulfur are changed obviously for the resin carbon material derived from the La 3+ adulterating polystyrene cation exchange resin. The contents of hydrogen and oxygen are increased, and the one of sulfur is decreased. The test results also indicate that it is more easily to form the stratum graphite minicrystal structure with bigger diameter for the La 3+ adulterating resin. According to the electrochemical test results, the electrode derived from La 3+ adulterating polystyrene cation exchange resin has much better electrochemical property, and the capacity of charge and discharge of the electrode is increased about 30 mAh·g -1 in average. 展开更多
关键词 rare earths ion adulterating polystyrene cation exchange resin carbon electrode material
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Controllable ion exchange synthesis of Ir/Carbon catalyst
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作者 朱少敏 姜玉玲 荣军 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2010年第2期283-285,共3页
In this paper,a carbon based iridium (Ir) catalyst was prepared by an ion exchange procedure using H2IrCl6 as precursor and a strong basic anion exchange resin as substrate. The Ir/Carbon sample was obtained by carbon... In this paper,a carbon based iridium (Ir) catalyst was prepared by an ion exchange procedure using H2IrCl6 as precursor and a strong basic anion exchange resin as substrate. The Ir/Carbon sample was obtained by carbonizing the precursor. Effects of carbonization parameters such as temperature and time on size and dispersion of iridium crystallite were studied. Samples were prepared at 400 oC and 500 oC to investigate the effect of carbonization temperature. The SEM image of the Ir/Carbon composite shows a hard particle of 0. 2 - 0. 4 mm in diameter,which maintains a spherical shape. The TEM images of the catalyst show that no obvious effects of carbonization temperature or time are observed on the iridium particle size. Calcinated Ir nanoparticles prepared in ion exchange still keep their small particle-sized and narrow-sized distribution. The content of Ir supported on carbon can be well controlled simply by adjusting the relative ratio of Ir to carbon. Such a promising synthesis procedure is a versatile approach that can be extended to the fabrication of some carbon-supported metal catalysts or as a simple,rapid,and highly sensitive method. 展开更多
关键词 Ir/carbon ion exchange NANOPARTICLE
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The fate of carbon resulting from pore water exchange in a mangrove and Spartina alterniflora ecozone
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作者 Weizhen Jiang Guizhi Wang +4 位作者 Qing Li Manab Kumar Dutta Shilei Jin Guiyuan Dai Yi Xu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第8期61-76,共16页
Mangrove and salt-marsh wetlands are important coastal carbon sinks.In order to quantify carbon export via pore water exchange and to evaluate subsequent fate of the exported carbon,we carried out continuous observati... Mangrove and salt-marsh wetlands are important coastal carbon sinks.In order to quantify carbon export via pore water exchange and to evaluate subsequent fate of the exported carbon,we carried out continuous observations in a mangrove-Spartina alterniflora ecozone in the Zhangjiang River Estuary,China.The carbon fluxes via pore water exchange were estimated using^(222)Rn and^(228)Ra as tracers to be(2.15±0.63)mol/(m^(2)∙d)for dissolved inorganic carbon(DIC)and(-0.008±0.07)mol/(m^(2)∙d)for dissolved organic carbon(DOC)in the wet season and(3.02±0.65)mol/(m^(2)∙d)for DIC and(-0.15±0.007)mol/(m^(2)∙d)for DOC in the dry season in the mangrove-dominated creek(M-creek),while(2.52±0.82)mol/(m^(2)∙d)for DIC and(0.02±0.09)mol/(m^(2)∙d)for DOC in the dry season in the S.alterniflora-dominated creek(SA-creek).The negative value means that pore water was a sink of DOC in the creek.The total carbon via pore water exchange in the tidal creeks in the mangroves accounted for 41%-55%of the net carbon fixed by mangrove vegetation and was 3-4 times as much as the soil carbon accretion in the mangroves.The exported carbon in the form of DIC contributed all of the carbon outwelling from the M-creek and 79%of the carbon outwelling from the SA-creek,implying effective fixation of carbon by the wetland ecosystem.Moreover,it resulted in 54%in the dry season,75%in the wet season of the carbon dioxide released from the M-creek to the atmosphere,and 84%of the release from the SA-creek.Therefore,quantification of pore water exchange and related soil carbon loss is essential to trace the fate of carbon fixed in intertidal wetlands. 展开更多
关键词 MANGROVE SALT-MARSH carbon dioxide carbon accretion carbon outwelling pore water exchange
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Processes of depositing platinum on carbon nanotubes and their effect on performance of proton exchange membrane fuel cell
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作者 YanhuiLi JunDing +3 位作者 JunfengChen ZongqiangMao CailuXu DehaiWu 《Journal of University of Science and Technology Beijing》 CSCD 2004年第4期349-353,共5页
The ultrafine platinum nanoparticles deposited on the surfaces of carbonnanotubes (Pt/CNTs) were prepared by a chemical precipitation method and used as the catalyst ofproton exchange membrane fuel cell. The depositin... The ultrafine platinum nanoparticles deposited on the surfaces of carbonnanotubes (Pt/CNTs) were prepared by a chemical precipitation method and used as the catalyst ofproton exchange membrane fuel cell. The depositing process parameters such as the solution pH value,Pt content and treatment temperature were analyzed. The experimental results show that the optimumprocess parameters to prepare Pt/CNTs are the solution pH value of 7.0, the theoretical Pt contentof 25 percent (mass fraction) and the heating temperature of 500 deg C, under the conditions thebest performance of the proton exchange membrane fuel cell can be obtained and its voltage can reach580 mV at a current density of 500 mA/cm^2. 展开更多
关键词 carbon nanotubes PLATINUM DEPOSITION proton exchange membrane fuel cell
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Air-Water Carbon Dioxide Exchange in the Littoral Zone of Lake Baikal (Ice-Free Period)
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作者 Valentina M. Domysheva Mikhail V. Panchenko +1 位作者 Dmitry A. Pestunov Mariya V. Sakirko 《International Journal of Geosciences》 2013年第10期1339-1345,共7页
Lake Baikal is one of the most unique natural environments in Siberia, and it affects to a large extent the natural state in this region. Processes of gas exchange in the air-water system have been studied in Lake Bai... Lake Baikal is one of the most unique natural environments in Siberia, and it affects to a large extent the natural state in this region. Processes of gas exchange in the air-water system have been studied in Lake Baikal since 2002. Measurements have been carried out in the littoral area on the western shore of Southern Baikal (51°51'N, 105°04'E). The method of accumulative chambers was prioritized for measuring carbon dioxide fluxes in the air-water system. Chemical analysis of the water samples collected every three hours at the chamber locations was carried out in the on-land laboratory. We measured pH, content of dissolved oxygen, bicarbonate, nitrate and phosphate. The CO2 content in the water was measured from pH values and the bicarbonate concentration. The total sink of CO2 on the water surface is increasing in the littoral area of Lake Baikal from 20 mg·CO2·m-2·day-1 in June to 110 mg·CO2·m-2·day-1 in August. The decrease in the flux rate usually begins in September from 95 mg·CO2·m-2·day-1 to the zero balance in late October - early November. The maximal rate of mean diurnal CO2 emissions is recorded in December in the pre-ice period (110 mg·CO2·m-2·day-1). Based on the long-term measurements during all seasons, the sink of atmospheric CO2 in the littoral zones of Lake Baikal was estimated to be 3 - 5 g·CO2·m-2. 展开更多
关键词 Gas exchange carbon Dioxide FLUX Dissolved GASES NUTRIENTS
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Modelling the impacts of cover crop management strategies on the water use,carbon exchange and yield of olive orchards
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作者 Alvaro López-Bernal Omar García-Tejera +1 位作者 Luca Testi Francisco J.Villalobos 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第1期283-295,共13页
Cover crops have long been proposed as an alternative soil management for minimizing erosion rates in olive stands while providing additional ecosystem services.However,the trade-off between these benefits and the com... Cover crops have long been proposed as an alternative soil management for minimizing erosion rates in olive stands while providing additional ecosystem services.However,the trade-off between these benefits and the competition for water with the trees makes the definition of optimal management practices a challenging task in semiarid climates.This work presents an improved version of OliveCan,a process-based simulation model of olive orchards that now can simulate the main impacts of cover crops on the water and carbon balances of olive orchards.Albeit simple in its formulation,the new model components were developed to deal with different cover crop management strategies.Examples are presented for simulation runs of a traditional olive orchard in the conditions of southern Spain,evaluating the effects of different widths for the strip occupied by the cover crop(Fcc)and two contrasting mowing dates.Results revealed that high Fccresulted in lower olive yields,but only when mowing was applied at the end of spring.In this regard,late mowing and high Fccwas associated with lower soil water content from spring to summer,coinciding with olive flowering and the earlier stages of fruit growth.Fccwas also negatively correlated with surface runoff irrespective of the mowing date.On the other hand,net ecosystem productivity(NEP)was substantially affected by both Fccand mowing date.Further simulations under future climate scenarios comparing the same management alternatives are also presented,showing substantial yield reductions by the end of the century and minor or negligible changes in NEP and seasonal runoff. 展开更多
关键词 carbon exchange Cover crops Crop modelling EVAPOTRANSPIRATION Olea europaea L
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A bibliometric analysis of carbon exchange in global drylands
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作者 LIU Zhaogang CHEN Zhi +2 位作者 YU Guirui ZHANG Tianyou YANG Meng 《Journal of Arid Land》 SCIE CSCD 2021年第11期1089-1102,共14页
Drylands refer to regions with an aridity index lower than 0.65,and billions of people depend on services provided by the critically important ecosystems in these areas.How ecosystem carbon exchange in global drylands... Drylands refer to regions with an aridity index lower than 0.65,and billions of people depend on services provided by the critically important ecosystems in these areas.How ecosystem carbon exchange in global drylands(CED)occurs and how climate change affects CED are critical to the global carbon cycle.Here,we performed a comprehensive bibliometric study on the fields of annual publications,marked journals,marked institutions,marked countries,popular keywords,and their temporal evolution to understand the temporal trends of CED research over the past 30 a(1991-2020).We found that the annual scientific publications on CED research increased significantly at an average growth rate of 7.93%.Agricultural Water Management ranked first among all journals and had the most citations.The ten most productive institutions were centered on drylands in America,China,and Australia that had the largest number and most citations of publications on CED research."Climate change"and climate-related(such as"drought","precipitation","temperature",and"rainfall")research were found to be the most popular study areas.Keywords were classified into five clusters,indicating the five main research focuses on CED studies:hydrological cycle,effects of climate change,carbon and water balance,productivity,and carbon-nitrogen-phosphorous coupling cycles.The temporal evolution of keywords further showed that the areas of focus on CED studies were transformed from classical pedology and agricultural research to applied ecology and then to global change ecological research over the past 30 a.In future CED studies,basic themes(such as"water","yield",and"salinity")and motor themes(such as"climate change","sustainability",and"remote sensing")will be the focus of research on CED.In particular,multiple integrated methods to understand climate change and ecosystem sustainability are potential new research trends and hotspots. 展开更多
关键词 bibliometric analysis DRYLANDS carbon exchange climate change arid areas water resources SUSTAINABILITY
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Impact of Powdered Activated Carbon and Anion Exchange Resin on Photocatalytic Treatment of Textile Wastewater
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作者 Preethi Grace Theva Neethi Dhas Holger Gulyas Ralf Otterpohl 《Journal of Environmental Protection》 2015年第3期191-203,共13页
In order to clarify the impact of activated carbon and anion exchange resin on photocatalytic oxidation (PCO) of textile industry wastewater, TiO2-based PCO was investigated with aqueous solutions containing the react... In order to clarify the impact of activated carbon and anion exchange resin on photocatalytic oxidation (PCO) of textile industry wastewater, TiO2-based PCO was investigated with aqueous solutions containing the reactive dye Reactive Blue 4 (RB4) and with a textile dye house effluent in the absence and in the presence of powdered activated carbon (PAC) and the anion exchange resin Lewatit MP 500. Addition of Lewatit improved RB4 removal to a larger extent than PAC addition. Contrasting to chloride and sulfate, hydrogen carbonate clearly inhibited PCO of RB4. However, the depression of dye removal by hydrogen carbonate was minute in the presence of Lewatit although the hydrogen carbonate concentration was not markedly decreased. Unfortunately, the beneficial effect of Lewatit addition on PCO nearly disappeared when the Lewatit/TiO2 mixture was reused three times. This was probably caused by oxidative damage of the resin. Color removal from the real dye house effluent during PCO was improved by Lewatit, but not by PAC. Contrastingly, PAC addition increased TOC removal by PCO from the real wastewater to some extent, while Lewatit had no impact. Sorbent addition does not lead to an acceptable area demand for solar PCO of the dye house effluent. 展开更多
关键词 ACTIVATED carbon ANION exchange Hybrid Process PHOTOCATALYTIC Oxidation TEXTILE Industry EFFLUENT
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Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells
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作者 Jung A.Hong Min-Hyoung Jung +10 位作者 Sung Yong Cho Eun-Byeol Park Daehee Yang Young-Hoon Kim Sang-Hyeok Yang Woo-Sung Jang Jae Hyuck Jang Hyo June Lee Sungchul Lee Hu Young Jeong Young-Min Kim 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第11期359-367,I0010,共10页
The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the car... The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the nanoscale.However,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far.Therefore,a reliable methodology is required for the 3D geometrical evaluation of the carbon structure.Here,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution.This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D networking.These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation.This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes. 展开更多
关键词 Electron tomography Fuel cell Proton exchange membrane Membrane electrode assembly carbon corrosion
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Spatial variability in carbon dioxide exchange processes within wet sedge meadows in the Canadian High Arctic
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作者 Claire M.WRIGHT Amy C.BLASER +1 位作者 Paul M.TREITZ Neal A.SCOTT 《Advances in Polar Science》 CSCD 2021年第1期1-19,共19页
Wet sedge meadows are the most productive plant communities in the High Arctic.However,the controls on carbon dioxide(CO_(2))exchange processes within wet sedge communities-and the scale at which they operate-are poor... Wet sedge meadows are the most productive plant communities in the High Arctic.However,the controls on carbon dioxide(CO_(2))exchange processes within wet sedge communities-and the scale at which they operate-are poorly understood.Here,the factors controlling CO_(2)exchange of wet sedge meadows experiencing different moisture regimes are examined.Environmental data are used to create predictive models of CO_(2)exchange on multiple temporal scales.Automated chamber systems recorded CO_(2)fluxes at 30-minute intervals at wet sedge sites in the Canadian High Arctic from June to August in 2014 and 2015.Static chambers were also deployed over a larger spatial extent in 2014.Our results show that wet sedge communities were strong CO_(2)sinks during the growing season(−7.67 to−44.36 g C·m^(−2)).CO_(2)exchange rates in wetter and drier areas within wet sedge meadows differed significantly(Wilcoxon,p<0.001),suggesting that soil moisture regimes within vegetation types influence net CO_(2)balance.Random Forest models explained a significant amount of the variability in CO_(2)flux rates over time(R2=0.46 to 0.90).The models showed that the drivers of CO_(2)exchange in these communities vary temporally.Variable moisture regimes indirectly influenced CO_(2)fluxes given that they exhibit different vegetation and temperature-response characteristics.We suggest that the response of a single vegetation type to environmental changes may vary depending on microenvironment variability within that community. 展开更多
关键词 High Arctic carbon dioxide exchange wet sedge soil moisture
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Nanoshell-Containing Carbon Cathode Catalyst for Proton Exchange Membrane Fuel Cell from Herbaceous Plants Lignin
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作者 Naokatsu Kannari Machiko Takigami +3 位作者 Takuya Maie Hiroyuki Honda Sayaka Kusadokoro Jun-ichi Ozaki 《Smart Grid and Renewable Energy》 2013年第7期10-15,共6页
Nanoshell-containing carbon (NSCC) is one of the Pt-surrogate catalysts for proton exchange membrane fuel cell (PEMFC) invented by us to promote oxygen reduction reaction (ORR), the cathode reaction of the cell. In th... Nanoshell-containing carbon (NSCC) is one of the Pt-surrogate catalysts for proton exchange membrane fuel cell (PEMFC) invented by us to promote oxygen reduction reaction (ORR), the cathode reaction of the cell. In the present study, we selected one of renewable resources, lignin from herbaceous plants as the carbon precursor for NSCC. The lignin was admixed with cobalt phthalocyanine (CoPc), the nanoshell (NS) forming catalyst, and then carbonized at 1000℃. Transmission electron microscopy and X-ray diffraction studies confirmed the formation of NS structure. The ORR activity of the prepared NSCC increased with the amount of CoPc, and the activity of lignin-based NSCC was higher than that of phenol-formaldehyde resin-based NSCC with the same amount of CoPc added. Surface analysis by X-ray photoelectron spectroscopy revealed no metal species on the NSCC but higher N/C ratio for the lignin-based NSCC by two folds. This study shows the possibility of lignin as a precursor of NSCC cathode catalyst for PEMFC. 展开更多
关键词 PROTON exchange Membrane Fuel Cell Oxygen Reduction Reaction LIGNIN Nanoshell-Containing carbon
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