scholarly journals O<sub>2</sub> : CO<sub>2</sub> exchange ratio for net turbulent flux observed in an urban area of Tokyo, Japan, and its application to an evaluation of anthropogenic CO<sub>2</sub> emissions

2020 ◽  
Vol 20 (9) ◽  
pp. 5293-5308
Author(s):  
Shigeyuki Ishidoya ◽  
Hirofumi Sugawara ◽  
Yukio Terao ◽  
Naoki Kaneyasu ◽  
Nobuyuki Aoki ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Urban Area ◽  
Co2 Emission ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Co2 Fluxes ◽  
Diurnal Cycles ◽  
Co2 Concentrations ◽  
Human Respiration ◽  
Two Peaks

Abstract. In order to examine O2 consumption and CO2 emission in a megacity, continuous observations of atmospheric O2 and CO2 concentrations, along with CO2 flux, have been carried out simultaneously since March 2016 at the Yoyogi (YYG) site located in the middle of Tokyo, Japan. An average O2 : CO2 exchange ratio for net turbulent O2 and CO2 fluxes (ORF) between the urban area and the overlaying atmosphere was obtained based on an aerodynamic method using the observed O2 and CO2 concentrations. The yearly mean ORF was found to be 1.62, falling within the range of the average OR values of liquid and gas fuels, and the annual average daily mean O2 flux at YYG was estimated to be −16.3 µmol m−2 s−1 based on the ORF and CO2 flux. By using the observed ORF and CO2 flux, along with the inventory-based CO2 emission from human respiration, we estimated the average diurnal cycles of CO2 fluxes from gas and liquid fuel consumption separately for each season. Both the estimated and inventory-based CO2 fluxes from gas fuel consumption showed average diurnal cycles with two peaks, one in the morning and another one in the evening; however, the evening peak of the inventory-based gas consumption was much larger than that estimated from the CO2 flux. This can explain the discrepancy between the observed and inventory-based total CO2 fluxes at YYG. Therefore, simultaneous observations of ORF and CO2 flux are useful in validating CO2 emission inventories from statistical data.

scholarly journals Consumption of atmospheric O<sub>2</sub> in an Urban Area of Tokyo, Japan derived from continuous observations of O<sub>2</sub> and CO<sub>2</sub> concentrations and CO<sub>2</sub> flux

2019 ◽  
Author(s):  
Shigeyuki Ishidoya ◽  
Hirofumi Sugawara ◽  
Yukio Terao ◽  
Naoki Kaneyasu ◽  
Nobuyuki Aoki ◽  
...  
Keyword(s):  
Urban Area ◽  
Consumption Rate ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
O2 Consumption ◽  
Co2 Fluxes ◽  
Aerodynamic Method ◽  
Co2 Concentrations ◽  
Global Mean

Abstract. In order to estimate the atmospheric O2 consumption in a megacity, continuous observations of atmospheric O2 and CO2 concentrations and of CO2 flux have been carried out simultaneously at the Yoyogi (YYG) site in middle of Tokyo, Japan since March 2016. An average O2 : CO2 exchange ratio for net turbulent O2 and CO2 fluxes (ORF) between the urban area and the overlying atmosphere was obtained based on an aerodynamic method using the observed O2 and CO2 concentrations. The yearly mean ORF was found to be 1.62, falling within the range of the average OR values of liquid and gas fuels. Seasonally different diurnal ORF cycles at YYG indicated that the consumption of gas fuels was larger in the winter than that in the summer, especially in the morning and late in the evening. By using the ORF and CO2 flux values, the annual mean O2 consumption rate was estimated to be −16.3 μmol m−2 s−1, which is more than 350 times larger than the global mean atmospheric O2 consumption rate (about −4 μmol yr−1), implying that our life in a megacity is far from sustainable from a viewpoint of the conservation of atmospheric O2.

scholarly journals Impacts of a decadal drainage disturbance on surface–atmosphere fluxes of carbon dioxide in a permafrost ecosystem

2016 ◽  
Vol 13 (18) ◽  
pp. 5315-5332 ◽  
Author(s):  
Fanny Kittler ◽  
Ina Burjack ◽  
Chiara A. R. Corradi ◽  
Martin Heimann ◽  
Olaf Kolle ◽  
...  
Keyword(s):  
Co2 Flux ◽  
Growing Season ◽  
Co2 Exchange ◽  
Ecosystem Structure ◽  
Co2 Fluxes ◽  
Near Surface ◽  
The Past ◽  
Tundra Ecosystem ◽  
Tussock Tundra ◽  
Hydrologic Conditions

Abstract. Hydrologic conditions are a major controlling factor for carbon exchange processes in high-latitude ecosystems. The presence or absence of water-logged conditions can lead to significant shifts in ecosystem structure and carbon cycle processes. In this study, we compared growing season CO2 fluxes of a wet tussock tundra ecosystem from an area affected by decadal drainage to an undisturbed area on the Kolyma floodplain in northeastern Siberia. For this comparison we found the sink strength for CO2 in recent years (2013–2015) to be systematically reduced within the drained area, with a minor increase in photosynthetic uptake due to a higher abundance of shrubs outweighed by a more pronounced increase in respiration due to warmer near-surface soil layers. Still, in comparison to the strong reduction of fluxes immediately following the drainage disturbance in 2005, recent CO2 exchange with the atmosphere over this disturbed part of the tundra indicate a higher carbon turnover, and a seasonal amplitude that is comparable again to that within the control section. This indicates that the local permafrost ecosystem is capable of adapting to significantly different hydrologic conditions without losing its capacity to act as a net sink for CO2 over the growing season. The comparison of undisturbed CO2 flux rates from 2013–2015 to the period of 2002–2004 indicates that CO2 exchange with the atmosphere was intensified, with increased component fluxes (ecosystem respiration and gross primary production) over the past decade. Net changes in CO2 fluxes are dominated by a major increase in photosynthetic uptake, resulting in a stronger CO2 sink in 2013–2015. Application of a MODIS-based classification scheme to separate the growing season into four sub-seasons improved the interpretation of interannual variability by illustrating the systematic shifts in CO2 uptake patterns that have occurred in this ecosystem over the past 10 years and highlighting the important role of the late growing season for net CO2 flux budgets.

scholarly journals Technical Note: Cost-efficient approaches to measure carbon dioxide (CO<sub>2</sub>) fluxes and concentrations in terrestrial and aquatic environments using mini loggers

2015 ◽  
Vol 12 (12) ◽  
pp. 3849-3859 ◽  
Author(s):  
D. Bastviken ◽  
I. Sundgren ◽  
S. Natchimuthu ◽  
H. Reyier ◽  
M. Gålfalk
Keyword(s):  
Co2 Flux ◽  
Technical Note ◽  
Aquatic Environments ◽  
Co2 Fluxes ◽  
Stream Network ◽  
Co2 Concentrations ◽  
Direct Measurements ◽  
Cost Efficient ◽  
Carbon Balances ◽  
Global Carbon

Abstract. Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be unknown as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore, it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soil or water, or CO2 concentrations in surface water, are typically labor intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil–atmosphere and lake–atmosphere fluxes, as well as of spatiotemporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO2aq) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor-efficient alternative for direct measurements and monitoring of CO2 flux and pCO2aq in terrestrial and aquatic environments.

scholarly journals Regulation of CO<sub>2</sub> emissions from temperate streams and reservoirs

2013 ◽  
Vol 10 (11) ◽  
pp. 7539-7551 ◽  
Author(s):  
S. Halbedel ◽  
M. Koschorreck
Keyword(s):  
Co2 Emission ◽  
Water Reservoir ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Small Degree ◽  
Dominant Factor ◽  
Physical Factors ◽  
Metabolic Processes ◽  
Piston Velocity ◽  
Co2 Concentrations

Abstract. It has become more and more evident that CO2 emission (FCO2) from freshwater systems is an important part of the global carbon cycle. To date, only a few studies have addressed the different mechanisms that regulate FCO2 in lotic and lentic systems. In a comparative study we investigated how different biogeochemical and physical factors can affect FCO2 values in streams and reservoirs. We examined the seasonal variability in CO2 concentrations and emissions from four streams and two pre-dams of a large drinking water reservoir located in the same catchment, and compared them with environmental factors that were measured concurrently. All the streams were generally supersaturated with CO2 throughout the year, while both reservoirs functioned to a small degree as CO2 sinks during summer stratification and CO2 sources after circulation had set in. FCO2 from streams ranged from 23 to 355 mmol m−2 d−1 and exceeded the fluxes recorded for the reservoirs (−8.9 to 161.1 mmol m−2 d−1). Both the generally high piston velocity (k) and the CO2 oversaturation contributed to the higher FCO2 from streams in comparison to lakes. In both streams and reservoirs FCO2 was mainly governed by the CO2 concentration (r = 0.92, p < 0.001 for dams; r = 0.90, p < 0.001 for streams), which was in turn affected by metabolic processes and nutrients in both systems and also by lateral inflow in the streams. Besides CO2 concentration, physical factors also influence FCO2 in lakes and streams. During stratification, FCO2 in both pre-dams was regulated by primary production in the epilimnion, which led to a decrease of FCO2. During circulation, when CO2 from the hypolimnion was mixed with the epilimnion, FCO2 increased on account of the CO2 input from the hypolimnion. The CO2 from the hypolimnion originates from the mineralisation of organic matter. FCO2 from streams was mainly influenced by geomorphological and hydrological factors affecting k, which is less relevant in low-wind lakes. Under high-wind conditions, however, k regulates FCO2 from lotic systems as well. We developed a theoretical framework describing the role of the different regulation mechanisms for FCO2 from streams and lakes. In summary, the dominant factor affecting FCO2 is the concentration of CO2 in the surface water. Lake stratification has a very important regulatory effect on FCO2 from lakes on account of its influence on CO2 concentrations and metabolic processes. Nevertheless, FCO2 values in heterotrophic streams are generally higher. The higher k values are responsible for the comparatively high degree of FCO2. On a Central European scale, CO2 emission from streams is probably of greater importance than the CO2 flux from standing waters.

scholarly journals A regional carbon data assimilation system and its preliminary evaluation in East Asia

2015 ◽  
Vol 15 (2) ◽  
pp. 1087-1104 ◽  
Author(s):  
Z. Peng ◽  
M. Zhang ◽  
X. Kou ◽  
X. Tian ◽  
X. Ma
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Preliminary Evaluation ◽  
Co2 Fluxes ◽  
Scaling Factors ◽  
Multi Scale ◽  
Co2 Concentrations ◽  
Inflation Factor

Abstract. In order to optimize surface CO2 fluxes at grid scales, a regional surface CO2 flux inversion system (Carbon Flux Inversion system and Community Multi-scale Air Quality, CFI-CMAQ) has been developed by applying the ensemble Kalman filter (EnKF) to constrain the CO2 concentrations and applying the ensemble Kalman smoother (EnKS) to optimize the surface CO2 fluxes. The smoothing operator is associated with the atmospheric transport model to constitute a persistence dynamical model to forecast the surface CO2 flux scaling factors. In this implementation, the "signal-to-noise" problem can be avoided; plus, any useful observed information achieved by the current assimilation cycle can be transferred into the next assimilation cycle. Thus, the surface CO2 fluxes can be optimized as a whole at the grid scale in CFI-CMAQ. The performance of CFI-CMAQ was quantitatively evaluated through a set of Observing System Simulation Experiments (OSSEs) by assimilating CO2 retrievals from GOSAT (Greenhouse Gases Observing Satellite). The results showed that the CO2 concentration assimilation using EnKF could constrain the CO2 concentration effectively, illustrating that the simultaneous assimilation of CO2 concentrations can provide convincing CO2 initial analysis fields for CO2 flux inversion. In addition, the CO2 flux optimization using EnKS demonstrated that CFI-CMAQ could, in general, reproduce true fluxes at grid scales with acceptable bias. Two further sets of numerical experiments were conducted to investigate the sensitivities of the inflation factor of scaling factors and the smoother window. The results showed that the ability of CFI-CMAQ to optimize CO2 fluxes greatly relied on the choice of the inflation factor. However, the smoother window had a slight influence on the optimized results. CFI-CMAQ performed very well even with a short lag-window (e.g. 3 days).

scholarly journals Effects of Different Water Management and Fertilizer Applications on CO2 Fluxes from a Selected Myanmar Rice (Oryza sativa L.) Cultivar

2020 ◽  
pp. 22-37
Author(s):  
Saw Min ◽  
Martin Rulik
Keyword(s):  
Water Management ◽  
Co2 Emission ◽  
Management Practices ◽  
Oryza Sativa L ◽  
Management Practice ◽  
Co2 Flux ◽  
Organic Manure ◽  
Inorganic Fertilizer ◽  
Co2 Uptake ◽  
Co2 Fluxes

The application of nitrogen fertilizer and the water management practices are important to optimize potential yields in rice cultivation. Moreover, they may affect the emissions patterns of methane (CH4) and carbon dioxide (CO2) emission. Compared to methane, knowledge about the combined effects of different fertilizer rates together with different water management practices on CO2 fluxes are scarce. Therefore, this study aims to assess CO2 fluxes of a selected rice cultivar in response to different fertilizer applications and water management practices. The treatments included two different applications of inorganic fertilizer (recommended rate and farmer’s practice), organic manure application and water management practices; continuous flooding (CF) and alternate wetting and drying (AWD). Mean total CO2 flux in CF was -30.82 g CO2 m-2 d-1 during daytime and 29.64 g CO2 m-2 d-1 during nighttime. Surprisingly, the average net CO2 fluxes were negative under both CF (-49 mg CO2 m-2h-1) and AWD practices (-127 mg CO2 m-2h-1), indicating a net CO2 uptake by the rice plants. Inorganic fertilizer applications led to considerably higher net CO2 emissions compared to the control under both CF and AWD. Conversely, CO2 emission fluxes in the treatment with organic manure showed negative net CO2 fluxes under both water management practices and while revealing the same fresh biomass as observed in other treatments (inorganic fertilizer and control). Taken together, modifications of current cultivation systems toward using organic manure, that emit less CO2, could effectively mitigate CO2 impacts regardless of the selected water management practice.

scholarly journals Technical Note: Cost-efficient approaches to measure carbon dioxide (CO<sub>2</sub>) fluxes and concentrations in terrestrial and aquatic environments using mini loggers

2015 ◽  
Vol 12 (3) ◽  
pp. 2357-2380 ◽  
Author(s):  
D. Bastviken ◽  
I. Sundgren ◽  
S. Natchimuthu ◽  
H. Reyier ◽  
M. Gålfalk
Keyword(s):  
Temporal Dynamics ◽  
Co2 Flux ◽  
Technical Note ◽  
Aquatic Environments ◽  
Co2 Fluxes ◽  
Stream Network ◽  
Co2 Concentrations ◽  
Direct Measurements ◽  
Spatio Temporal ◽  
Global Carbon

Abstract. Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be neglected as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soils or waters, or CO2 concentrations in surface water, are typically labour intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil–atmosphere and lake–atmosphere fluxes, as well as of spatio-temporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO2aq) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor efficient alternative for direct measurements and monitoring of CO2 flux and pCO2aq in terrestrial and aquatic environments.

scholarly journals A regional carbon flux data assimilation system and its preliminary evaluation in East Asia

2014 ◽  
Vol 14 (14) ◽  
pp. 20345-20381
Author(s):  
Z. Peng ◽  
M. Zhang ◽  
X. Kou ◽  
X. Tian ◽  
X. Ma
Keyword(s):  
Carbon Flux ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Preliminary Evaluation ◽  
Co2 Fluxes ◽  
Scaling Factors ◽  
Co2 Concentrations ◽  
Inflation Factor

Abstract. In order to optimize surface CO2 fluxes at finer scales, a regional surface CO2 flux inversion system (Carbon Flux Inversion system and Community Multi-scale Air Quality, CFI-CMAQ) has been developed by simultaneously assimilating CO2 concentrations and surface CO2 fluxes into the regional modeling system, CMAQ. The smoothing operator is associated with the atmospheric transport model to constitute a persistence dynamical model to forecast the surface CO2 flux scaling factors. In this implementation, the "signal-to-noise" problem can be avoided; plus, any useful observed information achieved by the current assimilation cycle can be transferred into the next assimilation cycle. Thus, the surface CO2 fluxes can be optimized as a whole at the grid scale in CFI-CMAQ. The performance of CFI-CMAQ was quantitatively evaluated through a set of Observing System Simulation Experiments (OSSEs) by assimilating CO2 retrievals from GOSAT (Greenhouse Gases Observing Satellite). The results showed that the CO2 concentration assimilation using the ensemble Kalman filter (EnKF) could constrain the CO2 concentrations effectively, illustrating that the simultaneous assimilation of CO2 concentrations can provide convincing CO2 initial analysis fields for CO2 flux inversion. In addition, the CO2 flux optimization using the ensemble Kalman smoother (EnKS) demonstrated that CFI-CMAQ could in general reproduce true fluxes at finer scales with acceptable bias. Two further sets of numerical experiments were conducted to investigate the sensitivities of the inflation factor of scaling factors and the smoother window. The results showed that the ability of CFI-CMAQ to optimize CO2 fluxes greatly relied on the choice of the inflation factor. However, the smoother window had a slight influence on the optimized results. CFI-CMAQ performed very well even with a short lag-window (e.g. 3 days).

scholarly journals CO<sub>2</sub> flux determination by closed-chamber methods can be seriously biased by inappropriate application of linear regression

2007 ◽  
Vol 4 (6) ◽  
pp. 1005-1025 ◽  
Author(s):  
L. Kutzbach ◽  
J. Schneider ◽  
T. Sachs ◽  
M. Giebels ◽  
H. Nykänen ◽  
...  
Keyword(s):  
Linear Regression ◽  
Nonlinear Regression ◽  
Co2 Flux ◽  
Exponential Model ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Closed Chamber ◽  
Exponential Regression ◽  
Closure Time ◽  
Over Time

Abstract. Closed (non-steady state) chambers are widely used for quantifying carbon dioxide (CO2) fluxes between soils or low-stature canopies and the atmosphere. It is well recognised that covering a soil or vegetation by a closed chamber inherently disturbs the natural CO2 fluxes by altering the concentration gradients between the soil, the vegetation and the overlying air. Thus, the driving factors of CO2 fluxes are not constant during the closed chamber experiment, and no linear increase or decrease of CO2 concentration over time within the chamber headspace can be expected. Nevertheless, linear regression has been applied for calculating CO2 fluxes in many recent, partly influential, studies. This approach has been justified by keeping the closure time short and assuming the concentration change over time to be in the linear range. Here, we test if the application of linear regression is really appropriate for estimating CO2 fluxes using closed chambers over short closure times and if the application of nonlinear regression is necessary. We developed a nonlinear exponential regression model from diffusion and photosynthesis theory. This exponential model was tested with four different datasets of CO2 flux measurements (total number: 1764) conducted at three peatlands sites in Finland and a tundra site in Siberia. Thorough analyses of residuals demonstrated that linear regression was frequently not appropriate for the determination of CO2 fluxes by closed-chamber methods, even if closure times were kept short. The developed exponential model was well suited for nonlinear regression of the concentration over time c(t) evolution in the chamber headspace and estimation of the initial CO2 fluxes at closure time for the majority of experiments. However, a rather large percentage of the exponential regression functions showed curvatures not consistent with the theoretical model which is considered to be caused by violations of the underlying model assumptions. Especially the effects of turbulence and pressure disturbances by the chamber deployment are suspected to have caused unexplainable curvatures. CO2 flux estimates by linear regression can be as low as 40% of the flux estimates of exponential regression for closure times of only two minutes. The degree of underestimation increased with increasing CO2 flux strength and was dependent on soil and vegetation conditions which can disturb not only the quantitative but also the qualitative evaluation of CO2 flux dynamics. The underestimation effect by linear regression was observed to be different for CO2 uptake and release situations which can lead to stronger bias in the daily, seasonal and annual CO2 balances than in the individual fluxes. To avoid serious bias of CO2 flux estimates based on closed chamber experiments, we suggest further tests using published datasets and recommend the use of nonlinear regression models for future closed chamber studies.

scholarly journals First experimental evidence for the CO<sub>2</sub>-driven origin of Stromboli's major explosions

2011 ◽  
Vol 3 (1) ◽  
pp. 411-430 ◽  
Author(s):  
A. Aiuppa ◽  
M. Burton ◽  
P. Allard ◽  
T. Caltabiano ◽  
G. Giudice ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Co2 Emission ◽  
Weight Ratio ◽  
Co2 Flux ◽  
Recent Model ◽  
Stromboli Volcano ◽  
Plumbing System ◽  
Gas Leakage ◽  
Basaltic Volcanoes ◽  
Monitoring Strategies

Abstract. We report on the first detection of CO2 flux precursors of the till now unforecastable larger than normal ("major") explosions that intermittently occur at Stromboli volcano (Italy). Automated survey of the crater plume emissions in the period 2006–2010, during which 12 such explosions happened, demonstrate that these events are systematically preceded by a brief phase of increasing CO2/SO2 weight ratio (up to >40) and CO2 flux (>1300 t/d) with respect to the time-averaged values of 3.7 and ~500 t/d typical for standard Stromboli's activity. These signals are best explained by the accumulation of CO2-rich gas at a discontinuity of the plumbing system (decreasing CO2 emission at the surface), followed by increasing gas leakage prior to the explosion. Our observations thus support the recent model of Allard (2010) for a CO2-rich gas trigger of recurrent major explosions at Stromboli, and demonstrate the possibility to forecast these events in advance from geochemical precursors. These observations and conclusions have clear implications for monitoring strategies at other open-vent basaltic volcanoes worldwide.

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