220Rn/222Rn Isotope Pair as a Natural Proxy for Soil Gas Transport

2013 ◽  
Vol 47 (24) ◽  
pp. 14044-14050 ◽  
Author(s):  
Stephan Huxol ◽  
Matthias S. Brennwald ◽  
Ruth Henneberger ◽  
Rolf Kipfer
Keyword(s):  
Gas Transport ◽  
Soil Gas

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

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;

Poly-Use Multi-Level Sampling System for Soil-Gas Transport Analysis in the Vadose Zone

2013 ◽  
Vol 47 (19) ◽  
pp. 11122-11130 ◽  
Author(s):  
Philipp A. Nauer ◽  
Eleonora Chiri ◽  
Martin H. Schroth
Keyword(s):  
Vadose Zone ◽  
Gas Transport ◽  
Soil Gas ◽  
Sampling System ◽  
Transport Analysis ◽  
Multi Level

scholarly journals Isotopic fractionation corrections for the radiocarbon composition of CO<sub>2</sub> in the soil gas environment must include diffusion and mixing

2018 ◽  
Author(s):  
Jocelyn E. Egan ◽  
David R. Bowling ◽  
David A. Risk
Keyword(s):  
Gas Transport ◽  
Transport Model ◽  
Stable Carbon Isotope ◽  
Correction Method ◽  
Soil Gas ◽  
Co2 Production ◽  
Biological Production ◽  
Gas Environment ◽  
Diffusive Mixing ◽  
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 caused primarily by photosynthesis. Although researchers apply this correction routinely, it has not been evaluated for the soil gas environment, where both diffusive gas transport and diffusive mixing are important. Towards this end we applied an analytical soil gas transport model across a range of soil diffusivities and biological CO2 production rates, allowing us to control the radiocarbon (Δ14C) and stable isotope (δ13C) compositions of modeled soil CO2 production and atmospheric CO2. This approach allowed us to assess the bias that results from using the conventional correction method for estimating Δ14C of soil production. We found that the conventional correction is inappropriate for interpreting the radio-isotopic composition of CO2 from biological production, because it does not account for diffusion and diffusive mixing. The resultant Δ14C bias associated with the traditional correction is highest (up to 150 ‰) in soils with low biological production and/or high soil diffusion rates. We propose a new solution for radiocarbon applications in the soil gas environment that fully accounts for diffusion and diffusive mixing.

scholarly journals Soil gas transport above a jet fuel/solvent spill at Plattsburgh Air Force Base

2000 ◽  
Vol 36 (9) ◽  
pp. 2531-2547 ◽  
Author(s):  
David W. Ostendorf ◽  
Erich S. Hinlein ◽  
Alan J. Lutenegger ◽  
Shawn P. Kelley
Keyword(s):  
Air Force ◽  
Gas Transport ◽  
Jet Fuel ◽  
Soil Gas ◽  
Air Force Base

scholarly journals Investigating two-dimensional soil gas transport of trichloroethylene in vapor intrusion scenarios involving surface pavements using a pilot-scale tank

2019 ◽  
Vol 371 ◽  
pp. 138-145 ◽  
Author(s):  
Genfu Wang ◽  
Shuaishuai Ma ◽  
Jonathan Ström ◽  
Eric Suuberg ◽  
Yijun Yao ◽  
...  
Keyword(s):  
Gas Transport ◽  
Pilot Scale ◽  
Soil Gas ◽  
Two Dimensional ◽  
Vapor Intrusion

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
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