Details
| Original language | English |
|---|---|
| Article number | G03023 |
| Journal | Journal of Geophysical Research: Biogeosciences |
| Volume | 113 |
| Issue number | 3 |
| Publication status | Published - 19 Aug 2008 |
| Externally published | Yes |
Abstract
Thermokarst wetlands and ponds in the subarctic, which are located in land surface depressions resulting from permafrost melt, are strong sources of CH4, but little is known about respiration processes supporting these emissions. We determined CH4 fluxes and concentration profiles of dissolved gases and anions and some δ13C ratios of CO 2 and CH4 in a thermokarst pond and adjacent smaller thermokarst depressions in the forest tundra near Igarka, northern Siberia in August 2006. Methane was emitted at 110-170 mg m-2 d-1 and produced mostly by CO2 reduction, which also provided high Gibbs free energies on the order of 50-70 KJ mol-1 H2 due to high H2concentrations. The diffusive flux calculated from CH 4 gradients in the floating mat contributed <2% to emissions. CH4 was apparently not oxidized deeper than 20 cm into the floating mat and the water body below. Anaerobic respiration required to reproduce nonsteady state CO2 concentration maxima in the floating mat above the water body was 30-80 nmol cm-3 d-1 or 250 mg m -2 d-1 and thus on a similar order of magnitude as CH 4 fluxes. The results suggest that floating mat-covered thermokarst ponds located in northern Siberian bogs effectively convert recently fixed carbon into CH4 and thus allow for emissions independently from the finite, bog-derived carbon source. The relative contribution of recently fixed and old bog-derived carbon to C fluxes requires further investigation, however.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Agricultural and Biological Sciences(all)
- Forestry
- Earth and Planetary Sciences(all)
- Oceanography
- Agricultural and Biological Sciences(all)
- Aquatic Science
- Environmental Science(all)
- Ecology
- Environmental Science(all)
- Water Science and Technology
- Agricultural and Biological Sciences(all)
- Soil Science
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
- Earth and Planetary Sciences(all)
- Earth-Surface Processes
- Earth and Planetary Sciences(all)
- Atmospheric Science
- Earth and Planetary Sciences(all)
- Earth and Planetary Sciences (miscellaneous)
- Earth and Planetary Sciences(all)
- Space and Planetary Science
- Earth and Planetary Sciences(all)
- Palaeontology
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In: Journal of Geophysical Research: Biogeosciences, Vol. 113, No. 3, G03023, 19.08.2008.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - A snapshot of CO2 and CH4 evolution in a thermokarst pond near Igarka, northern Siberia
AU - Blodau, Christian
AU - Rees, Rainer
AU - Flessa, Heiner
AU - Rodionov, Andrej
AU - Guggenberger, Georg
AU - Knorr, Klaus Holger
AU - Shibistova, Olga
AU - Zrazhevskaya, Galina
AU - Mikheeva, Natalia
AU - Kasansky, Oleg A.
PY - 2008/8/19
Y1 - 2008/8/19
N2 - Thermokarst wetlands and ponds in the subarctic, which are located in land surface depressions resulting from permafrost melt, are strong sources of CH4, but little is known about respiration processes supporting these emissions. We determined CH4 fluxes and concentration profiles of dissolved gases and anions and some δ13C ratios of CO 2 and CH4 in a thermokarst pond and adjacent smaller thermokarst depressions in the forest tundra near Igarka, northern Siberia in August 2006. Methane was emitted at 110-170 mg m-2 d-1 and produced mostly by CO2 reduction, which also provided high Gibbs free energies on the order of 50-70 KJ mol-1 H2 due to high H2concentrations. The diffusive flux calculated from CH 4 gradients in the floating mat contributed <2% to emissions. CH4 was apparently not oxidized deeper than 20 cm into the floating mat and the water body below. Anaerobic respiration required to reproduce nonsteady state CO2 concentration maxima in the floating mat above the water body was 30-80 nmol cm-3 d-1 or 250 mg m -2 d-1 and thus on a similar order of magnitude as CH 4 fluxes. The results suggest that floating mat-covered thermokarst ponds located in northern Siberian bogs effectively convert recently fixed carbon into CH4 and thus allow for emissions independently from the finite, bog-derived carbon source. The relative contribution of recently fixed and old bog-derived carbon to C fluxes requires further investigation, however.
AB - Thermokarst wetlands and ponds in the subarctic, which are located in land surface depressions resulting from permafrost melt, are strong sources of CH4, but little is known about respiration processes supporting these emissions. We determined CH4 fluxes and concentration profiles of dissolved gases and anions and some δ13C ratios of CO 2 and CH4 in a thermokarst pond and adjacent smaller thermokarst depressions in the forest tundra near Igarka, northern Siberia in August 2006. Methane was emitted at 110-170 mg m-2 d-1 and produced mostly by CO2 reduction, which also provided high Gibbs free energies on the order of 50-70 KJ mol-1 H2 due to high H2concentrations. The diffusive flux calculated from CH 4 gradients in the floating mat contributed <2% to emissions. CH4 was apparently not oxidized deeper than 20 cm into the floating mat and the water body below. Anaerobic respiration required to reproduce nonsteady state CO2 concentration maxima in the floating mat above the water body was 30-80 nmol cm-3 d-1 or 250 mg m -2 d-1 and thus on a similar order of magnitude as CH 4 fluxes. The results suggest that floating mat-covered thermokarst ponds located in northern Siberian bogs effectively convert recently fixed carbon into CH4 and thus allow for emissions independently from the finite, bog-derived carbon source. The relative contribution of recently fixed and old bog-derived carbon to C fluxes requires further investigation, however.
UR - http://www.scopus.com/inward/record.url?scp=69549124252&partnerID=8YFLogxK
U2 - 10.1029/2007JG000652
DO - 10.1029/2007JG000652
M3 - Article
AN - SCOPUS:69549124252
VL - 113
JO - Journal of Geophysical Research: Biogeosciences
JF - Journal of Geophysical Research: Biogeosciences
SN - 0148-0227
IS - 3
M1 - G03023
ER -