Methane and Carbon Dioxide in Coastal Marsh Sediments
In order to better understand processes of diagenetic gas production in organic-rich sediments, CH4 and CO2 were analyzed, using two extraction techniques, in several environments of the South Louisiana marshlands. Investigation of twelve surface cores and two 100-cm cores indicated that total methane ranged in concentration from 0.12 to 12.2 µl/gm dry sediment, and dissolved methane ranged from 0.13 to 7.4 µl/ml interstitial water. Total CO2 in the interstitial water ranged from 224 to 410 µl/ml IW. Carbon isotope ratios were determined on CO2 released from sediment under vacuum. Dissolved organic carbon in the interstitial water of surface sediments ranged from 15.0 to 38.0 mg C/l. The environmental variation and mechanism of methane production are discussed.
KeywordsCarbon Isotope Composition Interstitial Water Carbon Isotope Ratio Marsh Sediment Short Core
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