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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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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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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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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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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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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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STUDY ON THE ELECTROCHEMICAL BEHAVIOR OF ION EXCHANGE MEMBRANE IN PREPARING POTASSIUM CARBONATE
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作者 杨维驿 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 1985年第1期31-47,共17页
This investigation describes the one step preparation of potassium carbonate by electrolysis of potas-sium chloride solution in electrolyzers with various Nation membranes.Potassium bicarbonate solution wasfed to the ... This investigation describes the one step preparation of potassium carbonate by electrolysis of potas-sium chloride solution in electrolyzers with various Nation membranes.Potassium bicarbonate solution wasfed to the cathode compartment,where it was converted into carbonate by reaction with the hydroxideformed at cathode.Because of the low OH^- concentration in the cathode compartment,the back migrationof OH^- through the membrane was almost negligible,resulting in a higher current efficiency,say 90% or more.In this study,electroconductivity,mass transfer,current efficiency and cell voltage were measured.Thefeasibility of the process was discussed and the optimal conditions examined. 展开更多
关键词 KOH STUDY ON THE ELECTROCHEMICAL BEHAVIOR OF ION exchange MEMBRANE IN PREPARING POTASSIUM carbonATE RATE
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Application of remote sensing,an artificial neural network leaf area model,and a process-based simulation model to estimate carbon storage in Florida slash pine plantations. 被引量:4
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作者 Douglas A.Shoemaker Wendell P.Cropper Jr 《Journal of Forestry Research》 SCIE CAS CSCD 2010年第2期171-176,I0005,共7页
Carbon sequestration in forests is of great interest due to concerns about global climate change.Carbon storage rates depend on ecosystem fluxes(photosynthesis and ecosystem respiration),typically quantified as net ... Carbon sequestration in forests is of great interest due to concerns about global climate change.Carbon storage rates depend on ecosystem fluxes(photosynthesis and ecosystem respiration),typically quantified as net ecosystem exchange(NEE).Methods to estimate forest NEE without intensive site sampling are needed to accurately assess rates of carbon sequestration at stand-level and larger scales.We produced spatially-explicit estimates of NEE for 9 770 ha of slash pine(Pinus elliottii) plantations in North-Central Florida for a single year by coupling remote sensing-based estimates of leaf area index(LAI) with a process-based growth simulation model.LAI estimates produced from a neural-network modeling of ground plot and Landsat TM satellite data had a mean of 1.06(range 0-3.93,including forest edges).Using the neural network LAI values as inputs,the slash pine simulation model(SPM2) estimates of NEE ranged from-5.52 to 11.06 Mg·ha^-1·a^-1with a mean of 3.47 Mg·ha^-1·a^-1Total carbon storage for the year was 33920 t,or about 3.5 tons per hectare.Both estimated LAI and NEE were highly sensitive to fertilization. 展开更多
关键词 artificial neural network leaf area carbon exchange slash pine NEE forest carbon
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Carbon dioxide fluxes of tundra vegetation communities on an esker top in the low-Arctic
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作者 Peter M.LAFLEUR A.Brett CAMPEAU Sohee KANG 《Advances in Polar Science》 CSCD 2020年第3期167-177,共11页
Previous studies have shown that carbon dioxide fluxes vary considerably among Arctic environments and it is important to assess these differences in order to develop our understanding of the role of Arctic tundra in ... Previous studies have shown that carbon dioxide fluxes vary considerably among Arctic environments and it is important to assess these differences in order to develop our understanding of the role of Arctic tundra in the global carbon cycle. Although many previous studies have examined tundra carbon dioxide fluxes, few have concentrated on elevated terrain(hills and ridge tops) that is exposed to harsh environmental conditions resulting in sparse vegetation cover and seemingly low productivity. In this study we measured carbon dioxide(CO2) exchange of four common tundra communities on the crest of an esker located in the central Canadian low-Arctic. The objectives were to quantify and compare CO2 fluxes from these communities, investigate responses to environmental variables and qualitatively compare fluxes with those from similar communities growing in less harsh lowland tundra environments. Measurements made during July and August 2010 show there was little difference in net ecosystem exchange(NEE) and gross ecosystem production(GEP) among the three deciduous shrub communities, Arctous alpina, Betula glandulosa and Vaccinium uliginosum, with means ranging from -4.09 to -6.57 μmol·m^-2·s^-1 and -7.92 to -9.24 μmol·m^-2·s^-1, respectively. Empetrum nigrum communities had significantly smaller mean NEE and GEP(-1.74 and -4.08 μmol·m^-2·s^-1, respectively). Ecosystem respiration(ER) was similar for all communities(2.56 to 3.03 μmol·m^-2·s^-1), except the B. glandulosa community which had a larger mean flux(4.66 μmol·m^-2·s^-1). Overall, fluxes for these esker-top communities were near the upper range of fluxes reported for other tundra communities. ER was related to soil temperature in all of the communities. Only B. glandulosa GEP and ER showed sensitivity to a persistent decline in soil moisture throughout the study. These findings may have important implications for how esker tops would be treated in construction of regional carbon budgets and for predicting the impacts of climate change on Arctic tundra future carbon budgets. 展开更多
关键词 tundra carbon exchange net ecosystem exchange gross ecosystem productivity ecosystem respiration low-Arctic esker top xerophytes
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Investigations of Carbon Sequestration and Storage Using Advanced Geospatial Analysis
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作者 Joonghyeok Heo John DeCicco 《Journal of Energy and Power Engineering》 2018年第5期223-230,共8页
This research demonstrated quantitative methods of geospatial analysis applicable to carbon sequestration and storage in the conterminous United Sates. We identified national-scale NEP (net ecosystem production) cha... This research demonstrated quantitative methods of geospatial analysis applicable to carbon sequestration and storage in the conterminous United Sates. We identified national-scale NEP (net ecosystem production) changes for conversions to and from crop, and land in frequent conversion among forest, wetland, pasture and rangeland. The trend showed an increase in the margins of the Corn Belt states and coincided with land conversion from previous non-cropland to cropland in the United States. This research will not only improve the engineering understanding of carbon dioxide removal options involving the terrestrial biosphere, but will also inform decision-making in the carbon emission impacts. Therefore, it will provide a spatio-temporal reference for analyzing the national-level carbon exchange systems in the United States. 展开更多
关键词 carbon sequestration carbon exchange temporal filter spatial analysis zonal statistic.
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Carbon Fluxes and Sinks:the Consumption of Atmospheric and Soil CO_2 by Carbonate Rock Dissolution 被引量:21
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作者 CAO Jianhua YUAN Daoxian +3 位作者 Chris GROVES HUANG Fen YANG Hui LU Qian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2012年第4期963-972,共10页
Carbonate rock outcrops cover 9%-16% of the continental area and are the principal source of the dissolved inorganic carbon (DIC) transferred by rivers to the oceans, a consequence their dissolution. Current estimat... Carbonate rock outcrops cover 9%-16% of the continental area and are the principal source of the dissolved inorganic carbon (DIC) transferred by rivers to the oceans, a consequence their dissolution. Current estimations suggest that the flux falls between 0.1-0.6 PgC/a. Taking the intermediate value (0.3 PgC/a), it is equal to 18% of current estimates of the terrestrial vegetation net carbon sink and 38% of the soil carbon sink. In China, the carbon flux from carbonate rock dissolution is estimated to be 0.016 PgC/a, which accounts for 21%, 87.5%-150% and 2.3 times of the forest, shrub and grassland net carbon sinks respectively, as well as 23%-40% of the soil carbon sink flux. Carbonate dissolution is sensitive to environmental and climatic changes, the rate being closely correlated with precipitation, temperature, also with soil and vegetation cover. HCO3 in the water is affected by hydrophyte photosynthesis, resulting in part of the HCO~ being converted into DOC and POC, which may enhance the potential of carbon sequestration by carbonate rock dissolution. The possible turnover time of this carbon is roughly equal to that of the sea water cycle (2000a). The uptake of atmospheric/soil CO2 by carbonate rock dissolution thus plays an important role in the global carbon cycle, being one of the most important sinks. A major research need is to better evaluate the net effect of this sink in comparison to an oceanic source from carbonate mineral precipitation. 展开更多
关键词 carbonate rock carbon transfer carbon flux and sink exchange between inorganic carbon and organic carbon
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Application of least squares vector machines in modelling water vapor and carbon dioxide fluxes over a cropland 被引量:1
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作者 秦钟 于强 +2 位作者 李俊 吴志毅 胡秉民 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE EI CAS CSCD 2005年第6期491-495,共5页
Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a s... Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem. 展开更多
关键词 Least squares support vector machines (LS-SVMs) Water vapor and carbon dioxide fluxes exchange Radial basis function (RBF) neural networks
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Gap Filling of Net Ecosystem CO<sub>2</sub>Exchange (NEE) above Rain-Fed Maize Using Artificial Neural Networks (ANNs) 被引量:1
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作者 Babak Safa Timothy J. Arkebauer +2 位作者 Qiuming Zhu Andy Suyker Suat Irmak 《Journal of Software Engineering and Applications》 2021年第5期150-171,共22页
<span style="font-family:Verdana;">The eddy covariance technique is an accurate and direct tool to measure the Net Ecosystem Exchange (NEE) of carbon dioxide. However, sometimes conditions are not amen... <span style="font-family:Verdana;">The eddy covariance technique is an accurate and direct tool to measure the Net Ecosystem Exchange (NEE) of carbon dioxide. However, sometimes conditions are not amenable to measurements using this technique. Thus, different methods have been developed to allow gap-filling and quality assessment of eddy covariance data sets. In this study first, two different Artificial Neural Networks (ANNs) approaches, the Multi-layer Perceptron (MLP) trained by the Back-Propagation (BP) algorithm, and the Radial Basis Function (RBF), were used to fill missing NEE data measured above rain-fed maize at the University of Nebraska-Lincoln Agricultural Research and Development Center near Mead, Nebraska. The gap-filled data were then compared by different statistical indices to gap-filled data obtained with the technique suggested by Suyker and Verma in 2005 [S&V method], and the ANN approach presented by Papale in 2003. The results showed that the RBF network was able to find better fits for missing values compared to the MLP (BP) network and S&V method. In addition, unlike the S&V method, which depends on different gap-filling procedures over the year;the structure of RBF and MLP (BP) networks was constant. However, data analysis indicated Papale’s approach gave better fits than the RBF and MLP (BP) methods. Thus, based on this work, Papale’s approach is the best method to estimate the missing data;though the applied statistical indices, which were used for model evaluation, show little difference between Papale’s approach and the RBF and MLP (BP).</span> 展开更多
关键词 Gap Filling Net Ecosystem exchange of carbon Dioxide Artificial Neural Networks Eddy Covariance System
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Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates 被引量:4
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作者 Ming Liu Hong-feng Xu +1 位作者 Jie Fu Ying Tian 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第7期844-849,共6页
Ni–Cr enrichment on stainless steel SS316 L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thi... Ni–Cr enrichment on stainless steel SS316 L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316 L substrate. The corrosion resistance of this film in 0.5 mol·L^(-1) H_2SO_4 solution containing 5 ppm F- at 80°C was investigated using polarization tests. The results showed that the surface treatment of the SS316 L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316 L, the Ag-doped carbon-coated SS316 L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell(PEMFC) and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 m?·cm^2 to 21.6 m?·cm^2 at a compaction pressure of 1.2 MPa. 展开更多
关键词 proton exchange membrane fuel cells bipolar plates stainless steel silver carbon spraying corrosion
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Decadal shifts in Qingzang Plateau lake carbon dynamics (1970-2020): From predominant carbon sources to emerging sinks
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作者 Di Shen Yu Li +6 位作者 Yafeng Wang Shouliang Huo Yong Liu Junjie Jia Shuoyue Wang Kun Sun Yang Gao 《Environmental Science and Ecotechnology》 SCIE 2024年第5期123-132,共10页
The evasion of carbon dioxide(CO_(2))from lakes significantly influences the global carbon equilibrium.Amidst global climatic transformations,the role of Qingzang Plateau(QZP)lakes as carbon(C)sources or sinks remains... The evasion of carbon dioxide(CO_(2))from lakes significantly influences the global carbon equilibrium.Amidst global climatic transformations,the role of Qingzang Plateau(QZP)lakes as carbon(C)sources or sinks remains a subject of debate.Furthermore,accurately quantifying their contribution to the global carbon budget presents a formidable challenge.Here,spanning half a century(1970e2020),we utilize a synthesis of literature and empirical field data to assess the CO_(2) exchange flux of QZP lakes.We find markedly higher CO_(2) exchange flux in the southeast lakes than that in the northern and western regions from 1970 to 2000.During this time,both freshwater and saltwater lakes served primarily as carbon sources.The annual CO_(2) exchange flux was estimated at 2.04±0.37 Tg(Tg)C yr1,mainly influenced by temperature fluctuations.The CO_(2) exchange flux patterns underwent a geographical inversion between 2000 and 2020,with increased levels in the west and decreased levels in the east.Notably,CO_(2) emissions from freshwater lakes diminished,and certain saltwater lakes in the QTP transitioned from carbon sources to sinks.From 2000 to 2020,the annual CO_(2) exchange flux from QZP lakes is estimated at 1.34±0.50 Tg C yr1,with solar radiation playing a more pronounced role in carbon emissions.Cumulatively,over the past five decades,QZP lakes have generally functioned as carbon sources.Nevertheless,the total annual CO_(2) emissions have declined since the year 2000,indicating a potential shift trend from being a carbon source to a sink,mirroring broader patterns of global climate change.These findings not only augment our understanding of the carbon cycle in plateau aquatic systems but also provide crucial data for refining China's carbon budget. 展开更多
关键词 carbon source carbon sink carbon exchange flux Qingzang Plateau Global climate change
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Water-use efficiency in response to simulated increasing precipitation in a temperate desert ecosystem of Xinjiang, China 被引量:6
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作者 HUANG Gang LI Yan +2 位作者 MU Xiaohan ZHAO Hongmei CAO Yanfeng 《Journal of Arid Land》 SCIE CSCD 2017年第6期823-836,共14页
Water-use efficiency(WUE) is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored... Water-use efficiency(WUE) is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE. Here, we analyzed the responses of leaf WUE, ecosystem carbon and water exchanges, ecosystem WUE, and plant community composition changes under normal conditions and also under extra 15% or 30% increases in annual precipitation in a temperate desert ecosystem of Xinjiang, China. We found that leaf WUE and ecosystem WUE showed inconsistent responses to increasing precipitation. Leaf WUE consistently decreased as precipitation increased. By contrast, the responses of the ecosystem WUE to increasing precipitation are different in different precipitation regimes: increasing by 33.9% in the wet year(i.e., the normal precipitation years)and decreasing by 4.1% in the dry year when the precipitation was about 30% less than that in the wet year.We systematically assessed the herbaceous community dynamics, community composition, and vegetation coverage to explain the responses of ecosystem WUE, and found that the between-year discrepancy in ecosystem WUE was consistent with the extent to which plant biomass was stimulated by the increase in precipitation. Although there was no change in the relative significance of ephemerals in the plant community, its greater overall plant biomass drove an increased ecosystem WUE under the conditions of increasing precipitation in 2011. However, the slight increase in plant biomass exerted no significant effect on ecosystem WUE in 2012. Our findings suggest that an alteration in the dominant species in this plant community can induce a shift in the carbon-and water-based economics of desert ecosystems. 展开更多
关键词 desert ecosystem ecosystem water-use efficiency gross carbon exchange increasing precipitation leaf water-use efficiency net carbon exchange Gurbantunggut Desert
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The Effect of Low Night and High Day Temperatures on Photosynthesis in Tomato
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作者 Arne B.Hückstadt A.Suthaparan +1 位作者 L.M.Mortensen H.R.Gislerod 《American Journal of Plant Sciences》 2013年第12期2323-2331,共9页
If low night temperatures can be combined with high day temperatures, providing optimal growth conditions for plants, a significant energy saving can be achieved in greenhouses. Lowering the night temperature from 18&... If low night temperatures can be combined with high day temperatures, providing optimal growth conditions for plants, a significant energy saving can be achieved in greenhouses. Lowering the night temperature from 18°C to 10°C-11°C for 8 h had no negative effect on the CO2 exchange rate (CER) during the following light period in tomato. This was found both in plants grown in artificial light only or in combination with daylight. Allowing the temperature to increase from 20°C to about 40°C, in parallel with an increasing solar photon flux density (PFD) from 0 up to about 800 μmol·m-2·s-1 in the greenhouse during summer, progressively increased CER when the CO2 concentration was maintained at 900 μmol·mol-1. At 400 μmol·mol-1 CO2, maximum CER was reached at about 600 μmol·m-2·s-1 PFD combined with a temperature of 32°C, and leveled out with a further increase in PFD and temperature. Maximum CER at high CO2 concentration was around 100% higher than at low CO2 level. Under early autumn conditions, CER increased up to about 500 μmol·m-2·s-1 PFD/32°C at low CO2 and up to about 600 μmol·m-2·s-1 PFD/35°C at high CO2. An elevated CO2 level doubled the CER in this experiment as well. Measurements of chlorophyll fluorescence showed no effect of low night temperature, high day temperature or CO2 concentration on the quantum yield of photosynthesis, indicating that no treatment negatively affected the efficiency of the photosynthetic apparatus. The results showed that low night temperatures may be combined with very high day temperatures without any loss of daily photosynthesis particularly in a CO2 enriched atmosphere. If this can be combined with normal plant development and no negative effects on the yield, significant energy savings can be achieved in greenhouses. 展开更多
关键词 carbon exchange Rate(CER) Chlorophyll Fluorescence CO2 Concentration Day Temperature Night Temperature Photon Flux Density(PFD) Solanum lycopersicon L.
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The Effect of Wide-Range Photosynthetic Active Radiations on Photosynthesis,Growth and Flowering of Rosa sp.and Kalanchoe blossfeldiana 被引量:4
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作者 Leiv M.Mortensen 《American Journal of Plant Sciences》 2014年第11期1489-1498,共10页
Miniature roses (Rosa sp.) and Kalanchoe blossfeldiana were grown at photon flux densities (PFD) ranging from 60 to 670 μmol·m-2·s-1 (associated with a temperature gradient from 20.0°C to 24.0°C [... Miniature roses (Rosa sp.) and Kalanchoe blossfeldiana were grown at photon flux densities (PFD) ranging from 60 to 670 μmol·m-2·s-1 (associated with a temperature gradient from 20.0°C to 24.0°C [TEMP1]) and from 50 to 370μmol·m-2-s-1 (associated with a temperature gradient from 22.5°C to 26.5°C [TEMP2]). The experiment was conducted in a greenhouse compartment at latitude 59° north in mid-winter. The daily photosynthetic active radiations (PAR) ranged from 4.3 to 48.2 and 3.6 to 26.6 mol·m-2·day-1 in the TEMP1 and TEMP2 treatments, respectively. Time until flowering in miniature roses decreased from about 50 to 35 days in the TEMP1 treatment and from 50 to 25 days in the TEMP2 treatment, when the PFD increased from 50 to 370μmol·m-2·s-1. In Kalanchoe time until flowering was decreased to the same extent (about 15 days) in both temperature treatments when PFD increased from 50 to 370 μmol·m-2·s-1. The number of flowers and the plant dry weight in miniature roses increased up to 300 – 400 μmol·m-2·s-1 PFD (21.6 - 28.8 mol·m-2 day-1 PAR), while flower stem fresh weight and plant dry weight in Kalanchoe increased up to 200 – 300 μmol·m-2·s-1 at TEMP1. Measurements of the diurnal carbon dioxide exchange rates (CER) in daylight in small plant stands of roses in summertime showed that CER was saturated at about 300 μmol·m-2·s-1 PFD at 370 μmol·mol-1 CO2 and at 400 – 500 μmol·m-2·s-1 PFD at 800 μmol·mol-1 CO2. For Kalanchoe similar results were obtained. Increasing the CO2 concentration from 370 to 800 μmol·mol-1 increased the CER in roses (48%) as well in Kalanchoe (69%). It was concluded that 15 to 20 mol·m-2·day-1 combined with about 24°C air temperature and high CO2 concentration will give a very good growth with lot of flowers within a short production time in miniature roses. For Kalanchoe 10 to 15 mol·m-2·day-1 combined with about 20°C and high CO2 produced a similar result. 展开更多
关键词 Ait Temperature carbon Dioxide exchange Rate FLOWERING GROWTH Kalanchoe blossfeldiana Miniature Rose Photon Flux Density Photosynthetic Active Radiation
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Soil Microbiological Activity and Carbon Dynamics in the Current Climate Change Scenarios:A Review 被引量:14
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作者 Javid A.SOFI Aabid H.LONE +5 位作者 Mumtaz A.GANIE Naseer A.DAR Sajad A.BHAT Malik MUKHTAR Mohd Ashraf DAR Shazia RAMZAN 《Pedosphere》 SCIE CAS CSCD 2016年第5期577-591,共15页
Microbial activities are affected by a myriad of factors with end points involved in nutrient cycling and carbon sequestration issues.Because of their prominent role in the global carbon balance and their possible rol... Microbial activities are affected by a myriad of factors with end points involved in nutrient cycling and carbon sequestration issues.Because of their prominent role in the global carbon balance and their possible role in carbon sequestration, soil microbes are very important organisms in relation to global climate changes. This review focuses mainly on the responses of soil microbes to climate changes and subsequent effects on soil carbon dynamics. An overview table regarding extracellular enzyme activities(EAA) with all relevant literature data summarizes the effects of different ecosystems under various experimental treatments on EAA. Increasing temperature, altered soil moisture regimes, and elevated carbon dioxide significantly affect directly or indirectly soil microbial activities.High temperature regimes can increase the microbial activities which can provide positive feedback to climate change, whereas lower moisture condition in pedosystem can negate the increase, although the interactive effects still remain unanswered. Shifts in soil microbial community in response to climate change have been determined by gene probing, phospholipid fatty acid analysis(PLFA),terminal restriction length polymorphism(TRFLP), and denaturing gradient gel electrophoresis(DGGE), but in a recent investigations,omic technological interventions have enabled determination of the shift in soil microbe community at a taxa level, which can provide very important inputs for modeling C sequestration process. The intricacy and diversity of the soil microbial population and how it responds to climate change are big challenges, but new molecular and stable isotope probing tools are being developed for linking fluctuations in microbial diversity to ecosystem function. 展开更多
关键词 carbon cycling carbon dioxide carbon exchange carbon sequestration microbe community soil enzymes soil moisture soil temperature
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Determining whether Qinghai–Tibet Plateau waterbodies have acted like carbon sinks or sources over the past 20 years 被引量:7
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作者 Junjie Jia Kun Sun +4 位作者 Sidan Lü Mingxu Li Yafeng Wang Guirui Yu Yang Gao 《Science Bulletin》 SCIE EI CAS CSCD 2022年第22期2345-2357,共13页
Half of all of China’s lakes are on the Qinghai–Tibet Plateau(QTP),which are mainly distributed at altitudes above 4000 m asl.Being under conditions of progressively intensifying anthropogenic activities and climate... Half of all of China’s lakes are on the Qinghai–Tibet Plateau(QTP),which are mainly distributed at altitudes above 4000 m asl.Being under conditions of progressively intensifying anthropogenic activities and climate change,the debate on whether QTP lakes act as carbon(C)sinks or sources remains unresolved.This study explores QTP lake C exchange processes and characteristics over the past two decades through field monitoring and data integration.Results reveal high lake carbon dioxide(CO_(2))exchange flux distribution patterns in its western and southern regions and correspondingly low values in its eastern and northern regions.Lake CO_(2)exchange flux rates also show significant temporal differences where those in the 2000s and 2010s were significantly higher compared to the 2020s.Annual total CO_(2)emission flux from QTP lakes has increased from 1.60 Tg Ca^(-1)in the 2000s to 6.87 Tg Ca^(-1)in the 2010s before decreasing to 1.16 Tg Ca^(-1)in the 2020s.However,QTP lakes have generally acted as C sinks when annual ice-cover periods are included in the estimation of annual C budgets.Consequently,QTP lakes are gradually evolving towards C sinks.Some small-sized freshwater lakes on the QTP exhibit C sequestration characteristics while low-mid altitude saltwater lakes also act as C sinks.Therefore,owing to the high uncertainties in the estimation of C exchange flux,the QTP lake C sink capacity has been largely underestimated. 展开更多
关键词 carbon budget carbon cycle carbon exchange flux Global climate change carbon emissions
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