scholarly journals Unified measurement system with suction control for measuring hysteresis in soil-gas transport parameters

2012 ◽  
Vol 48 (2) ◽  
Author(s):  
Md Abdur Rouf ◽  
Shoichiro Hamamoto ◽  
Ken Kawamoto ◽  
Toshihiro Sakaki ◽  
Toshiko Komatsu ◽  
...  
Keyword(s):  
Measurement System ◽  
Gas Transport ◽  
Soil Gas ◽  
Transport Parameters ◽  
Suction Control

scholarly journals Characterization of Gas Transport Properties of Compacted Solid Waste Materials

Environments ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 26
Author(s):  
Muhammad Rashid Iqbal ◽  
Hiniduma Liyanage Damith Nandika ◽  
Yugo Isobe ◽  
Ken Kawamoto
Keyword(s):  
Hydraulic Conductivity ◽  
Solid Waste ◽  
Gas Transport ◽  
Bottom Ash ◽  
Gas Diffusion ◽  
Saturated Hydraulic Conductivity ◽  
Dry Density ◽  
Transport Parameters ◽  
Functional Relations ◽  
Mixed Waste

Gas transport parameters such as gas diffusivity (Dp/D0), air permeability (ka), and their dependency on void space (air-filled porosity, ε) in a waste body govern convective air and gas diffusion at solid waste dumpsites and surface emission of various gases generated by microbial processes under aerobic and anaerobic decompositions. In this study, Dp/D0(ε) and ka(ε) were measured on dumping solid waste in Japan such as incinerated bottom ash and unburnable mixed waste as well as a buried waste sample (dumped for 20 years). Sieved samples with variable adjusted moistures were compacted by a standard proctor method and used for a series of laboratory tests for measuring compressibility, saturated hydraulic conductivity, and gas transport parameters. Results showed that incinerated bottom ash and unburnable mixed waste did not give the maximum dry density and optimum moisture content. Measured compressibility and saturated hydraulic conductivity of tested samples varied widely depending on the types of materials. Based on the previously proposed Dp/D0(ε) models, the diffusion-based tortuosity (T) was analyzed and unique power functional relations were found in T(ε) and could contribute to evaluating the gas diffusion process in the waste body compacted at different moisture conditions.

scholarly journals Technical Note: Isotopic corrections for the radiocarbon composition of CO<sub>2</sub> in the soil gas environment must account for diffusion and diffusive mixing

2019 ◽  
Vol 16 (16) ◽  
pp. 3197-3205
Author(s):  
Jocelyn E. Egan ◽  
David R. Bowling ◽  
David A. Risk
Keyword(s):  
Gas Transport ◽  
Transport Model ◽  
Stable Carbon Isotope ◽  
Technical Note ◽  
Soil Gas ◽  
Soil Production ◽  
Gas Environment ◽  
Diffusive Mixing ◽  
Mass Dependent ◽  
Mass Dependent Fractionation

Abstract. Earth system scientists working with radiocarbon in organic samples use a stable carbon isotope (δ13C) correction to account for mass-dependent fractionation, but it has not been evaluated for the soil gas environment, wherein both diffusive gas transport and diffusive mixing are important. Using theory and an analytical soil gas transport model, we demonstrate that the conventional correction is inappropriate for interpreting the radioisotopic composition of CO2 from biological production because it does not account for important gas transport mechanisms. Based on theory used to interpret δ13C of soil production from soil CO2, we propose a new solution for radiocarbon applications in the soil gas environment that fully accounts for both mass-dependent diffusion and mass-independent diffusive mixing.

Characterizing the impact of diffusive and advective soil gas transport on the measurement and interpretation of the isotopic signal of soil respiration

2010 ◽  
Vol 42 (3) ◽  
pp. 435-444 ◽  
Author(s):  
Zachary E. Kayler ◽  
Elizabeth W. Sulzman ◽  
William D. Rugh ◽  
Alan C. Mix ◽  
Barbara J. Bond
Keyword(s):  
Soil Respiration ◽  
Gas Transport ◽  
Soil Gas ◽  
The Impact ◽  
Isotopic Signal

scholarly journals Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 46 ◽  
Author(s):  
Elisa Esposito ◽  
Irene Mazzei ◽  
Marcello Monteleone ◽  
Alessio Fuoco ◽  
Mariolino Carta ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Gas Transport ◽  
Gas Permeability ◽  
Time Lag ◽  
Gas Diffusion ◽  
Gas Permeation ◽  
Spectrometric Analysis ◽  
Competitive Sorption ◽  
Transport Parameters ◽  
Mixed Gas

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

scholarly journals Synthesis and gas transport parameters of membranes modified by star­shaped nanocrystalline palladium

2019 ◽  
Vol 486 (2) ◽  
pp. 163-167
Author(s):  
I. S. Petriev ◽  
S. N. Bolotin ◽  
V. Yu. Frolov ◽  
M. G. Baryshev
Keyword(s):  
Low Temperature ◽  
Flux Density ◽  
Hydrogen Transfer ◽  
Gas Transport ◽  
Transport Parameters ◽  
Alloy Films ◽  
Hydrogen Flux ◽  
Palladium Membranes

Methods have been developed to modify the surface of Pd-23%Ag alloy films in order to increase the rate of hydrogen transfer with appearance of palladium coatings of the “nanostar” and “nanopore” types. The gas transport parameters of the membranes which surface is activated using the developed methods were investigated. The modification of surface of Pd-Ag films synthesized by star-like palladium nanocrystallites allows achieving a hydrogen flux density of up to 0.75 mmol / (s × m2) - that is 1.7 times more than in case of modification modified by “nanopore” type coating of sufficiently thin palladium membranes (< 10 µm) under low temperature (<100 °C) and pressure (<0.6 MPa).

Gas Transport Parameters in the Vadose Zone: Development and Tests of Power-Law Models for Air Permeability

2006 ◽  
Vol 5 (4) ◽  
pp. 1205-1215 ◽  
Author(s):  
Ken Kawamoto ◽  
Per Moldrup ◽  
Per Schjønning ◽  
Bo V. Iversen ◽  
Toshiko Komatsu ◽  
...  
Keyword(s):  
Power Law ◽  
Vadose Zone ◽  
Gas Transport ◽  
Air Permeability ◽  
Transport Parameters ◽  
Zone Development

Development of an in-situ CO­2 gradient sampler

2020 ◽  
Author(s):  
Laurin Osterholt ◽  
Martin Maier
Keyword(s):  
Gradient Method ◽  
Gas Transport ◽  
Soil Gas ◽  
Diffusivity Coefficient ◽  
Tracer Gas ◽  
3D Print ◽  
Gas Diffusivity ◽  
Gas Fluxes ◽  
Set Up

&lt;p&gt;Gas fluxes between soil and atmosphere play an important role for the global greenhouse gas budgets. Several methods are available to determine soil gas fluxes. Besides the commonly used chamber methods the gradient method becomes more and more important. Chamber methods have the disadvantage that the microclimate can be influenced by the chamber which can affect gas fluxes. This problem does not occur with the gradient method. Furthermore the gradient method has the advantage that it can provide information about the depth profile of gas production and consumption in the soil.&lt;/p&gt;&lt;p&gt;The concept of the gradient method is to calculate gas fluxes by the vertical concentration gradient of a gas in the soil. For the calculation of the flux the effective diffusivity coefficient of the soil is needed. This can be approximated by models or by lab measurements. However, both of these approaches often fail in explaining site specific characteristics and spatial variability. Another way to determine soil gas diffusivity is to apply the gradient method using a tracer gas. By the injection of a tracer gas with known flux soil gas diffusivity can be measured in-situ.&lt;/p&gt;&lt;p&gt;We developed an innovative sampling set-up to apply an improved gradient method including the possibility to determine soil gas diffusivity in situ. We designed a sampler with build-in CO&lt;sub&gt;2&lt;/sub&gt; sensors in multiple depths that can easily be installed into the soil. With this sampler CO&lt;sub&gt;2&lt;/sub&gt; concentrations can be measured continuously in several depths. This enables the identification of short-time effects such as the influence of wind-induced pressure pumping on gas transport. The sampler allows tracer gas injection into the soil for in-situ diffusivity measurement. We decided for CO&lt;sub&gt;2 &lt;/sub&gt;as a tracer gas because it can be measured with small sensors which keep the set-up simple. To account for the natural CO&lt;sub&gt;2&lt;/sub&gt; production in the soil we developed a differential gas profile approach. Using an additional reference sampler allows measuring the natural CO&lt;sub&gt;2&lt;/sub&gt; gradient without the tracer signal, and thus subtracting the tracer CO&lt;sub&gt;2&lt;/sub&gt; signal from the natural CO&lt;sub&gt;2&lt;/sub&gt; signal.&lt;/p&gt;&lt;p&gt;The sampler consists of one 3D print segment per depth each containing one CO&lt;sub&gt;2&lt;/sub&gt; sensor. These parts can be combined to a sampler with flexible amount of measurement depths. The construction with individual segments allows a better maintenance in case of sensor defects. For the installation of the sampler a hole has to be drilled, into which the sampler is inserted. To prevent gas bypassing along the wall of the drill hole we equipped each segment with an inflatable gasket between the measurement locations.&lt;/p&gt;&lt;p&gt;In a next step we will evaluate the sampler and test it in the lab and under different environmental conditions. We expect that with this sampler we will be able to run gas transport experiments in the field with a high temporal resolution and relatively low effort.&lt;/p&gt;&lt;p&gt;&lt;em&gt;Acknowledgements&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;We thank Alfred Baer and Sven Kolbe for the technical support.&lt;/em&gt;&lt;/p&gt;

Two decades of no-till in the Oberacker long-term field experiment: Part II. Soil porosity and gas transport parameters

2016 ◽  
Vol 163 ◽  
pp. 130-140 ◽  
Author(s):  
Ingrid Martínez ◽  
Andreas Chervet ◽  
Peter Weisskopf ◽  
Wolfgang G. Sturny ◽  
Jan Rek ◽  
...  
Keyword(s):  
Field Experiment ◽  
Gas Transport ◽  
Soil Porosity ◽  
Transport Parameters ◽  
No Till ◽  
Term Field
Sign in / Sign up

Export Citation Format

Share Document