Spectroscopic determination of co sub 2 concentration in situ.
IR spectral transmittance of combustion gases and carbon dioxide concentration in situ
MOLECULAR SPECTROSCOPY↗
SEARCH · Engineering Papers
Results for “concentric carbon”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Technology advancement of the electrochemical CO2 concentrating process
Two multicell, liquid-cooled, advanced electrochemical depolarized carbon dioxide concentrator modules were fabricated. The cells utilized advanced, lightweight, plated anode current collectors, internal liquid cooling and lightweight cell frames. Both were designed to meet the carbon dioxide removal requirements of one-person, i.e., 1.0 kg/d (2.2 lb/d).
Schubert, F. H.↗
Enhanced ordering in length-polydisperse carbon nanotube solutions at high concentrations as revealed by small angle X-ray scattering
Carbon nanotubes (CNTs) are stiff, all-carbon macromolecules with diameters as small as one nanometer and few microns long. Solutions of CNTs in chlorosulfonic acid (CSA) follow the phase behavior of rigid rod polymers interacting via a repulsive potential and display a liquid crystalline phase at sufficiently high concentration. Here, we show that small-angle X-ray scattering and polarized light microscopy data can be combined to characterize quantitatively the morphology of liquid crystalline phases formed in CNT solutions at concentrations from 3 to 6.5% by volume. We find that upon increasing their concentration, CNTs self-assemble into a liquid crystalline phase with a pleated texture and with a large inter-particle spacing that could be indicative of a transition to higher-order liquid crystalline phases. We explain how thermal undulations of CNTs can enhance their electrostatic repulsion and increase their effective diameter by an order of magnitude. By calculating the critical concentration, where the mean amplitude of undulation of an unconstrained rod becomes comparable to the rod spacing, we find that thermal undulations start to affect steric forces at concentrations as low as the isotropic cloud point in CNT solutions.
36 MATERIALS SCIENCE↗
BTRIC Technical Support for Appalachia: FY 2023 Summary Report on Net Negative Carbon Building Demonstration with AgPod
This study investigates the effects of various concentrations of carbon dioxide (CO 2 ) on the photosynthesis and biomass accumulation of crops growing in an Agricultural Pod (AgPod). The initial test crop was kale. It has been found that increasing the CO 2 concentration in the AgPod promotes higher photosynthetic rates in kale plants up to 1300 ppm (highest CO 2 concentration). An interesting finding was that net photosynthetic rates of kale leaves remain unsaturated until unusually high levels of photosynthetically active radiation (PAR, > 1200 µmolm-2s-1) and CO 2 concentration (> 1100 ppm) are reached. Such high levels of saturating PAR and CO 2 concentration values rarely occur under natural conditions, suggesting a promising potential for carbon capture via enriched greenhouse crop production. This task is one part of an overall plan to incorporate an AgPod to utilize carbon captured from the atmosphere to achieve net negative carbon emissions in a small neighborhood or community.
54 ENVIRONMENTAL SCIENCES↗
Adaptation of SUBSTOR for controlled-environment potato production with elevated carbon dioxide
The SUBSTOR crop growth model was adapted for controlled-environment hydroponic production of potato (Solanum tuberosum L. cv. Norland) under elevated atmospheric carbon dioxide concentration. Adaptations included adjustment of input files to account for cultural differences between the field and controlled environments, calibration of genetic coefficients, and adjustment of crop parameters including radiation use efficiency. Source code modifications were also performed to account for the absorption of light reflected from the surface below the crop canopy, an increased leaf senescence rate, a carbon (mass) balance to the model, and to modify the response of crop growth rate to elevated atmospheric carbon dioxide concentration. Adaptations were primarily based on growth and phenological data obtained from growth chamber experiments at Rutgers University (New Brunswick, N.J.) and from the modeling literature. Modified-SUBSTOR predictions were compared with data from Kennedy Space Center's Biomass Production Chamber for verification. Results show that, with further development, modified-SUBSTOR will be a useful tool for analysis and optimization of potato growth in controlled environments.
NASA Discipline Life Support Systems↗
B33C-0612: Evaluation of Simulated Biospheric Carbon Dioxide Fluxes and Atmospheric Concentrations Using Global in Situ Observations
Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emission sources and biospheric sources/sinks. Global biospheric fluxes of CO2 are controlled by complex processes facilitating the exchange of carbon between terrestrial ecosystems and the atmosphere. These processes which play a key role in these terrestrial ecosystem-atmosphere carbon exchanges are currently not fully understood, resulting in large uncertainties in the quantification of biospheric CO2 fluxes. Current models with these inherent deficiencies have difficulties simulating the global carbon cycle with high accuracy. We are developing a new modeling platform, GEOS-Chem-CASA by integrating the year-specific NASA-CASA (National Aeronautics and Space Administration - Carnegie Ames Stanford Approach) biosphere model with the GEOS-Chem (Goddard Earth Observation System-Chemistry) chemical transport model to improve the simulation of atmosphere-terrestrial ecosystem carbon exchange. We use NASA-CASA to explicitly represent the exchange of CO2 between terrestrial ecosystem and atmosphere by replacing the baseline GEOS-Chem land net CO2 flux and forest biomass burning CO2 emissions. We will present the estimation and evaluation of these "bottom-up" land CO2 fluxes, simulated atmospheric mixing ratios, and forest disturbance changes over the last decade. In addition, we will present our initial comparison of atmospheric column-mean dry air mole fraction of CO2 predicted by the model and those retrieved from NASA's OCO-2 (Orbiting Carbon Observatory-2) satellite instrument and model-predicted surface CO2 mixing ratios with global in situ observations. This evaluation is the first step necessary for our future work planned to constrain the estimates of biospheric carbon fluxes through "top-down" inverse modeling, which will improve our understanding of the processes controlling atmosphere-terrestrial ecosystem greenhouse gas exchanges, especially over regions which lack in situ observations.
in situ observations↗
Mid-Latitude Freshwater Availability Reduced by Projected Vegetation Responses to Climate Change
Plants are expected to generate more global-scale runoff under increasing atmospheric carbon dioxide concentrations through their influence on surface resistance to evapotranspiration. Recent studies using Earth System Models from phase 5 of the Coupled Model Intercomparison Project ostensibly reaffirm this result, further suggesting that plants will ameliorate the dire reductions in water availability projected by other studies that use aridity metrics. Here we complicate this narrative by analysing the change in precipitation partitioning to plants, runoff and storage in multiple Earth system models under both high carbon dioxide concentrations and warming. We show that projected plant responses directly reduce future runoff across vast swaths of North America, Europe and Asia because bulk canopy water demands increase with additional vegetation growth and longer and warmer growing seasons. These runoff declines occur despite increased surface resistance to evapotranspiration and vegetation total water use efficiency, even in regions with increasing or unchanging precipitation. We demonstrate that constraining the large uncertainty in the multimodel ensemble with regional-scale observations of evapotranspiration partitioning strengthens these results. We conclude that terrestrial vegetation plays a large and unresolved role in shaping future regional freshwater availability, one that will not ubiquitously ameliorate future warming-driven surface drying.
Mankin, Justin S.↗
Correction: Acid–base concentration swing for direct air capture of carbon dioxide
Correction for ‘Acid–base concentration swing for direct air capture of carbon dioxide’ by Anatoly Rinberg and Michael J. Aziz, Energy Adv. , 2024, https://doi.org/10.1039/d4ya00251b.
Rinberg, Anatoly↗
Technology advancement of the electrochemical CO2 concentrating process
A five-cell, liquid-cooled advanced electrochemical depolarized carbon dioxide concentrator module was fabricated. The cells utilized the advanced, lightweight, plated anode current collector concept and internal liquid-cooling. The five cell module was designed to meet the carbon dioxide removal requirements of one man and was assembled using plexiglass endplates. This one-man module was tested as part of an integrated oxygen generation and recovery subsystem.
Schubert, F. H.↗
Accelerated screening of carbon dioxide capture by liquid sorbents
The sustainability potential of carbon capture, concentration, and utilization technologies motivates accelerated discovery of carbon dioxide sorbents, for which we present a high throughput screening instrument.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Aircraft instrumentation system for the remote sensing of carbon monoxide
A light twin-engine aircraft has been instrumented with a carbon monoxide remote gas sensor system and test flown over the Southern Lake Michigan basin during August, 1976. The remote sensor is based on the gas filter correlation technique. The radiance levels from the sensor along with the data on the surface temperature, air temperature, dewpoint, and altitude were digitized and recorded on seven-track magnetic tape. Air samples were collected at various altitudes over selected sites for later analysis of carbon monoxide concentration and comparison with the inferred concentration from the remote sensor. The values of carbon monoxide obtained from the air samples and the values inferred from the remote sensor for data collected over water are in good agreement.
Beck, S. M.↗
Initial Land Use/Cover Distribution Substantially Affects Global Carbon and Local Temperature Projections in the Integrated Earth System Model
Initial land cover distribution varies among Earth system models, an uncertainty in initial conditions that can substantially affect carbon and climate projections. We use the integrated Earth System Model to show that a 3.9 M km2 difference in 2005 global forest area (9–14% of total forest area) generates uncertainties in initial atmospheric CO2 concentration, terrestrial carbon, and local temperature that propagate through a future simulation following the Representative Concentration Pathway 4.5. By 2095, the initial 6 ppmv uncertainty range increases to 9 ppmv and the initial 26 PgC uncertainty range in terrestrial carbon increases to 33 PgC. The initial uncertainty range in annual average local temperature of -0.74 to 0.96 °C persists throughout the future simulation, with a seasonal maximum in Dec-Jan-Feb. These results highlight the importance of accurately characterizing historical land use and land cover to reduce overall initial condition uncertainty.
Di Vittorio, Alan↗
Solubilities of carbon dioxide and water in rhyolitic melt at 850 C and 750 bars
Concentrations of carbon dioxide and water dissolved in glasses quenched from rhyolitic melts equilibrated with H2O-CO2 fluids at 850 C and 750 bar were measured using IR spectroscopy; concentrations of H2O and CO2 in the quenched fluids were measured manometrically. The mole fraction of CO2 in the quenched fluid ranged from 0.06 to 0.91. Concentrations of CO2 in the coexisting rhyolitic melt increased from 23(+/-6) ppm for the sample equilibrated with the most CO2-poor fluid to 515(+/-16) ppm for that equilibrated with the most CO2-rich fluid. The water content of the melt varied from 0.51(+/-0.06) to 3.34(+/-0.08) wt pct. Our results show that concentrations of molecular CO2 and H2O in the glasses obey Henry's Law; the mole fractions of molecular CO2 and molecular H2O in the quenched melts are proportional to their fugacities in the coexisting vapor. CO2 contents of vapor-saturated melts are not enhanced by addition of water to CO2-rich vapor, contrary to previous reports for silicate melts at higher pressures. The Henrian behavior of CO2 and H2O at low pressure considerably simplifies modeling of the degassing of silicic magmas.
Blank, J. G.↗
Venus upper atmosphere neutral gas composition - First observations of the diurnal variations
Measurements of the composition, temperature, and diurnal variations of the major neutral constituents in the thermosphere of Venus are being made with a quadrupole mass spectrometer on the Pioneer Venus Orbiter. Concentrations of carbon dioxide, carbon monoxide, molecular nitrogen, atomic oxygen, and helium are presented, in addition to an empirical model of the data. The concentrations of the heavy gases, carbon dioxide, carbon monoxide, and molecular nitrogen, rapidly decrease from the evening terminator toward the nightside; the concentration of atomic oxygen remains nearly constant and the helium concentration increases, an indication of a nightside bulge. The kinetic temperature inferred from scale heights drops rapidly from 230 K at the terminator to 130 K at a solar zenith angle of 120 deg, and to 112 K at the antisolar point.
Niemann, H. B.↗
Salt marsh soil organic carbon is regulated by drivers of microbial activity
Abstract Soil organic carbon is the foundation for soil health and a livable climate. Organic carbon is concentrated in coastal wetland soils, but dynamics that govern carbon persistence in coastal ecosystems remain incompletely understood. Whether microbial activity results in a gain or loss of carbon depends on environmental conditions that regulate microbial community attributes. We sought to identify which drivers of microbial activity have the greatest impact on organic carbon content in salt marsh soils. To address this question, we used the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) statement to compile data on soil and ecosystem characteristics from 50 studies of over 60 salt marshes located around the world. We conducted a meta-analysis with structural equation modeling, including mediation and moderation analyses, to identify environmental drivers of salt marsh soil organic carbon content. High salinity, pH, nitrogen, and phosphorus were associated with increased microbial biomass carbon and soil organic carbon. Correlations between microbial biomass and organic carbon were strengthened by soil salinity and nitrogen, and weakened by soil water content. These results suggest that environmental conditions that control microbial growth and activity have potential to preserve or degrade organic carbon in salt marsh soils.
Erb, Hailey (ORCID:0000000337295634)↗
Action Effectiveness Monitoring and Research of Dredged Material Placement at Woodland Islands (Final Report)
Benthic invertebrates play critical ecosystem roles including the breakdown of organic matter, sediment mixing, and nutrient cycling. In the lower Columbia River and estuary, benthic invertebrates provide a foraging resource for threatened and endangered juvenile salmon. Driven by the goal to create low velocity, shallow water, and riparian shrub habitats to benefit juvenile salmon, the USACE placed 237,000 CY of dredged material, resulting in the deposition of 13.5 acres of sand on the off-channel margins at Woodland Islands. The Pacific Northwest National Laboratory (PNNL) designed and implemented an action effectiveness research study to understand how dredged material placement at Woodland Islands affected sediment conditions and benthic invertebrate assemblages. A Before-After-Control-Impact, or BACI, study design was used to evaluate the response of environmental conditions and benthic invertebrates to dredged material placement. The design included one impact site and two control sites. Sampling occurred for two years prior to dredged material placement and two years after. Our study found that spatial variation was a significant factor for both environmental and biological response variables which suggests local conditions are important considerations for mechanisms affecting benthic assemblages. We found that off-channel habitats across all locations sampled were producing benthic invertebrates, many of which are common prey items for juvenile salmon and steelhead—e.g., insects, chironomids, crustaceans, and corophium. There was a significant BACI effect (i.e., an effect at the dredged material placement site, relative to conditions at the control sites) for concentration of carbon and ammonium in sediment, but not for phosphorous concentrations or for percent sand. The estimated abundance for the three invertebrate response variables—total abundance, total chironomid abundance, and total corophium abundance—was significantly lower at the impact site after dredged material placement, compared to the control sites. At Woodland Island, the estimated mean abundance for all invertebrates combined decreased 28% after dredged material placement. Estimated mean abundances of chironomid and corophium decreased by 8% and 88%, respectively. While invertebrate abundances were lower after dredged placement, the composition of benthic invertebrates was similar before and after placement suggesting that as the new habitat feature evolves recolonization will likely follow. These findings provide a foundation for understanding potential benefits and consequences of repurposing dredged material for habitat creation in the LCRE.
54 ENVIRONMENTAL SCIENCES↗
Toxicity of pyrolysis gases from synthetic polymers
The screening test method was used to investigate toxicity in polyethylene, polystyrene, polymethyl methacrylate, polyaryl sulfone, polyether sulfone, polyphenyl sulfone, and polyphenylene sulfide. Changing from a rising temperature program to a fixed temperature program resulted on shorter times to animal responses. This effect was attributed in part to more rapid generation of toxicants. The toxicants from the sulfur containing polymers appeared to act more rapidly than the toxicants from the other polymers. It was not known whether this effect was due primarily to difference in concentration or in the nature of the toxicants. The carbon monoxide concentration found did not account for the results observed with the sulfur containing polymers. Polyphenyl sulfone appeared to exhibit the least toxicity among the sulfur containing polymers evaluated under these test conditions.
Hilado, C. J.↗
Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers
The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.
Hilado, C. J.↗