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Methane Production and Emissions from Four Reclaimed and Pristine Wetlands of Southeastern United States
Author(s) -
Schipper Louis A.,
Reddy K. R.
Publication year - 1994
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1994.03615995005800040039x
Subject(s) - wetland , methane , environmental science , soil water , swamp , environmental chemistry , flux (metallurgy) , hydrology (agriculture) , marsh , surface water , soil science , environmental engineering , chemistry , ecology , geology , geotechnical engineering , organic chemistry , biology
Wetlands are significant contributors to global CH 4 emission. We measured CH 4 emissions at two pristine wetlands [Okefenokee swamp and the Everglades (Water Conservation Area 2A)] and two reclaimed wetlands (Sunny Hill Farm and Apopka Marsh) in Southeastern USA, and we attempted to relate emissions to CH 4 production rates of the soil and the soil's biological and chemical properties. Methane emissions through cattail [ Typha sp.] and waterlily [ Nymphaea ordorata (L.)] ranged from 0.09 to 1.7 g CH 4 m −2 d −1 and exhibited high spatial and temporal variability. Diffusive flux of CH 4 was calculated using dissolved CH 4 profiles in the soil pore water and accounted for <5% of the plant‐mediated emissions. Potential CH 4 production rates were measured as a function of depth using soil samples obtained at 2‐cm increments. Methane production rates were the same order of magnitude at all sites (<1–70 ng CH 4 ‐C g −1 soil C d −1 ) and were highest in the surface soils (0–6 cm) at three of the wetland sites, indicating that the predominant source of C available to methanogens was in the surface soils. Methane production rates in the top 24 cm ranged from 0.3 to 1.1 g CH 4 m −2 d −1 and annual C losses due to anaerobic decomposition accounted for between 0.68 and 3.7% of the total C in the surface 24‐cm soil depth. Methane production was observed at sites with porewater SO 4 concentrations of up to 20 mg SO 4 ‐S L −1 , suggesting that methanogenesis occurred in the same soil layer as SO 4 reduction, possibly in microsites where SO 4 concentration was depleted.