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| Titel |
Inorganic carbon fluxes across the vadose zone of planted and unplanted soil mesocosms |
| VerfasserIn |
E. M. Thaysen, D. Jacques, S. Jessen, C. E. Andersen, E. Laloy, P. Ambus, D. Postma, I. Jakobsen |
| 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 ; 11, no. 24 ; Nr. 11, no. 24 (2014-12-17), S.7179-7192 |
| Datensatznummer |
250117742
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| Publikation (Nr.) |
 copernicus.org/bg-11-7179-2014.pdf |
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| Zusammenfassung |
The efflux of carbon dioxide (CO2) from soils influences atmospheric
CO2 concentrations and thereby climate change. The partitioning of
inorganic carbon (C) fluxes in the vadose zone between emission to
the atmosphere and to the groundwater was investigated to reveal controlling
underlying mechanisms. Carbon dioxide partial pressure in the soil gas
(pCO2), alkalinity, soil moisture and temperature were measured over
depth and time in unplanted and planted (barley) mesocosms. The dissolved
inorganic carbon (DIC) percolation flux was calculated from the pCO2,
alkalinity and the water flux at the mesocosm bottom. Carbon dioxide
exchange between the soil surface and the atmosphere was measured at regular
intervals. The soil diffusivity was determined from soil radon-222
(222Rn) emanation rates and soil air Rn concentration profiles and was
used in conjunction with measured pCO2 gradients to calculate the soil
CO2 production. Carbon dioxide fluxes were modeled using the HP1
module of the Hydrus 1-D software.
The average CO2 effluxes to the atmosphere from unplanted and planted
mesocosm ecosystems during 78 days of experiment were 0.1 ± 0.07 and
4.9 ± 0.07 μmol C m−2 s−1, respectively, and grossly
exceeded the corresponding DIC percolation fluxes of 0.01 ± 0.004 and
0.06 ± 0.03 μmol C m−2 s−1. Plant biomass was high
in the mesocosms as compared to a standard field situation. Post-harvest
soil respiration (Rs) was only 10% of the Rs during plant
growth, while the post-harvest DIC percolation flux was more than one-third
of the flux during growth. The Rs was controlled by production and
diffusivity of CO2 in the soil. The DIC percolation flux was largely
controlled by the pCO2 and the drainage flux due to low solution pH.
Modeling suggested that increasing soil alkalinity during plant growth was
due to nutrient buffering during root nitrate uptake. |
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