Termites: A Potentially Large Source of Atmospheric Methane, Carbon Dioxide, and Molecular Hydrogen

Science ◽  
1982 ◽  
Vol 218 (4572) ◽  
pp. 563-565 ◽  
Author(s):  
P. R. ZIMMERMAN ◽  
J. P. GREENBERG ◽  
S. O. WANDIGA ◽  
P. J. CRUTZEN
Keyword(s):  
Carbon Dioxide ◽  
Molecular Hydrogen ◽  
Atmospheric Methane ◽  
Large Source ◽  
Methane Carbon

scholarly journals Local structure and distortions of mixed methane-carbon dioxide hydrates

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Bernadette R. Cladek ◽  
S. Michelle Everett ◽  
Marshall T. McDonnell ◽  
Matthew G. Tucker ◽  
David J. Keffer ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Exchange Process ◽  
Carbon Dioxide Sequestration ◽  
Distribution Functions ◽  
Atomic Scale ◽  
Mixed Gas ◽  
Pure Compounds ◽  
Dynamics Simulations ◽  
Pair Distribution Functions ◽  
Methane Carbon

AbstractA vast source of methane is found in gas hydrate deposits, which form naturally dispersed throughout ocean sediments and arctic permafrost. Methane may be obtained from hydrates by exchange with hydrocarbon byproduct carbon dioxide. It is imperative for the development of safe methane extraction and carbon dioxide sequestration to understand how methane and carbon dioxide co-occupy the same hydrate structure. Pair distribution functions (PDFs) provide atomic-scale structural insight into intermolecular interactions in methane and carbon dioxide hydrates. We present experimental neutron PDFs of methane, carbon dioxide and mixed methane-carbon dioxide hydrates at 10 K analyzed with complementing classical molecular dynamics simulations and Reverse Monte Carlo fitting. Mixed hydrate, which forms during the exchange process, is more locally disordered than methane or carbon dioxide hydrates. The behavior of mixed gas species cannot be interpolated from properties of pure compounds, and PDF measurements provide important understanding of how the guest composition impacts overall order in the hydrate structure.

Effects of Pore Sizes on Dissociation Temperatures and Pressures of Methane, Carbon Dioxide, and Propane Hydrates in Porous Media

2002 ◽  
Vol 106 (4) ◽  
pp. 820-826 ◽  
Author(s):  
Tsutomu Uchida ◽  
Takao Ebinuma ◽  
Satoshi Takeya ◽  
Jiro Nagao ◽  
Hideo Narita
Keyword(s):  
Carbon Dioxide ◽  
Porous Media ◽  
Pore Sizes ◽  
Methane Carbon

Solid-Fluid Phase Equilibria Measurement for Mixtures of Methane, Carbon-Dioxide and N-Hexadecane

2021 ◽  
Author(s):  
Oluwakemi Victoria Eniolorunda ◽  
Antonin Chapoy ◽  
Rod Burgass
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Equation Of State ◽  
Phase Equilibria ◽  
Activity Coefficients ◽  
Fluid Phase ◽  
Ternary Mixtures ◽  
Binary Interaction ◽  
Thermodynamic Models ◽  
Methane Carbon

Abstract In this study, new experimental data using a reliable approach are reported for solid-fluid phase equilibrium of ternary mixtures of Methane-Carbon-dioxide- n-Hexadecane for 30-73 mol% CO2 and pressures up to 24 MPa. The effect of varying CO2 composition on the overall phase transition of the systems were investigated. Three thermodynamic models were used to predict the liquid phase fugacity, this includes the Peng Robison equation of state (PR-EoS), Soave Redlich-Kwong equation of state (SRK-EoS) and the Cubic plus Association (CPA) equation of state with the classical mixing rule and a group contribution approach for calculating binary interaction parameters in all cases. To describe the wax (solid) phase, three activity coefficient models based on the solid solution theory were investigated: the predictive universal quasichemical activity coefficients (UNIQUAC), Universal quasi-chemical Functional Group activity coefficients (UNIFAC) and the predictive Wilson approach. The solid-fluid equilibria experimental data gathered in this experimental work including those from saturated and under-saturated conditions were used to check the reliability of the various phase equilibria thermodynamic models.

scholarly journals Optical tools for ocean monitoring and research

Ocean Science ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 661-684 ◽  
Author(s):  
C. Moore ◽  
A. Barnard ◽  
P. Fietzek ◽  
M. R. Lewis ◽  
H. M. Sosik ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ocean Color ◽  
Analytical Techniques ◽  
Optical Measurements ◽  
Physical Parameters ◽  
Optical Tools ◽  
Wide Range ◽  
Radiance Distribution ◽  
Ocean Monitoring ◽  
Methane Carbon

Abstract. Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time.

Study on flame-vortex interaction in a spark ignition engine fueled with methane/carbon dioxide gases

2018 ◽  
Vol 91 (1) ◽  
pp. 133-144 ◽  
Author(s):  
Xin Zhang ◽  
Tao Wang ◽  
Jian Xu ◽  
Shizhuo Zheng ◽  
Xiaosen Hou
Keyword(s):  
Carbon Dioxide ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Vortex Interaction ◽  
Methane Carbon

RUMEN GAS ANALYSIS BY GAS-SOLID CHROMATOGRAPHY

1961 ◽  
Vol 41 (2) ◽  
pp. 187-196 ◽  
Author(s):  
J. M. McArthur ◽  
J. E. Miltimore
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Hydrogen Sulphide ◽  
Sample Volume ◽  
Gas Analysis ◽  
Complete Analysis ◽  
Thermal Detector ◽  
Thermal Detection ◽  
Methane Carbon

Methods are described for sampling and analysing rumen gases. The analysis requires less than 15 minutes for the determination of hydrogen, oxygen, nitrogen, methane, carbon monoxide, carbon dioxide, and hydrogen sulphide, i.e., for all gases occurring in the rumen. The method is sensitive and requires only a small quantity of sample, and the sample volume need not be known. The presence of water or other vapours in the sample does not influence the results. Relative thermal detector responses have been determined for gases which occur in the rumen. These eliminate the necessity for the calibration of gas chromatographs using thermal detection. The first complete analysis of rumen gas is presented.

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