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| Titel |
Atmospheric turbulence triggers pronounced diel pattern in karst carbonate geochemistry |
| VerfasserIn |
M. Roland, P. Serrano-Ortiz, A. S. Kowalski, Y. Godderis, E. P. Sánchez-Cañete, P. Ciais, F. Domingo, S. Cuezva, S. Sanchez-Moral, B. Longdoz, D. Yakir, R. Grieken, J. Schott, C. Cardell, I. A. Janssens |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 7 ; Nr. 10, no. 7 (2013-07-24), S.5009-5017 |
| Datensatznummer |
250018358
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| Publikation (Nr.) |
 copernicus.org/bg-10-5009-2013.pdf |
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| Zusammenfassung |
| CO2 exchange between terrestrial ecosystems and the atmosphere is key to
understanding the feedbacks between climate change and the land surface. In
regions with carbonaceous parent material, CO2 exchange patterns occur
that cannot be explained by biological processes, such as disproportionate
outgassing during the daytime or nighttime CO2 uptake during periods
when all vegetation is senescent. Neither of these phenomena can be
attributed to carbonate weathering reactions, since their CO2 exchange
rates are too small. Soil ventilation induced by high atmospheric turbulence
is found to explain atypical CO2 exchange between carbonaceous systems
and the atmosphere. However, by strongly altering subsurface CO2
concentrations, ventilation can be expected to influence carbonate weathering
rates. By imposing ventilation-driven CO2 outgassing in a carbonate
weathering model, we show here that carbonate geochemistry is accelerated and
does play a surprisingly large role in the observed CO2 exchange pattern
of a semi-arid ecosystem. We found that by rapidly depleting soil CO2
during the daytime, ventilation disturbs soil carbonate equilibria and
therefore strongly magnifies daytime carbonate precipitation and associated
CO2 production. At night, ventilation ceases and the depleted CO2
concentrations increase steadily. Dissolution of carbonate is now enhanced,
which consumes CO2 and largely compensates for the enhanced daytime
carbonate precipitation. This is why only a relatively small effect on global
carbonate weathering rates is to be expected. On the short term, however,
ventilation has a drastic effect on synoptic carbonate weathering rates,
resulting in a pronounced diel pattern that exacerbates the non-biological
behavior of soil–atmosphere CO2 exchanges in dry regions \mbox{with
carbonate soils}. |
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