Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

PubMed

Kalema, T; Viot, M

2014-02-01

The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sensitivity Analysis for Atmospheric Infrared Sounder (AIRS) CO2 Retrieval

NASA Technical Reports Server (NTRS)

Gat, Ilana

2012-01-01

The Atmospheric Infrared Sounder (AIRS) is a thermal infrared sensor able to retrieve the daily atmospheric state globally for clear as well as partially cloudy field-of-views. The AIRS spectrometer has 2378 channels sensing from 15.4 micrometers to 3.7 micrometers, of which a small subset in the 15 micrometers region has been selected, to date, for CO2 retrieval. To improve upon the current retrieval method, we extended the retrieval calculations to include a prior estimate component and developed a channel ranking system to optimize the channels and number of channels used. The channel ranking system uses a mathematical formalism to rapidly process and assess the retrieval potential of large numbers of channels. Implementing this system, we identifed a larger optimized subset of AIRS channels that can decrease retrieval errors and minimize the overall sensitivity to other iridescent contributors, such as water vapor, ozone, and atmospheric temperature. This methodology selects channels globally by accounting for the latitudinal, longitudinal, and seasonal dependencies of the subset. The new methodology increases accuracy in AIRS CO2 as well as other retrievals and enables the extension of retrieved CO2 vertical profiles to altitudes ranging from the lower troposphere to upper stratosphere. The extended retrieval method for CO2 vertical profile estimation using a maximum-likelihood estimation method. We use model data to demonstrate the beneficial impact of the extended retrieval method using the new channel ranking system on CO2 retrieval.

Effects of elevated root zone CO2 and air temperature on photosynthetic gas exchange, nitrate uptake, and total reduced nitrogen content in aeroponically grown lettuce plants.

PubMed

He, Jie; Austin, Paul T; Lee, Sing Kong

2010-09-01

Effects of elevated root zone (RZ) CO(2) and air temperature on photosynthesis, productivity, nitrate (NO(3)(-)), and total reduced nitrogen (N) content in aeroponically grown lettuce plants were studied. Three weeks after transplanting, four different RZ [CO(2)] concentrations [ambient (360 ppm) and elevated concentrations of 2000, 10,000, and 50,000 ppm] were imposed on plants grown at two air temperature regimes of 28 degrees C/22 degrees C (day/night) and 36 degrees C/30 degrees C. Photosynthetic CO(2) assimilation (A) and stomatal conductance (g(s)) increased with increasing photosynthetically active radiation (PAR). When grown at 28 degrees C/22 degrees C, all plants accumulated more biomass than at 36 degrees C/30 degrees C. When measured under a PAR >or=600 micromol m(-2) s(-1), elevated RZ [CO(2)] resulted in significantly higher A, lower g(s), and higher midday leaf relative water content in all plants. Under elevated RZ [CO(2)], the increase of biomass was greater in roots than in shoots, causing a lower shoot/root ratio. The percentage increase in growth under elevated RZ [CO(2)] was greater at 36 degrees C/30 degrees C although the total biomass was higher at 28 degrees C/22 degrees C. NO(3)(-) and total reduced N concentrations of shoot and root were significantly higher in all plants under elevated RZ [CO(2)] than under ambient RZ [CO(2)] of 360 ppm at both temperature regimes. At each RZ [CO(2)], NO(3)(-) and total reduced N concentration of shoots were greater at 28 degrees C/22 degrees C than at 36 degrees C/30 degrees C. At all RZ [CO(2)], roots of plants at 36 degrees C/30 degrees C had significantly higher NO(3)(-) and total reduced N concentrations than at 28 degrees C/22 degrees C. Since increased RZ [CO(2)] caused partial stomatal closure, maximal A and maximal g(s) were negatively correlated, with a unique relationship for each air temperature. However, across all RZ [CO(2)] and temperature treatments, there was a close correlation between

Room temperature CO and H2 sensing with carbon nanoparticles.

PubMed

Kim, Daegyu; Pikhitsa, Peter V; Yang, Hongjoo; Choi, Mansoo

2011-12-02

We report on a shell-shaped carbon nanoparticle (SCNP)-based gas sensor that reversibly detects reducing gas molecules such as CO and H(2) at room temperature both in air and inert atmosphere. Crystalline SCNPs were synthesized by laser-assisted reactions in pure acetylene gas flow, chemically treated to obtain well-dispersed SCNPs and then patterned on a substrate by the ion-induced focusing method. Our chemically functionalized SCNP-based gas sensor works for low concentrations of CO and H(2) at room temperature even without Pd or Pt catalysts commonly used for splitting H(2) molecules into reactive H atoms, while metal oxide gas sensors and bare carbon-nanotube-based gas sensors for sensing CO and H(2) molecules can operate only at elevated temperatures. A pristine SCNP-based gas sensor was also examined to prove the role of functional groups formed on the surface of functionalized SCNPs. A pristine SCNP gas sensor showed no response to reducing gases at room temperature but a significant response at elevated temperature, indicating a different sensing mechanism from a chemically functionalized SCNP sensor.

Sensitivity of Global Sea-Air CO2 Flux to Gas Transfer Algorithms, Climatological Wind Speeds, and Variability of Sea Surface Temperature and Salinity

NASA Technical Reports Server (NTRS)

McClain, Charles R.; Signorini, Sergio

2002-01-01

Sensitivity analyses of sea-air CO2 flux to gas transfer algorithms, climatological wind speeds, sea surface temperatures (SST) and salinity (SSS) were conducted for the global oceans and selected regional domains. Large uncertainties in the global sea-air flux estimates are identified due to different gas transfer algorithms, global climatological wind speeds, and seasonal SST and SSS data. The global sea-air flux ranges from -0.57 to -2.27 Gt/yr, depending on the combination of gas transfer algorithms and global climatological wind speeds used. Different combinations of SST and SSS global fields resulted in changes as large as 35% on the oceans global sea-air flux. An error as small as plus or minus 0.2 in SSS translates into a plus or minus 43% deviation on the mean global CO2 flux. This result emphasizes the need for highly accurate satellite SSS observations for the development of remote sensing sea-air flux algorithms.

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

PubMed

Ramalho, José C; Pais, Isabel P; Leitão, António E; Guerra, Mauro; Reboredo, Fernando H; Máguas, Cristina M; Carvalho, Maria L; Scotti-Campos, Paula; Ribeiro-Barros, Ana I; Lidon, Fernando J C; DaMatta, Fábio M

2018-01-01

Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO 2 ] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO 2 ] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO 2 ] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO 2 L -1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30-35 or 36-40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p -coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality), and only marginally, if at all, by elevated [CO 2 ]. However, the [CO 2 ] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids), thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p -coumaric acids, trigonelline, chroma, Hue angle, and color index), and increasing desirable features (acidity). Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO 2 ] (e.g., phosphorous) and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO 2 ] contributed to preserve bean quality by modifying and mitigating

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

PubMed Central

Ramalho, José C.; Pais, Isabel P.; Leitão, António E.; Guerra, Mauro; Reboredo, Fernando H.; Máguas, Cristina M.; Carvalho, Maria L.; Scotti-Campos, Paula; Ribeiro-Barros, Ana I.; Lidon, Fernando J. C.; DaMatta, Fábio M.

2018-01-01

Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO2] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO2] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO2] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO2 L-1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30–35 or 36–40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p-coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality), and only marginally, if at all, by elevated [CO2]. However, the [CO2] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids), thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p-coumaric acids, trigonelline, chroma, Hue angle, and color index), and increasing desirable features (acidity). Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO2] (e.g., phosphorous) and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO2] contributed to preserve bean quality by modifying and mitigating the heat impact

Field and Laboratory Measurements of Carbon Dioxide Mixing Ratios in Air Using the LI-COR LI-7000 CO2/H2O Analyzer

NASA Astrophysics Data System (ADS)

Murphy, P. C.; Lerner, B. M.; Williams, E. J.

2003-12-01

Air measurements of CO2 were made with a LI-COR LI-7000 CO2/H2O analyzer on the NOAA ship Ronald H. Brown during the New England Air Quality Study (NEAQS 2002) field campaign. This instrument is an improved version of the older model LI-6262 CO2/H2O analyzer, which uses a non-dispersive IR radiation absorption technique. During NEAQS, we operated the LI-7000 without temperature regulation, using a simple 2-point calibration scheme. An intercomparison between our measurements of atmospheric CO2 mixing ratios and those measured by a more sophisticated method, using temperature-regulation and a multipoint calibration with a LI-6252 CO2 analyzer (operated by AOML) shows generally good results ([CO2]AL = [CO2]AOML x 1.015 (0.010) - 5.7 (3.8) ppmv; R2 = 0.9889) in highly variable air masses. During subsequent laboratory studies, we evaluated the instrument for the manufacturer's claims of improvement in signal noise, sample gas temperature equilibration and zero drift with temperature. Further work examined the instrument's susceptibility to rapid temperature changes, which has been previously demonstrated to introduce error of several ppmv ° C-1 in the LI-6252. A change in the LI-7000 optical bench temperature of 12 ° C in 1 hour caused a sampling error of ˜3 ppmv CO2. Therefore, our lab investigations indicate that the LI-7000 would benefit from a temperature-controlled enclosure, as is used by the AOML group.

Effect of Elevated Atmospheric CO2 and Temperature on Leaf Optical Properties and Chlorophyll Content in Acer saccharum (Marsh.)

NASA Technical Reports Server (NTRS)

Carter, Gregory A.; Bahadur, Raj; Norby, Richard J.

1999-01-01

Elevated atmospheric CO2 pressure and numerous causes of plant stress often result in decreased leaf chlorophyll contents and thus would be expected to alter leaf optical properties. Hypotheses that elevated carbon dioxide pressure and air temperature would alter leaf optical properties were tested for sugar maple (Acer saccharum Marsh.) in the middle of its fourth growing season under treatment. The saplings had been growing since 1994 in open-top chambers at Oak Ridge, Tennessee under the following treatments: 1) Ambient CO2 pressure and air temperature (control); 2) CO2 pressure approximately 30 Pa above ambient; 3) Air temperatures 3 C above ambient; 4) Elevated CO2 and air temperature. Spectral reflectance, transmittance, and absorptance in the visible spectrum (400-720 nm) did not change significantly (rho = 0.05) in response to any treatment compared with control values. Although reflectance, transmittance, and absorptance at 700 nm correlated strongly with leaf chlorophyll content, chlorophyll content was not altered significantly by the treatments. The lack of treatment effects on pigmentation explained the non-significant change in optical properties in the visible spectrum. Optical properties in the near-infrared (721-850 nm) were similarly unresponsive to treatment with the exception of an increased absorptance in leaves that developed under elevated air temperature alone. This response could not be explained by the data, but might have resulted from effects of air temperature on leaf internal structure. Results indicated no significant potential for detecting leaf optical responses to elevated CO2 or temperature by the remote sensing of reflected radiation in the 400-850 nm spectrum.

Net sea-air CO2 fluxes and modelled pCO2 in the southwestern subtropical Atlantic continental shelf during spring 2010 and summer 2011

NASA Astrophysics Data System (ADS)

Ito, Rosane Gonçalves; Garcia, Carlos Alberto Eiras; Tavano, Virginia Maria

2016-05-01

Sea-air CO2 fluxes over continental shelves vary substantially in time on both seasonal and sub-seasonal scales, driven primarily by variations in surface pCO2 due to several oceanic mechanisms. Furthermore, coastal zones have not been appropriately considered in global estimates of sea-air CO2 fluxes, despite their importance to ecology and to productivity. In this work, we aimed to improve our understanding of the role played by shelf waters in controlling sea-air CO2 fluxes by investigating the southwestern Atlantic Ocean (21-35°S) region, where physical, chemical and biological measurements were made on board the Brazilian R. V. Cruzeiro do Sul during late spring 2010 and early summer 2011. Features such as discharge from the La Plata River, intrusions of tropical waters on the outer shelf due to meandering and flow instabilities of the Brazil Current, and coastal upwelling in the Santa Marta Grande Cape and São Tomé Cape were detected by both in situ measurements and ocean colour and thermal satellite imagery. Overall, shelf waters in the study area were a source of CO2 to the atmosphere, with an average of 1.2 mmol CO2 m-2 day-1 for the late spring and 11.2 mmol CO2 m-2 day-1 for the early summer cruises. The spatial variability in ocean pCO2 was associated with surface ocean properties (temperature, salinity and chlorophyll-a concentration) in both the slope and shelf waters. Empirical algorithms for predicting temperature-normalized surface ocean pCO2 as a function of surface ocean properties were shown to perform well in both shelf and slope waters, except (a) within cyclonic eddies produced by baroclinic instability of the Brazil Current as detected by satellite SST imagery and (b) in coastal upwelling regions. In these regions, surface ocean pCO2 values were higher as a result of upwelled CO2-enriched subsurface waters. Finally, a pCO2 algorithm based on both sea surface temperature and surface chlorophyll-a was developed that enabled the spatial

Surface Ocean pCO2 Seasonality and Sea-Air CO2 Flux Estimates for the North American East Coast

NASA Technical Reports Server (NTRS)

Signorini, Sergio; Mannino, Antonio; Najjar, Raymond G., Jr.; Friedrichs, Marjorie A. M.; Cai, Wei-Jun; Salisbury, Joe; Wang, Zhaohui Aleck; Thomas, Helmuth; Shadwick, Elizabeth

2013-01-01

Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between 3.4 and 5.4 Tg C/yr (areal average of 0.7 to 1.0 mol CO2 /sq m/yr) over the period 2003-2010.

Growth of mature boreal Norway spruce was not affected by elevated [CO(2)] and/or air temperature unless nutrient availability was improved.

PubMed

Sigurdsson, Bjarni D; Medhurst, Jane L; Wallin, Göran; Eggertsson, Olafur; Linder, Sune

2013-11-01

The growth responses of mature Norway spruce (Picea abies (L.) Karst.) trees exposed to elevated [CO(2)] (CE; 670-700 ppm) and long-term optimized nutrient availability or elevated air temperature (TE; ±3.9 °C) were studied in situ in northern Sweden in two 3 year field experiments using 12 whole-tree chambers in ca. 40-year-old forest. The first experiment (Exp. I) studied the interactions between CE and nutrient availability and the second (Exp. II) between CE and TE. It should be noted that only air temperature was elevated in Exp. II, while soil temperature was maintained close to ambient. In Exp. I, CE significantly increased the mean annual height increment, stem volume and biomass increment during the treatment period (25, 28, and 22%, respectively) when nutrients were supplied. There was, however, no significant positive CE effect found at the low natural nutrient availability. In Exp. II, which was conducted at the natural site fertility, neither CE nor TE significantly affected height or stem increment. It is concluded that the low nutrient availability (mainly nitrogen) in the boreal forests is likely to restrict their response to the continuous rise in [CO(2)] and/or TE.

Deriving a sea surface climatology of CO2 fugacity in support of air-sea gas flux studies

NASA Astrophysics Data System (ADS)

Goddijn-Murphy, L. M.; Woolf, D. K.; Land, P. E.; Shutler, J. D.; Donlon, C.

2014-07-01

Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean Carbon Dioxide (CO2) Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. fCO2 is highly sensitive to temperature and the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrent with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air-sea CO2 fluxes it is therefore desirable to calculate fCO2 valid for climate quality SST. This paper presents a method for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using climate quality SST data from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air-sea CO2 flux, and hence the presented fCO2 distributions can be used in air-sea gas flux calculations together with climatologies of other climate variables.

Ambient-temperature co-oxidation catalysts

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Schryer, David R.; Brown, Kenneth G.; Kielin, Erik J.

1991-01-01

Oxidation catalysts which operate at ambient temperature were developed for the recombination of carbon monoxide (CO) and oxygen (O2) dissociation products which are formed during carbon dioxide (CO2) laser operation. Recombination of these products to regenerate CO2 allows continuous operation of CO2 lasers in a closed cycle mode. Development of these catalyst materials provides enabling technology for the operation of such lasers from space platforms or in ground based facilities without constant gas consumption required for continuous open cycle operation. Such catalysts also have other applications in various areas outside the laser community for removal of CO from other closed environments such as indoor air and as an ambient temperature catalytic converter for control of auto emissions.

Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions

USDA-ARS?s Scientific Manuscript database

The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the ma...

Rice grain yield and quality responses to free-air CO2 enrichment combined with soil and water warming.

PubMed

Usui, Yasuhiro; Sakai, Hidemitsu; Tokida, Takeshi; Nakamura, Hirofumi; Nakagawa, Hiroshi; Hasegawa, Toshihiro

2016-03-01

Rising air temperatures are projected to reduce rice yield and quality, whereas increasing atmospheric CO2 concentrations ([CO2 ]) can increase grain yield. For irrigated rice, ponded water is an important temperature environment, but few open-field evaluations are available on the combined effects of temperature and [CO2 ], which limits our ability to predict future rice production. We conducted free-air CO2 enrichment and soil and water warming experiments, for three growing seasons to determine the yield and quality response to elevated [CO2 ] (+200 μmol mol(-1) , E-[CO2 ]) and soil and water temperatures (+2 °C, E-T). E-[CO2 ] significantly increased biomass and grain yield by approximately 14% averaged over 3 years, mainly because of increased panicle and spikelet density. E-T significantly increased biomass but had no significant effect on the grain yield. E-T decreased days from transplanting to heading by approximately 1%, but days to the maximum tiller number (MTN) stage were reduced by approximately 8%, which limited the panicle density and therefore sink capacity. On the other hand, E-[CO2 ] increased days to the MTN stage by approximately 4%, leading to a greater number of tillers. Grain appearance quality was decreased by both treatments, but E-[CO2 ] showed a much larger effect than did E-T. The significant decrease in undamaged grains (UDG) by E-[CO2 ] was mainly the result of an increased percentage of white-base grains (WBSG), which were negatively correlated with grain protein content. A significant decrease in grain protein content by E-[CO2 ] accounted in part for the increased WBSG. The dependence of WBSG on grain protein content, however, was different among years; the slope and intercept of the relationship were positively correlated with a heat dose above 26 °C. Year-to-year variation in the response of grain appearance quality demonstrated that E-[CO2 ] and rising air temperatures synergistically reduce grain appearance quality of

Low pCO2 Air-Polarized CO2 Concentrator Development

NASA Technical Reports Server (NTRS)

Schubert, Franz H.

1997-01-01

Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

Crop responses to elevated CO2 and interactions with H2O, N, and temperature.

PubMed

Kimball, Bruce A

2016-06-01

About twenty-seven years ago, free-air CO2 enrichment (FACE) technology was developed that enabled the air above open-field plots to be enriched with CO2 for entire growing seasons. Since then, FACE experiments have been conducted on cotton, wheat, ryegrass, clover, potato, grape, rice, barley, sugar beet, soybean, cassava, rape, mustard, coffee (C3 crops), and sorghum and maize (C4 crops). Elevated CO2 (550ppm from an ambient concentration of about 353ppm in 1990) decreased evapotranspiration about 10% on average and increased canopy temperatures about 0.7°C. Biomass and yield were increased by FACE in all C3 species, but not in C4 species except when water was limiting. Yields of C3 grain crops were increased on average about 19%. Copyright © 2016 Elsevier Ltd. All rights reserved.

ELEVATED TEMPERATURE, SOIL MOISTURE AND SEASONALITY BUT NOT CO2 AFFECT CANOPY ASSIMILATION AND SYSTEM RESPIRATION IN SEEDLING DOUGLAS-FIR ECOSYSTEMS

EPA Science Inventory

We investigated the effects of elevated atmospheric CO2 and air temperature on C cycling in trees and associated soil system, focusing on canopy CO2 assimilation (Asys) and system CO2 loss through respiration (Rsys). We hypothesized that both elevated CO2 and elevated temperature...

Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

PubMed

Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

2013-08-01

An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. © 2013 John Wiley & Sons Ltd.

Controlling the temperature of bones using pulsed CO2 lasers: observations and mathematical modeling.

PubMed

Lévesque, Luc; Noël, Jean-Marc; Scott, Calum

2015-12-01

Temperature of porcine bone specimens are investigated by aiming a pulsed CO2 laser beam at the bone-air surface. This method of controlling temperature is believed to be flexible in medical applications as it avoids the uses of thermal devices, which are often cumbersome and generate rather larger temperature variations with time. The control of temperature using this method is modeled by the heat-conduction equation. In this investigation, it is assumed that the energy delivered by the CO2 laser is confined within a very thin surface layer of roughly 9 μm. It is shown that temperature can be maintained at a steady temperature using a CO2 laser and we demonstrate that the method can be adapted to be used in tandem with another laser beam. This method to control the temperature is believed to be useful in de-contamination of bone during the implantation treatment, in bone augmentation when using natural or synthetic materials and in low-level laser therapy.

Implications of High Temperature and Elevated CO2 on Flowering Time in Plants

PubMed Central

Jagadish, S. V. Krishna; Bahuguna, Rajeev N.; Djanaguiraman, Maduraimuthu; Gamuyao, Rico; Prasad, P. V. Vara; Craufurd, Peter Q.

2016-01-01

Flowering is a crucial determinant for plant reproductive success and seed-set. Increasing temperature and elevated carbon-dioxide (e[CO2]) are key climate change factors that could affect plant fitness and flowering related events. Addressing the effect of these environmental factors on flowering events such as time of day of anthesis (TOA) and flowering time (duration from germination till flowering) is critical to understand the adaptation of plants/crops to changing climate and is the major aim of this review. Increasing ambient temperature is the major climatic factor that advances flowering time in crops and other plants, with a modest effect of e[CO2].Integrated environmental stimuli such as photoperiod, temperature and e[CO2] regulating flowering time is discussed. The critical role of plant tissue temperature influencing TOA is highlighted and crop models need to substitute ambient air temperature with canopy or floral tissue temperature to improve predictions. A complex signaling network of flowering regulation with change in ambient temperature involving different transcription factors (PIF4, PIF5), flowering suppressors (HvODDSOC2, SVP, FLC) and autonomous pathway (FCA, FVE) genes, mainly from Arabidopsis, provides a promising avenue to improve our understanding of the dynamics of flowering time under changing climate. Elevated CO2 mediated changes in tissue sugar status and a direct [CO2]-driven regulatory pathway involving a key flowering gene, MOTHER OF FT AND TFL1 (MFT), are emerging evidence for the role of e[CO2] in flowering time regulation. PMID:27446143

Dynamic Response of CoSb2O6 Trirutile-Type Oxides in a CO2 Atmosphere at Low-Temperatures

PubMed Central

Guillén-Bonilla, Alex; Rodríguez-Betancourtt, Verónica-María; Flores-Martínez, Martín; Blanco-Alonso, Oscar; Reyes-Gómez, Juan; Gildo-Ortiz, Lorenzo; Guillén-Bonilla, Héctor

2014-01-01

Experimental work on the synthesis of the CoSb2O6 oxide and its CO2 sensing properties is presented here. The oxide was synthesized by a microwave-assisted colloidal method in presence of ethylenediamine after calcination at 600 °C. This CoSb2O6 oxide crystallized in a tetragonal structure with cell parameters a = 4.6495 and c = 9.2763 Å, and space group P42/mnm. To prove its physical, chemical and sensing properties, the oxide was subjected to a series of tests: Raman spectroscopy, Scanning Electron Microscopy (SEM) and impedance (Z) measurements. Microstructures, like columns, bars and hollow hemispheres, were observed. For the CO2 sensing test, a thick film of CoSb2O6 was used, measuring the impedance variations on the presence of air/CO2 flows (0.100 sccm/0.100 sccm) using AC (alternating current) signals in the frequency-range 0.1–100 kHz and low relative temperatures (250 and 300 °C). The CO2 sensing results were quite good. PMID:25162232

In situ X-ray ptychography imaging of high-temperature CO2 acceptor particle agglomerates

NASA Astrophysics Data System (ADS)

Høydalsvik, Kristin; Bø Fløystad, Jostein; Zhao, Tiejun; Esmaeili, Morteza; Diaz, Ana; Andreasen, Jens W.; Mathiesen, Ragnvald H.; Rønning, Magnus; Breiby, Dag W.

2014-06-01

Imaging nanoparticles under relevant reaction conditions of high temperature and gas pressure is difficult because conventional imaging techniques, like transmission electron microscopy, cannot be used. Here we demonstrate that the coherent diffractive imaging technique of X-ray ptychography can be used for in situ phase contrast imaging in structure studies at atmospheric pressure and elevated temperatures. Lithium zirconate, a candidate CO2 capture material, was studied at a pressure of one atmosphere in air and in CO2, at temperatures exceeding 600 °C. Images with a spatial resolution better than 200 nm were retrieved, and possibilities for improving the experiment are described.

Direct capture of CO 2 from ambient air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanz-Perez, Eloy S.; Murdock, Christopher R.; Didas, Stephanie A.

The increase in the global atmospheric CO 2 concentration resulting from over a century of combustion of fossil fuels has been associated with significant global climate change. With the global population increase driving continued increases in fossil fuel use, humanity’s primary reliance on fossil energy for the next several decades is assured. Traditional modes of carbon capture such as precombustion and postcombustion CO 2 capture from large point sources can help slow the rate of increase of the atmospheric CO 2 concentration, but only the direct removal of CO 2 from the air, or “direct air capture” (DAC), can actuallymore » reduce the global atmospheric CO 2 concentration. The past decade has seen a steep rise in the use of chemical sorbents that are cycled through sorption and desorption cycles for CO 2 removal from ultradilute gases such as air. This Review provides a historical overview of the field of DAC, along with an exhaustive description of the use of chemical sorbents targeted at this application. Solvents and solid sorbents that interact strongly with CO 2 are described, including basic solvents, supported amine and ammonium materials, and metal-organic frameworks (MOFs), as the primary classes of chemical sorbents. Hypothetical processes for the deployment of such sorbents are discussed, as well as the limited array of technoeconomic analyses published on DAC. Overall, it is concluded that there are many new materials that could play a role in emerging DAC technologies. Furthermore, these materials need to be further investigated and developed with a practical sorbent-air contacting process in mind if society is to make rapid progress in deploying DAC as a means of mitigating climate change.« less

Direct capture of CO 2 from ambient air

DOE PAGES

Sanz-Perez, Eloy S.; Murdock, Christopher R.; Didas, Stephanie A.; ...

2016-08-25

The increase in the global atmospheric CO 2 concentration resulting from over a century of combustion of fossil fuels has been associated with significant global climate change. With the global population increase driving continued increases in fossil fuel use, humanity’s primary reliance on fossil energy for the next several decades is assured. Traditional modes of carbon capture such as precombustion and postcombustion CO 2 capture from large point sources can help slow the rate of increase of the atmospheric CO 2 concentration, but only the direct removal of CO 2 from the air, or “direct air capture” (DAC), can actuallymore » reduce the global atmospheric CO 2 concentration. The past decade has seen a steep rise in the use of chemical sorbents that are cycled through sorption and desorption cycles for CO 2 removal from ultradilute gases such as air. This Review provides a historical overview of the field of DAC, along with an exhaustive description of the use of chemical sorbents targeted at this application. Solvents and solid sorbents that interact strongly with CO 2 are described, including basic solvents, supported amine and ammonium materials, and metal-organic frameworks (MOFs), as the primary classes of chemical sorbents. Hypothetical processes for the deployment of such sorbents are discussed, as well as the limited array of technoeconomic analyses published on DAC. Overall, it is concluded that there are many new materials that could play a role in emerging DAC technologies. Furthermore, these materials need to be further investigated and developed with a practical sorbent-air contacting process in mind if society is to make rapid progress in deploying DAC as a means of mitigating climate change.« less

Economic and energetic analysis of capturing CO2 from ambient air

PubMed Central

House, Kurt Zenz; Baclig, Antonio C.; Ranjan, Manya; van Nierop, Ernst A.; Wilcox, Jennifer; Herzog, Howard J.

2011-01-01

Capturing carbon dioxide from the atmosphere (“air capture”) in an industrial process has been proposed as an option for stabilizing global CO2 concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO2, making it cost competitive with mainstream CO2 mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO2 emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems. Our empirical analyses of operating commercial processes suggest that the energetic and financial costs of capturing CO2 from the air are likely to have been underestimated. Specifically, our analysis of existing gas separation systems suggests that, unless air capture significantly outperforms these systems, it is likely to require more than 400 kJ of work per mole of CO2, requiring it to be powered by CO2-neutral power sources in order to be CO2 negative. We estimate that total system costs of an air capture system will be on the order of $1,000 per tonne of CO2, based on experience with as-built large-scale trace gas removal systems. PMID:22143760

Temperature effects on microbial respiration assessed with CO2-exchange and continuous culture techniques

NASA Astrophysics Data System (ADS)

Lehmeier, C.; Min, K.; Song, C.; Ballantyne, F.; Billings, S. A.

2012-12-01

Recent work attempts to incorporate requirements of soil microorganisms for carbon and other resources, and how these requirements may respond to temperature, into theoretical concepts of soil organic matter decomposition and climate change. Because of the difficulties of measuring resource fluxes in natural soils, empirical data to guide these concepts remain scarce. Here, we present an experimental system that combines continuous culture techniques with CO2 measurements to study carbon fluxes through microbes in a reductionist, controlled environment amenable to experimental manipulation. In this pilot study, we quantified mass specific respiration rates (MSR) and δ13C of respired CO2 of Pseudomonas fluorescens, a Gram-negative bacterium common to soils, grown at 15°C and 25°C with otherwise identical environmental conditions. The microbes were grown in a 1.9 L bioreactor, in 0.9 L of nutrient medium with C:N:P atomic ratios of 100:10:3, and with 10 mM cellobiose as the carbon source. A peristaltic pump continuously supplied the bioreactor with sterile medium, and removed medium from the bioreactor, at a rate of 63 mL h-1. Both vessels were contained within a temperature incubator, and stir bars provided continuously well mixed volumes. CO2-free air was continuously bubbled through the reactor medium so to provide the microbes with O2; a cavity ring down spectrometer withdrew reactor headspace air and measured concentration and δ13C of the CO2. Air supply was regulated with a pressure/mass flow controller to approx. 27 mL min-1. In both temperature regimes, the pH of the bioreactor as well as concentration and δ13C of the CO2 in the head space air were constant over the course of 1 d, such that any imbalances in the CO2-H2CO3 equilibrium were considered negligible in the assessment of microbial respiration rates and the δ13C of respired CO2. After this time period, reactor medium was passed through a 0.22 μm filter and the filtrate dried for 24 h to obtain

Seasonal and spatial variations in surface pCO2 and air-sea CO2 flux in the Chesapeake Bay

NASA Astrophysics Data System (ADS)

Cai, W. J.; Chen, B.

2017-12-01

Bay-wide observations of surface water partial pressure of carbon dioxide (pCO2) were conducted in May, June, August, and October 2016 to study the spatial and seasonal variations in surface pCO2 and to estimate air-sea CO2 flux in the Chesapeake Bay. Overall, high surface pCO2 in the upper-bay decreased downstream rapidly below the atmospheric value near the bay bridge in the mid-bay and then increased slightly to the lower-bay where pCO2 approached the atmospheric level. Over the course of a year, pCO2 was higher than 1000 µatm in the upper bay and the highest pCO2 (2500 µatm) was observed in August. Significant biologically-induced pCO2 undersaturation was observed at the upper part of the mid-bay in August with pCO2 as low as 50 µatm and oversaturated DO% of 200%. In addition to biological control, vertical mixing and upwelling controlled by wind direction and tidal stage played an important role in controlling surface pCO2 in the mid-bay as is evidenced by co-occurrence of high pCO2 with low temperature and low oxygen or high salinity from the subsurface. These physical processes occurred regularly and in short time scale of hours, suggesting they must be considered in the assessment of annual air-sea CO2 flux. Seasonally, the upper-bay acted as a source for atmospheric CO2 over the course of a year. The boundary of upper and mid bay transited from a CO2 source to a sink from May to August and was a source again in October due to strong biological production in summer. In contrast, the mid-bay represented as a CO2 source with large temporal variation due to dynamic hydrographic settings. The lower-bay transited from a weak sink in May to equilibrated with the atmosphere from June to August, while became a source again in October. Moreover, the CO2 flux could be reversed very quickly under episodic severe weather events. Thus further research, including the influence of severe weather and subsequent bloom, is needed to get better understanding of the carbon

Diffuse CO 2 soil degassing and CO 2 and H 2S concentrations in air and related hazards at Vulcano Island (Aeolian arc, Italy)

NASA Astrophysics Data System (ADS)

Carapezza, M. L.; Barberi, F.; Ranaldi, M.; Ricci, T.; Tarchini, L.; Barrancos, J.; Fischer, C.; Perez, N.; Weber, K.; Di Piazza, A.; Gattuso, A.

2011-10-01

La Fossa crater on Vulcano Island is quiescent since 1890. Periodically it undergoes "crises" characterized by marked increase of temperature (T), gas output and concentration of magmatic components in the crater fumaroles (T may exceed 600 °C). During these crises, which so far did not lead to any eruptive reactivation, the diffuse CO 2 soil degassing also increases and in December 2005 an anomalous CO 2 flux of 1350 tons/day was estimated by 1588 measurements over a surface of 1.66 km 2 extending from La Fossa crater to the inhabited zone of Vulcano Porto. The crater area and two other anomalously degassing sites (Levante Beach and Palizzi) have been periodically investigated from December 2004 to August 2010 for diffuse CO 2 soil flux. They show a marked variation with time of the degassing rate, with synchronous maxima in December 2005. Carbon dioxide soil flux and environmental parameters have been also continuously monitored for over one year by an automatic station at Vulcano Porto. In order to assess the hazard of the endogenous gas emissions, CO 2 and H 2S air concentrations have been measured by Tunable Diode Laser profiles near the fumaroles of the crater rim and of the Levante Beach area, where also the viscous gas flux has been estimated. In addition, CO 2 air concentration has been measured both indoor and outdoor in an inhabited sector of Vulcano Porto. Results show that in some sites usually frequented by tourists there is a dangerous H 2S air concentration and CO 2 exceeds the hazardous thresholds in some Vulcano houses. These zones should be immediately monitored for gas hazard should a new crisis arise.

Evidence for divergence of response in Indica, Japonica, and wild rice to high CO2 x temperature interaction

USDA-ARS?s Scientific Manuscript database

Previous studies suggest that the intraspecific variability of rice yield response to rising carbon dioxide concentration, [CO2], could serve as a basis of selection to improve genotypes for future high CO2 conditions. However, assessment of responses to elevated [CO2] must consider air temperature,...

Temperature characteristics of fusion splicing Hollow Core Photonic Crystal Fiber by sinusoidal modulation CO2 laser

NASA Astrophysics Data System (ADS)

Fu, Guangwei; Li, Kuixing; Fu, Xinghu; Bi, Weihong

2013-07-01

During the fusion splicing Hollow Core Photonic Crystal Fiber (HC-PCF), the air-holes collapse easily due to the improper fusion duration time and optical power. To analyze the temperature characteristics of fusion splicing HC-PCF, a heating method by sinusoidal modulation CO2 laser has been proposed. In the sinusoidal modulation, the variation relationships among laser power, temperature difference and angular frequency are analyzed. The results show that the theoretical simulation is basically in accordance with the experimental data. Therefore, a low-loss fusion splicing can be achieved by modulating the CO2 laser frequency to avoid the air-holes collapse of HC-PCF. Further, the errors are also given.

Effect of diurnal and seasonal temperature variation on Cussac cave ventilation using co2 assessment

NASA Astrophysics Data System (ADS)

Peyraube, Nicolas; Lastennet, Roland; Villanueva, Jessica Denila; Houillon, Nicolas; Malaurent, Philippe; Denis, Alain

2017-08-01

Cussac cave was investigated to assess the cave air temperature variations and to understand its ventilation regime. This cave is located in an active karst system in the south west part of France. It has a single entrance and is considered as a cold air trap. In this study, air mass exchanges were probed. Measurements of temperature and Pco2 with a 30-min frequency were made in several locations close to the cave entrance. Speed of the air flow was also measured at the door of cave entrance. Results show that cave air Pco2 varies from 0.18 to 3.33 %. This cave appears to be a CO2 source with a net mass of 2319 tons blown in 2009. Carbon-stable isotope of CO2 (13Cco2) ranges from -20.6 ‰ in cold season to -23.8 ‰ in warm season. Cave air is interpreted as a result of a mix between external air and an isotopically depleted air, coming from the rock environment. The isotopic value of the light member varies through time, from -23.9 to -22.5 ‰. Furthermore, this study ascertains that the cave never stops in communicating with the external air. The ventilation regime is identified. (1) In cold season, the cave inhales at night and blows a little at the warmest hours. However, in warm season, (2) cave blows at night, but (3) during the day, a convection loop takes place in the entrance area and prevents the external air from entering the cave, confirming the cold air trap.

Small CO2 Sensors Operate at Lower Temperature

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Xu, Jennifer C.

2009-01-01

Solid-electrolyte-based amperometric sensors for measuring concentrations of CO2 in air are being developed for use in detection of fires, environmental monitoring, and other applications where liquid-based electrochemical cells are problematic. These sensors are small (sizes of the order of a millimeter), are robust, are amenable to batch fabrication at relatively low cost, and exhibit short response times (seconds) and wide detection ranges. A sensor of this type at a previous stage of development included a solid electrolyte of Na3Zr2Si2PO12 deposited mainly between interdigitated Pt electrodes on an alumina substrate, all overcoated with an auxiliary solid electrolyte of (Na2CO3:BaCO3 in a molar ratio of 1:1.7). It was necessary to heat this device to a temperature as high as 600 C to obtain the desired sensitivity and rapid response. Heating sensors increases the power consumption of the sensor system and complicates the use of the sensor in some applications. Thus, decreasing a sensor s power consumption while maintaining its performance is a technical goal of ongoing development.

Energy and material balance of CO2 capture from ambient air.

PubMed

Zeman, Frank

2007-11-01

Current Carbon Capture and Storage (CCS) technologies focus on large, stationary sources that produce approximately 50% of global CO2 emissions. We propose an industrial technology that captures CO2 directly from ambient air to target the remaining emissions. First, a wet scrubbing technique absorbs CO2 into a sodium hydroxide solution. The resultant carbonate is transferred from sodium ions to calcium ions via causticization. The captured CO2 is released from the calcium carbonate through thermal calcination in a modified kiln. The energy consumption is calculated as 350 kJ/mol of CO2 captured. It is dominated by the thermal energy demand of the kiln and the mechanical power required for air movement. The low concentration of CO2 in air requires a throughput of 3 million cubic meters of air per ton of CO2 removed, which could result in significant water losses. Electricity consumption in the process results in CO2 emissions and the use of coal power would significantly reduce to net amount captured. The thermodynamic efficiency of this process is low but comparable to other "end of pipe" capture technologies. As another carbon mitigation technology, air capture could allow for the continued use of liquid hydrocarbon fuels in the transportation sector.

Arctic Ocean CO2 uptake: an improved multiyear estimate of the air-sea CO2 flux incorporating chlorophyll a concentrations

NASA Astrophysics Data System (ADS)

Yasunaka, Sayaka; Siswanto, Eko; Olsen, Are; Hoppema, Mario; Watanabe, Eiji; Fransson, Agneta; Chierici, Melissa; Murata, Akihiko; Lauvset, Siv K.; Wanninkhof, Rik; Takahashi, Taro; Kosugi, Naohiro; Omar, Abdirahman M.; van Heuven, Steven; Mathis, Jeremy T.

2018-03-01

We estimated monthly air-sea CO2 fluxes in the Arctic Ocean and its adjacent seas north of 60° N from 1997 to 2014. This was done by mapping partial pressure of CO2 in the surface water (pCO2w) using a self-organizing map (SOM) technique incorporating chlorophyll a concentration (Chl a), sea surface temperature, sea surface salinity, sea ice concentration, atmospheric CO2 mixing ratio, and geographical position. We applied new algorithms for extracting Chl a from satellite remote sensing reflectance with close examination of uncertainty of the obtained Chl a values. The overall relationship between pCO2w and Chl a was negative, whereas the relationship varied among seasons and regions. The addition of Chl a as a parameter in the SOM process enabled us to improve the estimate of pCO2w, particularly via better representation of its decline in spring, which resulted from biologically mediated pCO2w reduction. As a result of the inclusion of Chl a, the uncertainty in the CO2 flux estimate was reduced, with a net annual Arctic Ocean CO2 uptake of 180 ± 130 Tg C yr-1. Seasonal to interannual variation in the CO2 influx was also calculated.

Variations in atmospheric CO2 growth rates coupled with tropical temperature

PubMed Central

Wang, Weile; Ciais, Philippe; Nemani, Ramakrishna R.; Canadell, Josep G.; Piao, Shilong; Sitch, Stephen; White, Michael A.; Hashimoto, Hirofumi; Milesi, Cristina; Myneni, Ranga B.

2013-01-01

Previous studies have highlighted the occurrence and intensity of El Niño–Southern Oscillation as important drivers of the interannual variability of the atmospheric CO2 growth rate, but the underlying biogeophysical mechanisms governing such connections remain unclear. Here we show a strong and persistent coupling (r2 ≈ 0.50) between interannual variations of the CO2 growth rate and tropical land–surface air temperature during 1959 to 2011, with a 1 °C tropical temperature anomaly leading to a 3.5 ± 0.6 Petagrams of carbon per year (PgC/y) CO2 growth-rate anomaly on average. Analysis of simulation results from Dynamic Global Vegetation Models suggests that this temperature–CO2 coupling is contributed mainly by the additive responses of heterotrophic respiration (Rh) and net primary production (NPP) to temperature variations in tropical ecosystems. However, we find a weaker and less consistent (r2 ≈ 0.25) interannual coupling between CO2 growth rate and tropical land precipitation than diagnosed from the Dynamic Global Vegetation Models, likely resulting from the subtractive responses of tropical Rh and NPP to precipitation anomalies that partly offset each other in the net ecosystem exchange (i.e., net ecosystem exchange ≈ Rh − NPP). Variations in other climate variables (e.g., large-scale cloudiness) and natural disturbances (e.g., volcanic eruptions) may induce transient reductions in the temperature–CO2 coupling, but the relationship is robust during the past 50 y and shows full recovery within a few years after any such major variability event. Therefore, it provides an important diagnostic tool for improved understanding of the contemporary and future global carbon cycle. PMID:23884654

Microclimatic Performance of a Free-Air Warming and CO2 Enrichment Experiment in Windy Wyoming, USA

PubMed Central

LeCain, Daniel; Smith, David; Morgan, Jack; Kimball, Bruce A.; Pendall, Elise; Miglietta, Franco

2015-01-01

In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO2) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO2 enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night) but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms-1 average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was not warmed by the system, therefore convective warming was minor. Elevated CO2 had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO2. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming for much of the

CO2 Capture from the Air: Technology Assessment and Implications for Climate Policy

NASA Astrophysics Data System (ADS)

Keith, D. W.

2002-05-01

It is physically possible to capture CO2 directly from the air and immobilize it in geological structures. Today, there are no large-scale technologies that achieve air capture at reasonable cost. Yet, strong arguments suggest that it will comparatively easy to develop practical air capture technologies on the timescales relevant to climate policy [1]. This paper first analyzes the cost of air capture and then assesses the implications for climate policy. We first analyze the lower bound on the cost needed for air capture, describing the thermodynamic and physical limits to the use of energy and land. We then compare the costs of air capture to the cost of capture from combustion exhaust streams. While the intrinsic minimum energy requirement is larger for air capture, we argue that air capture has important structural advantages, such as the reduction of transport costs and the larger potential for economies of scale. These advantages suggest that, in the long-run air capture be competitive with other methods of achieving deep emissions reductions. We provide a preliminary engineering-economic analysis of an air capture system based on CaO to CaCO3 chemical looping [1]. We analyze the possibility of doing the calcination in a modified pressurized fluidized bed combustor (PFBC) burning coal in a CO2 rich atmosphere with oxygen supplied by an air separation unit. The CaCO3-to-coal ratio would be ~2:1 and the system would be nearly thermally neutral. PFBC systems have been demonstrated at capacities of over 100 MW. Such systems already include CaCO3 injection for sulfur control, and operate at suitable temperatures and pressures for calcination. We assess the potential to recover heat from the dissolution of CaO in order to reduce the overall energy requirements. We analyze the possibility of adapting existing large water/air heat exchangers for use as contacting systems to capture CO2 from the air using the calcium hydroxide solution. The implications of air capture

Which are the most important parameters for modelling carbon assimilation in boreal Norway spruce under elevated [CO(2)] and temperature conditions?

PubMed

Hall, Marianne; Medlyn, Belinda E; Abramowitz, Gab; Franklin, Oskar; Räntfors, Mats; Linder, Sune; Wallin, Göran

2013-11-01

Photosynthesis is highly responsive to environmental and physiological variables, including phenology, foliage nitrogen (N) content, atmospheric CO2 concentration ([CO2]), irradiation (Q), air temperature (T) and vapour pressure deficit (D). Each of these responses is likely to be modified by long-term changes in climatic conditions such as rising air temperature and [CO2]. When modelling photosynthesis under climatic changes, which parameters are then most important to calibrate for future conditions? To assess this, we used measurements of shoot carbon assimilation rates and microclimate conditions collected at Flakaliden, northern Sweden. Twelve 40-year-old Norway spruce trees were enclosed in whole-tree chambers and exposed to elevated [CO2] and elevated air temperature, separately and in combination. The treatments imposed were elevated temperature, +2.8 °C in July/August and +5.6 °C in December above ambient, and [CO2] (ambient CO2 ∼370 μ mol mol(-1), elevated CO2 ∼700 μ mol mol(-1)). The relative importance of parameterization of Q, T and D responses for effects on the photosynthetic rate, expressed on a projected needle area, and the annual shoot carbon uptake was quantified using an empirical shoot photosynthesis model, which was developed and fitted to the measurements. The functional form of the response curves was established using an artificial neural network. The [CO2] treatment increased annual shoot carbon (C) uptake by 50%. Most important was effects on the light response curve, with a 67% increase in light-saturated photosynthetic rate, and a 52% increase in the initial slope of the light response curve. An interactive effect of light saturated photosynthetic rate was found with foliage N status, but no interactive effect for high temperature and high CO2. The air temperature treatment increased the annual shoot C uptake by 44%. The most important parameter was the seasonality, with an elongation of the growing season by almost 4

[Steam and air co-injection in removing TCE in 2D-sand box].

PubMed

Wang, Ning; Peng, Sheng; Chen, Jia-Jun

2014-07-01

Steam and air co-injection is a newly developed and promising soil remediation technique for non-aqueous phase liquids (NAPLs) in vadose zone. In this study, in order to investigate the mechanism of the remediation process, trichloroethylene (TCE) removal using steam and air co-injection was carried out in a 2-dimensional sandbox with different layered sand structures. The results showed that co-injection perfectly improved the "tailing" effect compared to soil vapor extraction (SVE), and the remediation process of steam and air co-injection could be divided into SVE stage, steam strengthening stage and heat penetration stage. Removal ratio of the experiment with scattered contaminant area was higher and removal speed was faster. The removal ratios from the two experiments were 93.5% and 88.2%, and the removal periods were 83.9 min and 90.6 min, respectively. Steam strengthened the heat penetration stage. The temperature transition region was wider in the scattered NAPLs distribution experiment, which reduced the accumulation of TCE. Slight downward movement of TCE was observed in the experiment with TCE initially distributed in a fine sand zone. And such downward movement of TCE reduced the TCE removal ratio.

Global and Regional Seasonal Variability of Mid-Tropospheric CO2 as Measured by the Atmospheric Infrared Sounder (AIRS)

NASA Technical Reports Server (NTRS)

Pagano, Thomas S.; Olsen, Edward T.; Nguyen, Hai

2012-01-01

The Atmospheric Infrared Sounder (AIRS) is a hyperspectral infrared instrument on the Earth Observing System (EOS) Aqua Spacecraft, launched on May 4, 2002 into a near polar sun-synchronous orbit. AIRS has 2378 infrared channels ranging from 3.7 ?m to 15.4 ?m and a 13.5 km footprint at nadir. AIRS, in conjunction with the Advanced Microwave Sounding Unit (AMSU), produces temperature profiles with 1K/km accuracy on a global scale, as well as water vapor profiles and trace gas amounts for CO2, CO, SO2, O3 and CH4. AIRS CO2 climatologies have been shown to be useful for identifying anomalies associated with geophysical events such as El Nino-Southern Oscillation or Madden-Julian oscillation. In this study, monthly representations of mid-tropospheric CO2 are constructed from 10 years of AIRS Version 5 monthly Level 3 data. We compare the AIRS mid-tropospheric CO2 representations to ground-based measurements from the Scripps and National Oceanic and Atmospheric Administration Climate Modeling and Diagnostics Laboratory (NOAA CMDL) ground networks to better understand the phase lag of the CO2 seasonal cycle between the surface and middle troposphere. Results show only a small phase lag in the tropics that grows to approximately two months in the northern latitudes.

Simultaneous assimilation of AIRS and GOSAT CO2 observations with Ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Liu, J.; Kalnay, E.; Fung, I.; Kang, J.

2012-12-01

Lack of CO2 vertical information could lead to bias in the surface CO2 flux estimation (Stephens et al., 2007). Liu et al. (2012) showed that assimilating AIRS CO2 observations, which are sensitive to middle to upper troposphere CO2, improves CO2 concentration, especially in the middle to upper troposphere. GOSAT is sensitive to CO2 over the whole column, but the spatial coverage is sparser than AIRS. In this study, we assimilate AIRS and GOSAT CO2 observations simultaneously along with surface flask CO2 observations and meteorology observations with Ensemble Kalman filter (EnKF) to constrain CO2 vertical profiles simulated by NCAR carbon-climate model. We will show the impact of assimilating AIRS and GOSAT CO2 on the CO2 vertical gradient, seasonal cycle and spatial gradient by assimilating only GOSAT or AIRS and comparing to the control experiment. The quality of CO2 analysis will be examined by validating against independent CO2 aircraft observations, and analyzing the relationship between CO2 analysis fields and major circulation, such as Madden Julian Oscillation. We will also discuss the deficiencies of the observation network in understanding the carbon cycle.

Flue-gas and direct-air capture of CO2 by porous metal–organic materials

PubMed Central

2017-01-01

Sequestration of CO2, either from gas mixtures or directly from air (direct air capture), is a technological goal important to large-scale industrial processes such as gas purification and the mitigation of carbon emissions. Previously, we investigated five porous materials, three porous metal–organic materials (MOMs), a benchmark inorganic material, Zeolite 13X and a chemisorbent, TEPA-SBA-15, for their ability to adsorb CO2 directly from air and from simulated flue-gas. In this contribution, a further 10 physisorbent materials that exhibit strong interactions with CO2 have been evaluated by temperature-programmed desorption for their potential utility in carbon capture applications: four hybrid ultramicroporous materials, SIFSIX-3-Cu, DICRO-3-Ni-i, SIFSIX-2-Cu-i and MOOFOUR-1-Ni; five microporous MOMs, DMOF-1, ZIF-8, MIL-101, UiO-66 and UiO-66-NH2; an ultramicroporous MOM, Ni-4-PyC. The performance of these MOMs was found to be negatively impacted by moisture. Overall, we demonstrate that the incorporation of strong electrostatics from inorganic moieties combined with ultramicropores offers improved CO2 capture performance from even moist gas mixtures but not enough to compete with chemisorbents. This article is part of the themed issue ‘Coordination polymers and metal–organic frameworks: materials by design’. PMID:27895255

In situ X-ray ptychography imaging of high-temperature CO{sub 2} acceptor particle agglomerates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Høydalsvik, Kristin; Bø Fløystad, Jostein; Esmaeili, Morteza

2014-06-16

Imaging nanoparticles under relevant reaction conditions of high temperature and gas pressure is difficult because conventional imaging techniques, like transmission electron microscopy, cannot be used. Here we demonstrate that the coherent diffractive imaging technique of X-ray ptychography can be used for in situ phase contrast imaging in structure studies at atmospheric pressure and elevated temperatures. Lithium zirconate, a candidate CO{sub 2} capture material, was studied at a pressure of one atmosphere in air and in CO{sub 2}, at temperatures exceeding 600 °C. Images with a spatial resolution better than 200 nm were retrieved, and possibilities for improving the experiment are described.

High temperature chemical kinetic study of the H2-CO-CO2-NO reaction system

NASA Technical Reports Server (NTRS)

Jachimowski, C. J.

1975-01-01

An experimental study of the kinetics of the H2-CO-CO2-NO reaction system was made behind incident shock waves at temperatures of 2460 and 2950 K. The overall rate of the reaction was measured by monitoring radiation from the CO + O yields CO2 + h upoilon reaction. Correlation of these data with a detailed reaction mechanism showed that the high-temperature rate of the reaction N + OH yields NO + H can be described by the low-temperature (320 K) rate coefficient. Catalytic dissociation of molecular hydrogen was an important reaction under the tests conditions.

Monitoring of CoS 2 reactions using high-temperature XRD coupled with gas chromatography (GC)

DOE PAGES

Rodriguez, Mark A.; Coker, Eric Nicholas; Griego, James J. M.; ...

2016-04-18

High-temperature X-ray diffraction with concurrent gas chromatography (GC) was used to study cobalt disulfide cathode pellets disassembled from thermal batteries. When CoS 2 cathode materials were analyzed in an air environment, oxidation of the K(Br, Cl) salt phase in the cathode led to the formation of K 2SO 4 that subsequently reacted with the pyrite-type CoS 2 phase leading to cathode decomposition between ~260 and 450 °C. Here, independent thermal analysis experiments, i.e. simultaneous thermogravimetric analysis/differential scanning calorimetry/mass spectrometry (MS), augmented the diffraction results and support the overall picture of CoS 2 decomposition. Both gas analysis measurements (i.e. GC andmore » MS) from the independent experiments confirmed the formation of SO 2 off-gas species during breakdown of the CoS 2. In contrast, characterization of the same cathode material under inert conditions showed the presence of CoS 2 throughout the entire temperature range of analysis.« less

Extraction of CO2 from air samples for isotopic analysis and limits to ultra high precision delta18O determination in CO2 gas.

PubMed

Werner, R A; Rothe, M; Brand, W A

2001-01-01

The determination of delta18O values in CO2 at a precision level of +/-0.02 per thousand (delta-notation) has always been a challenging, if not impossible, analytical task. Here, we demonstrate that beyond the usually assumed major cause of uncertainty - water contamination - there are other, hitherto underestimated sources of contamination and processes which can alter the oxygen isotope composition of CO2. Active surfaces in the preparation line with which CO2 comes into contact, as well as traces of air in the sample, can alter the apparent delta18O value both temporarily and permanently. We investigated the effects of different surface materials including electropolished stainless steel, Duran glass, gold and quartz, the latter both untreated and silanized. CO2 frozen with liquid nitrogen showed a transient alteration of the 18O/16O ratio on all surfaces tested. The time to recover from the alteration as well as the size of the alteration varied with surface type. Quartz that had been ultrasonically cleaned for several hours with high purity water (0.05 microS) exhibited the smallest effect on the measured oxygen isotopic composition of CO2 before and after freezing. However, quartz proved to be mechanically unstable with time when subjected to repeated large temperature changes during operation. After several days of operation the gas released from the freezing step contained progressively increasing trace amounts of O2 probably originating from inclusions within the quartz, which precludes the use of quartz for cryogenically trapping CO2. Stainless steel or gold proved to be suitable materials after proper pre-treatment. To ensure a high trapping efficiency of CO2 from a flow of gas, a cold trap design was chosen comprising a thin wall 1/4" outer tube and a 1/8" inner tube, made respectively from electropolished stainless steel and gold. Due to a considerable 18O specific isotope effect during the release of CO2 from the cold surface, the thawing time had to

Reducing the cost of Ca-based direct air capture of CO2.

PubMed

Zeman, Frank

2014-10-07

Direct air capture, the chemical removal of CO2 directly from the atmosphere, may play a role in mitigating future climate risk or form the basis of a sustainable transportation infrastructure. The current discussion is centered on the estimated cost of the technology and its link to "overshoot" trajectories, where atmospheric CO2 levels are actively reduced later in the century. The American Physical Society (APS) published a report, later updated, estimating the cost of a one million tonne CO2 per year air capture facility constructed today that highlights several fundamental concepts of chemical air capture. These fundamentals are viewed through the lens of a chemical process that cycles between removing CO2 from the air and releasing the absorbed CO2 in concentrated form. This work builds on the APS report to investigate the effect of modifications to the air capture system based on suggestions in the report and subsequent publications. The work shows that reduced carbon electricity and plastic packing materials (for the contactor) may have significant effects on the overall price, reducing the APS estimate from $610 to $309/tCO2 avoided. Such a reduction does not challenge postcombustion capture from point sources, estimated at $80/tCO2, but does make air capture a feasible alternative for the transportation sector and a potential negative emissions technology. Furthermore, air capture represents atmospheric reductions rather than simply avoided emissions.

Climate change impacts on sea-air fluxes of CO2 in three Arctic seas: a sensitivity study using Earth observation

NASA Astrophysics Data System (ADS)

Land, P. E.; Shutler, J. D.; Cowling, R. D.; Woolf, D. K.; Walker, P.; Findlay, H. S.; Upstill-Goddard, R. C.; Donlon, C. J.

2013-12-01

We applied coincident Earth observation data collected during 2008 and 2009 from multiple sensors (RA2, AATSR and MERIS, mounted on the European Space Agency satellite Envisat) to characterise environmental conditions and integrated sea-air fluxes of CO2 in three Arctic seas (Greenland, Barents, Kara). We assessed net CO2 sink sensitivity due to changes in temperature, salinity and sea ice duration arising from future climate scenarios. During the study period the Greenland and Barents seas were net sinks for atmospheric CO2, with integrated sea-air fluxes of -36 ± 14 and -11 ± 5 Tg C yr-1, respectively, and the Kara Sea was a weak net CO2 source with an integrated sea-air flux of +2.2 ± 1.4 Tg C yr-1. The combined integrated CO2 sea-air flux from all three was -45 ± 18 Tg C yr-1. In a sensitivity analysis we varied temperature, salinity and sea ice duration. Variations in temperature and salinity led to modification of the transfer velocity, solubility and partial pressure of CO2 taking into account the resultant variations in alkalinity and dissolved organic carbon (DOC). Our results showed that warming had a strong positive effect on the annual integrated sea-air flux of CO2 (i.e. reducing the sink), freshening had a strong negative effect and reduced sea ice duration had a small but measurable positive effect. In the climate change scenario examined, the effects of warming in just over a decade of climate change up to 2020 outweighed the combined effects of freshening and reduced sea ice duration. Collectively these effects gave an integrated sea-air flux change of +4.0 Tg C in the Greenland Sea, +6.0 Tg C in the Barents Sea and +1.7 Tg C in the Kara Sea, reducing the Greenland and Barents sinks by 11% and 53%, respectively, and increasing the weak Kara Sea source by 81%. Overall, the regional integrated flux changed by +11.7 Tg C, which is a 26% reduction in the regional sink. In terms of CO2 sink strength, we conclude that the Barents Sea is the most

Potential for reducing air-pollutants while achieving 2 °C global temperature change limit target.

PubMed

Hanaoka, Tatsuya; Akashi, Osamu; Fujiwara, Kazuya; Motoki, Yuko; Hibino, Go

2014-12-01

This study analyzes the potential to reduce air pollutants while achieving the 2 °C global temperature change limit target above pre-industrial levels, by using the bottom-up optimization model, AIM/Enduse[Global]. This study focuses on; 1) estimating mitigation potentials and costs for achieving 2 °C, 2.5 °C, and 3 °C target scenarios, 2) assessing co-benefits of reducing air pollutants such as NOx, SO2, BC, PM, and 3) analyzing features of sectoral attributions in Annex I and Non-Annex I groups of countries. The carbon tax scenario at 50 US$/tCO2-eq in 2050 can reduce GHG emissions more than the 3 °C target scenario, but a higher carbon price around 400 US$/tCO2-eq in 2050 is required to achieve the 2 °C target scenario. However, there is also a co-benefit of large reduction potential of air pollutants, in the range of 60-80% reductions in 2050 from the reference scenario while achieving the 2 °C target. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems

PubMed Central

Rezende, Renan de Souza; Gonçalves Júnior, José Francisco; Lopes, Aline; Piedade, Maria Teresa Fernandez; Cavalcante, Heloide de Lima; Hamada, Neusa

2017-01-01

Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams. PMID:29190723

Thermal decomposition of sewage sludge under N2, CO2 and air: Gas characterization and kinetic analysis.

PubMed

Hernández, Ana Belén; Okonta, Felix; Freeman, Ntuli

2017-07-01

Thermochemical valorisation processes that allow energy to be recovered from sewage sludge, such as pyrolysis and gasification, have demonstrated great potential as convenient alternatives to conventional sewage sludge disposal technologies. Moreover, these processes may benefit from CO 2 recycling. Today, the scaling up of these technologies requires an advanced knowledge of the reactivity of sewage sludge and the characteristics of the products, specific to the thermochemical process. In this study the behaviour of sewage sludge during thermochemical conversion, under different atmospheres (N 2 , CO 2 and air), was studied, using TGA-FTIR, in order to understand the effects of different atmospheric gases on the kinetics of degradation and on the gaseous products. The different steps observed during the solid degradation were related with the production of different gaseous compounds. A higher oxidative degree of the atmosphere surrounding the sample resulted in higher reaction rates and a shift of the degradation mechanisms to lower temperatures, especially for the mechanisms taking place at temperatures above 400 °C. Finally, a multiple first-order reaction model was proposed to compare the kinetic parameters obtained under different atmospheres. Overall, the highest activation energies were obtained for combustion. This work proves that CO 2 , an intermediate oxidative atmosphere between N 2 and air, results in an intermediate behaviour (intermediate peaks in the derivative thermogravimetric curves and intermediate activation energies) during the thermochemical decomposition of sewage sludge. Overall, it can be concluded that the kinetics of these different processes require a different approach for their scaling up and specific consideration of their characteristic reaction temperatures and rates should be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Measurement of air exchange rates in different indoor environments using continuous CO2 sensors.

PubMed

You, Yan; Niu, Can; Zhou, Jian; Liu, Yating; Bai, Zhipeng; Zhang, Jiefeng; He, Fei; Zhang, Nan

2012-01-01

A new air exchange rate (AER) monitoring method using continuous CO2 sensors was developed and validated through both laboratory experiments and field studies. Controlled laboratory simulation tests were conducted in a 1-m3 environmental chamber at different AERs (0.1-10.0 hr(-1)). AERs were determined using the decay method based on box model assumptions. Field tests were conducted in classrooms, dormitories, meeting rooms and apartments during 2-5 weekdays using CO2 sensors coupled with data loggers. Indoor temperature, relative humidity (RH), and CO2 concentrations were continuously monitored while outdoor parameters combined with on-site climate conditions were recorded. Statistical results indicated that good laboratory performance was achieved: duplicate precision was within 10%, and the measured AERs were 90%-120% of the real AERs. Average AERs were 1.22, 1.37, 1.10, 1.91 and 0.73 hr(-1) in dormitories, air-conditioned classrooms, classrooms with an air circulation cooling system, reading rooms, and meeting rooms, respectively. In an elderly particulate matter exposure study, all the homes had AER values ranging from 0.29 to 3.46 hr(-1) in fall, and 0.12 to 1.39 hr(-1) in winter with a median AER of 1.15.

Laminar Flame Velocity and Temperature Exponent of Diluted DME-Air Mixture

NASA Astrophysics Data System (ADS)

Naseer Mohammed, Abdul; Anwar, Muzammil; Juhany, Khalid A.; Mohammad, Akram

2017-03-01

In this paper, the laminar flame velocity and temperature exponent diluted dimethyl ether (DME) air mixtures are reported. Laminar premixed mixture of DME-air with volumetric dilutions of carbon dioxides (CO2) and nitrogen (N2) are considered. Experiments were conducted using a preheated mesoscale high aspect-ratio diverging channel with inlet dimensions of 25 mm × 2 mm. In this method, flame velocities are extracted from planar flames that were stabilized near adiabatic conditions inside the channel. The flame velocities are then plotted against the ratio of mixture temperature and the initial reference temperature. A non-linear power law regression is observed suitable. This regression analysis gives the laminar flame velocity at the initial reference temperature and temperature exponent. Decrease in the laminar flame velocity and increase in temperature exponent is observed for CO2 and N2 diluted mixtures. The addition of CO2 has profound influence when compared to N2 addition on both flame velocity and temperature exponent. Numerical prediction of the similar mixture using a detailed reaction mechanism is obtained. The computational mechanism predicts higher magnitudes for laminar flame velocity and smaller magnitudes of temperature exponent compared to experimental data.

Growth strategy of Norway spruce under air elevated [CO2

NASA Astrophysics Data System (ADS)

Pokorny, R.; Urban, O.; Holisova, P.; Sprtova, M.; Sigut, L.; Slipkova, R.

2012-04-01

Plants will respond to globally increasing atmospheric CO2 concentration ([CO2]) by acclimation or adaptation at physiological and morphological levels. Considering the temporal onset, physiological responses may be categorized as short-term and morphological ones as long-term responses. The degree of plant growth responses, including cell division and cell expansion, is highly variable. It depends mainly on the specie's genetic predisposition, environment, mineral nutrition status, duration of CO2 enrichment, and/or synergetic effects of other stresses. Elevated [CO2] causes changes in tissue anatomy, quantity, size, shape and spatial orientation and can result in altered sink strength. Since, there are many experimental facilities for the investigation of elevated [CO2] effects on trees: i) closed systems or open top chambers (OTCs), ii) semi-open systems (for example glass domes with adjustable lamella windows - DAWs), and iii) free-air [CO2] enrichments (FACE); the results are still unsatisfactory due to: i) relatively short-term duration of experiments, ii) cultivation of young plants with different growth strategy comparing to old ones, iii) plant cultivation under artificial soil and weather conditions, and iv) in non-representative stand structure. In this contribution we are discussing the physiological and morphological responses of Norway spruce trees cultivated in DAWs during eight consecutive growing seasons in the context with other results from Norway spruce cultivation under air-elevated [CO2] conditions. On the level of physiological responses, we discuss the changes in the rate of CO2 assimilation, assimilation capacity, photorespiration, dark respiration, stomatal conductance, water potential and transpiration, and the sensitivity of these physiological processes to temperature. On the level of morphological responses, we discuss the changes in bud and growth phenology, needle and shoot morphology, architecture of crown and root system, wood

Interactive effect of elevated CO2 and temperature on coral physiology

NASA Astrophysics Data System (ADS)

Grottoli, A. G.; Cai, W.; Warner, M.; Melman, T.; Schoepf, V.; Baumann, J.; Matsui, Y.; Pettay, D. T.; Hoadley, K.; Xu, H.; Wang, Y.; Li, Q.; Hu, X.

2011-12-01

Increases in ocean acidification and temperature threaten coral reefs globally. However, the interactive effect of both lower pH and higher temperature on coral physiology and growth are poorly understood. Here, we present preliminary findings from a replicated controlled experiment where four species of corals (Acorpora millepora, Pocillopora damicornis, Montipora monasteriata, Turbinaria reniformis) were reared under the following six treatments for three weeks: 1) 400ppm CO2 and ambient temperature, 2) 400ppm CO2 and elevated temperature, 3) 650ppm CO2 and ambient temperature, 4) 650ppm CO2 and elevated temperature, 5) 800ppm CO2 and ambient temperature, 6) 800ppm CO2 and elevated temperature. Initial findings of photophysiological health (Fv/Fm), calcification rates (as measured by both buoyant weight and the total alkalinity methods), and energy reserves will be presented.

The High Accuracy Measurement of CO2 Mixing Ratio Profiles Using Ground Based 1.6 μm CO2-DIAL with Temperature Measurement Techniques in the Lower-Atmosphere

NASA Astrophysics Data System (ADS)

Abo, M.; Shibata, Y.; Nagasawa, C.

2017-12-01

We have developed a ground based direct detection three-wavelength 1.6 μm differential absorption lidar (DIAL) to achieve measurements of vertical CO2 concentration and temperature profiles in the atmosphere. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement is realized. Conventionally, we have obtained the vertical profile of absorption cross sections using the atmospheric temperature profile by the objective analysis and the atmospheric pressure profile calculated by the pressure height equation. Comparison of atmospheric pressure profiles calculated from this equation and those obtained from radiosonde observations at Tateno, Japan is consistent within 0.2 % below 3 km altitude. But the temperature dependency of the CO2 density is 0.25 %/°C near the surface. Moreover, the CO2 concentration is often evaluated by the mixing ratio. Because the air density is related by the ideal gas law, the mixing ratio is also related by the atmospheric temperature. Therefore, the temperature affects not only accuracy of CO2 concentration but the CO2 mixing ratio. In this paper, some experimental results of the simultaneous measurement of atmospheric temperature profiles and CO2 mixing ratio profiles are reported from 0.4 to 2.5 km altitude using the three-wavelength 1.6 μm DIAL system. Temperature profiles of CO2 DIAL measurement were sometimes different from those of objective analysis below 1.5 km altitude. These differences are considered to be due to regionality at the lidar site. The temperature difference of 5.0 °C corresponds to a CO2 mixing ratio difference of 8.0 ppm at 500 m altitude. This cannot be ignored in estimates of regional sources and sinks of CO2. This three-wavelength CO2 DIAL technique can estimate accurately temporal behavior of CO2 mixing ratio profiles in the lower atmosphere

Amine-tethered solid adsorbents coupling high adsorption capacity and regenerability for CO2 capture from ambient air.

PubMed

Choi, Sunho; Gray, McMahan L; Jones, Christopher W

2011-05-23

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO (2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous CO concentration and temperature measurements using tunable diode laser absorption spectroscopy near 2.3 μm

NASA Astrophysics Data System (ADS)

Sane, Anup; Satija, Aman; Lucht, Robert P.; Gore, Jay P.

2014-10-01

Simultaneous measurements of carbon monoxide (CO) mole fraction and temperature using tunable diode laser absorption spectroscopy (TDLAS) near 2.3 μm are reported. The measurement method uses ro-vibrational transitions [R(27): v″ = 1 → v' = 3] and [R(6): v″ = 0 → v' = 2] in the first overtone band of CO near 2.3 μm (~4,278 cm-1). The measurements were performed in the post flame environment of fuel rich premixed ethylene-air flames with a N2 co-flow, stabilized over a water cooled McKenna burner. Non-uniformity in the temperature and CO mole fraction, along the absorption line of sight, in the mixing layer of the co-flow, was considered during data analysis. The TDLAS based temperature measurements (±80 K) were in good agreement with those obtained using N2 vibrational coherent anti-Stokes Raman scattering (±20 K), and the CO mole fraction measurements were in good agreement with the equilibrium values, for equivalence ratios lower than 1.8. A signal to noise ratio of 45 was achieved at an equivalence ratio of 1 for a CO concentration of 0.8 % at 1,854 K.

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air

PubMed Central

Jung, Heejung S.; Grady, Michael L.; Victoroff, Tristan; Miller, Arthur L.

2017-01-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm3, although CO2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm3. We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50–75% maintained lower CO2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants’ exposures to particulate matter and CO2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO2 accumulation. PMID:28781568

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air.

PubMed

Jung, Heejung S; Grady, Michael L; Victoroff, Tristan; Miller, Arthur L

2017-07-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO 2 ) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO 2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm 3 , although CO 2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO 2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm 3 . We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO 2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO 2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO 2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO 2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO 2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO 2 accumulation.

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air

NASA Astrophysics Data System (ADS)

Jung, Heejung S.; Grady, Michael L.; Victoroff, Tristan; Miller, Arthur L.

2017-07-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm3, although CO2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm3. We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO2 accumulation.

Quantifying the air quality-CO2 tradeoff potential for airports

NASA Astrophysics Data System (ADS)

Ashok, Akshay; Dedoussi, Irene C.; Yim, Steve H. L.; Balakrishnan, Hamsa; Barrett, Steven R. H.

2014-12-01

Aircraft movements on the airport surface are responsible for CO2 emissions that contribute to climate change and other emissions that affect air quality and human health. While the potential for optimizing aircraft surface movements to minimize CO2 emissions has been assessed, the implications of CO2 emissions minimization for air quality have not been quantified. In this paper, we identify conditions in which there is a tradeoff between CO2 emissions and population exposure to O3 and secondary PM2.5 - i.e. where decreasing fuel burn (which is directly proportional to CO2 emissions) results in increased exposure. Fuel burn and emissions are estimated as a function of thrust setting for five common gas turbine engines at 34 US airports. Regional air quality impacts, which are dominated by ozone and secondary PM2.5, are computed as a function of airport location and time using the adjoint of the GEOS-Chem chemistry-transport model. Tradeoffs between CO2 emissions and population exposure to PM2.5 and O3 occur between 2-18% and 5-60% of the year, respectively, depending on airport location, engine type, and thrust setting. The total duration of tradeoff conditions is 5-12 times longer at maximum thrust operations (typical for takeoff) relative to 4% thrust operations (typical for taxiing). Per kilogram of additional fuel burn at constant thrust setting during tradeoff conditions, reductions in population exposure to PM2.5 and O3 are 6-13% and 32-1060% of the annual average (positive) population exposure per kilogram fuel burn, where the ranges encompass the medians over the 34 airports. For fuel burn increases due to thrust increases (i.e. for constant operating time), reductions in both PM2.5 and O3 exposure are 1.5-6.4 times larger in magnitude than those due to increasing fuel burn at constant thrust (i.e. increasing operating time). Airports with relatively high population exposure reduction potentials - which occur due to a combination of high duration and

Tree and forest water use under elevated CO2 and temperature in Scandinavian boreal forest

NASA Astrophysics Data System (ADS)

Berg Hasper, Thomas; Wallin, Göran; Lamba, Shubhangi; Sigurdsson, Bjarni D.; Laudon, Hjalmar; Medhurst, Jane L.; Räntfors, Mats; Linder, Sune; Uddling, Johan

2014-05-01

According to experimental studies and models, rising atmospheric carbon dioxide concentration ([CO2]) and temperature have the potential to affect stomatal conductance and, consequently, tree and forest transpiration. This effect has in turn the capacity to influence the terrestrial energy and water balance, including affecting of the magnitude of river runoff. Furthermore, forest productivity is currently water-limited in southern Scandinavia and in a near future, under the projected climatic change, this limitation may become a reality in the central and northern parts of Scandinavia. In this study we examine the water-use responses in 12 40-year old native boreal Norway spruce (Picea abies (L.) Karst.) trees exposed to a factorial combination of two levels of [CO2] (ambient and doubled) and temperature (ambient and +2.8 °C in summer / +5.6 °C in winter), as well as of entire boreal forests to temporal variation in [CO2], temperature and precipitation over the past 50 years in central and northern Sweden. The controlled factorial CO2 and temperature whole-tree chamber experiment at Flakaliden study site demonstrated that Norway spruce trees lacked elevated [CO2]-induced water savings at guard cell, shoot, and tree levels in the years of measurements. Experimentally, elevated temperature did not result in increased shoot or tree water use as stomatal closure fully cancelled the effect of higher vapour pressure deficit in warmed air environment. Consistent with these results, large scale river runoff data and evapotranspiration estimates from large forested watersheds in central Sweden supported lack of elevated CO2-mediated water savings, and rather suggested that the increasing evapotranspiration trend found in this study was primarily linked to increasing precipitation, rising temperature and more efficient forest management. The results from the whole-tree chamber experiment and boreal forested watersheds have important implications for more accurate

Air-sea CO2 flux pattern along the southern Bay of Bengal waters

NASA Astrophysics Data System (ADS)

Shanthi, R.; Poornima, D.; Naveen, M.; Thangaradjou, T.; Choudhury, S. B.; Rao, K. H.; Dadhwal, V. K.

2016-12-01

Physico-chemical observations made from January 2013 to March 2015 in coastal waters of the southwest Bay of Bengal show pronounced seasonal variation in physico-chemical parameters including total alkalinity (TA: 1927.390-4088.642 μmol kg-1), chlorophyll (0.13-19.41 μg l-1) and also calculated dissolved inorganic carbon (DIC: 1574.219-3790.954 μmol kg-1), partial pressure of carbon dioxide (pCO2: 155.520-1488.607 μatm) and air-sea CO2 flux (FCO2: -4.808 to 11.255 mmol Cm-2 d-1). Most of the physical parameters are at their maximum during summer due to the increased solar radiation at cloud free conditions, less or no riverine inputs, and lack of vertical mixing of water column which leads to the lowest nutrients concentration, dissolved oxygen (DO), biological production, pCO2 and negative flux of CO2 to the atmosphere. Chlorophyll and DO concentrations enhanced due to increased nutrients during premonsoon and monsoon season due to the vertical mixing of water column driven by the strong winds and external inputs at respective seasons. The constant positive loading of nutrients, TA, DIC, chlorophyll, pCO2 and FCO2 against atmospheric temperature (AT), lux, sea surface temperature (SST), pH and salinity observed in principal component analysis (PCA) suggested that physical and biological parameters play vital role in the seasonal distribution of pCO2 along the southwest Bay of Bengal. The annual variability of CO2 flux clearly depicted that the southwest Bay of Bengal switch from sink (2013) to source status in the recent years (2014 and 2015) and it act as significant source of CO2 to the atmosphere with a mean flux of 0.204 ± 1.449 mmol Cm-2 d-1.

Jena Reference Air Set (JRAS): a multi-point scale anchor for isotope measurements of CO2 in air

NASA Astrophysics Data System (ADS)

Wendeberg, M.; Richter, J. M.; Rothe, M.; Brand, W. A.

2013-03-01

The need for a unifying scale anchor for isotopes of CO2 in air was brought to light at the 11th WMO/IAEA Meeting of Experts on Carbon Dioxide in Tokyo 2001. During discussions about persistent discrepancies in isotope measurements between the worlds leading laboratories, it was concluded that a unifying scale anchor for Vienna Pee Dee Belemnite (VPDB) of CO2 in air was desperately needed. Ten years later, at the 2011 Meeting of Experts on Carbon Dioxide in Wellington, it was recommended that the Jena Reference Air Set (JRAS) become the official scale anchor for isotope measurements of CO2 in air (Brailsford, 2012). The source of CO2 used for JRAS is two calcites. After releasing CO2 by reaction with phosphoric acid, the gases are mixed into CO2-free air. This procedure ensures both isotopic stability and longevity of the CO2. That the reference CO2 is generated from calcites and supplied as an air mixture is unique to JRAS. This is made to ensure that any measurement bias arising from the extraction procedure is eliminated. As every laboratory has its own procedure for extracting the CO2, this is of paramount importance if the local scales are to be unified with a common anchor. For a period of four years, JRAS has been evaluated through the IMECC1 program, which made it possible to distribute sets of JRAS gases to 13 laboratories worldwide. A summary of data from the six laboratories that have reported the full set of results is given here along with a description of the production and maintenance of the JRAS scale anchors. 1 IMECC refers to the EU project "Infrastructure for Measurements of the European Carbon Cycle" (http://imecc.ipsl.jussieu.fr/).

Effects of sea-ice and biogeochemical processes and storms on under-ice water fCO2 during the winter-spring transition in the high Arctic Ocean: Implications for sea-air CO2 fluxes

NASA Astrophysics Data System (ADS)

Fransson, Agneta; Chierici, Melissa; Skjelvan, Ingunn; Olsen, Are; Assmy, Philipp; Peterson, Algot K.; Spreen, Gunnar; Ward, Brian

2017-07-01

We performed measurements of carbon dioxide fugacity (fCO2) in the surface water under Arctic sea ice from January to June 2015 during the Norwegian young sea ICE (N-ICE2015) expedition. Over this period, the ship drifted with four different ice floes and covered the deep Nansen Basin, the slopes north of Svalbard, and the Yermak Plateau. This unique winter-to-spring data set includes the first winter-time under-ice water fCO2 observations in this region. The observed under-ice fCO2 ranged between 315 µatm in winter and 153 µatm in spring, hence was undersaturated relative to the atmospheric fCO2. Although the sea ice partly prevented direct CO2 exchange between ocean and atmosphere, frequently occurring leads and breakup of the ice sheet promoted sea-air CO2 fluxes. The CO2 sink varied between 0.3 and 86 mmol C m-2 d-1, depending strongly on the open-water fractions (OW) and storm events. The maximum sea-air CO2 fluxes occurred during storm events in February and June. In winter, the main drivers of the change in under-ice water fCO2 were dissolution of CaCO3 (ikaite) and vertical mixing. In June, in addition to these processes, primary production and sea-air CO2 fluxes were important. The cumulative loss due to CaCO3 dissolution of 0.7 mol C m-2 in the upper 10 m played a major role in sustaining the undersaturation of fCO2 during the entire study. The relative effects of the total fCO2 change due to CaCO3 dissolution was 38%, primary production 26%, vertical mixing 16%, sea-air CO2 fluxes 16%, and temperature and salinity insignificant.

On the calculation of air-sea fluxes of CO2 in the presence of temperature and salinity gradients

NASA Astrophysics Data System (ADS)

Woolf, D. K.; Land, P. E.; Shutler, J. D.; Goddijn-Murphy, L. M.; Donlon, C. J.

2016-02-01

The presence of vertical temperature and salinity gradients in the upper ocean and the occurrence of variations in temperature and salinity on time scales from hours to many years complicate the calculation of the flux of carbon dioxide (CO2) across the sea surface. Temperature and salinity affect the interfacial concentration of aqueous CO2 primarily through their effect on solubility with lesser effects related to saturated vapor pressure and the relationship between fugacity and partial pressure. The effects of temperature and salinity profiles in the water column and changes in the aqueous concentration act primarily through the partitioning of the carbonate system. Climatological calculations of flux require attention to variability in the upper ocean and to the limited validity of assuming "constant chemistry" in transforming measurements to climatological values. Contrary to some recent analysis, it is shown that the effect on CO2 fluxes of a cool skin on the sea surface is large and ubiquitous. An opposing effect on calculated fluxes is related to the occurrence of warm layers near the surface; this effect can be locally large but will usually coincide with periods of low exchange. A salty skin and salinity anomalies in the upper ocean also affect CO2 flux calculations, though these haline effects are generally weaker than the thermal effects.

Temporal variability of air-sea CO2 exchange in a low-emission estuary

NASA Astrophysics Data System (ADS)

Mørk, Eva Thorborg; Sejr, Mikael Kristian; Stæhr, Peter Anton; Sørensen, Lise Lotte

2016-07-01

There is the need for further study of whether global estimates of air-sea CO2 exchange in estuarine systems capture the relevant temporal variability and, as such, the temporal variability of bulk parameterized and directly measured CO2 fluxes was investigated in the Danish estuary, Roskilde Fjord. The air-sea CO2 fluxes showed large temporal variability across seasons and between days and that more than 30% of the net CO2 emission in 2013 was a result of two large fall and winter storms. The diurnal variability of ΔpCO2 was up to 400 during summer changing the estuary from a source to a sink of CO2 within the day. Across seasons the system was suggested to change from a sink of atmospheric CO2 during spring to near neutral during summer and later to a source of atmospheric CO2 during fall. Results indicated that Roskilde Fjord was an annual low-emission estuary, with an estimated bulk parameterized release of 3.9 ± 8.7 mol CO2 m-2 y-1 during 2012-2013. It was suggested that the production-respiration balance leading to the low annual emission in Roskilde Fjord, was caused by the shallow depth, long residence time and high water quality in the estuary. In the data analysis the eddy covariance CO2 flux samples were filtered according to the H2Osbnd CO2 cross-sensitivity assessment suggested by Landwehr et al. (2014). This filtering reduced episodes of contradicting directions between measured and bulk parameterized air-sea CO2 exchanges and changed the net air-sea CO2 exchange from an uptake to a release. The CO2 gas transfer velocity was calculated from directly measured CO2 fluxes and ΔpCO2 and agreed to previous observations and parameterizations.

Data Assimilation Experiments Using Quality Controlled AIRS Version 5 Temperature Soundings

NASA Technical Reports Server (NTRS)

Susskind, Joel

2009-01-01

The AIRS Science Team Version 5 retrieval algorithm has been finalized and is now operational at the Goddard DAAC in the processing (and reprocessing) of all AIRS data. The AIRS Science Team Version 5 retrieval algorithm contains a number of significant improvements over Version 4. Two very significant improvements are described briefly below. 1) The AIRS Science Team Radiative Transfer Algorithm (RTA) has now been upgraded to accurately account for effects of non-local thermodynamic equilibrium on the AIRS observations. This allows for use of AIRS observations in the entire 4.3 micron CO2 absorption band in the retrieval algorithm during both day and night. Following theoretical considerations, tropospheric temperature profile information is obtained almost exclusively from clear column radiances in the 4.3 micron CO2 band in the AIRS Version 5 temperature profile retrieval step. These clear column radiances are a derived product that are indicative of radiances AIRS channels would have seen if the field of view were completely clear. Clear column radiances for all channels are determined using tropospheric sounding 15 micron CO2 observations. This approach allows for the generation of accurate values of clear column radiances and T(p) under most cloud conditions. 2) Another very significant improvement in Version 5 is the ability to generate accurate case-by-case, level-by-level error estimates for the atmospheric temperature profile, as well as for channel-by-channel clear column radiances. These error estimates are used for quality control of the retrieved products. Based on error estimate thresholds, each temperature profiles is assigned a characteristic pressure, pg, down to which the profile is characterized as good for use for data assimilation purposes. We have conducted forecast impact experiments assimilating AIRS quality controlled temperature profiles using the NASA GEOS-5 data assimilation system, consisting of the NCEP GSI analysis coupled with the

Performance of the air2stream model that relates air and stream water temperatures depends on the calibration method

NASA Astrophysics Data System (ADS)

Piotrowski, Adam P.; Napiorkowski, Jaroslaw J.

2018-06-01

A number of physical or data-driven models have been proposed to evaluate stream water temperatures based on hydrological and meteorological observations. However, physical models require a large amount of information that is frequently unavailable, while data-based models ignore the physical processes. Recently the air2stream model has been proposed as an intermediate alternative that is based on physical heat budget processes, but it is so simplified that the model may be applied like data-driven ones. However, the price for simplicity is the need to calibrate eight parameters that, although have some physical meaning, cannot be measured or evaluated a priori. As a result, applicability and performance of the air2stream model for a particular stream relies on the efficiency of the calibration method. The original air2stream model uses an inefficient 20-year old approach called Particle Swarm Optimization with inertia weight. This study aims at finding an effective and robust calibration method for the air2stream model. Twelve different optimization algorithms are examined on six different streams from northern USA (states of Washington, Oregon and New York), Poland and Switzerland, located in both high mountains, hilly and lowland areas. It is found that the performance of the air2stream model depends significantly on the calibration method. Two algorithms lead to the best results for each considered stream. The air2stream model, calibrated with the chosen optimization methods, performs favorably against classical streamwater temperature models. The MATLAB code of the air2stream model and the chosen calibration procedure (CoBiDE) are available as Supplementary Material on the Journal of Hydrology web page.

Climatological mean and decadal change in surface ocean pCO 2, and net sea-air CO 2 flux over the global oceans

NASA Astrophysics Data System (ADS)

Takahashi, Taro; Sutherland, Stewart C.; Wanninkhof, Rik; Sweeney, Colm; Feely, Richard A.; Chipman, David W.; Hales, Burke; Friederich, Gernot; Chavez, Francisco; Sabine, Christopher; Watson, Andrew; Bakker, Dorothee C. E.; Schuster, Ute; Metzl, Nicolas; Yoshikawa-Inoue, Hisayuki; Ishii, Masao; Midorikawa, Takashi; Nojiri, Yukihiro; Körtzinger, Arne; Steinhoff, Tobias; Hoppema, Mario; Olafsson, Jon; Arnarson, Thorarinn S.; Tilbrook, Bronte; Johannessen, Truls; Olsen, Are; Bellerby, Richard; Wong, C. S.; Delille, Bruno; Bates, N. R.; de Baar, Hein J. W.

2009-04-01

A climatological mean distribution for the surface water pCO 2 over the global oceans in non-El Niño conditions has been constructed with spatial resolution of 4° (latitude) ×5° (longitude) for a reference year 2000 based upon about 3 million measurements of surface water pCO 2 obtained from 1970 to 2007. The database used for this study is about 3 times larger than the 0.94 million used for our earlier paper [Takahashi et al., 2002. Global sea-air CO 2 flux based on climatological surface ocean pCO 2, and seasonal biological and temperature effects. Deep-Sea Res. II, 49, 1601-1622]. A time-trend analysis using deseasonalized surface water pCO 2 data in portions of the North Atlantic, North and South Pacific and Southern Oceans (which cover about 27% of the global ocean areas) indicates that the surface water pCO 2 over these oceanic areas has increased on average at a mean rate of 1.5 μatm y -1 with basin-specific rates varying between 1.2±0.5 and 2.1±0.4 μatm y -1. A global ocean database for a single reference year 2000 is assembled using this mean rate for correcting observations made in different years to the reference year. The observations made during El Niño periods in the equatorial Pacific and those made in coastal zones are excluded from the database. Seasonal changes in the surface water pCO 2 and the sea-air pCO 2 difference over four climatic zones in the Atlantic, Pacific, Indian and Southern Oceans are presented. Over the Southern Ocean seasonal ice zone, the seasonality is complex. Although it cannot be thoroughly documented due to the limited extent of observations, seasonal changes in pCO 2 are approximated by using the data for under-ice waters during austral winter and those for the marginal ice and ice-free zones. The net air-sea CO 2 flux is estimated using the sea-air pCO 2 difference and the air-sea gas transfer rate that is parameterized as a function of (wind speed) 2 with a scaling factor of 0.26. This is estimated by inverting

Response of sugarcane to carbon dioxide enrichment and elevated air temperature

USDA-ARS?s Scientific Manuscript database

Four sugarcane cultivars (CP 72-2086, CP 73-1547, CP 88-1508, and CP 80-1827) were grown in elongated temperature-gradient greenhouses (TGG) at ambient or elevated carbon dioxide (CO2) of 360 or 720 µmol CO2 mol-1 air (ppm, mole fraction basis), respectively. Elevated CO2 was maintained by injection...

Regenerable device for scrubbing breathable air of CO2 and moisture without special heat exchanger equipment

NASA Technical Reports Server (NTRS)

Tepper, E. H. (Inventor)

1977-01-01

The device concerns the circulation of cabin air through canisters which absorb and adsorb carbon dioxide, together with excess moisture, and return the scrubbed air to the cabin for recirculation. A coating on an inert substrate in granular form absorbs and adsorbs the impurities at standard temperatures and pressures, but desorbs such impurities at low pressures (vacuum) and standard temperatures. This fact is exploited by making the device in a stack of cells consisting of layers or cells which are isolated from one another flow-wise and are connected to separate manifolds and valving systems into two separate subsets. A first subset may be connected for the flow breathable air therethrough until the polyethyleneimine of its cells is saturated with CO2 and H2O. During the same period the second subset of cells is manifolded to a vacuum source.

The Effect of Breaking Waves on CO_2 Air-Sea Fluxes in the Coastal Zone

NASA Astrophysics Data System (ADS)

Gutiérrez-Loza, Lucía; Ocampo-Torres, Francisco J.; García-Nava, Héctor

2018-03-01

The influence of wave-associated parameters controlling turbulent CO_2 fluxes through the air-sea interface is investigated in a coastal region. A full year of high-quality data of direct estimates of air-sea CO_2 fluxes based on eddy-covariance measurements is presented. The study area located in Todos Santos Bay, Baja California, Mexico, is a net sink of CO_2 with a mean flux of -1.3 μmol m^{-2}s^{-1} (-41.6 mol m^{-2}yr^{-1} ). The results of a quantile-regression analysis computed between the CO_2 flux and, (1) wind speed, (2) significant wave height, (3) wave steepness, and (4) water temperature, suggest that the significant wave height is the most correlated parameter with the magnitude of the flux but the behaviour of the relation varies along the probability distribution function, with the slopes of the regression lines presenting both positive and negative values. These results imply that the presence of surface waves in coastal areas is the key factor that promotes the increase of the flux from and into the ocean. Further analysis suggests that the local characteristics of the aqueous and atmospheric layers might determine the direction of the flux.

Air-sea exchange of CO2 in the central and western equatorial Pacific in 1990

NASA Astrophysics Data System (ADS)

Ishii, Masao; Yoshikawa Inoue, Hisayuki

1995-09-01

Measurements of CO2 in marine boundary air and in surface seawater of the central and western Pacific west of 150°W were made during the period from September to December 1990. The meridional section along 150°W showed pCO2(sea) maximum over 410 µatm between the equator and 3°S due to strong equatorial upwelling. In the equatorial Pacific between 150°W and 179°E, pCO2(sea) decreased gradually toward the west as a result of biological CO2 uptake and surface sea temperature increase. Between 179°E and 170°E, the pCO2(sea) decreased steeply from 400 µatm to 350 µatm along with a decrease of salinity. West of 170°E, where the salinity is low owing to the heavy rainfall, pCO2(sea) was nearly equal to pCO2(air). The distribution of the atmospheric CO2 concentration showed a considerable variability (±3ppm) in the area north of the Intertropical Convergence Zone due to the regional net source-sink strength of the terrestrial biosphere. The net CO2 flux from the sea to the atmosphere in the equatorial region of the central and western Pacific (15°S-10°N, 140°E-150°W) was evaluated from the ΔpCO2 distribution and the several gas transfer coefficients reported so far. It ranged from 0.13 GtC year1-0.29 GtC year1. This CO2 outflux is thought to almost disappear during the period of an El Niño event.

Energy requirements for CO2 capture from ambient air (DAC) competitive with capture from flue-gas (PCC)

NASA Astrophysics Data System (ADS)

Meinrenken, Christoph

2015-03-01

Capture of CO2, whether from a flue gas source (PCC) or from distributed sources via ambient air (DAC), is a key enabling technology to provide carbon for sustainable synthetic energy carriers such as solar fuels. Based on thermodynamic minimum considerations, DAC is often expected to require about 3 times more energy (per ton CO2 captured) than PCC because CO2 in ambient air is more dilute. Here, we calculate the energy required for a humidity swing-based DAC installation that uses an anionic exchange resin as sorbent. The calculation uses recently measured equilibrium CO2 loadings of the sorbent as function of partial CO2 pressure, temperature, and humidity. We calculate the installation's electricity consumption to be about 45 kJ per mole of pure CO2 at 1 bar (scenario-dependent). Furthermore, we estimate the amount of heat provided by ambient air and thus provide context of the overall energy and entropy balance and thermodynamic minimum views. The electricity consumption is competitive with typical parasitic loads of PCC-equipped coal-fired power plants (40-50 kJ per mole at same pressure) and significantly lower than predicted for other DAC installations such as Na(OH) sorbent-based systems. Our analyses elucidate why DAC is not always more energy-intensive that PCC, thus alleviating often cited concerns of significant cost impediments. Financial support by ABB for research presented herein is gratefully acknowledged.

Validation of AIRS Retrievals of CO2 via Comparison to In Situ Measurements

NASA Technical Reports Server (NTRS)

Olsen, Edward T.; Chahine, Moustafa T.; Chen, Luke L.; Jiang, Xun; Pagano, Thomas S.; Yung, Yuk L.

2008-01-01

Topics include AIRS on Aqua, 2002-present with discussion about continued operation to 2011 and beyond and background, including spectrum, weighting functions, and initialization; comparison with aircraft and FTIR measurements in Masueda (CONTRAIL) JAL flask measurements, Park Falls, WI FTIR, Bremen, GDF, and Spitsbergen, Norway; AIRS retrievals over addition FTIR sites in Darwin, AU and Lauder, NZ; and mid-tropospheric carbon dioxide weather and contribution from major surface sources. Slide titles include typical AIRS infrared spectrum, AIRS sensitivity for retrieving CO2 profiles, independence of CO2 solution with respect to the initial guess, available in situ measurements for validation and comparison, comparison of collocated V1.5x AIRS CO2 (N_coll greater than or equal to 9) with INTEX-NA and SPURT;

Calibration of Relative Humidity Devices in Low-pressure, Low-temperature CO2 Environment

NASA Astrophysics Data System (ADS)

Genzer, Maria; Polkko, Jouni; Nikkanen, Timo; Hieta, Maria; Harri, Ari-Matti

2017-04-01

Calibration of relative humidity devices requires in minimum two humidity points - dry (0%RH) and (near)saturation (95-100%RH) - over the expected operational temperature and pressure range of the device. In terrestrial applications these are relatively easy to achieve using for example N2 gas as dry medium, and water vapor saturation chambers for producing saturation and intermediate humidity points. But for example in applications intended for meteorological measurements on Mars there is a need to achieve at least dry and saturation points in low-temperature, low-pressure CO2 environment. We have developed a custom-made, small, relatively low-cost calibration chamber able to produce both dry points and saturation points in Martian range pressure CO2, in temperatures down to -70°C. The system utilizes a commercially available temperature chamber for temperature control, vacuum vessels and pumps. The main pressure vessel with the devices under test inside is placed inside the temperature chamber, and the pressure inside is controlled by pumps and manual valves and monitored with a commercial pressure reference with calibration traceable to national standards. Air, CO2, or if needed another gas like N2, is used for filling the vessel until the desired pressure is achieved. Another pressure vessel with a dedicated pressure pump is used as the saturation chamber. This vessel is placed in the room outside the temperature chamber, partly filled with water and used for achieving saturated water vapor in room-temperature low-pressure environment. The saturation chamber is connected to the main pressure vessel via valves. In this system dry point, low-pressure CO2 environment is achieved by filling the main pressure vessel with dry CO2 gas until the desired pressure is achieved. A constant flow of gas is maintained with the pump and valves and monitored with the pressure reference. The saturation point is then achieved by adding some water vapor from the saturation

Advanced buffer materials for indoor air CO2 control in commercial buildings.

PubMed

Rajan, P E; Krishnamurthy, A; Morrison, G; Rezaei, F

2017-11-01

In this study, we evaluated solid sorbents for their ability to passively control indoor CO 2 concentration in buildings or rooms with cyclic occupancy (eg, offices, bedrooms). Silica supported amines were identified as suitable candidates and systematically evaluated in the removal of CO 2 from indoor air by equilibrium and dynamic techniques. In particular, sorbents with various amine loadings were synthesized using tetraethylenepentamine (TEPA), poly(ethyleneimine) (PEI) and a silane coupling agent 3-aminopropyltriethoxysilane (APS). TGA analysis indicates that TEPA impregnated silica not only displays a relatively high adsorption capacity when exposed to ppm level CO 2 concentrations, but also is capable of desorbing the majority of CO 2 by air flow (eg, by concentration gradient). In 10 L flow-through chamber experiments, TEPA-based sorbents reduced outlet CO 2 by up to 5% at 50% RH and up to 93% of CO 2 adsorbed over 8 hours was desorbed within 16 hours. In 8 m 3 flow-through chamber experiments, 18 g of the sorbent powder spread over a 2 m 2 area removed approximately 8% of CO 2 injected. By extrapolating these results to real buildings, we estimate that meaningful reductions in the CO 2 can be achieved, which may help reduce energy requirements for ventilation and/or improve air quality. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The OceanFlux Greenhouse Gases methodology for deriving a sea surface climatology of CO2 fugacity in support of air-sea gas flux studies

NASA Astrophysics Data System (ADS)

Goddijn-Murphy, L. M.; Woolf, D. K.; Land, P. E.; Shutler, J. D.; Donlon, C.

2015-07-01

Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean CO2 Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. As fCO2 is highly sensitive to temperature, the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrently with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air-sea CO2 fluxes, it is therefore desirable to calculate fCO2 valid for a more consistent and averaged SST. This paper presents the OceanFlux Greenhouse Gases methodology for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using monthly composite SST data on a 1° × 1° grid from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010, including the prediction errors of fCO2 produced by the spatial interpolation technique. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air-sea CO2 flux, and hence the presented fCO2 distributions can be used in air-sea gas flux calculations together with climatologies of other climate variables.

The urgency of the development of CO2 capture from ambient air

PubMed Central

Lackner, Klaus S.; Brennan, Sarah; Matter, Jürg M.; Park, A.-H. Alissa; Wright, Allen; van der Zwaan, Bob

2012-01-01

CO2 capture and storage (CCS) has the potential to develop into an important tool to address climate change. Given society’s present reliance on fossil fuels, widespread adoption of CCS appears indispensable for meeting stringent climate targets. We argue that for conventional CCS to become a successful climate mitigation technology—which by necessity has to operate on a large scale—it may need to be complemented with air capture, removing CO2 directly from the atmosphere. Air capture of CO2 could act as insurance against CO2 leaking from storage and furthermore may provide an option for dealing with emissions from mobile dispersed sources such as automobiles and airplanes. PMID:22843674

Simultaneous sensing of temperature, CO, and CO2 in a scramjet combustor using quantum cascade laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Spearrin, R. M.; Goldenstein, C. S.; Schultz, I. A.; Jeffries, J. B.; Hanson, R. K.

2014-07-01

A mid-infrared laser absorption sensor was developed for gas temperature and carbon oxide (CO, CO2) concentrations in high-enthalpy, hydrocarbon combustion flows. This diagnostic enables non-intrusive, in situ measurements in harsh environments produced by hypersonic propulsion ground test facilities. The sensing system utilizes tunable quantum cascade lasers capable of probing the fundamental mid-infrared absorption bands of CO and CO2 in the 4-5 µm wavelength domain. A scanned-wavelength direct absorption technique was employed with two lasers, one dedicated to each species, free-space fiber-coupled using a bifurcated hollow-core fiber for remote light delivery on a single line of sight. Scanned-wavelength modulation spectroscopy with second-harmonic detection was utilized to extend the dynamic range of the CO measurement. The diagnostic was field-tested on a direct-connect scramjet combustor for ethylene-air combustion. Simultaneous, laser-based measurements of carbon monoxide and carbon dioxide provide a basis for evaluating combustion completion or efficiency with temporal and spatial resolution in practical hydrocarbon-fueled engines.

The Potential Impact of CO2 and Air Temperature Increases on Krummholz's Transformation into Arborescent Form in the Southern Siberian Mountains

NASA Technical Reports Server (NTRS)

Kharuk, V. I.; Dvinskaya, M. L.; Im, S. T.; Ranson, K. J.

2011-01-01

Trees in the southern Siberian Mountains forest-tundra ecotone have considerably increased their radial and apical growth increments during the last few decades. This leads to the widespread vertical transformation of mat and prostrate krummholz forms of larch (Larix sibirica Ledeb) and Siberian pine (Pinus sibirica Du Tour). An analysis of the radial growth increments showed that these transformations began in the mid-1980s. Larch showed a greater resistance to the harsh alpine environment and attained a vertical growth form in areas where Siberian pine is still krummholz. Upper larch treeline is about 10 m higher than Siberian pine treeline. Observed apical and radial growth increment increases were correlated with CO2 concentration (r = 0.83-0.87), summer temperatures (r = 0.55-0.64), and "cold period" (i.e. September-May) air temperatures (r = 0.36-0.37). Positive correlation between growth increments and winter precipitation was attributed to snow cover protection for trees during wintertime.

Effects of air velocity on photosynthesis of plant canopies under elevated CO2 levels in a plant culture system.

PubMed

Kitaya, Y; Shibuya, T; Yoshida, M; Kiyota, M

2004-01-01

To obtain basic data for adequate air circulation for promoting plant growth in closed plant production modules in bioregenerative life support systems in space, effects of air velocities ranging from 0.1 to 0.8 m s-1 on photosynthesis in tomato seedlings canopies were investigated under atmospheric CO2 concentrations of 0.4 and 0.8 mmol mol-1. The canopy of tomato seedlings on a plug tray (0.4 x 0.4 m2) was set in a wind-tunnel-type chamber (0.6 x 0.4 x 0.3 m3) installed in a semi-closed-type assimilation chamber (0.9 x 0.5 x 0.4 m3). The net photosynthetic rate in the plant canopy was determined with the differences in CO2 concentrations between the inlet and outlet of the assimilation chamber multiplied by the volumetric air exchange rate of the chamber. Photosynthetic photon flux (PPF) on the plant canopy was kept at 0.25 mmol m-2 s-1, air temperature at 23 degrees C and relative humidity at 55%. The leaf area indices (LAIs) of the plant canopies were 0.6-2.5 and plant heights were 0.05-0.2 m. The net photosynthetic rate of the plant canopy increased with increasing air velocities inside plant canopies and saturated at 0.2 m s-1. The net photosynthetic rate at the air velocity of 0.4 m s-1 was 1.3 times that at 0.1 m s-1 under CO2 concentrations of 0.4 and 0.8 mmol mol-1. The net photosynthetic rate under CO2 concentrations of 0.8 mmol mol-1 was 1.2 times that under 0.4 mmol mol-1 at the air velocity ranging from 0.1 to 0.8 m s-1. The results confirmed the importance of controlling air movement for enhancing the canopy photosynthesis under an elevated CO2 level as well as under a normal CO2 level in the closed plant production modules. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Air-water CO2 Fluxes In Seasonal Hypoxia-influenced Green Bay, Lake Michigan

NASA Astrophysics Data System (ADS)

Lin, P.; Klump, J. V.; Guo, L.

2016-02-01

Increasing anthropogenic nutrient enrichment has led to seasonal hypoxia in Green Bay, the largest freshwater estuary in the Laurentian Great Lakes, but change in carbon dynamics associated with the development of hypoxia remains poorly understood. Variations in alkalinity, abundance of carbon species, and air-water CO2 fluxes were quantified under contrasting hypoxic conditions during summer 2014. Green Bay was characterized with high pH (average 8.62 ± 0.16 in August), high DIC concentrations (2113 - 3213 µmol/kg) and high pCO2 in the water column. pCO2 was mostly >700 µatm in June, resulting in a net CO2 source to the air, while pCO2 was mostly <650 µatm in August when hypoxic conditions occurred in Green Bay. In central Green Bay, pCO2 was the highest during both sampling months, accompanying by low dissolved oxygen (DO) and lower pH in the water column. In August, pCO2 was inversely correlated with DOC concentration and increased with DOC/DOP ratio, suggesting a control by organic matter on air-water CO2 dynamics and consumption of DO in Green Bay. Positive CO2 fluxes to the atmosphere during August were only observed in northern bay but a CO2 sink was found in southern Green Bay ( 40% of study area) with high biological production and terrestrial DOM. Daily CO2 flux ranged from 10.9 to 48.5 mmol-C m-2 d-1 in June with an average of 18.29 ± 7.44 mmol-C m-2 d-1, whereas it varied from 1.82 ± 1.18 mmol m-2 d-1 in the north to -2.05 ± 1.89 mmol m-2 d-1 in the south of Green Bay in August. Even though strong biological production reduced the CO2 emission, daily CO2 fluxes from Green Bay to the air were as high as 7.4 × 107 mole-C in June and 4.6 × 106 mole-C in August, suggesting a significant role of high-DIC lakes in global CO2 budget and cycling.

Single-component and binary CO2 and H2O adsorption of amine-functionalized cellulose.

PubMed

Gebald, Christoph; Wurzbacher, Jan A; Borgschulte, Andreas; Zimmermann, Tanja; Steinfeld, Aldo

2014-02-18

A fundamental analysis of single-component and binary CO2 and H2O adsorption of amine-functionalized nanofibrillated cellulose is carried out in the temperature range of 283-353 K and at CO2 partial pressures in the range of 0.02-105 kPa, where the ultralow partial pressure range is relevant for the direct capture of CO2 from atmospheric air. Single-component CO2 and H2O adsorption experimental data are fitted to the Toth and Guggenheim-Anderson-de Boer models, respectively. Corresponding heats of adsorption, derived from explicit solutions of the van't Hoff equation, are -50 kJ/mol CO2 and -48.8 kJ/mol H2O. Binary CO2/H2O adsorption measurements for humid air reveal that the presence of H2O at 2.55 kPa enhances CO2 adsorption, while the presence of CO2 at 0.045 kPa does not influence H2O adsorption. The energy demand of the temperature-vacuum-swing adsorption/desorption cycle for delivering pure CO2 from air increases significantly with H2O adsorption and indicates the need to reduce the hygroscopicity of the adsorbent.

Oxidation characteristics of MgF2 in air at high temperature

NASA Astrophysics Data System (ADS)

Chen, H. K.; Jie, Y. Y.; Chang, L.

2017-02-01

High temperature oxidation properties of MgF2 in air were studied. The changes of phase composition, macro surface morphology, weight and elemental composition of MgF2 samples with temperature were investigated by using XRD, EDS and gravimetric analyses. The results show that the oxidation reaction of MgF2 converted to MgO occurred at high temperature, and the reaction was accelerated by the increase of temperature and the presence of impurities. This result clarifies the understanding of the high temperature oxidation behavior of MgF2 in air, and provides a theoretical basis for the reasonable application of MgF2 in optical coating materials, electronic ceramic materials and magnesium melt protection.

Analysis of the CO 2 Chemisorption in Li 5FeO 4, a New High Temperature CO 2 Captor Material. Effect of the CO 2 and O 2 Partial Pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lara-García, Hugo A.; Sanchez-Camacho, Pedro; Duan, Yuhua

Pentalithium ferrite (Li 5FeO 4) was tested in this paper as possible CO 2 captor, both by theoretical calculations and experimental measurements. The pristine Li 5FeO 4 compound with orthorhombic structure was synthesized via solid-state reaction and it was structural and microstructurally characterized. Later, sample was heat-treated at temperatures from room temperature to 900 °C under different CO 2 or CO 2–O 2 atmospheres. Li 5FeO 4 exhibits excellent CO 2 chemisorption abilities with a capture capacity about 12.9 mmol/g, which is outstanding in comparison to other previously reported ceramic captors. This material is able to react with CO 2more » from 200 °C to approximately 715 °C showing a high kinetic of reaction even at CO 2 partial pressure values as low as 0.2. Finally and additionally, results suggest that oxygen addition does enhance the CO 2 chemisorption on Li 5FeO 4 at temperatures below 700 °C, although oxygen addition seems to favor the desorption process at higher temperatures.« less

Analysis of the CO 2 Chemisorption in Li 5FeO 4, a New High Temperature CO 2 Captor Material. Effect of the CO 2 and O 2 Partial Pressures

DOE PAGES

Lara-García, Hugo A.; Sanchez-Camacho, Pedro; Duan, Yuhua; ...

2017-01-23

Pentalithium ferrite (Li 5FeO 4) was tested in this paper as possible CO 2 captor, both by theoretical calculations and experimental measurements. The pristine Li 5FeO 4 compound with orthorhombic structure was synthesized via solid-state reaction and it was structural and microstructurally characterized. Later, sample was heat-treated at temperatures from room temperature to 900 °C under different CO 2 or CO 2–O 2 atmospheres. Li 5FeO 4 exhibits excellent CO 2 chemisorption abilities with a capture capacity about 12.9 mmol/g, which is outstanding in comparison to other previously reported ceramic captors. This material is able to react with CO 2more » from 200 °C to approximately 715 °C showing a high kinetic of reaction even at CO 2 partial pressure values as low as 0.2. Finally and additionally, results suggest that oxygen addition does enhance the CO 2 chemisorption on Li 5FeO 4 at temperatures below 700 °C, although oxygen addition seems to favor the desorption process at higher temperatures.« less

Attaining whole-ecosystem warming using air and deep-soil heating methods with an elevated CO2 atmosphere

NASA Astrophysics Data System (ADS)

Hanson, Paul J.; Riggs, Jeffery S.; Nettles, W. Robert; Phillips, Jana R.; Krassovski, Misha B.; Hook, Leslie A.; Gu, Lianhong; Richardson, Andrew D.; Aubrecht, Donald M.; Ricciuto, Daniel M.; Warren, Jeffrey M.; Barbier, Charlotte

2017-02-01

This paper describes the operational methods to achieve and measure both deep-soil heating (0-3 m) and whole-ecosystem warming (WEW) appropriate to the scale of tall-stature, high-carbon, boreal forest peatlands. The methods were developed to allow scientists to provide a plausible set of ecosystem-warming scenarios within which immediate and longer-term (1 decade) responses of organisms (microbes to trees) and ecosystem functions (carbon, water and nutrient cycles) could be measured. Elevated CO2 was also incorporated to test how temperature responses may be modified by atmospheric CO2 effects on carbon cycle processes. The WEW approach was successful in sustaining a wide range of aboveground and belowground temperature treatments (+0, +2.25, +4.5, +6.75 and +9 °C) in large 115 m2 open-topped enclosures with elevated CO2 treatments (+0 to +500 ppm). Air warming across the entire 10 enclosure study required ˜ 90 % of the total energy for WEW ranging from 64 283 mega Joules (MJ) d-1 during the warm season to 80 102 MJ d-1 during cold months. Soil warming across the study required only 1.3 to 1.9 % of the energy used ranging from 954 to 1782 MJ d-1 of energy in the warm and cold seasons, respectively. The residual energy was consumed by measurement and communication systems. Sustained temperature and elevated CO2 treatments were only constrained by occasional high external winds. This paper contrasts the in situ WEW method with closely related field-warming approaches using both aboveground (air or infrared heating) and belowground-warming methods. It also includes a full discussion of confounding factors that need to be considered carefully in the interpretation of experimental results. The WEW method combining aboveground and deep-soil heating approaches enables observations of future temperature conditions not available in the current observational record, and therefore provides a plausible glimpse of future environmental conditions.

Do all leaf photosynthesis parameters of rice acclimate to elevated CO2 , elevated temperature, and their combination, in FACE environments?

PubMed

Cai, Chuang; Li, Gang; Yang, Hailong; Yang, Jiaheng; Liu, Hong; Struik, Paul C; Luo, Weihong; Yin, Xinyou; Di, Lijun; Guo, Xuanhe; Jiang, Wenyu; Si, Chuanfei; Pan, Genxing; Zhu, Jianguo

2018-04-01

Leaf photosynthesis of crops acclimates to elevated CO 2 and temperature, but studies quantifying responses of leaf photosynthetic parameters to combined CO 2 and temperature increases under field conditions are scarce. We measured leaf photosynthesis of rice cultivars Changyou 5 and Nanjing 9108 grown in two free-air CO 2 enrichment (FACE) systems, respectively, installed in paddy fields. Each FACE system had four combinations of two levels of CO 2 (ambient and enriched) and two levels of canopy temperature (no warming and warmed by 1.0-2.0°C). Parameters of the C 3 photosynthesis model of Farquhar, von Caemmerer and Berry (the FvCB model), and of a stomatal conductance (g s ) model were estimated for the four conditions. Most photosynthetic parameters acclimated to elevated CO 2 , elevated temperature, and their combination. The combination of elevated CO 2 and temperature changed the functional relationships between biochemical parameters and leaf nitrogen content for Changyou 5. The g s model significantly underestimated g s under the combination of elevated CO 2 and temperature by 19% for Changyou 5 and by 10% for Nanjing 9108 if no acclimation was assumed. However, our further analysis applying the coupled g s -FvCB model to an independent, previously published FACE experiment showed that including such an acclimation response of g s hardly improved prediction of leaf photosynthesis under the four combinations of CO 2 and temperature. Therefore, the typical procedure that crop models using the FvCB and g s models are parameterized from plants grown under current ambient conditions may not result in critical errors in projecting productivity of paddy rice under future global change. © 2017 John Wiley & Sons Ltd.

Modeling Silicate Weathering for Elevated CO2 and Temperature

NASA Astrophysics Data System (ADS)

Bolton, E. W.

2016-12-01

A reactive transport model (RTM) is used to assess CO2 drawdown by silicate weathering over a wide range of temperature, pCO2, and infiltration rates for basalts and granites. Although RTM's have been used extensively to model weathering of basalts and granites for present-day conditions, we extend such modeling to higher CO2 that could have existed during the Archean and Proterozoic. We also consider a wide range of surface temperatures and infiltration rates. We consider several model basalt and granite compositions. We normally impose CO2 in equilibrium with the various atmospheric ranges modeled and CO2 is delivered to the weathering zone by aqueous transport. We also consider models with fixed CO2 (aq) throughout the weathering zone as could occur in soils with partial water saturation or with plant respiration, which can strongly influence pH and mineral dissolution rates. For the modeling, we use Kinflow: a model developed at Yale that includes mineral dissolution and precipitation under kinetic control, aqueous speciation, surface erosion, dynamic porosity, permeability, and mineral surface areas via sub-grid-scale grain models, and exchange of volatiles at the surface. Most of the modeling is done in 1D, but some comparisons to 2D domains with heterogeneous permeability are made. We find that when CO2 is fixed only at the surface, the pH tends toward higher values for basalts than granites, in large part due to the presence of more divalent than monovalent cations in the primary minerals, tending to decrease rates of mineral dissolution. Weathering rates increase (as expected) with increasing CO2 and temperature. This modeling is done with the support of the Virtual Planetary Laboratory.

Stability of CO2 hydrate under very high pressure and low temperature

NASA Astrophysics Data System (ADS)

Hirai, H.; Honda, M.; Kawamura, T.; Yamamoto, Y.; Yagi, T.

2009-12-01

CO2 hydrate is a clathrate compound and the crystal structure type is sI at low pressure. CO2-reduction in the atmosphere is one of the most urgent subjects for mankind. Some technical developments to seclude CO2 as CO2 hydrate in ocean floor have been proceeded. Looking around the solar system, existence of CO2 hydrate in and beneath Martian permafrost has been predicted from spacecraft probes and theoretical studies. Thus, its stability and properties under high pressures and low temperatures are of great interest for fundamental understanding of clathrate hydrate, for the ocean sequestration technology, and for planetary science. CO2 hydrate exhibits characteristic properties different from those of other gas hydrate such as methane hydrate. For example, phase boundary between hydrate and gas + water for many gas hydrates shows positive slope in pressure versus temperature field, and the gas hydrates are kept at pressures up to several GPa at room temperature. On the other hand, for CO2 hydrate, the phase boundary turns to negative slope from positive one at a certain critical point [Nakano et al., 1998], and it can exist only at low temperature regions. And, a theoretical study predicted that CO2 hydrate decompose at low temperature region [Longhi, 2005]. In this study, high pressure and low temperature experiments were performed to examine stability and phase changes of CO2 hydrate using diamond anvil cell in a pressure range from 0.1 to 2.5 GPa and a the temperature range from 65 to 265 K. X-ray diffractometry and Raman spectroscopy revealed that the known phase boundary was extended into lower temperature region, and that CO2 hydrate was kept at low temperature regions at least 65 K despite the theoretical prediction of decomposition. References [1] S. Nakano, M. Moritoki, K. Ohgaki, J. Chem. Eng. Data, 43, 807 (1998). [2] J. Longhi, Geochim. Cosmochim. Acta, 69, 529 (2005)

ELEVATED CO2 AND ELEVATED TEMPERATURE HAVE NO EFFECT ON DOUGLAS-FIR FINE-ROOT DYNAMICS IN NITROGEN-POOR SOIL

EPA Science Inventory

Here, we investigate fine-root production, mortality and standing crop of Douglas-fir (Pseudotsuga menziesii) seedlings exposed to elevated atmospheric CO2 and elevated air temperature. We hypothesized that these treatments would increase fine-root production, but that mortality ...

Randomized, double-blind trial of CO2 versus air insufflation in children undergoing colonoscopy.

PubMed

Homan, Matjaž; Mahkovic, Dora; Orel, Rok; Mamula, Petar

2016-05-01

Studies in adults have shown that postprocedural abdominal pain is reduced with the use of carbon dioxide (CO(2)) instead of air for insufflation during colonoscopy. The aim of our study was to compare postprocedural abdominal pain and girth in children undergoing colonoscopy using CO(2) or air for insufflation. This was a prospective, randomized, double-blind study that included 76 consecutive pediatric patients undergoing colonoscopy for various indications. Patients were randomly assigned to either CO(2) or air insufflation. At 2, 4, and 24 hours after the examination, the patients' pain was assessed by using the 11-point numerical rating scale. The waist circumference was measured 10 minutes and 2 and 4 hours after colonoscopy. A significantly higher proportion of patients had no pain after colonoscopy in the CO(2) group compared with the air group (82 vs 37% at 2 hours and 95% vs. 63% at 4 hours, P < .001). Mean abdominal pain scores 2 and 4 hours after the procedure were statistically significantly lower in the CO(2) group compared with the control air group (0.5 vs 2.6 at 2 hours and 0.1 vs 1.2 at 4 hours, P < .001). There was no difference in waist circumference between the 2 groups at all time intervals. The results of this randomized trial show clear benefits of CO(2) insufflation for colonoscopy in reducing postprocedural discomfort. ( NCT02407639.). Copyright © 2016 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production

PubMed Central

Rau, Greg H.; Carroll, Susan A.; Bourcier, William L.; Singleton, Michael J.; Smith, Megan M.; Aines, Roger D.

2013-01-01

We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H2 production to effect significant air CO2 absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 105-fold increase in OH− concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na2SO4 solutions when the anode was encased in powdered silicate mineral, either wollastonite or an ultramafic mineral. After electrolysis, full equilibration of the alkalized solution with air led to a significant pH reduction and as much as a 45-fold increase in dissolved inorganic carbon concentration. This demonstrated significant spontaneous air CO2 capture, chemical conversion, and storage as a bicarbonate, predominantly as NaHCO3. The excess OH− initially formed in these experiments apparently resulted via neutralization of the anolyte acid, H2SO4, by reaction with the base mineral silicate at the anode, producing mineral sulfate and silica. This allowed the NaOH, normally generated at the cathode, to go unneutralized and to accumulate in the bulk electrolyte, ultimately reacting with atmospheric CO2 to form dissolved bicarbonate. Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO2 captured), and inexpensive (<$100 per tonne of CO2 mitigated) removal of excess air CO2 with production of carbon-negative H2. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO2 emissions and in neutralizing or offsetting the effects of ongoing ocean acidification. PMID:23729814

On the importance of high-frequency air-temperature fluctuations for spectroscopic corrections of open-path carbon dioxide flux measurements

NASA Astrophysics Data System (ADS)

Bogoev, Ivan; Helbig, Manuel; Sonnentag, Oliver

2015-04-01

A growing number of studies report systematic differences in CO2 flux estimates obtained with the two main types of gas analyzers: compared to eddy-covariance systems based on closed-path (CP) gas analyzers, systems with open-path (OP) gas analyzers systematically overestimate CO2 uptake during daytime periods with high positive sensible heat fluxes, while patterns for differences in nighttime CO2 exchange are less obvious. These biases have been shown to correlate with the sign and the magnitude of the sensible heat flux and to introduce large uncertainties when calculating annual CO2 budgets. In general, CP and OP gas analyzers commonly used to measure the CO2 density in the atmosphere operate on the principle of infrared light absorption approximated by Beer-Lambert's law. Non-dispersive interference-based optical filter elements are used to select spectral bands with strong attenuation of light transmission, characteristic to the gas of interest. The intensity of the light passing through the optical sensing path depends primarily on the amount of absorber gas in the measurement volume. Besides the density of the gas, barometric pressure and air temperature are additional factors affecting the strength and the half-width of the absorption lines. These so-called spectroscopic effects are accounted for by measuring barometric pressure and air temperature in the sensing path and scaling the light-intensity measurements before applying the calibration equation. This approach works well for CP gas analyzers with an intake tube that acts as a low-pass filter on fast air-temperature fluctuations. Low-frequency response temperature sensors in the measurement cell are therefore sufficient to account for spectroscopic temperature effects. In contrast, OP gas analyzers are exposed to high-frequency air-temperature fluctuations associated with the atmospheric surface-layer turbulent heat exchange. If not corrected adequately, these fast air-temperature variations can cause

DOES SOIL CO2 EFFLUX ACCLIMATIZETO ELEVATED TEMPERATURE AND CO2 DURING LONG-TERM TREATMENT OF DOUGLAS-FIR SEEDLINGS?

EPA Science Inventory

We investigated the effects of elevated soil temperature and atmospheric CO2 efflux (SCE) during the third an fourth years of study. We hypothesized that elevated temperature would stimulate SCE, and elevated CO2 would also stimulate SCE with the stimulation being greater at hig...

Atmospheric CO2: principal control knob governing Earth's temperature.

PubMed

Lacis, Andrew A; Schmidt, Gavin A; Rind, David; Ruedy, Reto A

2010-10-15

Ample physical evidence shows that carbon dioxide (CO(2)) is the single most important climate-relevant greenhouse gas in Earth's atmosphere. This is because CO(2), like ozone, N(2)O, CH(4), and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO(2) and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

Room temperature magnetization in Co-doped anatase phase of TiO2

NASA Astrophysics Data System (ADS)

Karimipour, Masoud; Mageto, Maxwel Joel; Etefagh, Reyhaneh; Azhir, Elahe; Mwamburi, Mghendi; Topalian, Zareh

2013-01-01

CoxTi1-xO2 films were deposited by spray pyrolysis technique on Si(1 0 0) substrates at 475 °C. A hydro-alcoholic solution containing titanium (iv) isopropoxide and Co(NO3)2 with various Co doping levels from x = 0-0.015 in solution was used as spray solution. Grazing incident angle of X-ray diffraction illustrates that the CoxTi1-xO2 films are single phase and polycrystal with mixed orientations. Study of surface morphology of the films by atomic force microscope reveals that the annealing atmosphere does not significantly affect the grain size and the microstructure of the films. This study provides further insight into the importance of annealing atmosphere on magnetization of the films. Room temperature magneto-optical Kerr measurement was employed in polar mode. A hysteresis loop and a paramagnetic behavior have been recorded for samples annealed in H2 ambient gas and air, respectively. Chemical composition analysis by X-ray photo-electron spectroscopy showed that Co atoms are bounded to oxygen and no metallic clusters are present. Moreover, it indicates the formation of high spin Co2+ for the sample x = 0.008 annealed in H2 ambient gas. The origin of magnetization can be attributed to the contribution of oxygen vacancies in the spin polarization of the structure.

Choice of precipitant and calcination temperature of precursor for synthesis of NiCo2O4 for control of CO-CH4 emissions from CNG vehicles.

PubMed

Trivedi, Suverna; Prasad, Ram

2018-03-01

Compressed natural gas (CNG) is most appropriate an alternative of conventional fuel for automobiles. However, emissions of carbon-monoxide and methane from such vehicles adversely affect human health and environment. Consequently, to abate emissions from CNG vehicles, development of highly efficient and inexpensive catalysts is necessary. Thus, the present work attempts to scan the effects of precipitants (Na 2 CO 3 , KOH and urea) for nickel cobaltite (NiCo 2 O 4 ) catalysts prepared by co-precipitation from nitrate solutions and calcined in a lean CO-air mixture at 400°C. The catalysts were used for oxidation of a mixture of CO and CH 4 (1:1). The catalysts were characterized by X-ray diffractometer, Brunauer-Emmett-Teller surface-area, X-ray photoelectron spectroscopy; temperature programmed reduction and Scanning electron microscopy coupled with Energy-Dispersive X-Ray Spectroscopy. The Na 2 CO 3 was adjudged as the best precipitant for production of catalyst, which completely oxidized CO-CH 4 mixture at the lowest temperature (T 100 =350°C). Whereas, for catalyst prepared using urea, T 100 =362°C. On the other hand the conversion of CO-CH 4 mixture over the catalyst synthesized by KOH limited to 97% even beyond 400°C. Further, the effect of higher calcination temperatures of 500 and 600°C was examined for the best catalyst. The total oxidation of the mixture was attained at higher temperatures of 375 and 410°C over catalysts calcined at 500 and 600°C respectively. Thus, the best precipitant established was Na 2 CO 3 and the optimum calcination temperature of 400°C was found to synthesize the NiCo 2 O 4 catalyst for the best performance in CO-CH 4 oxidation. Copyright © 2017. Published by Elsevier B.V.

Dynamics of air-sea CO2 fluxes based on FerryBox measurements and satellite-based prediction of pCO2 in the Western English Channel

NASA Astrophysics Data System (ADS)

Marrec, Pierre; Thierry, Cariou; Eric, Mace; Pascal, Morin; Marc, Vernet; Yann, Bozec

2014-05-01

Since April 2012, we installed an autonomous FerryBox system on a Voluntary Observing Ship (VOS), which crosses the Western English Channel (WEC) between Roscoff and Plymouth on a daily basis. High-frequency data of sea surface temperature (SST), salinity (SSS), fluorescence, dissolved oxygen (DO) and partial pressure of CO2 (pCO2) were recorded for two years across the all-year mixed southern WEC (sWEC) and the seasonally stratified northern WEC (nWEC). These contrasting hydrographical provinces strongly influenced the spatio-temporal distributions of pCO2 and air-sea CO2 fluxes. During the productive period (from May to September), the nWEC acted as a sink for atmospheric CO2 of -5.6 mmolC m-2 d-1 and -4.6 mmolC m-2 d-1, in 2012 and 2013, respectively. During the same period, the sWEC showed significant inter-annual variability degassing CO2 to the atmosphere in 2012 (1.4 mmolC m-2 d-1) and absorbing atmospheric CO2 in 2013 (-1.6 mmolC m-2 d-1). In 2012, high-frequency data revealed that an intense and short (less than 10 days) summer phytoplankton bloom in the nWEC contributed to 31% of the total CO2 drawdown during the productive period, highlighting the necessity of pCO2 high-frequency measurements in coastal ecosystems. Based on this multi-annual dataset, we developed pCO2 algorithms using multiple linear regression (MLR) based on SST, SSS, chlorophyll-a (Chl-a) concentration, time, latitude and mixed layer depth to predict pCO2 in the two hydrographical provinces of the WEC. MLR were performed based on more than 200,000 underway observations spanning the range from 150 to 480 µatm. The root mean square errors (RMSE) of the MLR fit to the data were 17.2 µatm and 21.5 µatm for the s WEC and the nWEC with correlation coefficient (r²) of 0.71 and 0.79, respectively. We applied these algorithms to satellite SST and Chl-a products and to modeled SSS estimates in the entire WEC. Based on these high-frequency and satellite approaches, we will discuss the main

Children's exposure to indoor air in urban nurseries-part I: CO{sub 2} and comfort assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branco, P.T.B.S.; Alvim-Ferraz, M.C.M.; Martins, F.G.

2015-07-15

Indoor air quality (IAQ) in nurseries is an emerging case-study. Thus, this study, as the Part I of the larger study “Children's exposure to indoor air in urban nurseries”, aimed to: i) evaluate nurseries’ indoor concentrations of carbon dioxide (CO{sub 2}), a global IAQ indicator, in class and lunch rooms; ii) assess indoor comfort parameters–temperature (T) and relative humidity (RH); and iii) analyse them according to guidelines and references for IAQ, comfort and children's health. Indoor continuous measurements were performed. Non-compliances with guidelines were found in comfort parameters, which could cause discomfort situations and also microbial proliferation. Exceedances in CO{submore » 2} concentrations were also found and they were caused by poor ventilation and high classroom occupation. More efficient ventilation and control of comfort parameters, as well as to reduce occupation by reviewing Portuguese legislation on that matter, would certainly improve IAQ and comfort in nurseries and consequently safeguard children's health. - Highlights: • High occupation and poor ventilation were main determinants of IAQ in nurseries. • T and RH indoor values found in nurseries are likely to cause thermal discomfort. • Building characteristics and an inadequate ventilation determined T and RH values. • High CO{sub 2} concentrations found could indicate accumulation of other air pollutants.« less

Improving rice models for more reliable prediction of responses of rice yield to CO2 and temperature elevaton

USDA-ARS?s Scientific Manuscript database

Materials and Methods The simulation exercise and model improvement were implemented in phase-wise. In the first modelling activities, the model sensitivities were evaluated to given CO2 concentrations varying from 360 to 720 'mol mol-1 at an interval of 90 'mol mol-1 and air temperature increments...

Change of properties after oxidation of IG-11 graphite by air and CO 2 gas

NASA Astrophysics Data System (ADS)

Lim, Yun-Soo; Chi, Se-Hwan; Cho, Kwang-Yun

2008-02-01

Artificial graphite is typically manufactured by carbonization of a shaped body of a kneaded mixture using granular cokes as a filler and pitch as a binder. It undergoes a pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation in air or a CO 2 atmosphere on IG-11 graphite samples is investigated in this study. The results show a localized oxidation process that progressively reveals the large coke particles with increasing level of overall weight loss in air. The surface of the graphite was peeled off and no change was found in the specific gravity after air oxidation. However, the specific gravity of graphite was continuously decreased by CO 2 oxidation. The decrease in the specific gravity by CO 2 oxidation was due to CO 2 gas that progressed from the surface to the interior. The pore shape after CO 2 oxidation differed from that under air oxidation.

Synthesis and detection the oxidization of Co cores of Co@SiO2 core-shell nanoparticles by in situ XRD and EXAFS.

PubMed

Zhang, Kunhao; Zhao, Ziyan; Wu, Zhonghua; Zhou, Ying

2015-01-01

In this paper, the Co@SiO2 core-shell nanoparticles were prepared by the sol-gel method. The oxidization of Co core nanoparticles was studied by the synchrotron radiation-based techniques including in situ X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) up to 800°C in air and N2 protection conditions, respectively. It was found that the oxidization of Co cores is undergoing three steps regardless of being in air or in N2 protection condition. In the first step ranging from room temperature to 200°C, the Co cores were dominated by Co(0) state as well as small amount of Co(2+) ions. When temperature was above 300°C, the interface between Co cores and SiO2 shells was gradually oxidized into Co(2+), and the CoO layer was observed. As the temperature increasing to 800°C, the Co cores were oxidized to Co3O4 or Co3O4/CoO. Nevertheless, the oxidization kinetics of Co cores is different for the Co@SiO2 in air and N2 gas conditions. Generally, the O2 in the air could get through the SiO2 shells easily onto the Co core surface and induce the oxidization of the Co cores due to the mesoporous nature of the SiO2 shells. However, in N2 gas condition, the O atoms can only be from the SiO2 shells, so the diffusion effect of O atoms in the interface between Co core and SiO2 shell plays a key role.

Mo2NiB2-type Sm2Co2Al and Sm2Co2Ga compounds: Magnetic properties and giant low-temperature coercivity

NASA Astrophysics Data System (ADS)

Morozkin, A. V.; Garshev, A. V.; Yapaskurt, V. O.; Yao, Jinlei; Nirmala, R.; Quezado, S.; Malik, S. K.

2018-04-01

The magnetic ordering of Mo2NiB2-type Sm2Co2Al and Sm2Co2Ga (Immm, No. 71, oI10) compounds has been established using bulk magnetic measurements. Polycrystalline Sm2Co2Al and Sm2Co2Ga undergo ferromagnetic transitions (TC) at 50 K and 62 K, respectively, and low-temperature field induced transitions (Tm) around 14 K and 16 K (in a field of 10 kOe), respectively. Between TC and Tm Sm2Co2Al and Sm2Co2Ga are soft ferromagnets. Below Tm Sm2Co2Al and Sm2Co2Ga exhibit permanent magnet properties with a residual magnetization per samarium of 0.38 μB and 0.36 μB, respectively, and a large coercive field of 69 kOe and 72 kOe, respectively, at 5 K. The magnetocaloric effects of Sm2Co2Al and Sm2Co2Ga were calculated in terms of isothermal magnetic entropy change and they reach maximum values of -1.62 J/kg K and -1.31 J/kg K for a field change of 50 kOe at 50 K and 58 K, respectively. Low temperature magnetic ordering with enhanced anisotropy in Sm2Co2Al and Sm2Co2Ga is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +1.63 J/kg K and +1.06 J/kg K for a field change of 50 kOe at 10 K and 8 K, respectively. The magnetocaloric effects of Sm2Co2Al and Sm2Co2Ga were calculated in terms of isothermal magnetic entropy change and they reach maximum values of -1.62 J/kg K and -1.31 J/kg K for a field change of 50 kOe at 50 K and 58 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Sm2Co2Al and Sm2Co2Ga is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +1.63 J/kg K and +1.06 J/kg K for a field change of 50 kOe at 10 K and 8 K, respectively.

Stable solid and aqueous H2CO3 from CO2 and H2O at high pressure and high temperature

NASA Astrophysics Data System (ADS)

Wang, Hongbo; Zeuschner, Janek; Eremets, Mikhail; Troyan, Ivan; Willams, Jonathan

2016-01-01

Carbonic acid (H2CO3) forms in small amounts when CO2 dissolves in H2O, yet decomposes rapidly under ambient conditions of temperature and pressure. Despite its fleeting existence, H2CO3 plays an important role in the global carbon cycle and in biological carbonate-containing systems. The short lifetime in water and presumed low concentration under all terrestrial conditions has stifled study of this fundamental species. Here, we have examined CO2/H2O mixtures under conditions of high pressure and high temperature to explore the potential for reaction to H2CO3 inside celestial bodies. We present a novel method to prepare solid H2CO3 by heating CO2/H2O mixtures at high pressure with a CO2 laser. Furthermore, we found that, contrary to present understanding, neutral H2CO3 is a significant component in aqueous CO2 solutions above 2.4 GPa and 110 °C as identified by IR-absorption and Raman spectroscopy. This is highly significant for speciation of deep C-O-H fluids with potential consequences for fluid-carbonate-bearing rock interactions. As conditions inside subduction zones on Earth appear to be most favorable for production of aqueous H2CO3, a role in subduction related phenomena is inferred.

Stable solid and aqueous H2CO3 from CO2 and H2O at high pressure and high temperature

PubMed Central

Wang, Hongbo; Zeuschner, Janek; Eremets, Mikhail; Troyan, Ivan; Willams, Jonathan

2016-01-01

Carbonic acid (H2CO3) forms in small amounts when CO2 dissolves in H2O, yet decomposes rapidly under ambient conditions of temperature and pressure. Despite its fleeting existence, H2CO3 plays an important role in the global carbon cycle and in biological carbonate-containing systems. The short lifetime in water and presumed low concentration under all terrestrial conditions has stifled study of this fundamental species. Here, we have examined CO2/H2O mixtures under conditions of high pressure and high temperature to explore the potential for reaction to H2CO3 inside celestial bodies. We present a novel method to prepare solid H2CO3 by heating CO2/H2O mixtures at high pressure with a CO2 laser. Furthermore, we found that, contrary to present understanding, neutral H2CO3 is a significant component in aqueous CO2 solutions above 2.4 GPa and 110 °C as identified by IR-absorption and Raman spectroscopy. This is highly significant for speciation of deep C–O–H fluids with potential consequences for fluid-carbonate-bearing rock interactions. As conditions inside subduction zones on Earth appear to be most favorable for production of aqueous H2CO3, a role in subduction related phenomena is inferred. PMID:26813580

Stable solid and aqueous H2CO3 from CO2 and H2O at high pressure and high temperature.

PubMed

Wang, Hongbo; Zeuschner, Janek; Eremets, Mikhail; Troyan, Ivan; Willams, Jonathan

2016-01-27

Carbonic acid (H2CO3) forms in small amounts when CO2 dissolves in H2O, yet decomposes rapidly under ambient conditions of temperature and pressure. Despite its fleeting existence, H2CO3 plays an important role in the global carbon cycle and in biological carbonate-containing systems. The short lifetime in water and presumed low concentration under all terrestrial conditions has stifled study of this fundamental species. Here, we have examined CO2/H2O mixtures under conditions of high pressure and high temperature to explore the potential for reaction to H2CO3 inside celestial bodies. We present a novel method to prepare solid H2CO3 by heating CO2/H2O mixtures at high pressure with a CO2 laser. Furthermore, we found that, contrary to present understanding, neutral H2CO3 is a significant component in aqueous CO2 solutions above 2.4 GPa and 110 °C as identified by IR-absorption and Raman spectroscopy. This is highly significant for speciation of deep C-O-H fluids with potential consequences for fluid-carbonate-bearing rock interactions. As conditions inside subduction zones on Earth appear to be most favorable for production of aqueous H2CO3, a role in subduction related phenomena is inferred.

Emissions of CO2 and criteria air pollutants from mobile sources: Insights from integrating real-time traffic data into local air quality models

NASA Astrophysics Data System (ADS)

Gately, Conor; Hutyra, Lucy

2016-04-01

In 2013, on-road mobile sources were responsible for over 26% of U.S. fossil fuel carbon dioxide (ffCO2) emissions, and over 34% of both CO and NOx emissions. However, accurate representations of these emissions at the scale of urban areas remains a difficult challenge. Quantifying emissions at the scale of local streets and highways is critical to provide policymakers with the information needed to develop appropriate mitigation strategies and to guide research into the underlying process that drive mobile emissions. Quantification of vehicle ffCO2 emissions at high spatial and temporal resolutions requires a detailed synthesis of data on traffic activity, roadway attributes, fleet characteristics and vehicle speeds. To accurately characterize criteria air pollutant emissions, information on local meteorology is also critical, as the temperature and relative humidity can affect emissions rates of these pollutants by as much as 400%. As the health impacts of air pollutants are more severe for residents living in close proximity (<500m) to road sources, it is critical that inventories of these emissions rely on highly resolved source data to locate potential hot-spots of exposure. In this study we utilize real-time GPS estimates of vehicle speeds to estimate ffCO2 and criteria air pollutant emissions at multiple spatial and temporal scales across a large metropolitan area. We observe large variations in emissions associated with diurnal activity patterns, congestion, sporting and civic events, and weather anomalies. We discuss the advantages and challenges of using highly-resolved source data to quantify emissions at a roadway scale, and the potential of this methodology for forecasting the air quality impacts of changes in infrastructure, urban planning policies, and regional climate.

Emissions of CO2 and criteria air pollutants from mobile sources: Insights from integrating real-time traffic data into local air quality models

NASA Astrophysics Data System (ADS)

Gately, C.; Hutyra, L.; Sue Wing, I.; Peterson, S.; Janetos, A.

2015-12-01

In 2013, on-road mobile sources were responsible for over 26% of U.S. fossil fuel carbon dioxide (ffCO2) emissions, and over 34% of both CO and NOx emissions. However, accurate representations of these emissions at the scale of urban areas remains a difficult challenge. Quantifying emissions at the scale of local streets and highways is critical to provide policymakers with the information needed to develop appropriate mitigation strategies and to guide research into the underlying process that drive mobile emissions. Quantification of vehicle ffCO2 emissions at high spatial and temporal resolutions requires a detailed synthesis of data on traffic activity, roadway attributes, fleet characteristics and vehicle speeds. To accurately characterize criteria air pollutant emissions, information on local meteorology is also critical, as the temperature and relative humidity can affect emissions rates of these pollutants by as much as 400%. As the health impacts of air pollutants are more severe for residents living in close proximity (<500m) to road sources, it is critical that inventories of these emissions rely on highly resolved source data to locate potential hot-spots of exposure. In this study we utilize real-time GPS estimates of vehicle speeds to estimate ffCO2 and criteria air pollutant emissions at multiple spatial and temporal scales across a large metropolitan area. We observe large variations in emissions associated with diurnal activity patterns, congestion, sporting and civic events, and weather anomalies. We discuss the advantages and challenges of using highly-resolved source data to quantify emissions at a roadway scale, and the potential of this methodology for forecasting the air quality impacts of changes in infrastructure, urban planning policies, and regional climate.

Improving Forecast Skill by Assimilation of Quality Controlled AIRS Version 5 Temperature Soundings

NASA Technical Reports Server (NTRS)

Susskind, Joel; Reale, Oreste

2009-01-01

The AIRS Science Team Version 5 retrieval algorithm has been finalized and is now operational at the Goddard DAAC in the processing (and reprocessing) of all AIRS data. The AIRS Science Team Version 5 retrieval algorithm contains two significant improvements over Version 4: 1) Improved physics allows for use of AIRS observations in the entire 4.3 micron CO2 absorption band in the retrieval of temperature profile T(p) during both day and night. Tropospheric sounding 15 micron CO2 observations are now used primarily in the generation of cloud cleared radiances R(sub i). This approach allows for the generation of accurate values of R(sub i) and T(p) under most cloud conditions. 2) Another very significant improvement in Version 5 is the ability to generate accurate case-by-case, level-by-level error estimates for the atmospheric temperature profile, as well as for channel-by-channel error estimates for R(sub i). These error estimates are used for Quality Control of the retrieved products. We have conducted forecast impact experiments assimilating AIRS temperature profiles with different levels of Quality Control using the NASA GEOS-5 data assimilation system. Assimilation of Quality Controlled T(p) resulted in significantly improved forecast skill compared to that obtained from analyses obtained when all data used operationally by NCEP, except for AIRS data, is assimilated. We also conducted an experiment assimilating AIRS radiances uncontaminated by clouds, as done operationally by ECMWF and NCEP. Forecast resulting from assimilated AIRS radiances were of poorer quality than those obtained assimilating AIRS temperatures.

Effects of open-air temperature on air temperature inside biological safety cabinet.

PubMed

Umemura, Masayuki; Shigeno, Katsuro; Yamamura, Keiko; Osada, Takashi; Soda, Midori; Yamada, Kiyofumi; Ando, Yuichi; Wakiya, Yoshifumi

2011-02-14

In Japan, biological safety cabinets (BSCs) are normally used by medical staff while handling antineoplastic agents. We have also set up a class II B2 BSC at the Division of Chemotherapy for Outpatients. The air temperature inside this BSC, however, decreases in winter. We assumed that this decrease is caused by the intake of open-air. Therefore, we investigated the effects of low open-air temperature on the BSC temperature and the time of admixtures of antineoplastic agents. The studies were conducted from January 1 to March 31, 2008. The outdoor air temperature was measured in the shade near the intake nozzle of the BSC and was compared with the BSC temperature. The correlation between the outdoor air temperature and the BSC temperature, the dissolution time of cyclophosphamide (CPA) and gemcitabine (GEM), and accurate weight measurement of epirubicin (EPI) solution were investigated for low and normal BSC temperatures. The BSC temperature was correlated with the open-air temperature for open-air temperatures of 5-20°C (p < 0.0001). The dissolution of CPA and GEM at these temperatures was significantly delayed as compared to that at 25°C (p < 0.01 and p < 0.0001, respectively). The weight measurement of EPI solution using a syringe method lacks accuracy because of its high coefficient of viscosity at low temperatures (p < 0.01). These results suggest that the BSC temperature decreases below room temperature in winter when air is drawn from outdoors. We showed that the BSC temperature affects the dissolution rate of antineoplastic agents. Further, we suggested that the BSC temperature drop might delay the affair of the admixtures of antineoplastic agents and increase the waiting time of outpatients for chemotherapy.

Stem respiration of Populus species in the third year of free-air CO2 enrichment.

PubMed

Gielen, Birgit; Scarascia-Mugnozza, Giuseppe; Ceulemans, Reinhart

2003-04-01

Carbon cycling in ecosystems, and especially in forests, is intensively studied to predict the effects of global climate change, and the role which forests may play in 'changing climate change'. One of the questions is whether the carbon balance of forests will be affected by increasing atmospheric CO2 concentrations. Regarding this question, effects of elevated [CO2] on woody-tissue respiration have frequently been neglected. Stem respiration of three Populus species (P. alba L. (Clone 2AS-11), P. nigra L. (Clone Jean Pourtet), and P. x euramericana (Clone I-214)) was measured in a managed, high-density forest plantation exposed to free-air CO2 enrichment (POPFACE). During the period of measurements, in May of the third year, stem respiration rates were not affected by the FACE treatment. Moreover, FACE did not influence the relationships between respiration rate and both stem temperature and relative growth rate. The results were supported by the reported absence of a FACE-effect on growth and stem wood density.

Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Bing; Khadra, Ghassan; Tuaillon-Combes, Juliette

2016-09-29

Co1-xPtx clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al2O3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged duster samples were characterized by grazing-incidence X-ray absorption spectroscopy (GIXAS) and then pretreated with diluted hydrogenmore » and further exposed to the mixture of diluted CO and H-2 up to 225 degrees C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the dusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the dusters. For example, a low Pt/Co ratio (x <= 0.5) facilitates the formation of Co(OH)(2), whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co3O4 composition instead through the formation of a Co-Pt core-shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co1-xPtx alloy dusters. The obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less

Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–xPt x Clusters under H 2 and CO + H 2 Atmospheres

DOE PAGES

Yang, Bing; Khadra, Ghassan; Tuaillon-Combes, Juliette; ...

2016-08-25

In this study, Co 1–xPt x clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al 2O 3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged cluster samples were characterized by grazing-incidence X-ray absorption spectroscopymore » (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H 2 up to 225°C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the clusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the clusters. For example, a low Pt/Co ratio (x ≤ 0.5) facilitates the formation of Co(OH) 2, whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co 3O 4 composition instead through the formation of a Co–Pt core–shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co 1–xPt x alloy clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less

Ice Surface Temperature Variability in the Polar Regions and the Relationships to 2 Meter Air Temperatures

NASA Astrophysics Data System (ADS)

Hoyer, J.; Madsen, K. S.; Englyst, P. N.

2017-12-01

Determining the surface and near surface air temperature from models or observations in the Polar Regions is challenging due to the extreme conditions and the lack of in situ observations. The errors in near surface temperature products are typically larger than for other regions of the world, and the potential for using Earth Observations is large. As part of the EU project, EUSTACE, we have developed empirical models for the relationship between the satellite observed skin ice temperatures and 2m air temperatures. We use the Arctic and Antarctic Sea and sea ice Surface Temperatures from thermal Infrared satellite sensors (AASTI) reanalysis to estimate daily surface air temperature over land ice and sea ice for the Arctic and the Antarctic. Large efforts have been put into collecting and quality controlling in situ observations from various data portals and research projects. The reconstruction is independent of numerical weather prediction models and thus provides an important alternative to modelled air temperature estimates. The new surface air temperature data record has been validated against more than 58.000 independent in situ measurements for the four surface types: Arctic sea ice, Greenland ice sheet, Antarctic sea ice and Antarctic ice sheet. The average correlations are 92-97% and average root mean square errors are 3.1-3.6°C for the four surface types. The root mean square error includes the uncertainty of the in-situ measurement, which ranges from 0.5 to 2°C. A comparison with ERA-Interim shows a consistently better performance of the satellite based air temperatures than the ERA-Interim for the Greenland ice sheet, when compared against observations not used in any of the two estimates. This is encouraging and demonstrates the values of these products. In addition, the procedure presented here works on satellite observations that are available in near real time and this opens up for a near real time estimation of the surface air temperature over

Phase equilibria and crystal chemistry of the CaO-1/2 >Nd2O3-CoOz system at 885 °C in air

NASA Astrophysics Data System (ADS)

Wong-Ng, W.; Laws, W.; Talley, K. R.; Huang, Q.; Yan, Y.; Martin, J.; Kaduk, J. A.

2014-07-01

The phase diagram of the CaO-1/2 >Nd2O3-CoOz system at 885 °C in air has been determined. The system consists of two calcium cobaltate compounds that have promising thermoelectric properties, namely, the 2D thermoelectric oxide solid solution, (Ca3-xNdx)Co4O9-z (0≤x≤0.5), which has a misfit layered structure, and Ca3Co2O6 which consists of 1D chains of alternating CoO6 trigonal prisms and CoO6 octahedra. Ca3Co2O6 was found to be a point compound without the substitution of Nd on the Ca site. The reported Nd2CoO4 phase was not observed at 885 °C. A ternary (Ca1-xNd1+x)CoO4-z (x=0) phase, or (CaNdCo)O4-z, was found to be stable at this temperature. A solid solution region of distorted perovskite (Nd1-xCax)CoO3-z (0≤x≤0.25, space group Pnma) was established. In the peripheral binary systems, while a solid solution region was identified for (Nd1-xCax)2O3-z (0≤x≤0.2), Nd was not found to substitute in the Ca site of CaO. Six solid solution tie-line regions and six three-phase regions were determined in the CaO-Nd2O3-CoOz system in air.

CO2 insufflation versus air insufflation for endoscopic submucosal dissection: A meta-analysis of randomized controlled trials.

PubMed

Li, Xuan; Dong, Hao; Zhang, Yifeng; Zhang, Guoxin

2017-01-01

Carbon dioxide (CO2) insufflation is increasingly used for endoscopic submucosal dissection (ESD) owing to the faster absorption of CO2 as compared to that of air. Studies comparing CO2 insufflation and air insufflation have reported conflicting results. This meta-analysis is aimed to assess the efficacy and safety of use of CO2 insufflation for ESD. Clinical trials of CO2 insufflation versus air insufflation for ESD were searched in PubMed, Embase, the Cochrane Library and Chinese Biomedical Literature Database. We performed a meta-analysis of all randomized controlled trials (RCTs). Eleven studies which compared the use of CO2 insufflation and air insufflation, with a combined study population of 1026 patients, were included in the meta-analysis (n = 506 for CO2 insufflation; n = 522 for air insufflation). Abdominal pain and VAS scores at 6h and 24h post-procedure in the CO2 insufflation group were significantly lower than those in the air insufflation group, but not at 1h and 3h after ESD. The percentage of patients who experienced pain 1h and 24h post-procedure was obviously decreased. Use of CO2 insufflation was associated with lower VAS scores for abdominal distention at 1h after ESD, but not at 24h after ESD. However, no significant differences were observed with respect to postoperative transcutaneous partial pressure carbon dioxide (PtcCO2), arterial blood carbon dioxide partial pressure (PaCO2), oxygen saturation (SpO2%), abdominal circumference, hospital stay, white blood cell (WBC) counts, C-Reactive protein (CRP) level, dosage of sedatives used, incidence of dysphagia and other complications. Use of CO2 insufflation for ESD was safe and effective with regard to abdominal discomfort, procedure time, and the residual gas volume. However, there appeared no significant differences with respect to other parameters namely, PtcCO2, PaCO2, SpO2%, abdominal circumference, hospital stay, sedation dosage, complications, WBC, CRP, and dysphagia.

EFFECTS OF ELEVATED CO2 AND TEMPERATURE ON SOIL C AND N: RESULTS OF A DOUGLAS FIR MESOCOSM STUDY

EPA Science Inventory

We conducted a 4-year study on the effects of elevated CO2 and elevated air temperature on Douglas fir seedlings growing under controlled exposure conditions in outdoor sun-lit mesocosms. 1+1 seedlings were planted in mesocosms in Corvallis, OR in the spring of 1993 in a reconstr...

Spatio-temporal visualization of air-sea CO2 flux and carbon budget using volume rendering

NASA Astrophysics Data System (ADS)

Du, Zhenhong; Fang, Lei; Bai, Yan; Zhang, Feng; Liu, Renyi

2015-04-01

This paper presents a novel visualization method to show the spatio-temporal dynamics of carbon sinks and sources, and carbon fluxes in the ocean carbon cycle. The air-sea carbon budget and its process of accumulation are demonstrated in the spatial dimension, while the distribution pattern and variation of CO2 flux are expressed by color changes. In this way, we unite spatial and temporal characteristics of satellite data through visualization. A GPU-based direct volume rendering technique using half-angle slicing is adopted to dynamically visualize the released or absorbed CO2 gas with shadow effects. A data model is designed to generate four-dimensional (4D) data from satellite-derived air-sea CO2 flux products, and an out-of-core scheduling strategy is also proposed for on-the-fly rendering of time series of satellite data. The presented 4D visualization method is implemented on graphics cards with vertex, geometry and fragment shaders. It provides a visually realistic simulation and user interaction for real-time rendering. This approach has been integrated into the Information System of Ocean Satellite Monitoring for Air-sea CO2 Flux (IssCO2) for the research and assessment of air-sea CO2 flux in the China Seas.

Modeling forest C and N allocation responses to free-air CO2 enrichment

NASA Astrophysics Data System (ADS)

Luus, Kristina; De Kauwe, Martin; Walker, Anthony; Werner, Christian; Iversen, Colleen; McCarthy, Heather; Medlyn, Belinda; Norby, Richard; Oren, Ram; Zak, Donald; Zaehle, Sönke

2015-04-01

Vegetation allocation patterns and soil-vegetation partitioning of C and N are predicted to change in response to rising atmospheric concentrations of CO2. These allocation responses to rising CO2 have been examined at the ecosystem level through through free-air CO2 enrichment (FACE) experiments, and their global implications for the timing of progressive N limitation (PNL) and C sequestration have been predicted for ~100 years using a variety of ecosystem models. However, recent FACE model-data syntheses studies [1,2,3] have indicated that ecosystem models do not capture the 5-10 year site-level ecosystem allocation responses to elevated CO2. This may be due in part to the missing representation of the rhizosphere interactions between plants and soil biota in models. Ecosystem allocation of C and N is altered by interactions between soil and vegetation through the priming effect: as plant N availability diminishes, plants respond physiologically by altering their tissue allocation strategies so as to increase rates of root growth and rhizodeposition. In response, either soil organic material begins to accumulate, which hastens the onset of PNL, or soil microbes start to decompose C more rapidly, resulting in increased N availability for plant uptake, which delays PNL. In this study, a straightforward approach for representing rhizosphere interactions in ecosystem models was developed through which C and N allocation to roots and rhizodeposition responds dynamically to elevated CO2 conditions, modifying soil decomposition rates without pre-specification of the direction in which soil C and N accumulation should shift in response to elevated CO2. This approach was implemented in a variety of ecosystem models ranging from stand (G'DAY), to land surface (CLM 4.5, O-CN), to dynamic global vegetation (LPJ-GUESS) models. Comparisons against data from three forest FACE sites (Duke, Oak Ridge & Rhinelander) indicated that representing rhizosphere interactions allowed

Temperature, traffic-related air pollution, and heart rate variability in a panel of healthy adults.

PubMed

Wu, Shaowei; Deng, Furong; Liu, Youcheng; Shima, Masayuki; Niu, Jie; Huang, Qinsheng; Guo, Xinbiao

2013-01-01

Both ambient temperature and air pollution have been associated with alterations in cardiac autonomic function, but the responsive patterns associated with temperature exposure and the interactive effects of temperature and air pollution remain largely unclear. We investigated the associations between personal temperature exposure and cardiac autonomic function as reflected by heart rate variability (HRV) in a panel of 14 healthy taxi drivers in the context of traffic-related air pollution. We collected real-time data on study subjects' in-car exposures to temperature and traffic-related air pollutants including particulate matter with an aerodynamic diameter ≤2.5 μm (PM(2.5)) and carbon monoxide (CO) and HRV indices during work time (8:30-21:00) on 48 sampling days in the warm season (May-September) and cold season (October-March). We applied mixed-effects models and loess models adjusting for potential confounders to examine the associations between temperature and HRV indices. We found nonlinear relationships between temperature and HRV indices in both the warm and cold seasons. Linear regression stratified by temperature levels showed that increasing temperature levels were associated with declines in standard deviation of normal-to-normal intervals over different temperature strata and increases in low-frequency power and low-frequency:high-frequency ratio in higher temperature range (>25 °C). PM(2.5) and CO modified these associations to various extents. Temperature was associated with alterations in cardiac autonomic function in healthy adults in the context of traffic-related air pollution. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of air flow directions on composting process temperature profile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulcu, Recep; Yaldiz, Osman

2008-07-01

In this study, chicken manure mixed with carnation wastes was composted by using three different air flow directions: R1-sucking (downward), R2-blowing (upward) and R3-mixed. The aim was to find out the most appropriate air flow direction type for composting to provide more homogenous temperature distribution in the reactors. The efficiency of each aeration method was evaluated by monitoring the evolution of parameters such as temperature, moisture content, CO{sub 2} and O{sub 2} ratio in the material and dry material losses. Aeration of the reactors was managed by radial fans. The results showed that R3 resulted in a more homogenous temperaturemore » distribution and high dry material loss throughout the composting process. The most heterogeneous temperature distribution and the lowest dry material loss were obtained in R2.« less

A Sensitivity Analysis of the Impact of Rain on Regional and Global Sea-Air Fluxes of CO2

PubMed Central

Shutler, J. D.; Land, P. E.; Woolf, D. K.; Quartly, G. D.

2016-01-01

The global oceans are considered a major sink of atmospheric carbon dioxide (CO2). Rain is known to alter the physical and chemical conditions at the sea surface, and thus influence the transfer of CO2 between the ocean and atmosphere. It can influence gas exchange through enhanced gas transfer velocity, the direct export of carbon from the atmosphere to the ocean, by altering the sea skin temperature, and through surface layer dilution. However, to date, very few studies quantifying these effects on global net sea-air fluxes exist. Here, we include terms for the enhanced gas transfer velocity and the direct export of carbon in calculations of the global net sea-air fluxes, using a 7-year time series of monthly global climate quality satellite remote sensing observations, model and in-situ data. The use of a non-linear relationship between the effects of rain and wind significantly reduces the estimated impact of rain-induced surface turbulence on the rate of sea-air gas transfer, when compared to a linear relationship. Nevertheless, globally, the rain enhanced gas transfer and rain induced direct export increase the estimated annual oceanic integrated net sink of CO2 by up to 6%. Regionally, the variations can be larger, with rain increasing the estimated annual net sink in the Pacific Ocean by up to 15% and altering monthly net flux by > ± 50%. Based on these analyses, the impacts of rain should be included in the uncertainty analysis of studies that estimate net sea-air fluxes of CO2 as the rain can have a considerable impact, dependent upon the region and timescale. PMID:27673683

Attaining whole-ecosystem warming using air and deep-soil heating methods with an elevated CO₂ atmosphere

DOE PAGES

Hanson, Paul J.; Riggs, Jeffery S.; Nettles, IV, W. Robert; ...

2017-02-24

This paper describes the operational methods to achieve and measure both deep-soil heating (0–3 m) and whole-ecosystem warming (WEW) appropriate to the scale of tall-stature, high-carbon, boreal forest peatlands. The methods were developed to allow scientists to provide a plausible set of ecosystem-warming scenarios within which immediate and longer-term (1 decade) responses of organisms (microbes to trees) and ecosystem functions (carbon, water and nutrient cycles) could be measured. Elevated CO 2 was also incorporated to test how temperature responses may be modified by atmospheric CO 2 effects on carbon cycle processes. The WEW approach was successful in sustaining a widemore » range of aboveground and belowground temperature treatments (+0, +2.25, +4.5, +6.75 and +9 °C) in large 115 m 2 open-topped enclosures with elevated CO 2 treatments (+0 to +500 ppm). Air warming across the entire 10 enclosure study required ~90 % of the total energy for WEW ranging from 64 283 mega Joules (MJ) d –1 during the warm season to 80 102 MJ d –1 during cold months. Soil warming across the study required only 1.3 to 1.9 % of the energy used ranging from 954 to 1782 MJ d –1 of energy in the warm and cold seasons, respectively. The residual energy was consumed by measurement and communication systems. Sustained temperature and elevated CO 2 treatments were only constrained by occasional high external winds. This paper contrasts the in situ WEW method with closely related field-warming approaches using both aboveground (air or infrared heating) and belowground-warming methods. It also includes a full discussion of confounding factors that need to be considered carefully in the interpretation of experimental results. As a result, the WEW method combining aboveground and deep-soil heating approaches enables observations of future temperature conditions not available in the current observational record, and therefore provides a plausible glimpse of future environmental

Attaining whole-ecosystem warming using air and deep-soil heating methods with an elevated CO₂ atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, Paul J.; Riggs, Jeffery S.; Nettles, IV, W. Robert

This paper describes the operational methods to achieve and measure both deep-soil heating (0–3 m) and whole-ecosystem warming (WEW) appropriate to the scale of tall-stature, high-carbon, boreal forest peatlands. The methods were developed to allow scientists to provide a plausible set of ecosystem-warming scenarios within which immediate and longer-term (1 decade) responses of organisms (microbes to trees) and ecosystem functions (carbon, water and nutrient cycles) could be measured. Elevated CO 2 was also incorporated to test how temperature responses may be modified by atmospheric CO 2 effects on carbon cycle processes. The WEW approach was successful in sustaining a widemore » range of aboveground and belowground temperature treatments (+0, +2.25, +4.5, +6.75 and +9 °C) in large 115 m 2 open-topped enclosures with elevated CO 2 treatments (+0 to +500 ppm). Air warming across the entire 10 enclosure study required ~90 % of the total energy for WEW ranging from 64 283 mega Joules (MJ) d –1 during the warm season to 80 102 MJ d –1 during cold months. Soil warming across the study required only 1.3 to 1.9 % of the energy used ranging from 954 to 1782 MJ d –1 of energy in the warm and cold seasons, respectively. The residual energy was consumed by measurement and communication systems. Sustained temperature and elevated CO 2 treatments were only constrained by occasional high external winds. This paper contrasts the in situ WEW method with closely related field-warming approaches using both aboveground (air or infrared heating) and belowground-warming methods. It also includes a full discussion of confounding factors that need to be considered carefully in the interpretation of experimental results. As a result, the WEW method combining aboveground and deep-soil heating approaches enables observations of future temperature conditions not available in the current observational record, and therefore provides a plausible glimpse of future environmental

The catalytic effect of H2O on the hydrolysis of CO32- in hydrated clusters and its implication in the humidity driven CO2 air capture.

PubMed

Xiao, Hang; Shi, Xiaoyang; Zhang, Yayun; Liao, Xiangbiao; Hao, Feng; Lackner, Klaus S; Chen, Xi

2017-10-18

The hydration of ions in nanoscale hydrated clusters is ubiquitous and essential in many physical and chemical processes. Here we show that the hydrolysis reaction is strongly affected by relative humidity. The hydrolysis of CO 3 2- with n = 1-8 water molecules is investigated using an ab initio method. For n = 1-5 water molecules, all the reactants follow a stepwise pathway to the transition state. For n = 6-8 water molecules, all the reactants undergo a direct proton transfer to the transition state with overall lower activation free energy. The activation free energy of the reaction is dramatically reduced from 10.4 to 2.4 kcal mol -1 as the number of water molecules increases from 1 to 6. Meanwhile, the degree of hydrolysis of CO 3 2- is significantly increased compared to the bulk water solution scenario. Incomplete hydration shells facilitate the hydrolysis of CO 3 2- with few water molecules to be not only thermodynamically favorable but also kinetically favorable. We showed that the chemical kinetics is not likely to constrain the speed of CO 2 air capture driven by the humidity-swing. Instead, the pore-diffusion of ions is expected to be the time-limiting step in the humidity driven CO 2 air capture. The effect of humidity on the speed of CO 2 air capture was studied by conducting a CO 2 absorption experiment using IER with a high ratio of CO 3 2- to H 2 O molecules. Our result is able to provide valuable insights into designing efficient CO 2 air-capture sorbents.

Agroecosystem productivity in a warmer and CO2 enriched atmosphere

NASA Astrophysics Data System (ADS)

Bernacchi, Carl; Köhler, Iris; Ort, Donald; Long, Steven; Clemente, Thomas

2017-04-01

A number of in-field manipulative experiments have been conducted that address the response of key ecosystem services of major agronomic species to rising CO2. Global warming, however, is inextricably linked to rising greenhouse gases in general, of which CO2 is the most dominant. Therefore, agroecosystem functioning in future conditions requires an understanding of plant responses to both rising CO2 and increased temperatures. Few in-field manipulative experiments have been conducted that supplement both heating and CO2 above background concentrations. Here, the results of six years of experimentation using a coupled Free Air CO2 Enrichment (FACE) technology with variable output infrared heating arrays are reported. The manipulative experiment increased temperatures (+ 3.5˚ C) and CO2 (+ 200 μmol mol-1) above background levels for on two major agronomic crop species grown throughout the world, Zea mays (maize) and Glycine max (soybean). The first phase of this research addresses the response of plant physiological parameters to growth in elevated CO2 and warmer temperatures for maize and soybean grown in an open-air manipulative experiment. The results show that any increase in ecosystem productivity associated with rising CO2 is either similar or is offset by growth at higher temperatures, inconsistent with the perceived benefits of higher CO2 plus warmer temperatures on agroecosystem productivity. The second phase of this research addresses the opportunity to genetically modify soybean to allow for improved productivity under high CO2 and warmer temperatures by increasing a key photosynthetic carbon reduction cycle enzyme, SPBase. The results from this research demonstrates that manipulation of the photosynthetic pathway can lead to higher productivity in high CO2 and temperature relative to the wild-type control soybean. Overall, this research advances the understanding of the physiological responses of two major crops, and the impact on ecosystem services

Potential air contamination during CO2 angiography using a hand-held syringe: theoretical considerations and gas chromatography.

PubMed

Cho, David R; Cho, Kyung J; Hawkins, Irvin F

2006-01-01

To assess air contamination in the hand-held syringes currently used for CO2 delivery and to determine whether there is an association between their position and the rate of air contamination. Assessment of air contamination in the syringe (20 ml) included theoretical modeling, mathematical calculation, and gas chromatography (GC). The model was used with Fick's first law to calculate the diffusion of CO2 and the amount of air contamination. For GC studies, the syringes were placed in the upright, horizontal, and inverted positions and gas samples were obtained after 5, 10, 20, 30, and 60 min. All trials with each position for each sampling time were performed five times. The amounts of air contamination with time calculated mathematically were 5-10% less than those of GC. With the diffusivity of air-CO2 at 0.1599 cm2/sec (9.594 cm2/min), air contamination was calculated to be 60% at 60 min. With GC air contamination was 13% at 5 min, 31% at 20 min, 43% at 30 min, and 68% at 60 min. There was no difference in air contamination between the different syringe positions. Air contamination occurs in hand-held syringes filled with CO2 when they are open to the ambient air. The amounts of air contamination over time are similar among syringes placed in the upright, horizontal, and inverted positions.

Effects of elevated CO2 and temperature on Gynostemma pentaphyllum physiology and bioactive compounds.

PubMed

Chang, Jia-Dong; Mantri, Nitin; Sun, Bin; Jiang, Li; Chen, Ping; Jiang, Bo; Jiang, Zhengdong; Zhang, Jialei; Shen, Jiahao; Lu, Hongfei; Liang, Zongsuo

2016-06-01

Recently, an important topic of research has been how climate change is seriously threatening the sustainability of agricultural production. However, there is surprisingly little experimental data regarding how elevated temperature and CO2 will affect the growth of medicinal plants and production of bioactive compounds. Here, we comprehensively analyzed the effects of elevated CO2 and temperature on the photosynthetic process, biomass, total sugars, antioxidant compounds, antioxidant capacity, and bioactive compounds of Gynostemma pentaphyllum. Two different CO2 concentrations [360 and 720μmolmol(-1)] were imposed on plants grown at two different temperature regimes of 23/18 and 28/23°C (day/night) for 60days. Results show that elevated CO2 and temperature significantly increase the biomass, particularly in proportion to inflorescence total dry weight. The chlorophyll content in leaves increased under the elevated temperature and CO2. Further, electron transport rate (ETR), photochemical quenching (qP), actual photochemical quantum yield (Yield), instantaneous photosynthetic rate (Photo), transpiration rate (Trmmol) and stomatal conductance (Cond) also increased to different degrees under elevated CO2 and temperature. Moreover, elevated CO2 increased the level of total sugars and gypenoside A, but decreased the total antioxidant capacity and main antioxidant compounds in different organs of G. pentaphyllum. Accumulation of total phenolics and flavonoids also decreased in leaves, stems, and inflorescences under elevated CO2 and temperature. Overall, our data indicate that the predicted increase in atmospheric temperature and CO2 could improve the biomass of G. pentaphyllum, but they would reduce its health-promoting properties. Copyright © 2016 Elsevier GmbH. All rights reserved.

Synchronous change of atmospheric CO2 and Antarctic temperature during the last deglacial warming.

PubMed

Parrenin, F; Masson-Delmotte, V; Köhler, P; Raynaud, D; Paillard, D; Schwander, J; Barbante, C; Landais, A; Wegner, A; Jouzel, J

2013-03-01

Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last deglacial warming, using data from five Antarctic ice cores. We infer the phasing between CO2 concentration and Antarctic temperature at four times when their trends change abruptly. We find no significant asynchrony between them, indicating that Antarctic temperature did not begin to rise hundreds of years before the concentration of atmospheric CO2, as has been suggested by earlier studies.

Elevated temperature and CO(2) concentration effects on xylem anatomy of Scots pine.

PubMed

Kilpeläinen, Antti; Gerendiain, Ane Zubizarreta; Luostarinen, Katri; Peltola, Heli; Kellomäki, Seppo

2007-09-01

We studied the effects of elevated temperature and carbon dioxide concentration ([CO(2)]) alone and together on wood anatomy of 20-year-old Scots pine (Pinus sylvestris L.) trees. The study was conducted in 16 closed chambers, providing a factorial combination of two temperature regimes and two CO(2) concentrations (ambient and elevated), with four trees in each treatment. The climate scenario included a doubling of [CO(2)] and a corresponding increase of 2-6 degrees C in temperature at the site depending on the season. Anatomical characteristics analyzed were annual earlywood, latewood and ring widths, intra-ring wood densities (earlywood, latewood and mean wood density), tracheid width, length, wall thickness, lumen diameter, wall thickness:lumen diameter ratio and mass per unit length (coarseness), and numbers of rays, resin canals and tracheids per xylem cross-sectional area. Elevated [CO(2)] increased ring width in four of six treatment years; earlywood width increased in the first two years and latewood width in the third year. Tracheid walls in both the earlywood and latewood tended to become thicker over the 6-year treatment period when temperature or [CO(2)] was elevated alone, whereas in the combined treatment they tended to become thinner relative to the tracheids of trees grown under ambient conditions. Latewood tracheid lumen diameters were larger in all the treatments relative to ambient conditions over the 6-year period, whereas lumen diameters in earlywood increased only in response to elevated [CO(2)] and were 3-6% smaller in the treatments with elevated temperature than in ambient conditions. Tracheid width, length and coarseness were greater in trees grown in elevated than in ambient temperature. The number of resin canals per mm(2) decreased in the elevated [CO(2)] treatment and increased in the elevated temperature treatments relative to ambient conditions. The treatments decreased the number of rays and tracheids per mm(2) of cross

Co-control of local air pollutants and CO2 in the Chinese iron and steel industry.

PubMed

Mao, Xianqiang; Zeng, An; Hu, Tao; Zhou, Ji; Xing, Youkai; Liu, Shengqiang

2013-01-01

The present study proposes an integrated multipollutant cocontrol strategy framework in the context of the Chinese iron and steel industry. The unit cost of pollutant reduction (UCPR) was used to examine the cost-effectiveness of each emission reduction measure. The marginal abatement cost (MAC) curves for SO2, NOx, PM2.5, and CO2 were drawn based on the UCPR and the abatement potential. Air pollutant equivalence (APeq) captures the nature of the damage value-weights of various air pollutants and acts as uniformization multiple air pollutants index. Single pollutant abatement routes designed in accordance with the corresponding reduction targets revealed that the cocontrol strategy has promising potential. Moreover, with the same reduction cost limitations as the single pollutant abatement routes, the multipollutant cocontrol routes are able to obtain more desirable pollution reduction and health benefits. Co-control strategy generally shows cost-effective advantage over single-pollutant abatement strategy. The results are robust to changing parameters according to sensitivity analysis. Co-control strategy would be an important step to achieve energy/carbon intensity targets and pollution control targets in China. Though cocontrol strategy has got some traction in policy debates, there are barriers to integrate it into policy making in the near future in China.

CARS Temperature and Species Measurements For Air Vehicle Propulsion Systems

NASA Technical Reports Server (NTRS)

Danehy, Paul M.; Gord, James R.; Grisch, Frederic; Klimenko, Dmitry; Clauss, Walter

2005-01-01

The coherent anti-Stokes Raman spectroscopy (CARS) method has recently been used in the United States and Europe to probe several different types of propulsion systems for air vehicles. At NASA Langley Research Center in the United States, CARS has been used to simultaneously measure temperature and the mole fractions of N2, O2 and H2 in a supersonic combustor, representative of a scramjet engine. At Wright- Patterson Air Force Base in the United States, CARS has been used to simultaneously measure temperature and mole fractions of N2, O2 and CO2, in the exhaust stream of a liquid-fueled, gas-turbine combustor. At ONERA in France and the DLR in Germany researchers have used CARS to measure temperature and species concentrations in cryogenic LOX-H2 rocket combustion chambers. The primary aim of these measurements has been to provide detailed flowfield information for computational fluid dynamics (CFD) code validation.

Toward a lithium-"air" battery: the effect of CO2 on the chemistry of a lithium-oxygen cell.

PubMed

Lim, Hyung-Kyu; Lim, Hee-Dae; Park, Kyu-Young; Seo, Dong-Hwa; Gwon, Hyeokjo; Hong, Jihyun; Goddard, William A; Kim, Hyungjun; Kang, Kisuk

2013-07-03

Lithium-oxygen chemistry offers the highest energy density for a rechargeable system as a "lithium-air battery". Most studies of lithium-air batteries have focused on demonstrating battery operations in pure oxygen conditions; such a battery should technically be described as a "lithium-dioxygen battery". Consequently, the next step for the lithium-"air" battery is to understand how the reaction chemistry is affected by the constituents of ambient air. Among the components of air, CO2 is of particular interest because of its high solubility in organic solvents and it can react actively with O2(-•), which is the key intermediate species in Li-O2 battery reactions. In this work, we investigated the reaction mechanisms in the Li-O2/CO2 cell under various electrolyte conditions using quantum mechanical simulations combined with experimental verification. Our most important finding is that the subtle balance among various reaction pathways influencing the potential energy surfaces can be modified by the electrolyte solvation effect. Thus, a low dielectric electrolyte tends to primarily form Li2O2, while a high dielectric electrolyte is effective in electrochemically activating CO2, yielding only Li2CO3. Most surprisingly, we further discovered that a high dielectric medium such as DMSO can result in the reversible reaction of Li2CO3 over multiple cycles. We believe that the current mechanistic understanding of the chemistry of CO2 in a Li-air cell and the interplay of CO2 with electrolyte solvation will provide an important guideline for developing Li-air batteries. Furthermore, the possibility for a rechargeable Li-O2/CO2 battery based on Li2CO3 may have merits in enhancing cyclability by minimizing side reactions.

The effects of cooling systems on CO2-lased human enamel.

PubMed

Lian, H J; Lan, W H; Lin, C P

1996-12-01

The thermal effects on dentin during CO2 laser irradiation on human enamel were investigated. To simulate the clinical practice, two cooling methods (air and water spray) were applied immediately after laser exposure, whereas one group without cooling was served as control. Three hundred and sixty uniform tooth blocks were obtained from freshly extracted human third molars. Temperature change measurements were made via electrical thermocouple implanted within the tooth block 2 mm away from the enamel surface. Experimental treatments consisted of lasing without cooling, lasing with 0.5-ml/sec water cooling, and lasing with 15-psi air cooling. Our results indicated that (1) both air- and water-cooling groups could reduce temperature elevation significantly; (2) the larger power energy resulted in the higher temperature elevation. In conclusion, for CO2 laser irradiation on human enamel both water- and air-cooling methods may be effective on prevention of thermal damage of pulp.

The effect of CO2 at low temperature and pressure on solutions supersaturated with silica in the presence of limestone and dolomite

USGS Publications Warehouse

Lovering, T.G.; Patten, L.E.

1962-01-01

The effect of 1 atm of CO2 over initially neutral solutions supersaturated with silica, at room temperature, as contrasted with 1 atm of air was determined over a period of 5 months, together with changes brought about by the introduction of calcite and dolomite to these solutions in the form of either chips or finely ground powder. In the absence of CO2 all solutions quickly reached equilibrium and no silica precipitated. In the presence of CO2 approximately two-thirds of the silica precipitated as silica gel within the first 2 months; the amount of silica precipitated was not affected by the presence of limestone or dolomite. Silica gel precipitated as a fine powder in the presence of finely ground calcite and dolomite, but as a cloudy gelatinous mass in the presence of coarse chips of dolomite and calcite, and in the absence of either calcite or dolomite. Preferential leaching of calcium from dolomite took place, both in the presence of air and in the presence of CO2, but was more pronounced in the presence of air. There was no evidence of physical replacement of either limestone or dolomite by precipitated silica. ?? 1962.

Measurements of CO, CO2, OH, and H2O in room-temperature and combustion gases by use of a broadly current-tuned multisection InGaAsP diode laser.

PubMed

Upschulte, B L; Sonnenfroh, D M; Allen, M G

1999-03-20

A new laser technology that achieves nearly 100-nm quasi-continuous tuning with only injection-current control in a four-section grating-coupler sampled-reflector laser was used to detect CO and CO(2) simultaneously in room-temperature gas mixtures. The same grating-coupler sampled-reflector laser was used to perform in situ measurements of CO, H(2)O, and OH in the exhaust gases of a CH(4)-air flame. This laser is being evaluated for inclusion in a multispecies combustion-emissions exhaust-analysis sensor, and its operational characteristics as they have an impact on gas sensing are described. Preliminary results suggest that this single laser can be used to replace multilaser sensor configurations for some combustion-emissions monitoring applications.

Nitrous oxide flux under changing temperature and CO2

EPA Science Inventory

We are investigating nitrous oxide flux seasonal trends and response to temperature and CO2 increases in a boreal peatland. Peatlands located in boreal regions make up a third of global wetland area and are expected to have the highest temperature increases in response to climat...

Leaf Shape Responds to Temperature but Not CO2 in Acer rubrum

PubMed Central

Royer, Dana L.

2012-01-01

The degree of leaf dissection and the presence of leaf teeth, along with tooth size and abundance, inversely correlate with mean annual temperature (MAT) across many plant communities. These relationships form the core of several methods for reconstructing MAT from fossils, yet the direct selection of temperature on tooth morphology has not been demonstrated experimentally. It is also not known if atmospheric CO2 concentration affects leaf shape, limiting confidence in ancient climate reconstructions because CO2 has varied widely on geologic timescales. Here I report the results of growing Acer rubrum (red maple) in growth cabinets at contrasting temperature and CO2 conditions. The CO2 treatment imparted no significant differences in leaf size and shape, while plants grown at cooler temperatures tended to have more teeth and more highly dissected leaves. These results provide direct evidence for the selection of temperature on leaf shape in one species, and support a key link in many leaf-climate methods. More broadly, these results increase confidence for using leaf shape in fossils to reconstruct paleoclimate. PMID:23152921

High indoor CO2 concentrations in an office environment increases the transcutaneous CO2 level and sleepiness during cognitive work.

PubMed

Vehviläinen, Tommi; Lindholm, Harri; Rintamäki, Hannu; Pääkkönen, Rauno; Hirvonen, Ari; Niemi, Olli; Vinha, Juha

2016-01-01

The purpose of this study is to perform a multiparametric analysis on the environmental factors, the physiological stress reactions in the body, the measured alertness, and the subjective symptoms during simulated office work. Volunteer male subjects were monitored during three 4-hr work meetings in an office room, both in a ventilated and a non-ventilated environment. The environmental parameters measured included CO(2), temperature, and relative humidity. The physiological test battery consisted of measuring autonomic nervous system functions, salivary stress hormones, blood's CO(2)- content and oxygen saturation, skin temperatures, thermal sensations, vigilance, and sleepiness. The study shows that we can see physiological changes caused by high CO(2) concentration. The findings support the view that low or moderate level increases in concentration of CO(2) in indoor air might cause elevation in the blood's transcutaneously assessed CO(2). The observed findings are higher CO(2) concentrations in tissues, changes in heart rate variation, and an increase of peripheral blood circulation during exposure to elevated CO(2) concentration. The subjective parameters and symptoms support the physiological findings. This study shows that a high concentration of CO(2) in indoor air seem to be one parameter causing physiological effects, which can decrease the facility user's functional ability. The correct amount of ventilation with relation to the number of people using the facility, functional air distribution, and regular breaks can counteract the decrease in functional ability. The findings of the study suggest that merely increasing ventilation is not necessarily a rational solution from a technical-economical viewpoint. Instead or in addition, more comprehensive, anthropocentric planning of space is needed as well as instructions and new kinds of reference values for the design and realization of office environments.

Cost Effective Measures to Reduce CO2 Emissions in the Air Freight Sector

NASA Technical Reports Server (NTRS)

Blinge, Magnus

2003-01-01

This paper presents cost effective measures to reduce CO2 emissions in the air freight sector. One door-to-door transport chain is studied in detail from a Scandinavian city to a city in southern Europe. The transport chain was selected by a group of representatives from the air freight sector in order to encompass general characteristics within the sector. Three different ways of shipping air cargo are studied, i.e., by air freighter, as belly freight (in passenger aircrafts) and trucking. CO2 emissions are calculated for each part of the transport chain and its relative importance towards the total amount CO2 emitted during the whole transport chain is shown. It is confirmed that the most CO2 emitting part of the transport chain is the actual flight and that it is in the take-off and climbing phases that most fuel are burned. It is also known that the technical development of aircraft implies a reduction in fuel consumption for each new generation of aircraft. Thus, the aircraft manufacturers have an important role in this development. Having confirmed these observations, this paper focuses on other factors that significantly affects the fuel consumption. Analyzed factors are, e.g., optimization of speed and altitude, traffic management, congestion on and around the airfields, tankering, "latest acceptance time" for goods and improving the load factor. The different factors relative contribution to the total emission levels for the transport chain has been estimated.

Feasibility of CO/sub 2/ monitoring to assess air quality in mines using diesel equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, J.H. Jr.

1987-01-01

The methodology includes: (1) establishing pollutant to CO/sub 2/ ratios for in-service equipment, (2) estimating pollutant concentrations from the ratios and in-mine CO/sub 2/ measurements, and (3) using an air quality index to combine the pollutants into a single number, which indicates the health hazard associated with the pollutants. For the methodology to be valid, the pollutant to CO/sub 2/ ratios must remain constant if engine operating conditions do not significantly change. However, due to the complex dynamics of the fuel injection system, the fuel-air combustion process, and the engine speed-load governing system, the pollutant to CO/sub 2/ ratios maymore » vary during repetitive, but transient engine speed-and-load operation. These transient effects were investigated. In addition, the influence of changing engine conditions due to engine maladjustment, and a practical means to evaluate engine condition were investigated to advance the methodology. The laboratory investigation determined that CO/sub 2/ is an effective indicator of engine exhaust pollutants. It was shown that the exhaust concentrations of carbon monoxide, carbon dioxide, oxides of nitrogen, hydrocarbons, and particulate matter do not significantly vary among repetitive, but transient engine speed-and-load duty cycles typical of in-service equipment. Based on an air quality index and threshold limit values, particulate matter exhibited the greatest adverse effect on air quality. Particulate mass was separated into volatile (organic soluble fraction) and nonvolatile (insoluble carbon fraction) components. Due to particulate concentrations, the engine operating conditions of overfueling and advanced injector timing had greater adverse effects on air quality than the conditions of retarded injector timing, intake air restriction, and Federal certification specifications.« less

Ambient air pollution, temperature and out-of-hospital coronary deaths in Shanghai, China.

PubMed

Dai, Jinping; Chen, Renjie; Meng, Xia; Yang, Changyuan; Zhao, Zhuohui; Kan, Haidong

2015-08-01

Few studies have evaluated the effects of ambient air pollution and temperature in triggering out-of-hospital coronary deaths (OHCDs) in China. We evaluated the associations of air pollution and temperature with daily OHCDs in Shanghai, China from 2006 to 2011. We applied an over-dispersed generalized additive model and a distributed lag nonlinear model to analyze the effects of air pollution and temperature, respectively. A 10 μg/m(3) increase in the present-day PM10, PM2.5, SO2, NO2 and CO were associated with increases in OHCD mortality of 0.49%, 0.68%, 0.88%, 1.60% and 0.08%, respectively. A 1 °C decrease below the minimum-mortality temperature corresponded to a 3.81% increase in OHCD mortality on lags days 0-21, and a 1 °C increase above minimum-mortality temperature corresponded to a 4.61% increase over lag days 0-3. No effects were found for in-hospital coronary deaths. This analysis suggests that air pollution, low temperature and high temperature may increase the risk of OHCDs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of winter temperature and summer drought on net ecosystem exchange of CO2 in a temperate peatland

NASA Astrophysics Data System (ADS)

Helfter, Carole; Campbell, Claire; Dinsmore, Kerry; Drewer, Julia; Coyle, Mhairi; Anderson, Margaret; Skiba, Ute; Nemitz, Eiko; Billett, Michael; Sutton, Mark

2014-05-01

Northern peatlands are one of the most important global sinks of atmospheric carbon dioxide (CO2); their ability to sequester C is a natural feedback mechanism controlled by climatic variables such as precipitation, temperature, length of growing season and period of snow cover. In the UK it has been predicted that peatlands could become a net source of carbon in response to climate change with climate models predicting a rise in global temperature of ca. 3oC between 1961-1990 and 2100. Land-atmosphere exchange of CO2in peatlands exhibits marked seasonal and inter-annual variations, which have significant short- and long-term effects on carbon sink strength. Net ecosystem exchange (NEE) of CO2 has been measured continuously by eddy-covariance (EC) at Auchencorth Moss (55° 47'32 N, 3° 14'35 W, 267 m a.s.l.), a temperate peatland in central Scotland, since 2002. Auchencorth Moss is a low-lying, ombrotrophic peatland situated ca. 20 km south-west of Edinburgh. Peat depth ranges from 5 m and the site has a mean annual precipitation of 1155 mm. The vegetation present within the flux measurement footprint comprises mixed grass species, heather and substantial areas of moss species (Sphagnum spp. and Polytrichum spp.). The EC system consists of a LiCOR 7000 closed-path infrared gas analyser for the simultaneous measurement of CO2 and water vapour and of a Gill Windmaster Pro ultrasonic anemometer. Over the 10 year period, the site was a consistent yet variable sink of CO2 ranging from -34.1 to -135.9 g CO2-C m-2 yr-1 (mean of -69.1 ± 33.6 g CO2-C m-2 yr-1). Inter-annual variability in NEE was positively correlated to the length of the growing seasons and mean winter air temperature explained 93% of the variability in summertime sink strength, indicating a phenological memory-effect. Plant development and productivity were stunted by colder winters causing a net reduction in the annual carbon sink strength of this peatland where autotrophic processes are thought to be

Crowdsourcing urban air temperatures from smartphone battery temperatures

NASA Astrophysics Data System (ADS)

Overeem, Aart; Robinson, James C. R.; Leijnse, Hidde; Steeneveld, Gert-Jan; Horn, Berthold K. P.; Uijlenhoet, Remko

2014-05-01

Accurate air temperature observations in urban areas are important for meteorology and energy demand planning. They are indispensable to study the urban heat island effect and the adverse effects of high temperatures on human health. However, the availability of temperature observations in cities is often limited. Here we show that relatively accurate air temperature information for the urban canopy layer can be obtained from an alternative, nowadays omnipresent source: smartphones. In this study, battery temperatures were collected by an Android application for smartphones. It has been shown that a straightforward heat transfer model can be employed to estimate daily mean air temperatures from smartphone battery temperatures for eight major cities around the world. The results demonstrate the enormous potential of this crowdsourcing application for real-time temperature monitoring in densely populated areas. Battery temperature data were collected by users of an Android application for cell phones (opensignal.com). The application automatically sends battery temperature data to a server for storage. In this study, battery temperatures are averaged in space and time to obtain daily averaged battery temperatures for each city separately. A regression model, which can be related to a physical model, is employed to retrieve daily air temperatures from battery temperatures. The model is calibrated with observed air temperatures from a meteorological station of an airport located in or near the city. Time series of air temperatures are obtained for each city for a period of several months, where 50% of the data is for independent verification. The methodology has been applied to Buenos Aires, London, Los Angeles, Paris, Mexico City, Moscow, Rome, and Sao Paulo. The evolution of the retrieved air temperatures often correspond well with the observed ones. The mean absolute error of daily air temperatures is less than 2 degrees Celsius, and the bias is within 1 degree

The Effects of Elevated pCO2, Hypoxia and Temperature on ...

EPA Pesticide Factsheets

Estuarine fish are acclimated to living in an environment with rapid and frequent changes in temperature, salinity, pH, and dissolved oxygen (DO) levels; the physiology of these organisms is well suited to cope with extreme thermal, hypercapnic, and hypoxic stress. While the adverse effects of low dissolved oxygen levels on estuarine fish has been well-documented, the interaction between low DO and elevated pCO2 is not well understood. There is some evidence that low DO and elevated pCO2 interact antagonistically, however little information exists on how projected changes of pCO2 levels in near-shore waters may affect estuarine species, and how these changes may specifically interact with dissolved oxygen and temperature. We explored the survivability of 7-day post fertilization sheepshead minnow, Cyprinodon variegatus, using short term exposure to the combined effects of elevated pCO2 (~1300 µatm; IPCC RCP 8.5) and low dissolved oxygen levels (~2 mg/L). Additionally, we determined if the susceptibility of these fish to elevated pCO2 and low DO was influenced by increases in temperature from 27.5°C to 35°C. Results from this study and future studies will be used to identify estuarine species and lifestages sensitive to the combined effects of elevated pCO2 and low dissolved oxygen. This project was created in order to better understand the interactive effects of projected pCO2 levels and hypoxia in estuarine organisms. This work is currently focused on the se

Binding CO2 from Air by a Bulky Organometallic Cation Containing Primary Amines.

PubMed

Luo, Yang-Hui; Chen, Chen; Hong, Dan-Li; He, Xiao-Tong; Wang, Jing-Wen; Ding, Ting; Wang, Bo-Jun; Sun, Bai-Wang

2018-03-21

The organometallic cation 1 (Fe(bipy-NH 2 ) 3 2+ , bipy-NH 2 = 4,4'-diamino-2,2'-bipyridine), which was constructed in situ in solution, can bind CO 2 from air effectively with a stoichiometric ratio of 1:4 (1/CO 2 ), through the formation of "H-bonded CO 2 " species: [CO 2 -OH-CO 2 ] - and [CO 2 -CO 2 -OH] - . These two species, along with the captured individual CO 2 molecules, connected 1 into a novel 3D (three-dimensional) architecture, that was crystal 1·2(OH - )·4(CO 2 ). The adsorption isotherms, recycling investigations, and the heat capacity of 1 have been investigated; the results revealed that the organometallic cation 1 can be recycled at least 10 times for the real-world CO 2 capture applications. The strategies presented here may provide new hints for the development of new alkanolamine-related absorbents or technologies for CO 2 capture and sequestration.

Microplastics co-gasification with biomass: Modelling syngas characteristics at low temperatures

NASA Astrophysics Data System (ADS)

Ramos, Ana; Tavares, Raquel; Rouboa, Abel

2018-05-01

To assess the syngas produced through the gasification of microplastics at low temperatures, distinct blends of polyethylene terephthalate (PET) with biomass (vine pruning) were modelled using Aspen Plus. Critical gasification parameters such as co-fuel mixture, temperature and hydrogen production were evaluated, under two different gasifier agents (air and O2). Results have shown that higher PET ratios and higher temperatures (< 1200 °C) lead to enhanced hydrogen yields, for both atmospheres. The calorific content was also seen to increase with growing temperatures, superior LHV being achieved for the mixture with less microplastics fraction (9.2 MJ/Nm3) for both air and O2 environments. A final high-quality syngas was achieved, the dominant requirement determining which parameter to optimize: on one hand, higher H2 contents were seen for the blend with higher microplastic fraction, and on the other higher LHV was achieved for the equimolar mixture.

Constraining the Stratosphere-Troposphere Exchange of Radiocarbon using AirCore 14CO2 Measurements

NASA Astrophysics Data System (ADS)

Chen, H.

2016-12-01

Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the upper atmosphere due to reactions of nitrogen nuclei with thermal neutrons that are induced by cosmic rays. 14C is quickly oxidized to 14CO, which is then further oxidized to 14CO2 by OH. To this end, better understanding the radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, upper atmospheric 14C observations have been very sparse to constrain the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14CO2 measurements using AirCore samples from Sodankylä, Northern Finland, along with regular AirCore profiles of CO2, CH4, and CO since 2013. In this study, we calculate the stratosphere-troposphere exchange of 14C using the correlation between 14CO2 and N2O, and the estimated N2O loss rate. Besides this, we assess the impact of the mean age of air on 14CO2 profiles. Furthermore, we will evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange.

Detonability of H/sub 2/-air-diluent mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tieszen, S.R.; Sherman, M.P.; Benedick, W.B.

1987-06-01

This report describes the Heated Detonation Tube (HDT). Detonation cell width and velocity results are presented for H/sub 2/-air mixtures, undiluted and diluted with CO/sub 2/ and H/sub 2/O for a range of H/sub 2/ concentration, initial temperature and pressure. The results show that the addition of either CO/sub 2/ or H/sub 2/O significantly increases the detonation cell width and hence reduces the detonability of the mixture. The results also show that the detonation cell width is reduced (detonability is increased) for increased initial temperature and/or pressure.

Evidence for a temperature-induced spin-state transition of Co3+ in La2-xSrxCoO4

NASA Astrophysics Data System (ADS)

Hollmann, N.; Haverkort, M. W.; Benomar, M.; Cwik, M.; Braden, M.; Lorenz, T.

2011-05-01

We study the magnetic susceptibility of mixed-valent La2-xSrxCoO4 single crystals in the doping range of 0.5⩽x⩽0.8 for temperatures up to 1000 K. The magnetism below room temperature is described by paramagnetic Co2+ in the high-spin state and by Co3+ in the nonmagnetic low-spin state. At high temperatures, an increase in susceptibility is seen, which we attribute to a temperature-induced spin-state transition of Co3+. The susceptibility is analyzed by comparison to full-multiplet calculations for the thermal population of the high- and intermediate-spin states of Co3+.

Air temperature recordings in infant incubators.

PubMed Central

Aynsley-Green, A; Roberton, N R; Rolfe, P

1975-01-01

Air temperatures were continuously recorded inside four incubators with proportional heating control and six incubators with on/off heating cycles, during routine use. The air temperatures in the former were constant throughout, with a gradient between the roof and above-mattress air temperature not exceeding 1 degree C. In contrast, the recordings from the latter models showed a regular cyclical oscillation, the duration of the cycle varying from 14 to 44 minutes. Each incubator had a characteristic profile. The roof air temperature could vary by as much as 7-1 degrees C and the above-mattress air temperature by as much as 2-6 degrees C during the cycle. The oscillation persisted in the air temperatures recorded inside an open-ended hemicylindrical heat shield when used inside these incubators, but was markedly reduced inside a closed-ended heat shield, Carbon dioxide concentration did not increase significantly inside the latter. Images FIG. 1 FIG. 2 PMID:1147654

A study of the interacting effects of elevated temperature and CO2 on the skeletal growth of two Caribbean coral species

NASA Astrophysics Data System (ADS)

Langdon, C.; Baker, A.; Jones, P.

2011-12-01

A study was conducted to investigate how corals may be impacted by the combination of rising temperature and declining pH. In a fully crossed experimental design two important Caribbean reef-building coral species Acropora cervicornis and Montastraea faveolata were exposed to combinations of a normal (26°C) and elevated (32°C) temperature and normal (380 ppm) and elevated (800 ppm) CO2 level. Nine colonies of each species were placed in eight tanks. Two tanks were assigned to each of the four temperature and CO2 combinations. The CO2 level was controlled by bubbling with either outside air or outside air enriched with CO2 gas to achieve the desired CO2 concentration in the tank. Corals were pre-conditioned for 39 days under 26°C and 380 ppm. The temperature and CO2 in the experimental tanks was then ramped up at a rate of 0.3°C and 30 ppm per day over a two week period. The skeletal growth of the corals was measured weekly over 62 days using an optical or laser micrometer. At the end of the high temperature and CO2 part the experiment the ability of the corals to recover from these stressful conditions was examined for 56 days. The CO2 in the high CO2 tanks was reduced to 380 ppm and the temperature in the 32°C 380 tanks was reduced to 26°C. This experiment is our second attempt to measure short term changes in skeletal growth as a function of temperature and CO2. In the first year none of the corals grew. We eventually discovered that supplemental feeding was necessary. The results of the second year's experiment are interesting but exhibit a great deal of variability. Forty-four percent of A. cervicornis colonies exhibited a decline in growth of 45% and seventy-seven percent of the M. faveolata colonies experienced a decline of 44% under 800 ppm and recovered quickly when the CO2 was lowered to 380 ppm during the recovery phase. However, the other colonies either failed to grow at all, showed no response to CO2 or seemed to grow more quickly under elevated

Improved Surface and Tropospheric Temperatures Determined Using Only Shortwave Channels: The AIRS Science Team Version-6 Retrieval Algorithm

NASA Technical Reports Server (NTRS)

Susskind, Joel; Blaisdell, John; Iredell, Lena

2011-01-01

The Goddard DISC has generated products derived from AIRS/AMSU-A observations, starting from September 2002 when the AIRS instrument became stable, using the AIRS Science Team Version-5 retrieval algorithm. The AIRS Science Team Version-6 retrieval algorithm will be finalized in September 2011. This paper describes some of the significant improvements contained in the Version-6 retrieval algorithm, compared to that used in Version-5, with an emphasis on the improvement of atmospheric temperature profiles, ocean and land surface skin temperatures, and ocean and land surface spectral emissivities. AIRS contains 2378 spectral channels covering portions of the spectral region 650 cm(sup -1) (15.38 micrometers) - 2665 cm(sup -1) (3.752 micrometers). These spectral regions contain significant absorption features from two CO2 absorption bands, the 15 micrometers (longwave) CO2 band, and the 4.3 micrometers (shortwave) CO2 absorption band. There are also two atmospheric window regions, the 12 micrometer - 8 micrometer (longwave) window, and the 4.17 micrometer - 3.75 micrometer (shortwave) window. Historically, determination of surface and atmospheric temperatures from satellite observations was performed using primarily observations in the longwave window and CO2 absorption regions. According to cloud clearing theory, more accurate soundings of both surface skin and atmospheric temperatures can be obtained under partial cloud cover conditions if one uses observations in longwave channels to determine coefficients which generate cloud cleared radiances R(sup ^)(sub i) for all channels, and uses R(sup ^)(sub i) only from shortwave channels in the determination of surface and atmospheric temperatures. This procedure is now being used in the AIRS Version-6 Retrieval Algorithm. Results are presented for both daytime and nighttime conditions showing improved Version-6 surface and atmospheric soundings under partial cloud cover.

Potassium-based sorbents from fly ash for high-temperature CO2 capture.

PubMed

Sanna, Aimaro; Maroto-Valer, M Mercedes

2016-11-01

Potassium-fly ash (K-FA) sorbents were investigated for high-temperature CO 2 sorption. K-FAs were synthesised using coal fly ash as source of silica and aluminium. The synthesised materials were also mixed with Li 2 CO 3 and Ca(OH) 2 to evaluate their effect on CO 2 capture. Temperature strongly affected the performance of the K-FA sorbents, resulting in a CO 2 uptake of 1.45 mmol CO 2 /g sorbent for K-FA 1:1 at 700 °C. The CO 2 sorption was enhanced by the presence of Li 2 CO 3 (10 wt%), with the K-FA 1:1 capturing 2.38 mmol CO 2 /g sorbent at 700 °C in 5 min. This sorption was found to be similar to previously developed Li-Na-FA (2.54 mmol/g) and Li-FA (2.4 mmol/g) sorbents. The presence of 10 % Li 2 CO 3 also accelerated sorption and desorption. The results suggest that the increased uptake of CO 2 and faster reaction rates in presence of K-FA can be ascribed to the formation of K-Li eutectic phase, which favours the diffusion of potassium and CO 2 in the material matrix. The cyclic experiments showed that the K-FA materials maintained stable CO 2 uptake and reaction rates over 10 cycles.

Soybean leaf hydraulic conductance does not acclimate to growth at elevated [CO2] or temperature in growth chambers or in the field.

PubMed

Locke, Anna M; Sack, Lawren; Bernacchi, Carl J; Ort, Donald R

2013-09-01

Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status. Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming. In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility. Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change.

Soybean leaf hydraulic conductance does not acclimate to growth at elevated [CO2] or temperature in growth chambers or in the field

PubMed Central

Locke, Anna M.; Sack, Lawren; Bernacchi, Carl J.; Ort, Donald R.

2013-01-01

Background and Aims Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status. Methods Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming. Key results In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility. Conclusions Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change. PMID:23864003

Temperature dependence of differential conductance in Co-based Heusler alloy Co2TiSn and superconductor Pb junctions

NASA Astrophysics Data System (ADS)

Ooka, Ryutaro; Shigeta, Iduru; Umetsu, Rie Y.; Nomura, Akiko; Yubuta, Kunio; Yamauchi, Touru; Kanomata, Takeshi; Hiroi, Masahiko

2018-05-01

We investigated temperature dependence of differential conductance G (V) in planar junctions consisting of Co-based Heusler alloy Co2TiSn and superconductor Pb. Ferromagnetic Co2TiSn was predicted to be half-metal by first-principles band calculations. The spin polarization P of Co2TiSn was deduced to be 60.0% at 1.4 K by the Andreev reflection spectroscopy. The G (V) spectral shape was smeared gradually with increasing temperature and its structure was disappeared above the superconducting transition temperature Tc. Theoretical model analysis revealed that the superconducting energy gap Δ was 1.06 meV at 1.4 K and the Tc was 6.8 K , indicating that both values were suppressed from bulk values. However, the temperature dependent Δ (T) behavior was in good agreement with that of the Bardeen-Cooper-Schrieffer (BCS) theory. The experimental results exhibit that the superconductivity of Pb attached to half-metallic Co2TiSn was kept the conventional BCS mechanism characterized strong-coupling superconductors while its superconductivity was slightly suppressed by the superconducting proximity effect at the Co2TiSn/Pb interface.

The BErkeley Atmospheric CO2 Observation Network: field calibration and evaluation of low-cost air quality sensors

NASA Astrophysics Data System (ADS)

Kim, Jinsol; Shusterman, Alexis A.; Lieschke, Kaitlyn J.; Newman, Catherine; Cohen, Ronald C.

2018-04-01

The newest generation of air quality sensors is small, low cost, and easy to deploy. These sensors are an attractive option for developing dense observation networks in support of regulatory activities and scientific research. They are also of interest for use by individuals to characterize their home environment and for citizen science. However, these sensors are difficult to interpret. Although some have an approximately linear response to the target analyte, that response may vary with time, temperature, and/or humidity, and the cross-sensitivity to non-target analytes can be large enough to be confounding. Standard approaches to calibration that are sufficient to account for these variations require a quantity of equipment and labor that negates the attractiveness of the sensors' low cost. Here we describe a novel calibration strategy for a set of sensors, including CO, NO, NO2, and O3, that makes use of (1) multiple co-located sensors, (2) a priori knowledge about the chemistry of NO, NO2, and O3, (3) an estimate of mean emission factors for CO, and (4) the global background of CO. The strategy requires one or more well calibrated anchor points within the network domain, but it does not require direct calibration of any of the individual low-cost sensors. The procedure nonetheless accounts for temperature and drift, in both the sensitivity and zero offset. We demonstrate this calibration on a subset of the sensors comprising BEACO2N, a distributed network of approximately 50 sensor nodes, each measuring CO2, CO, NO, NO2, O3 and particulate matter at 10 s time resolution and approximately 2 km spacing within the San Francisco Bay Area.

Atmospheric CO2 Concentrations--The Canadian Background Air Pollution Monitoring Network (1993) (NDP-034)

DOE Data Explorer

Trivett, N. B. A. [Environment Canada, Atmospheric Environment Service, Downsview, Ontario, Canada; Hudec, V. C. [Environment Canada, Atmospheric Environment Service, Downsview, Ontario, Canada; Wong, C. S. [Marine Carbon Research Centre, Institute of Ocean Sciences, Sidney, British Columbia, Canada

1993-01-01

Flask air samples collected at roughly weekly intervals at three Canadian sites [Alert, Northwest Territories (July 1975 through July 1992); Sable Island, Nova Scotia (March 1975 through July 1992); and Cape St. James, British Columbia (May 1979 through July 1992)] were analyzed for CO2 concentration with the measurements directly traceable to the WMO primary CO2 standards. Each record includes the date, atmospheric CO2 concentration, and flask classification code. They provide an accurate record of CO2 concentration levels in Canada during the past two decades. Because these data are directly traceable to WMO standards, this record may be compared with records from other Background Air Pollution Monitoring Network (BAPMoN) stations. The data are in three files (one for each of the monitoring stations) ranging in size from 9.4 to 20.1 kB.

The mass and speed dependence of meteor air plasma temperatures

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

2004-01-01

The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

The mass and speed dependence of meteor air plasma temperatures.

PubMed

Jenniskens, Peter; Laux, Christophe O; Wilson, Michael A; Schaller, Emily L

2004-01-01

The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

Fuel consumption and CO2/pollutant emissions of mobile air conditioning at fleet level - new data and model comparison.

PubMed

Weilenmann, Martin F; Alvarez, Robert; Keller, Mario

2010-07-01

Mobile air conditioning (MAC) systems are the second-largest energy consumers in cars after driving itself. While different measurement series are available to illustrate their behavior in hot ambient conditions, little data are available for lower temperatures. There are also no data available on diesel vehicles, despite these being quite common in Europe (up to 70% of the fleet in some countries). In the present study, six representative modern diesel passenger cars were tested. In combination with data from previous measurements on gasoline cars, a new model was developed - EEMAC = Empa Emission model for Mobile Air Conditioning systems - to predict emissions from air conditioning. The measurements obtained show that A/C activity still occurs at temperatures below the desired interior temperature. The EEMAC model was applied to the average meteorological year of a central European region and compared with the US EPA MOBILE6 model. As temperatures in central Europe are often below 20 degrees C (the point below which the two models differ), the overall results differ clearly. The estimated average annual CO(2) output according to EEMAC is six times higher than that of MOBILE6. EEMAC also indicates that around two-thirds of the fuel used for air conditioning could be saved by switching the MAC system off below 18 degrees C.

Matrix isolation of fullerene-derived CO 2 at ambient temperature

NASA Astrophysics Data System (ADS)

Taylor, Roger; Pénicaud, Alain; Tower, Nicole J.

1998-10-01

Heating fullerene oxides, e.g. C 120O, C 70O, C 60O and C 60O 2, in a KBr matrix at 225°C under 0.2 mbar vacuum, produces a sharp IR band at 2330 cm -1 due to matrix-isolated CO 2. The band is also obtained by heating a KBr matrix of the insoluble deposits that fullerenes form on standing in air. The matrices are extremely stable and are unchanged even by prolonged heating at 225°C under vacuum. Heating a KBr matrix of the deposit from C 84 produces also a sharp stable band at 2035 cm -1 consistent with matrix-isolated C 3. Similar treatment of C 70F 38O produces matrices containing both CO 2 and CO, the latter being of lower stability.

CO.sub.2 separation from low-temperature flue gases

DOEpatents

Dilmore, Robert; Allen, Douglas; Soong, Yee; Hedges, Sheila

2010-11-30

Two methods are provide for the separation of carbon dioxide from the flue gases. The first method utilizes a phase-separating moiety dissolved in an aqueous solution of a basic moiety to capture carbon dioxide. The second method utilizes a phase-separating moiety as a suspended solid in an aqueous solution of a basic moiety to capture carbon dioxide. The first method takes advantage of the surface-independent nature of the CO.sub.2 absorption reactions in a homogeneous aqueous system. The second method also provides permanent sequestration of the carbon dioxide. Both methods incorporate the kinetic rate enhancements of amine-based scrubbing while eliminating the need to heat the entire amine solution (80% water) in order to regenerate and release CO.sub.2. Both methods also take advantage of the low-regeneration temperatures of CO.sub.2-bearing mineral systems such as Na.sub.2CO.sub.3/NaHCO.sub.3 and K.sub.2CO.sub.3/KHCO.sub.3.

Soil and water warming accelerates phenology and down-regulation of leaf photosynthesis of rice plants grown under free-air CO2 enrichment (FACE).

PubMed

Adachi, Minaco; Hasegawa, Toshihiro; Fukayama, Hiroshi; Tokida, Takeshi; Sakai, Hidemitsu; Matsunami, Toshinori; Nakamura, Hirofumi; Sameshima, Ryoji; Okada, Masumi

2014-02-01

To enable prediction of future rice production in a changing climate, we need to understand the interactive effects of temperature and elevated [CO2] (E[CO2]). We therefore examined if the effect of E[CO2] on the light-saturated leaf photosynthetic rate (Asat) was affected by soil and water temperature (NT, normal; ET, elevated) under open-field conditions at the rice free-air CO2 enrichment (FACE) facility in Shizukuishi, Japan, in 2007 and 2008. Season-long E[CO2] (+200 µmol mol(-1)) increased Asat by 26%, when averaged over two years, temperature regimes and growth stages. The effect of ET (+2°C) on Asat was not significant at active tillering and heading, but became negative and significant at mid-grain filling; Asat in E[CO2]-ET was higher than in ambient [CO2] (A[CO2])-NT by only 4%. Photosynthetic down-regulation at E[CO2] also became apparent at mid-grain filling; Asat compared at the same [CO2] in the leaf cuvette was significantly lower in plants grown in E[CO2] than in those grown in A[CO2]. The additive effects of E[CO2] and ET decreased Asat by 23% compared with that of A[CO2]-NT plants. Although total crop nitrogen (N) uptake was increased by ET, N allocation to the leaves and to Rubisco was reduced under ET and E[CO2] at mid-grain filling, which resulted in a significant decrease (32%) in the maximum rate of ribulose-1,5-bisphosphate carboxylation on a leaf area basis. Because the change in N allocation was associated with the accelerated phenology in E[CO2]-ET plants, we conclude that soil and water warming accelerates photosynthetic down-regulation at E[CO2].

Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H₂O, CO₂, CO, and temperature in combustion flows.

PubMed

Peng, Wen Yu; Goldenstein, Christopher S; Mitchell Spearrin, R; Jeffries, Jay B; Hanson, Ronald K

2016-11-20

The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H₂O, CO₂, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H₂O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO₂ and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H₂O, 0.6% CO₂, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

Coral Energy Reserves and Calcification in a High-CO2 World at Two Temperatures

PubMed Central

Schoepf, Verena; Grottoli, Andréa G.; Warner, Mark E.; Cai, Wei-Jun; Melman, Todd F.; Hoadley, Kenneth D.; Pettay, D. Tye; Hu, Xinping; Li, Qian; Xu, Hui; Wang, Yongchen; Matsui, Yohei; Baumann, Justin H.

2013-01-01

Rising atmospheric CO2 concentrations threaten coral reefs globally by causing ocean acidification (OA) and warming. Yet, the combined effects of elevated pCO2 and temperature on coral physiology and resilience remain poorly understood. While coral calcification and energy reserves are important health indicators, no studies to date have measured energy reserve pools (i.e., lipid, protein, and carbohydrate) together with calcification under OA conditions under different temperature scenarios. Four coral species, Acropora millepora, Montipora monasteriata, Pocillopora damicornis, Turbinaria reniformis, were reared under a total of six conditions for 3.5 weeks, representing three pCO2 levels (382, 607, 741 µatm), and two temperature regimes (26.5, 29.0°C) within each pCO2 level. After one month under experimental conditions, only A. millepora decreased calcification (−53%) in response to seawater pCO2 expected by the end of this century, whereas the other three species maintained calcification rates even when both pCO2 and temperature were elevated. Coral energy reserves showed mixed responses to elevated pCO2 and temperature, and were either unaffected or displayed nonlinear responses with both the lowest and highest concentrations often observed at the mid-pCO2 level of 607 µatm. Biweekly feeding may have helped corals maintain calcification rates and energy reserves under these conditions. Temperature often modulated the response of many aspects of coral physiology to OA, and both mitigated and worsened pCO2 effects. This demonstrates for the first time that coral energy reserves are generally not metabolized to sustain calcification under OA, which has important implications for coral health and bleaching resilience in a high-CO2 world. Overall, these findings suggest that some corals could be more resistant to simultaneously warming and acidifying oceans than previously expected. PMID:24146747

Improved Determination of Surface and Atmospheric Temperatures Using Only Shortwave AIRS Channels

NASA Technical Reports Server (NTRS)

Susskind,Joel

2009-01-01

AIRS was launched on EOS Aqua on May 4, 2002, together with AMSU-A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. AIRS is a grating spectrometer with a number of linear arrays of detectors with each detector sensitive to outgoing radiation in a characteristic frequency v(sub i) with a spectral band pass delta v(sub i) of roughly v(sub i) /1200. AIRS contains 2378 spectral channels covering portions of the spectral region 650 cm(exp -1) (15.38 gm) - 2665 cm(exp -1)' (3.752 micrometers). These spectral regions contain significant absorption features from two CO2 absorption bands, the 15 micrometer (longwave) CO2 band, and the 4.3 micrometer (shortwave) CO, absorption band. There are also two atmospheric window regions, the 12 micrometerm - 8 micrometer (longwave) window, and the 4.17 micrometer - 3.75 micrometer (shortwave) window. Historically, determination of surface and atmospheric temperatures from satellite observations was performed using primarily observations in the longwave window and CO2 absorption regions. One reason for this was concerns about the effects, during the day, of reflected sunlight and non-Local Thermodynamic Equilibrium (non-LTE) on the observed radiances in the shortwave portion of the spectrum. According to cloud clearing theory, more accurate soundings of both surface skin and atmospheric temperatures can be obtained under partial cloud cover conditions if one uses the longwave channels to determine cloud cleared radiances R(sub i) for all channels, and uses R(sub i) only from shortwave channels in the determination of surface and atmospheric temperatures. This procedure is now being used by the AIRS Science Team in preparation for the AIRS Version 6 Retrieval Algorithm. This paper describes how the effects on the radiances of solar radiation reflected by clouds and the Earth's surface, and also of non-LTE, are accounted for in the analysis of the data. Results are presented for both

Response of wheat growth, grain yield and water use to elevated CO2 under a Free-Air CO2 Enrichment (FACE) experiment and modelling in a semi-arid environment.

PubMed

O'Leary, Garry J; Christy, Brendan; Nuttall, James; Huth, Neil; Cammarano, Davide; Stöckle, Claudio; Basso, Bruno; Shcherbak, Iurii; Fitzgerald, Glenn; Luo, Qunying; Farre-Codina, Immaculada; Palta, Jairo; Asseng, Senthold

2014-12-05

The response of wheat crops to elevated CO 2 (eCO 2 ) was measured and modelled with the Australian Grains Free-Air CO 2 Enrichment experiment, located at Horsham, Australia. Treatments included CO 2 by water, N and temperature. The location represents a semi-arid environment with a seasonal VPD of around 0.5 kPa. Over 3 years, the observed mean biomass at anthesis and grain yield ranged from 4200 to 10 200 kg ha -1 and 1600 to 3900 kg ha -1 , respectively, over various sowing times and irrigation regimes. The mean observed response to daytime eCO 2 (from 365 to 550 μmol mol -1 CO 2 ) was relatively consistent for biomass at stem elongation and at anthesis and LAI at anthesis and grain yield with 21%, 23%, 21% and 26%, respectively. Seasonal water use was decreased from 320 to 301 mm (P = 0.10) by eCO 2 , increasing water use efficiency for biomass and yield, 36% and 31%, respectively. The performance of six models (APSIM-Wheat, APSIM-Nwheat, CAT-Wheat, CROPSYST, OLEARY-CONNOR and SALUS) in simulating crop responses to eCO 2 was similar and within or close to the experimental error for accumulated biomass, yield and water use response, despite some variations in early growth and LAI. The primary mechanism of biomass accumulation via radiation use efficiency (RUE) or transpiration efficiency (TE) was not critical to define the overall response to eCO 2 . However, under irrigation, the effect of late sowing on response to eCO 2 to biomass accumulation at DC65 was substantial in the observed data (~40%), but the simulated response was smaller, ranging from 17% to 28%. Simulated response from all six models under no water or nitrogen stress showed similar response to eCO 2 under irrigation, but the differences compared to the dryland treatment were small. Further experimental work on the interactive effects of eCO 2 , water and temperature is required to resolve these model discrepancies. © 2014 John Wiley & Sons Ltd.

[Responses of agricultural crops of free-air CO2 enrichment].

PubMed

Kimball, B A; Zhu, Jianguo; Cheng, Lei; Kobayashi, K; Bindi, M

2002-10-01

Over the past decade, free-air CO2 enrichment (FACE) experiments have been conducted on several agricultural crops: wheat(Triticum aestivum L.), perennial ryegrass (Lolium perenne), and rice(Oryza sativa L.) which are C3 grasses; sorghum (Sorghum bicolor (L.) Möench), a C4 grass; white clover (Trifolium repens), a C3 legume; potato (Solanum tuberosum L.), a C3 forb with tuber storage; and cotton (Gossypium hirsutum L.) and grape (Vitis vinifera L.) which are C3 woody perennials. Using reports from these experiments, the relative responses of these crops was discussed with regard to photosynthesis, stomatal conductance, canopy temperature, water use, water potential, leaf area index, shoot and root biomass accumulation, agricultural yield, radiation use efficiency, specific leaf area, tissue nitrogen concentration, nitrogen yield, carbohydrate concentration, phenology, soil microbiology, soil respiration, trace gas emissions, and soil carbon sequestration. Generally, the magnitude of these responses varied with the functional type of plant and with the soil nitrogen and water status. As expected, the elevated CO2 increased photosynthesis and biomass production and yield substantially in C3 species, but little in C4, and it decreased stomatal conductance and transpiration in both C3 and C4 species and greatly improved water-use efficiency in all the crops. Growth stimulations were as large or larger under water-stress compared to well-watered conditions. Growth stimulations of non-legumes were reduced at low soil nitrogen, whereas elevated CO2 strongly stimulated the growth of the clover legume both at ample and under low N conditions. Roots were generally stimulated more than shoots. Woody perennials had larger growth responses to elevated CO2, while at the same time, their reductions in stomatal conductance were smaller. Tissue nitrogen concentrations went down while carbohydrate and some other carbon-based compounds went up due to elevated CO2, with leaves and

Method of CO.sub.2 removal from a gasesous stream at reduced temperature

DOEpatents

Fisher, James C; Siriwardane, Ranjani V; Berry, David A; Richards, George A

2014-11-18

A method for the removal of H.sub.2O and CO.sub.2 from a gaseous stream comprising H.sub.2O and CO.sub.2, such as a flue gas. The method initially utilizes an H.sub.2O removal sorbent to remove some portion of the H.sub.2O, producing a dry gaseous stream and a wet H.sub.2O removal sorbent. The dry gaseous stream is subsequently contacted with a CO.sub.2 removal sorbent to remove some portion of the CO.sub.2, generating a dry CO.sub.2 reduced stream and a loaded CO.sub.2 removal sorbent. The loaded CO.sub.2 removal sorbent is subsequently heated to produce a heated CO.sub.2 stream. The wet H.sub.2O removal sorbent and the dry CO.sub.2 reduced stream are contacted in a first regeneration stage, generating a partially regenerated H.sub.2O removal sorbent, and the partially regenerated H.sub.2O removal sorbent and the heated CO.sub.2 stream are subsequently contacted in a second regeneration stage. The first and second stage regeneration typically act to retain an initial monolayer of moisture on the various removal sorbents and only remove moisture layers bound to the initial monolayer, allowing for relatively low temperature and pressure operation. Generally the applicable H.sub.2O sorption/desorption processes may be conducted at temperatures less than about 70.degree. C. and pressures less than 1.5 atmospheres, with certain operations conducted at temperatures less than about 50.degree. C.

CdO-based nanostructures as novel CO2 gas sensors

NASA Astrophysics Data System (ADS)

Krishnakumar, T.; Jayaprakash, R.; Prakash, T.; Sathyaraj, D.; Donato, N.; Licoccia, S.; Latino, M.; Stassi, A.; Neri, G.

2011-08-01

Crystalline Cd(OH)2/CdCO3 nanowires, having lengths in the range from 0.3 up to several microns and 5-30 nm in diameter, were synthesized by a microwave-assisted wet chemical route and used as a precursor to obtain CdO nanostructures after a suitable thermal treatment in air. The morphology and microstructure of the as-synthesized and annealed materials have been investigated by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and thermogravimetry-differential scanning calorimetry. The change in morphology and electrical properties with temperature has revealed a wire-to-rod transformation along with a decreases of electrical resistance. Annealed samples were printed on a ceramic substrate with interdigitated contacts to fabricate resistive solid state sensors. Gas sensing properties were explored by monitoring CO2 in synthetic air in the concentration range 0.2-5 v/v% (2000-50 000 ppm). The effect of annealing temperature, working temperature and CO2 concentration on sensing properties (sensitivity, response/recovery time and stability) were investigated. The results obtained demonstrate that CdO-based thick films have good potential as novel CO2 sensors for practical applications.

Surface Water pCO2 Variations and Sea-Air CO2 Fluxes During Summer in the Eastern Canadian Arctic

NASA Astrophysics Data System (ADS)

Burgers, T. M.; Miller, L. A.; Thomas, H.; Else, B. G. T.; Gosselin, M.; Papakyriakou, T.

2017-12-01

Based on a 2 year data set, the eastern Canadian Arctic Archipelago and Baffin Bay appear to be a modest summertime sink of atmospheric CO2. We measured surface water CO2 partial pressure (pCO2), salinity, and temperature throughout northern Baffin Bay, Nares Strait, and Lancaster Sound from the CCGS Amundsen during its 2013 and 2014 summer cruises. Surface water pCO2 displayed considerable variability (144-364 μatm) but never exceeded atmospheric concentrations, and average calculated CO2 fluxes in 2013 and 2014 were -12 and -3 mmol C m-2 d-1 (into the ocean), respectively. Ancillary measurements of chlorophyll a reveal low summertime productivity in surface waters. Based on total alkalinity and stable oxygen isotopes (δ18O) data, a strong riverine signal in northern Nares Strait coincided with relatively high surface pCO2, whereas areas of sea-ice melt occur with low surface pCO2. Further assessments, extending the seasonal observation period, are needed to properly constrain both seasonal and annual CO2 fluxes in this region.

Temperature characteristics and magnetization mechanism of Fe1.2Co films

NASA Astrophysics Data System (ADS)

Dong, Dashun; Fang, Qingqing; Wang, Wenwen; Yang, Jingjing

2017-11-01

Fe1.2Co films with various thicknesses were prepared on glass substrates by pulsed laser deposition (PLD). The Fe1.2Co crystal structure exhibited a preferred orientation in the <1 1 0> direction. Also, we found that changing the film thickness affected its magnetic properties and the formation of its reversed nucleus. By measuring magnetism-temperature (M-T) curves under applied field cooling (FC) and zero-field cooling (ZFC), we found that the mechanism of the formation and growth of the reversed nucleus played a main role in blocking the motion of domain walls: the mechanism was competition between a ferromagnetic phase (FM) and an anti-ferromagnetic phase (AFM) at 10-300 K. Moreover, we found that the reversed nucleus blocked the motion of magnetic domains more at 10 K than at 300 K. We suggest that the reversed nucleus affects the magnetism more at low temperatures, which causes the coercivity to be higher at low temperature than at room temperature. These results will help us to understand the magnetic properties and temperature characteristics of FeCo thin films.

Poly(ethylenimine)-Functionalized Monolithic Alumina Honeycomb Adsorbents for CO2 Capture from Air.

PubMed

Sakwa-Novak, Miles A; Yoo, Chun-Jae; Tan, Shuai; Rashidi, Fereshteh; Jones, Christopher W

2016-07-21

The development of practical and effective gas-solid contactors is an important area in the development of CO2 capture technologies. Target CO2 capture applications, such as postcombustion carbon capture and sequestration (CCS) from power plant flue gases or CO2 extraction directly from ambient air (DAC), require high flow rates of gas to be processed at low cost. Extruded monolithic honeycomb structures, such as those employed in the catalytic converters of automobiles, have excellent potential as structured contactors for CO2 adsorption applications because of the low pressure drop imposed on fluid moving through the straight channels of such structures. Here, we report the impregnation of poly(ethylenimine) (PEI), an effective aminopolymer reported commonly for CO2 separation, into extruded monolithic alumina to form structured CO2 sorbents. These structured sorbents are first prepared on a small scale, characterized thoroughly, and compared with powder sorbents with a similar composition. Despite consistent differences observed in the filling of mesopores with PEI between the monolithic and powder sorbents, their performance in CO2 adsorption is similar across a range of PEI contents. A larger monolithic cylinder (1 inch diameter, 4 inch length) is evaluated under conditions closer to those that might be used in large-scale applications and shows a similar performance to the smaller monoliths and powders tested initially. This larger structure is evaluated over five cycles of CO2 adsorption and steam desorption and demonstrates a volumetric capacity of 350 molCO2  m-3monolith and an equilibration time of 350 min under a 0.4 m s(-1) linear flow velocity through the monolith channels using 400 ppm CO2 in N2 as the adsorption gas at 30 °C. This volumetric capacity surpasses that of a similar technology considered previously, which suggested that CO2 could be removed from air at an operating cost as low as $100 per ton. © 2016 WILEY-VCH Verlag

FACE: Free-Air CO{sub 2} Enrichment for plant research in the field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendrey, G.R.

1992-08-01

Research programs concerning the effects of Carbon Dioxide(CO){sub 2} on cotton plants are described. Biological responses studied include foliage response to CO{sub 2} fluctuations; yield of cotton exposed to CO{sub 2} enrichment; responses of photosynthesis and stomatal conductance to elevated CO{sub 2} in field-grown cotton; cotton leaf and boll temperatures; root response to CO{sub 2} enrichment; and evaluations of cotton response to CO{sub 2} enrichment with canopy reflectance observations.

FACE: Free-Air CO[sub 2] Enrichment for plant research in the field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendrey, G.R.

1992-08-01

Research programs concerning the effects of Carbon Dioxide(CO)[sub 2] on cotton plants are described. Biological responses studied include foliage response to CO[sub 2] fluctuations; yield of cotton exposed to CO[sub 2] enrichment; responses of photosynthesis and stomatal conductance to elevated CO[sub 2] in field-grown cotton; cotton leaf and boll temperatures; root response to CO[sub 2] enrichment; and evaluations of cotton response to CO[sub 2] enrichment with canopy reflectance observations.

Nitrogen assimilation and transpiration: key processes conditioning responsiveness of wheat to elevated [CO2] and temperature.

PubMed

Jauregui, Iván; Aroca, Ricardo; Garnica, María; Zamarreño, Ángel M; García-Mina, José M; Serret, Maria D; Parry, Martin; Irigoyen, Juan J; Aranjuelo, Iker

2015-11-01

Although climate scenarios have predicted an increase in [CO(2)] and temperature conditions, to date few experiments have focused on the interaction of [CO(2)] and temperature effects in wheat development. Recent evidence suggests that photosynthetic acclimation is linked to the photorespiration and N assimilation inhibition of plants exposed to elevated CO(2). The main goal of this study was to analyze the effect of interacting [CO(2)] and temperature on leaf photorespiration, C/N metabolism and N transport in wheat plants exposed to elevated [CO(2)] and temperature conditions. For this purpose, wheat plants were exposed to elevated [CO(2)] (400 vs 700 µmol mol(-1)) and temperature (ambient vs ambient + 4°C) in CO(2) gradient greenhouses during the entire life cycle. Although at the agronomic level, elevated temperature had no effect on plant biomass, physiological analyses revealed that combined elevated [CO(2)] and temperature negatively affected photosynthetic performance. The limited energy levels resulting from the reduced respiratory and photorespiration rates of such plants were apparently inadequate to sustain nitrate reductase activity. Inhibited N assimilation was associated with a strong reduction in amino acid content, conditioned leaf soluble protein content and constrained leaf N status. Therefore, the plant response to elevated [CO(2)] and elevated temperature resulted in photosynthetic acclimation. The reduction in transpiration rates induced limitations in nutrient transport in leaves of plants exposed to elevated [CO(2)] and temperature, led to mineral depletion and therefore contributed to the inhibition of photosynthetic activity. © 2015 Scandinavian Plant Physiology Society.

CO2 concentration and temperature sensor for combustion gases using diode-laser absorption near 2.7 μm

NASA Astrophysics Data System (ADS)

Farooq, A.; Jeffries, J. B.; Hanson, R. K.

2008-03-01

A new tunable diode-laser sensor based on CO2 absorption near 2.7 μm is developed for high-resolution absorption measurements of CO2 concentration and temperature. The sensor probes the R(28) and P(70) transitions of the ν1+ν3 combination band of CO2 that has stronger absorption line-strengths than the bands near 1.5 μm and 2.0 μm used previously to sense CO2 in combustion gases. The increased absorption strength of transitions in this new wavelength range provides greatly enhanced sensitivity and the potential for accurate measurements in combustion gases with short optical path lengths. Simulated high-temperature spectra are surveyed to find candidate CO2 transitions isolated from water vapor interference. Measurements of line-strength, line position, and collisional broadening parameters are carried out for candidate CO2 transitions in a heated static cell as a function of temperature and compared to literature values. The accuracy of a fixed-wavelength CO2 absorption sensor is determined via measurement of known temperature and CO2 mole fraction in a static cell and shock-tube. Absorption measurements of CO2 are then made in a laboratory flat-flame burner and in ignition experiments of shock-heated n-heptane/O2/argon mixtures to illustrate the potential of this sensor for combustion and reacting-flow applications.

Constraining the subsoil carbon source to cave-air CO2 and speleothem calcite in central Texas

NASA Astrophysics Data System (ADS)

Bergel, Shelly J.; Carlson, Peter E.; Larson, Toti E.; Wood, Chris T.; Johnson, Kathleen R.; Banner, Jay L.; Breecker, Daniel O.

2017-11-01

Canonical models for speleothem formation and the subsurface carbon cycle invoke soil respiration as the dominant carbon source. However, evidence from some karst regions suggests that belowground CO2 originates from a deeper, older source. We therefore investigated the carbon sources to central Texas caves. Drip-water chemistry of two caves in central Texas implies equilibration with calcite at CO2 concentrations (PCO2_sat) higher than the maximum CO2 concentrations observed in overlying soils. This observation suggests that CO2 is added to waters after they percolate through the soils, which requires a subsoil carbon source. We directly evaluate the carbon isotope composition of the subsoil carbon source using δ13C measurements on cave-air CO2, which we independently demonstrate has little to no contribution from host rock carbon. We do so using the oxidative ratio, OR, defined as the number of moles of O2 consumed per mole of CO2 produced during respiration. However, additional belowground processes that affect O2 and CO2 concentrations, such as gas-water exchange and/or diffusion, may also influence the measured oxidative ratio, yielding an apparent OR (ORapparent). Cave air in Natural Bridge South Cavern has ORapparent values (1.09 ± 0.06) indistinguishable from those expected for respiration alone (1.08 ± 0.06). Pore space gases from soils above the cave have lower values (ORapparent = 0.67 ± 0.05) consistent with respiration and gas transport by diffusion. The simplest explanation for these observations is that cave air in NB South is influenced by respiration in open-system bedrock fractures such that neither diffusion nor exchange with water influence the composition of the cave air. The radiocarbon activities of NB South cave-air CO2 suggest the subsoil carbon source is hundreds of years old. The calculated δ13C values of the subsoil carbon source are consistent with tree-sourced carbon (perhaps decomposing root matter), the δ13C values of which

Photosynthesis of amphibious and obligately submerged plants in CO2-rich lowland streams.

PubMed

Sand-Jensen, Kaj; Frost-Christensen, Henning

1998-11-01

Small unshaded streams in lowland regions receive drainage water with high concentrations of free␣CO 2 , and they support an abundant growth of amphibious and obligately submerged plants. Our first objective was to measure the CO 2 regime during summer in a wide range of small alkaline Danish streams subject to wide variation in temperature, O 2 and CO 2 during the day. The second objective was to determine the effect of these variations on daily changes in light-saturated photosynthesis in water of a homophyllous and a heterophyllous amphibious species that only used CO 2 , and an obligately submerged species capable of using both HCO - 3 and CO 2 . We found that the median CO 2 concentrations of the streams were 11 and 6 times above air saturation in the morning and the afternoon, respectively, but stream sites with dense plant growth had CO 2 concentrations approaching air saturation in the afternoon. In contrast, outlets from lakes had low CO 2 concentrations close to, or below, air saturation. The amphibious species showed a reduction of photosynthesis in water from morning to afternoon along with the decline in CO 2 concentrations, while increasing temperature and O 2 had little effect on photosynthesis. Photosynthesis of the obligately submerged species varied little with the change of CO 2 because of HCO 3 - - use, and variations were mostly due to changes in O 2 concentration. Independent measurements showed that changes in temperature, O 2 and CO 2 could account for the daily variability of photosynthesis of all three species in water. The results imply that CO 2 supersaturation in small lowland streams is important for the rich representation of amphibious species and their contribution to system photosynthesis.

Impact of pressure and temperature on CO2-brine-mica contact angles and CO2-brine interfacial tension: Implications for carbon geo-sequestration.

PubMed

Arif, Muhammad; Al-Yaseri, Ahmed Z; Barifcani, Ahmed; Lebedev, Maxim; Iglauer, Stefan

2016-01-15

Precise characterization of wettability of CO2-brine-rock system and CO2-brine interfacial tension at reservoir conditions is essential as they influence capillary sealing efficiency of caprocks, which in turn, impacts the structural and residual trapping during CO2 geo-sequestration. In this context, we have experimentally measured advancing and receding contact angles for brine-CO2-mica system (surface roughness ∼12nm) at different pressures (0.1MPa, 5MPa, 7MPa, 10MPa, 15MPa, 20MPa), temperatures (308K, 323K, and 343K), and salinities (0wt%, 5wt%, 10wt%, 20wt% and 30wt% NaCl). For the same experimental matrix, CO2-brine interfacial tensions have also been measured using the pendant drop technique. The results indicate that both advancing and receding contact angles increase with pressure and salinity, but decrease with temperature. On the contrary, CO2-brine interfacial tension decrease with pressure and increase with temperature. At 20MPa and 308K, the advancing angle is measured to be ∼110°, indicating CO2-wetting. The results have been compared with various published literature data and probable factors responsible for deviations have been highlighted. Finally we demonstrate the implications of measured data by evaluating CO2 storage heights under various operating conditions. We conclude that for a given storage depth, reservoirs with lower pressures and high temperatures can store larger volumes and thus exhibit better sealing efficiency. Copyright © 2015 Elsevier Inc. All rights reserved.

Relative sensitivity of five Hawaiian coral species to high temperature under high-pCO2 conditions

NASA Astrophysics Data System (ADS)

Bahr, Keisha D.; Jokiel, Paul L.; Rodgers, Ku'ulei S.

2016-06-01

Coral reef ecosystems are presently undergoing decline due to anthropogenic climate change. The chief detrimental factors are increased temperature and increased pCO2. The purpose of this study was to evaluate the effect of these two stressors operating independently and in unison on the biological response of common Hawaiian reef corals. Manipulative experiments were performed using five species ( Porites compressa, Pocillopora damicornis, Fungia scutaria, Montipora capitata, and Leptastrea purpurea) in a continuous-flow mesocosm system under natural sunlight conditions. Corals were grown together as a community under treatments of high temperature (2 °C above normal maximum summer temperature), high pCO2 (twice present-day conditions), and with both factors acting in unison. Control corals were grown under present-day pCO2 and at normal summer temperatures. Leptastrea purpurea proved to be an extremely hardy coral. No change in calcification or mortality occurred under treatments of high temperature, high pCO2, or combined high temperature-high pCO2. The remaining four species showed reduced calcification in the high-temperature treatment. Two species ( L. purpurea and M. capitata) showed no response to increased pCO2. Also, high pCO2 ameliorated the negative effect of high temperature on the calcification rates of P. damicornis. Mortality was driven primarily by high temperature, with a negative synergistic effect in P. compressa only in the high-pCO2-high-temperature treatment. Results support the observation that biological response to temperature and pCO2 elevation is highly species-specific, so generalizations based on response of a single species might not apply to a diverse and complex coral reef community.

Temperature dependence of vibrational relaxation in the HF, DF, HF-CO2, and DF-CO2 systems

NASA Technical Reports Server (NTRS)

Lucht, R. A.; Cool, T. A.

1974-01-01

The laser excited fluorescence method has been employed to determine rate constants for V to V, R and V to R, T relaxation HF (nu = 1) and DF(nu = 1) by CO2 over the temperature range from 295 to 670 K. The self-deactivation rates for HF(nu = 1) and DF(nu = 1) by ground state molecules and the rate of V to V, R transfer from HF(nu = 1) and DF(nu = 1) to the CO2 (00/0/1) state exhibit a marked decrease with increasing temperature. The results provide additional evidence for the conversion of the large vibrational energy defects of the present systems into rotational motion of the hydrogen halide under the influence of a sizable attractive intermolecular potential well.

STRUCTURAL EFFECTS ON THE HIGH TEMPERATURE ADSORPTION OF CO2 ON A SYNTHETIC HYDROTALCITE

EPA Science Inventory

Hydrotalcite-like compounds (HTlcs) are solid sorbents that may potentially be used for high temperature separation and capture of CO₂. The high-temperature adsorption of CO₂ on Mg-Al-CO₃ HTlc is affected by structural changes that take place upo...

An air-liquid contactor for large-scale capture of CO2 from air.

PubMed

Holmes, Geoffrey; Keith, David W

2012-09-13

We present a conceptually simple method for optimizing the design of a gas-liquid contactor for capture of carbon dioxide from ambient air, or 'air capture'. We apply the method to a slab geometry contactor that uses components, design and fabrication methods derived from cooling towers. We use mass transfer data appropriate for capture using a strong NaOH solution, combined with engineering and cost data derived from engineering studies performed by Carbon Engineering Ltd, and find that the total costs for air contacting alone-no regeneration-can be of the order of $60 per tonne CO(2). We analyse the reasons why our cost estimate diverges from that of other recent reports and conclude that the divergence arises from fundamental design choices rather than from differences in costing methodology. Finally, we review the technology risks and conclude that they can be readily addressed by prototype testing.

A MIXED MODEL ANALYSIS OF SOIL CO2 EFFLUX AND NIGHT-TIME RESPIRATION RESPONSES TO ELEVATED CO2 AND TEMPERATURE

EPA Science Inventory

Abstract: We investigated the effects of elevated soil temperature and atmospheric CO2 on soil CO2 efflux and system respiration responses. The study was conducted in sun-lit controlled-environment chambers using two-year-old Douglas-fir seedlings grown in reconstructed litter-so...

Low-temperature CO oxidation over Cu/Pt co-doped ZrO2 nanoparticles synthesized by solution combustion.

PubMed

Singhania, Amit; Gupta, Shipra Mital

2017-01-01

Zirconia (ZrO 2 ) nanoparticles co-doped with Cu and Pt were applied as catalysts for carbon monoxide (CO) oxidation. These materials were prepared through solution combustion in order to obtain highly active and stable catalytic nanomaterials. This method allows Pt 2+ and Cu 2+ ions to dissolve into the ZrO 2 lattice and thus creates oxygen vacancies due to lattice distortion and charge imbalance. High-resolution transmission electron microscopy (HRTEM) results showed Cu/Pt co-doped ZrO 2 nanoparticles with a size of ca. 10 nm. X-ray diffraction (XRD) and Raman spectra confirmed cubic structure and larger oxygen vacancies. The nanoparticles showed excellent activity for CO oxidation. The temperature T 50 (the temperature at which 50% of CO are converted) was lowered by 175 °C in comparison to bare ZrO 2 . Further, they exhibited very high stability for CO reaction (time-on-stream ≈ 70 h). This is due to combined effect of smaller particle size, large oxygen vacancies, high specific surface area and better thermal stability of the Cu/Pt co-doped ZrO 2 nanoparticles. The apparent activation energy for CO oxidation is found to be 45.6 kJ·mol -1 . The CO conversion decreases with increase in gas hourly space velocity (GHSV) and initial CO concentration.

Co3O4 nanorod-supported Pt with enhanced performance for catalytic HCHO oxidation at room temperature

NASA Astrophysics Data System (ADS)

Yan, Zhaoxiong; Xu, Zhihua; Cheng, Bei; Jiang, Chuanjia

2017-05-01

Formaldehyde (HCHO) removal from air at room (ambient) temperature by effective catalysts is of significance for improving indoor air quality, and catalysts with high efficiency and good recyclability are highly desirable. In this study, platinum (Pt) supported on nanorod-shaped Co3O4 (Pt/Co3O4) was prepared by calcination of microwave-assisted synthesized Co3O4 precursor followed by NaBH4-reduction of Pt precursor. The as-prepared Co3O4 exhibited a morphology of nanorods with lengths of 400-700 nm and diameters of approximately 40-50 nm, which were self-assembled by nanoparticles. The Pt/Co3O4 catalyst exhibited a superior catalytic performance for HCHO oxidation at room temperature compared to Pt supported on commercial Co3O4 (Pt/Co3O4-c) and Pt supported on commercial TiO2 (Pt/TiO2), which is mainly due to the high oxygen mobility resulting from its distinct nanorod morphology, strong metal-support interaction between Pt and Co3O4, and the intrinsic redox nature of the Co3O4 support. This study provides new insights into the fabrication of high-performance catalysts for indoor air purification.

Room temperature spin valve effect in NiFe/WS2/Co junctions

PubMed Central

Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Siddique, Salma; Khan, Muhammad Farooq; Ramay, Shahid Mahmood

2016-01-01

The two-dimensional (2D) layered electronic materials of transition metal dichalcogenides (TMDCs) have been recently proposed as an emerging canddiate for spintronic applications. Here, we report the exfoliated single layer WS2-intelayer based spin valve effect in NiFe/WS2/Co junction from room temperature to 4.2 K. The ratio of relative magnetoresistance in spin valve effect increases from 0.18% at room temperature to 0.47% at 4.2 K. We observed that the junction resistance decreases monotonically as temperature is lowered. These results revealed that semiconducting WS2 thin film works as a metallic conducting interlayer between NiFe and Co electrodes. PMID:26868638

Comparison of Sea-Air CO2 Flux Estimates Using Satellite-Based Versus Mooring Wind Speed Data

NASA Astrophysics Data System (ADS)

Sutton, A. J.; Sabine, C. L.; Feely, R. A.; Wanninkhof, R. H.

2016-12-01

The global ocean is a major sink of anthropogenic CO2, absorbing approximately 27% of CO2 emissions since the beginning of the industrial revolution. Any variation or change in the ocean CO2 sink has implications for future climate. Observations of sea-air CO2 flux have relied primarily on ship-based underway measurements of partial pressure of CO2 (pCO2) combined with satellite, model, or multi-platform wind products. Direct measurements of ΔpCO2 (seawater - air pCO2) and wind speed from moored platforms now allow for high-resolution CO2 flux time series. Here we present a comparison of CO2 flux calculated from moored ΔpCO2 measured on four moorings in different biomes of the Pacific Ocean in combination with: 1) Cross-Calibrated Multi-Platform (CCMP) winds or 2) wind speed measurements made on ocean reference moorings excluded from the CCMP dataset. Preliminary results show using CCMP winds overestimates CO2 flux on average by 5% at the Kuroshio Extension Observatory, Ocean Station Papa, WHOI Hawaii Ocean Timeseries Station, and Stratus. In general, CO2 flux seasonality follows patterns of seawater pCO2 and SST with periods of CO2 outgassing during summer and CO2 uptake during winter at these locations. Any offsets or seasonal biases in CCMP winds could impact global ocean sink estimates using this data product. Here we present patterns and trends between the two CO2 flux estimates and discuss the potential implications for tracking variability and change in global ocean CO2 uptake.

Quantifying the impact of El Niño-driven variations in temperature and precipitation on regional atmospheric CO2 growth rate variations

NASA Astrophysics Data System (ADS)

Keppel-Aleks, G.; Butterfield, Z.; Doney, S. C.; Dlugokencky, E. J.; Miller, J.; Morton, D. C.

2017-12-01

Quantifying the climatic drivers of variations in atmospheric CO2 observations over a range of timescales is necessary to develop a mechanistic understanding of the global carbon cycle that will enable prediction of future changes. Here, we combine NOAA cooperative global air sampling network CO2 observations, remote sensing data, and a flux perturbation model to quantify the feedbacks between interannual variability in physical climate and the atmospheric CO2 growth rate. In particular, we focus on the differences between the 1997/1998 El Niño and the 2015/2016 El Niño during which atmospheric CO2 increased at an unprecedented rate. The flux perturbation model was trained on data from 1997 to 2012, and then used to predict regional atmospheric CO2 growth rate anomalies for the period from 2013 through 2016. Given gridded temperature anomalies from the Hadley Center's Climate Research Unit (CRU), precipitation anomalies from the Global Precipitation Climatology Project (GPCP), and fire emissions from the Global Fire Emissions Database (GFEDv4s), the model was able to the reproduce regional growth rate variations observed at marine boundary layer stations in the NOAA network, including the rapid CO2 growth rate in 2015/2016. The flux perturbation model output suggests that the carbon cycle responses differed for1997 and 2015 El Niño periods, with tropical precipitation anomalies causing a much larger net flux of CO2 to the atmosphere during the latter period, while direct fire emissions dominated the former. The flux perturbation model also suggests that high temperature stress in the Northern Hemisphere extratropics contributed almost one-third of the CO2 growth rate enhancement during the 2015 El Niño. We use satellite-based metrics for atmospheric column CO2, vegetation, and moisture to corroborate the regional El Niño impacts from the flux perturbation model. Finally, we discuss how these observational results and independent data on ocean air-sea flux

Single-coal-particle combustion in O{sub 2}/N{sub 2} and O{sub 2}/CO{sub 2} environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bejarano, Paula A.; Levendis, Yiannis A.

A fundamental investigation has been conducted on the combustion of single particles of a bituminous coal (45-53, 75-90, and 150-180 {mu}m), of a lignite coal (45-53 and 75-90 {mu}m), and of spherical and monodisperse synthetic chars (43 {mu}m) at increasing O{sub 2} mole fractions in either N{sub 2} or CO{sub 2} balance gases. The synthetic particles were used to facilitate the observation of combustion phenomena with minimum distractions from particle-to-particle variabilities. The laboratory setup consisted of a drop-tube furnace operated at temperatures of 1400 and 1600 K. A calibrated three-color pyrometer, interfaced with the furnace, recorded luminous particle temperature-time profiles.more » Experimental results revealed that coal particles burned at higher mean temperatures and shorter combustion times in O{sub 2}/N{sub 2} than in O{sub 2}/CO{sub 2} environments at analogous oxygen mole fractions. In the case of the bituminous coal used herein and for the experimental combustion conditions tested, measured volatile and char temperatures as in air (21% O{sub 2}) were attained with an oxygen content in the CO{sub 2} mixtures in the neighborhood of 30%. Bituminous coal volatile and char burnout times comparable to those in air (21% O{sub 2}) were attained with oxygen content in the CO{sub 2} mixtures in the range of 30-35%. In the case of the lignite coal burned, the corresponding differences in oxygen mole fractions, which result in similar particle temperatures and burnout times in the two different gas mixtures, were less pronounced. (author)« less

Interactive effects of CO2 enrichment and temperature on the growth of dioecious Hydrilla verticillata

USGS Publications Warehouse

Chen, De-Xing; Coughenour, M. B.; Eberts, Debra; Thullen, Joan S.

1994-01-01

Experiments of plant growth responses to different CO2 concentrations and temperatures were conducted in growth chambers to explore the interactive effects of atmospheric CO2 enrichment and temperature on the growth and dry matter allocation of dioecious Hydrilla [Hydrilla verticillata (L.f.) Royle]. Hydrilla plants were exposed to two atmospheric CO2 concentrations (350 and 700 ppm) and three temperatures (15, 25 and 32°C) under a 12-hr photoperiod for about 2 months. The plant growth analysis showed that elevated CO2 appeared to enhance the growth of Hydrilla, and that the percentage of the enhancement is strongly temperature-dependent. Maximum biomass production was achieved at 700 ppm CO2 and 32°C. At 15°C, the total dry matter production was increased about 27% by doubling CO2, due to a 26% enhancement of leaf biomass, a 34% enhancement of stem biomass and 16% enhancement of root biomass. At 25°C, the dry matter production was increased about 46% by doubling CO2, due to a 29% enhancement of leaf biomass, a 27% enhancement of stem biomass and 40% enhancement of root biomass. At 32°C, however, the percentage of the enhancement of total dry matter production by doubling CO2 was only about 7%. The dry matter allocation among different plant parts was influenced by temperature but not by elevated CO2 concentration.

Co-location of air capture, sub-ocean CO2 storage and energy production on the Kerguelen plateau

NASA Astrophysics Data System (ADS)

Goldberg, D.; Han, P.; Lackner, K.; Wang, T.

2011-12-01

How can carbon capture and storage activities be sustained from an energy perspective while keeping the entire activity out of sight and away from material risk and social refrain near populated areas? In light of reducing the atmospheric CO2 level to mitigate its effect on climate change, the combination of new air-capture technologies and large offshore storage reservoirs, supplemented by carbon neutral renewable energy, could address both of these engineering and public policy concerns. Because CO2 mixes rapidly in the atmosphere, air capture scrubbers could be located anywhere in the world. Although the power requirements for this technology may reduce net efficiencies, the local availability of carbon-neutral renewable energy for this purpose would eliminate some net energy loss. Certain locations where wind speeds are high and steady, such as those observed at high latitude and across the open ocean, appeal as carbon-neutral energy sources in close proximity to immense and secure reservoirs for geological sequestration of captured CO2. In particular, sub-ocean basalt flows are vast and carry minimal risks of leakage and damages compared to on-land sites. Such implementation of a localized renewable energy source coupled with carbon capture and storage infrastructure could result in a global impact of lowered CO2 levels. We consider an extreme location on the Kerguelen plateau in the southern Indian Ocean, where high wind speeds and basalt storage reservoirs are both plentiful. Though endowed with these advantages, this mid-ocean location incurs clear material and economic challenges due to its remoteness and technological challenges for CO2 capture due to constant high humidity. We study the wind energy-air capture power balance and consider related factors in the feasibility of this location for carbon capture and storage. Other remote oceanic sites where steady winds blow and near large geological reservoirs may be viable as well, although all would require

CO and NO2 Selective Monitoring by ZnO-Based Sensors

PubMed Central

Hjiri, Mokhtar; El Mir, Lassaad; Leonardi, Salvatore Gianluca; Donato, Nicola; Neri, Giovanni

2013-01-01

ZnO nanomaterials with different shapes were synthesized, characterized and tested in the selective monitoring of low concentration of CO and NO2 in air. ZnO nanoparticles (NPs) and nanofibers (NFs) were synthesized by a modified sol-gel method in supercritical conditions and electrospinning technique, respectively. CO and NO2 sensing tests have demonstrated that the annealing temperature and shape of zinc oxide nanomaterials are the key factors in modulating the electrical and sensing properties. Specifically, ZnO NPs annealed at high temperature (700 °C) have been found sensitive to CO, while they displayed negligible response to NO2. The opposite behavior has been registered for the one-dimensional ZnO NFs annealed at medium temperature (400 °C). Due to their adaptable sensitivity/selectivity characteristics, the developed sensors show promising applications in dual air quality control systems for closed ambient such as automotive cabin, parking garage and tunnels. PMID:28348340

Development of a Prototype Algal Reactor for Removing CO2 from Cabin Air

NASA Technical Reports Server (NTRS)

Patel, Vrajen; Monje, Oscar

2013-01-01

Controlling carbon dioxide in spacecraft cabin air may be accomplished using algal photobioreactors (PBRs). The purpose of this project was to evaluate the use of a commercial microcontroller, the Arduino Mega 2560, for measuring key photioreactor variables: dissolved oxygen, pH, temperature, light, and carbon dioxide. The Arduino platform is an opensource physical computing platform composed of a compact microcontroller board and a C++/C computer language (Arduino 1.0.5). The functionality of the Arduino platform can be expanded by the use of numerous add-ons or 'shields'. The Arduino Mega 2560 was equipped with the following shields: datalogger, BNC shield for reading pH sensor, a Mega Moto shield for controlling CO2 addition, as well as multiple sensors. The dissolved oxygen (DO) probe was calibrated using a nitrogen bubbling technique and the pH probe was calibrated via an Omega pH simulator. The PBR was constructed using a 2 L beaker, a 66 L box for addition of CO2, a micro porous membrane, a diaphragm pump, four 25 watt light bulbs, a MasterFiex speed controller, and a fan. The algae (wild type Synechocystis PCC6803) was grown in an aerated flask until the algae was dense enough to used in the main reactor. After the algae was grown, it was transferred to the 2 L beaker where CO2 consumption and O2 production was measured using the microcontroller sensor suite. The data was recorded via the datalogger and transferred to a computer for analysis.

Modeling of Single and Dual Reservoir Porous Media Compressed Gas (Air and CO2) Storage Systems

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Liu, H.; Borgia, A.; Pan, L.

2017-12-01

Intermittent renewable energy sources are causing increasing demand for energy storage. The deep subsurface offers promising opportunities for energy storage because it can safely contain high-pressure gases. Porous media compressed air energy storage (PM-CAES) is one approach, although the only facilities in operation are in caverns (C-CAES) rather than porous media. Just like in C-CAES, PM-CAES operates generally by injecting working gas (air) through well(s) into the reservoir compressing the cushion gas (existing air in the reservoir). During energy recovery, high-pressure air from the reservoir is mixed with fuel in a combustion turbine to produce electricity, thereby reducing compression costs. Unlike in C-CAES, the storage of energy in PM-CAES occurs variably across pressure gradients in the formation, while the solid grains of the matrix can release/store heat. Because air is the working gas, PM-CAES has fairly low thermal efficiency and low energy storage density. To improve the energy storage density, we have conceived and modeled a closed-loop two-reservoir compressed CO2 energy storage system. One reservoir is the low-pressure reservoir, and the other is the high-pressure reservoir. CO2 is cycled back and forth between reservoirs depending on whether energy needs to be stored or recovered. We have carried out thermodynamic and parametric analyses of the performance of an idealized two-reservoir CO2 energy storage system under supercritical and transcritical conditions for CO2 using a steady-state model. Results show that the transcritical compressed CO2 energy storage system has higher round-trip efficiency and exergy efficiency, and larger energy storage density than the supercritical compressed CO2 energy storage. However, the configuration of supercritical compressed CO2 energy storage is simpler, and the energy storage densities of the two systems are both higher than that of PM-CAES, which is advantageous in terms of storage volume for a given

EFFECTS OF ELEVATED CO2 AND TEMPERATURE ON GROWTH, BIOCHEMISTRY AND PHYSIOLOGY OF DOUGLAS-FIR

EPA Science Inventory

We examined the interactive effects of CO2 concentration and mean annual temperature on physiology, biochemistry and growth of Douglas fir seedlings. Seedlings were grown at ambient CO2 or ambient + 200 ppm CO2 and at ambient temperature or ambient + 4 ?C. Needle gas exchange m...

LASER ABSORPTION SPECTROSCOPY METHODS FOR SUBSURFACE MONITORING OF CO2 IN WATER AND AIR PHASES AT SEQUESTRATION SITES

NASA Astrophysics Data System (ADS)

Wu, S.; Romanak, K.; Yang, C.

2009-12-01

We report the development of two methods for subsurface monitoring of CO2 in both air and water phases at sequestration sites. The first method is based on line-of-sight (LOS) tunable laser spectroscopy. Funded by DOE, we demonstrated the Phase Insensitive Two Tone Frquency Modulation spectroscopy (PITTFM). FM reduces low frequency noise in the beam path due to scintillations; while the PI design gives the ease of installation. We demonstrated measurement over 1 mile distance with an accuracy of 3ppm of CO2 in normal air. Built-in switches shoot the laser beam into multi-directions, thus forming a cellular monitoring network covering 10 km^2. The system cost is under $100K, and COTS telecom components guarantee the reliability in the field over decades. Software will log the data and translate the 2D CO2 profile. When coupled with other parameters, it will be able to locate the point and rate of leakages. Field tests at SECARB sequestration site are proposed. The system also monitors other green house gases (GHG), e.g. CH4, which is also needed where EOR is pursued along with CO2 sequestration. Figures 1 through 2 give the results of this method. The second method is based on the latest technology advances in quantum cascade lasers (QCLs). The current state of the art technology to measure Total/Dissolved Inorganic Carbon (TIC/DIC) in water is menometer. Menometer is both time consuming and costly, and could not be used underground, i.e. high pressure and temperature. We propose to use high brightness QC lasers to extend the current Mid-IR optical path from 30 microns to over 500microns, thus providing the possibility to measure CO2 dissoveled (Aqueous phase) with an accuracy of 0.2mg/Liter. Preliminary results will be presented.

Air quality co-benefits of carbon pricing in China

NASA Astrophysics Data System (ADS)

Li, Mingwei; Zhang, Da; Li, Chiao-Ting; Mulvaney, Kathleen M.; Selin, Noelle E.; Karplus, Valerie J.

2018-05-01

Climate policies targeting energy-related CO2 emissions, which act on a global scale over long time horizons, can result in localized, near-term reductions in both air pollution and adverse human health impacts. Focusing on China, the largest energy-using and CO2-emitting nation, we develop a cross-scale modelling approach to quantify these air quality co-benefits, and compare them to the economic costs of climate policy. We simulate the effects of an illustrative climate policy, a price on CO2 emissions. In a policy scenario consistent with China's recent pledge to reach a peak in CO2 emissions by 2030, we project that national health co-benefits from improved air quality would partially or fully offset policy costs depending on chosen health valuation. Net health co-benefits are found to rise with increasing policy stringency.

Increasing canopy photosynthesis in rice can be achieved without a large increase in water use-A model based on free-air CO2 enrichment.

PubMed

Ikawa, Hiroki; Chen, Charles P; Sikma, Martin; Yoshimoto, Mayumi; Sakai, Hidemitsu; Tokida, Takeshi; Usui, Yasuhiro; Nakamura, Hirofumi; Ono, Keisuke; Maruyama, Atsushi; Watanabe, Tsutomu; Kuwagata, Tsuneo; Hasegawa, Toshihiro

2018-03-01

Achieving higher canopy photosynthesis rates is one of the keys to increasing future crop production; however, this typically requires additional water inputs because of increased water loss through the stomata. Lowland rice canopies presently consume a large amount of water, and any further increase in water usage may significantly impact local water resources. This situation is further complicated by changing the environmental conditions such as rising atmospheric CO 2 concentration ([CO 2 ]). Here, we modeled and compared evapotranspiration of fully developed rice canopies of a high-yielding rice cultivar (Oryza sativa L. cv. Takanari) with a common cultivar (cv. Koshihikari) under ambient and elevated [CO 2 ] (A-CO 2 and E-CO 2 , respectively) via leaf ecophysiological parameters derived from a free-air CO 2 enrichment (FACE) experiment. Takanari had 4%-5% higher evapotranspiration than Koshihikari under both A-CO 2 and E-CO 2 , and E-CO 2 decreased evapotranspiration of both varieties by 4%-6%. Therefore, if Takanari was cultivated under future [CO 2 ] conditions, the cost for water could be maintained at the same level as for cultivating Koshihikari at current [CO 2 ] with an increase in canopy photosynthesis by 36%. Sensitivity analyses determined that stomatal conductance was a significant physiological factor responsible for the greater canopy photosynthesis in Takanari over Koshihikari. Takanari had 30%-40% higher stomatal conductance than Koshihikari; however, the presence of high aerodynamic resistance in the natural field and lower canopy temperature of Takanari than Koshihikari resulted in the small difference in evapotranspiration. Despite the small difference in evapotranspiration between varieties, the model simulations showed that Takanari clearly decreased canopy and air temperatures within the planetary boundary layer compared to Koshihikari. Our results indicate that lowland rice varieties characterized by high-stomatal conductance can play a

Incidence of Temperature Inversion and their Impact on Air Quality: A Case Study of Delhi

NASA Astrophysics Data System (ADS)

Singh, V. P.

2016-12-01

In troposphere, an increase in temperature with the altitude produces stable atmosphere which prohibits the air pollutants dispersion. This study investigates the phenomenon of temperature inversion (TI), Lapse rate (LR) and its effects on air quality in respect of Ozone (O3), CO2, CO & PM2.5 over a megacity- Delhi (Study Time Period: 2006-2012). Because of huge population, urban sprawl and orographic location, this study can be very helpful for Delhi and cities like Delhi. Radiosonde observations for temperature was used for TI calculations over the region. Results indicate that TI generally occurs at 975-850 hPa. Also, the maximum number of inversions occur during winter months (December and January) especially at night time and early mornings. Furthermore, during winter months, the incidence of inversion is highest at both 00UTC and 12UTC while it is least during the monsoon months (July and August) at 00UTC. The LR is maximum in terms of magnitude (i.e. highly negative) during the summer months (May & June) every year indicating the strong heating effects that takes place during the day time in summer and also because the sensible heat flux from the surface to the atmosphere is significant even at 12UTC (i.e. around 5.30 P.M.) The bivariate correlation analysis for air quality variables reveals negative relationship of all air quality variables except O3 with rainfall. A positive relationship of LR with all air quality variables, except O3, was observed indicating the increase in pollutants' concentrations with an increase in LR. The correlation coefficient between LR and air pollutants CO, NO, NO2, PM2.5 were found to be 0.463, 0.346, 0.249 and 0.673 respectively. A negative correlation was found between wind speed and most of the air pollutants. Also, significantly, O3 had been the only air pollutant having a negative relationship with LR (both at 00UTC &12UTC).

Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

PubMed Central

Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio

2016-01-01

The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333

Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

NASA Astrophysics Data System (ADS)

Li, Bing; Ge, Xiaoming; Goh, F. W. Thomas; Hor, T. S. Andy; Geng, Dongsheng; Du, Guojun; Liu, Zhaolin; Zhang, Jie; Liu, Xiaogang; Zong, Yun

2015-01-01

An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm-2) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization

Process for CO.sub.2 capture using zeolites from high pressure and moderate temperature gas streams

DOEpatents

Siriwardane, Ranjani V [Morgantown, WV; Stevens, Robert W [Morgantown, WV

2012-03-06

A method for separating CO.sub.2 from a gas stream comprised of CO.sub.2 and other gaseous constituents using a zeolite sorbent in a swing-adsorption process, producing a high temperature CO.sub.2 stream at a higher CO.sub.2 pressure than the input gas stream. The method utilizes CO.sub.2 desorption in a CO.sub.2 atmosphere and effectively integrates heat transfers for optimizes overall efficiency. H.sub.2O adsorption does not preclude effective operation of the sorbent. The cycle may be incorporated in an IGCC for efficient pre-combustion CO.sub.2 capture. A particular application operates on shifted syngas at a temperature exceeding 200.degree. C. and produces a dry CO.sub.2 stream at low temperature and high CO.sub.2 pressure, greatly reducing any compression energy requirements which may be subsequently required.

Relationships between the Efficiencies of Photosystems I and II and Stromal Redox State in CO2-Free Air 1

PubMed Central

Harbinson, Jeremy; Foyer, Christine H.

1991-01-01

The responses of the efficiencies of photosystems I and II, stromal redox state (as indicated by NADP-malate dehydrogenase activation state), and activation of the Benson-Calvin cycle enzymes ribulose 1,5-bisphosphate carboxylase and fructose 1,6-bisphosphatase to varying irradiance were measured in pea (Pisum sativum L.) leaves operating close to the CO2 compensation point. A comparison of the relationships among these parameters obtained from leaves in air was made with those obtained when the leaves were maintained in air from which the CO2 had been removed. P700 was more oxidized at any measured irradiance in CO2-free air than in air. The relationship between the quantum efficiencies of the photosystems in CO2-free air was distinctly curvilinear in contrast to the predominantly linear relationship obtained with leaves in air. This nonlinearity may be consistent with the operation of cyclic electron flow around photosystem I because the quantum efficiency of photosystem II was much more restricted than the quantum efficiency of photosystem I. In CO2-free air, measured NADP-malate dehydrogenase activities varied considerably at low irradiances. However, at high irradiance the activity of the enzyme was low, implying that the stroma was oxidized. In contrast, fructose-1,6-bisphosphatase activities tended to increase with increasing electron flux through the photosystems. Ribulose-1,5-bisphosphate carboxylase activity remained relatively constant with respect to irradiance in CO2-free air, with an activation state 50% of maximum. We conclude that, at the CO2 compensation point and high irradiance, low redox states are favored and that cyclic electron flow may be substantial. These two features may be the requirements necessary to trigger and maintain the dissipative processes in the thylakoid membrane. PMID:16668401

Kinetics of CO(2) fluxes outgassing from champagne glasses in tasting conditions: the role of temperature.

PubMed

Liger-Belair, Gérard; Villaume, Sandra; Cilindre, Clara; Jeandet, Philippe

2009-03-11

Measurements of CO(2) fluxes outgassing from a flute poured with a standard Champagne wine initially holding about 11 g L(-1) of dissolved CO(2) were presented, in tasting conditions, all along the first 10 min following the pouring process. Experiments were performed at three sets of temperature, namely, 4 degrees C, 12 degrees C, and 20 degrees C, respectively. It was demonstrated that the lower the champagne temperature, the lower CO(2) volume fluxes outgassing from the flute. Therefore, the lower the champagne temperature, the lower its progressive loss of dissolved CO(2) concentration with time, which constitutes the first analytical proof that low champagne temperatures prolong the drink's chill and helps retains its effervescence. A correlation was also proposed between CO(2) volume fluxes outgassing from the flute poured with champagne and its continuously decreasing dissolved CO(2) concentration. Finally, the contribution of effervescence to the global kinetics of CO(2) release was discussed and modeled by the use of results developed over recent years. The temperature dependence of the champagne viscosity was found to play a major role in the kinetics of CO(2) outgassing from a flute. On the basis of this bubbling model, the theoretical influence of champagne temperature on CO(2) volume fluxes outgassing from a flute was discussed and found to be in quite good accordance with our experimental results.

Comparison of CO2 in air versus carbogen for the measurement of cerebrovascular reactivity with magnetic resonance imaging.

PubMed

Hare, Hannah V; Germuska, Michael; Kelly, Michael E; Bulte, Daniel P

2013-11-01

Measurement of cerebrovascular reactivity (CVR) can give valuable information about existing pathology and the risk of adverse events, such as stroke. A common method of obtaining regional CVR values is by measuring the blood flow response to carbon dioxide (CO2)-enriched air using arterial spin labeling (ASL) or blood oxygen level-dependent (BOLD) imaging. Recently, several studies have used carbogen gas (containing only CO2 and oxygen) as an alternative stimulus. A direct comparison was performed between CVR values acquired by ASL and BOLD imaging using stimuli of (1) 5% CO2 in air and (2) 5% CO2 in oxygen (carbogen-5). Although BOLD and ASL CVR values are shown to be correlated for CO2 in air (mean response 0.11±0.03% BOLD, 4.46±1.80% ASL, n=16 hemispheres), this correlation disappears during a carbogen stimulus (0.36±0.06% BOLD, 4.97±1.30% ASL). It is concluded that BOLD imaging should generally not be used in conjunction with a carbogen stimulus when measuring CVR, and that care must be taken when interpreting CVR as measured by ASL, as values obtained from different stimuli (CO2 in air versus carbogen) are not directly comparable.

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine.

PubMed

Chang, Christine Y; Fréchette, Emmanuelle; Unda, Faride; Mansfield, Shawn D; Ensminger, Ingo

2016-10-01

Rising global temperature and CO 2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO 2 , affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L -1 ) or elevated (800 μmol mol -1 ) CO 2 , and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO 2 (LTAC), elevated temperature/ambient CO 2 (ETAC), or elevated temperature/elevated CO 2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus Our findings suggest that exposure to elevated temperature and CO 2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO 2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low-temperature

Does the growth response of woody plants to elevated CO2 increase with temperature? A model-oriented meta-analysis.

PubMed

Baig, Sofia; Medlyn, Belinda E; Mercado, Lina M; Zaehle, Sönke

2015-12-01

The temperature dependence of the reaction kinetics of the Rubisco enzyme implies that, at the level of a chloroplast, the response of photosynthesis to rising atmospheric CO2 concentration (Ca ) will increase with increasing air temperature. Vegetation models incorporating this interaction predict that the response of net primary productivity (NPP) to elevated CO2 (eCa ) will increase with rising temperature and will be substantially larger in warm tropical forests than in cold boreal forests. We tested these model predictions against evidence from eCa experiments by carrying out two meta-analyses. Firstly, we tested for an interaction effect on growth responses in factorial eCa  × temperature experiments. This analysis showed a positive, but nonsignificant interaction effect (95% CI for above-ground biomass response = -0.8, 18.0%) between eCa and temperature. Secondly, we tested field-based eCa experiments on woody plants across the globe for a relationship between the eCa effect on plant biomass and mean annual temperature (MAT). This second analysis showed a positive but nonsignificant correlation between the eCa response and MAT. The magnitude of the interactions between CO2 and temperature found in both meta-analyses were consistent with model predictions, even though both analyses gave nonsignificant results. Thus, we conclude that it is not possible to distinguish between the competing hypotheses of no interaction vs. an interaction based on Rubisco kinetics from the available experimental database. Experiments in a wider range of temperature zones are required. Until such experimental data are available, model predictions should aim to incorporate uncertainty about this interaction. © 2015 John Wiley & Sons Ltd.