Spohn, Marie and Holzheu, Stefan
(2021).
Temperature controls diel oscillation of the CO2 concentration in a desert soil.
Biogeochemistry. 156
, 279-292
[Research article]
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Abstract
The diel dynamic of the CO2 concentration in soils in relation to temperature is not yet fully understood. Air temperature might control the soil CO2 concentration due to thermal convective venting at sites experiencing large temperature differences between the atmosphere and the soil. Therefore, the objective of this study was to determine the soil CO2 concentration and its temporal dynamic in a deep desert soil in relationship to soil and air temperature based on high frequency measurements. For this purpose, CO2 concentration and temperature were measured in six soil depths (ranging from 15 to 185 cm) in a coarse-textured desert soil in the North of Chile every 60 min together with precipitation and air temperature for one year. The mean CO2 concentration calculated across the whole measuring period increased linearly with soil depth from 463 ppm in 15 cm to 1542 ppm in 185 cm depth. We observed a strong diel oscillation of the CO2 concentration that decreased with soil depth and a hysteretic relationship between the topsoil CO2 concentration and both air and soil temperature. The Rayleigh-Darcy number calculated for different times indicates that thermal convective venting of the soil occurred during the night and in the early morning. A small precipitation event (4 mm) increased the CO2 concentrations in 15, 30, and 50 cm depths for several days but did not alter the amplitude of the diel oscillation of the CO2 concentration. The diel oscillation of the CO2 concentration and the hysteretic relationship between soil CO2 concentration and air temperature were likely caused by thermal convection, leading to transport of CO2-rich air from the soil to the atmosphere at night. In conclusion, our results indicate that the soil CO2 concentration can be largely controlled by convection caused by temperature differences, and not only by diffusion. The results have important implications as they provide further evidence that thermal convective venting contributes to gas exchange at sites experiencing large temperature differences between the atmosphere and the soil, which is relevant for soil chemical reactions.
Authors/Creators: | Spohn, Marie and Holzheu, Stefan | ||||||
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Title: | Temperature controls diel oscillation of the CO2 concentration in a desert soil | ||||||
Series Name/Journal: | Biogeochemistry | ||||||
Year of publishing : | 2021 | ||||||
Volume: | 156 | ||||||
Page range: | 279-292 | ||||||
Number of Pages: | 14 | ||||||
Publisher: | SPRINGER | ||||||
ISSN: | 0168-2563 | ||||||
Language: | English | ||||||
Publication Type: | Research article | ||||||
Article category: | Scientific peer reviewed | ||||||
Version: | Published version | ||||||
Copyright: | Creative Commons: Attribution 4.0 | ||||||
Full Text Status: | Public | ||||||
Subjects: | (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science | ||||||
Keywords: | Soil CO2 concentration, Desert soil, Hysteresis, Diel oscillation, Soil depth, Precipitation | ||||||
URN:NBN: | urn:nbn:se:slu:epsilon-p-113696 | ||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-113696 | ||||||
Additional ID: |
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ID Code: | 25855 | ||||||
Faculty: | S - Faculty of Forest Sciences | ||||||
Department: | (NL, NJ) > Dept. of Soil and Environment (S) > Dept. of Soil and Environment | ||||||
Deposited By: | SLUpub Connector | ||||||
Deposited On: | 18 Oct 2021 06:25 | ||||||
Metadata Last Modified: | 18 Oct 2021 06:31 |
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