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| Titel |
Using hydrologic measurements to investigate free-phase gas ebullition in a Maine peatland, USA |
| VerfasserIn |
C. E. Bon, A. S. Reeve, L. Slater, X. Comas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 3 ; Nr. 18, no. 3 (2014-03-10), S.953-965 |
| Datensatznummer |
250120300
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| Publikation (Nr.) |
 copernicus.org/hess-18-953-2014.pdf |
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| Zusammenfassung |
| Northern peatlands cover more than 350 million ha and are an important
source of methane (CH4) and other biogenic gases contributing to
climate change. Free-phase gas (FPG) accumulation and episodic release has
recently been recognized as an important mechanism for biogenic gas flux
from peatlands. It is likely that gas production and groundwater flow are
interconnected in peatlands: groundwater flow influences gas production by
regulating geochemical conditions and nutrient supply available for
methanogenesis, while FPG influences groundwater flow through a reduction in
peat permeability and by creating excess pore water pressures. Water samples
collected from three well sites at Caribou Bog, Maine, show substantial
dissolved CH4 (5–16 mg L−1) in peat waters below 2 m depth and an
increase in concentrations with depth. This suggests production and storage
of CH4 in deep peat that may be episodically released as FPG. Two min
increment pressure transducer data reveal approximately 5 cm
fluctuations in hydraulic head from both deep and shallow peat that are
believed to be indicative of FPG release. FPG release persists up to 24 h
during decreasing atmospheric pressure and a rising water table.
Preferential flow is seen towards an area of relatively lower hydraulic head
associated with the esker and pool system. Increased CH4 concentrations
are also found at the depth of the esker crest, suggesting that the high
permeability esker is acting as a conduit for groundwater flow, driving a
downward transport of labile carbon, resulting in higher rates of CH4
production. |
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