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Ecosystem and physiological controls over methane production in northern wetlandsPeat chemistry appears to exert primary control over methane production rates in the Canadian Northern Wetlands Study (NOWES) area. We determined laboratory methane production rate potentials in anaerobic slurries of samples collected from a transect of sites through the NOWES study area. We related methane production rates to indicators of resistance to microbial decay (peat C: N and lignin: N ratios) and experimentally manipulated substrate availability for methanogenesis using ethanol (EtOH) and plant litter. We also determined responses of methane production to pH and temperature. Methane production potentials declined along the gradient of sites from high rates in the coastal fens to low rates in the interior bogs and were generally highest in surface layers. Strong relationships between CH4 production potentials and peat chemistry suggested that methanogenesis was limited by fermentation rates. Methane production at ambient pH responded strongly to substrate additions in the circumneutral fens with narrow lignin: N and C: N ratios (delta CH4/delta EtOH = 0.9-2.3 mg/g) and weakly in the acidic bogs with wide C: N and lignin: N ratios (delta CH4/delta EtOH = -0.04-0.02 mg/g). Observed Q(sub 10) values ranged from 1.7 to 4.7 and generally increased with increasing substrate availability, suggesting that fermentation rates were limiting. Titration experiments generally demonstrated inhibition of methanogenesis by low pH. Our results suggest that the low rates of methane emission observed in interior bogs during NOWES likely resulted from pH and substrate quality limitation of the fermentation step in methane production and thus reflect intrinsically low methane production potentials. Low methane emission rates observed during NOWES will likely be observed in other northern wetland regions with similar vegetation chemistry.
Document ID
19950031266
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Valentine, David W.
(Colorado State Univ. Boulder, CO, United States)
Holland, Elisabeth A.
(National Center for Atmospheric Research, Boulder, CO United States)
Schimel, David S.
(National Center for Atmospheric Research, Boulder, CO United States)
Date Acquired
August 16, 2013
Publication Date
January 20, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: D1
ISSN: 0148-0227
Subject Category
Meteorology And Climatology
Accession Number
95A62865
Funding Number(s)
CONTRACT_GRANT: NAGW-1828
CONTRACT_GRANT: NAGW-2662
Distribution Limits
Public
Copyright
Other

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