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Title: Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes

Abstract

The exchange of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that exchange. We examined the method under hypothetical field conditions where diffusion was the only mechanism for gas transport and the atmosphere outside the chamber was maintained at a fixed concentration. Analytical and numerical solutions to the soil gas diffusion equation in one and there dimensions demonstrated that gas flux density to a static chamber deployed on the soil surface was less in magnitude than the ambient exchange rate in the absence of the chamber. This discrepancy, which increased with chamber deployment time and air-filled porosity of soil, is attributed to two physical factors: distortion of the soil gas concentration gradient (the magnitude was decreased in the vertical component and increased in the radial component) and the slow transport rate of diffusion relative to mixing within the chamber. Instantaneous flux density to a chamber decreased continuously with time; steepest decreases occurred so quickly following deployment and in response to such slight changes in mean chamber headspace concentration that they would likely go undetected by most field procedures.more » Adverse influences of these factors were reduced by mixing the chamber headspace, minimizing deployment time, maximizing the height and radius of the chamber, and pushing the rim of the chamber into the soil. 29 refs., 8 figs., 1 tab.« less

Authors:
;  [1];  [2];  [3];  [4]
  1. Geological Survey, Lakewood, CO (United States)
  2. Univ. of Colorado, Denver, CO (United States)
  3. USDA-ARS-NPA, Ft. Collins, CO (United States)
  4. NASA Ames Research Center, Moffett Field, CA (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
263227
Resource Type:
Journal Article
Journal Name:
Soil Science Society of America Journal
Additional Journal Information:
Journal Volume: 60; Journal Issue: 3; Other Information: PBD: May-Jun 1996
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; GASES; MASS TRANSFER; DIFFUSION; CARBON DIOXIDE; FLUX DENSITY; SOILS; ATMOSPHERES; EXPOSURE CHAMBERS; KINETICS; NUMERICAL SOLUTION

Citation Formats

Healy, R W, Striegl, R G, Russell, T F, Hutchinson, G L, and Livingston, G P. Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes. United States: N. p., 1996. Web. doi:10.2136/sssaj1996.03615995006000030009x.
Healy, R W, Striegl, R G, Russell, T F, Hutchinson, G L, & Livingston, G P. Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes. United States. https://doi.org/10.2136/sssaj1996.03615995006000030009x
Healy, R W, Striegl, R G, Russell, T F, Hutchinson, G L, and Livingston, G P. 1996. "Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes". United States. https://doi.org/10.2136/sssaj1996.03615995006000030009x.
@article{osti_263227,
title = {Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes},
author = {Healy, R W and Striegl, R G and Russell, T F and Hutchinson, G L and Livingston, G P},
abstractNote = {The exchange of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that exchange. We examined the method under hypothetical field conditions where diffusion was the only mechanism for gas transport and the atmosphere outside the chamber was maintained at a fixed concentration. Analytical and numerical solutions to the soil gas diffusion equation in one and there dimensions demonstrated that gas flux density to a static chamber deployed on the soil surface was less in magnitude than the ambient exchange rate in the absence of the chamber. This discrepancy, which increased with chamber deployment time and air-filled porosity of soil, is attributed to two physical factors: distortion of the soil gas concentration gradient (the magnitude was decreased in the vertical component and increased in the radial component) and the slow transport rate of diffusion relative to mixing within the chamber. Instantaneous flux density to a chamber decreased continuously with time; steepest decreases occurred so quickly following deployment and in response to such slight changes in mean chamber headspace concentration that they would likely go undetected by most field procedures. Adverse influences of these factors were reduced by mixing the chamber headspace, minimizing deployment time, maximizing the height and radius of the chamber, and pushing the rim of the chamber into the soil. 29 refs., 8 figs., 1 tab.},
doi = {10.2136/sssaj1996.03615995006000030009x},
url = {https://www.osti.gov/biblio/263227}, journal = {Soil Science Society of America Journal},
number = 3,
volume = 60,
place = {United States},
year = {Wed May 01 00:00:00 EDT 1996},
month = {Wed May 01 00:00:00 EDT 1996}
}