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Temperature controls diel oscillation of the CO2 concentration in a desert soil

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
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:
Type of IDID
DOI10.1007/s10533-021-00845-0
Web of Science (WoS)000693869800001
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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