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- Title
Microbial conversion of inorganic carbon to dimethyl sulfide in anoxic lake sediment (Pluβsee, Germany).
- Authors
Lin, Y.-S.; Heuer, V. B.; Ferdelman, T. G.; Hinrichs, K.-U.
- Abstract
In anoxic environments, volatile methylated sulfides including methanethiol (MT) and dimethyl sulfide (DMS) link the pools of inorganic and organic carbon with the sulfur cycle. However, direct formation of methylated sulfides from reduction of dissolved inorganic carbon has previously not been demonstrated. During examination of the hydrogenotrophic microbial activity at different temperatures in the anoxic sediment from Lake Pluβsee, DMS formation was detected at 55 °C and was enhanced when bicarbonate was supplemented. Addition of both bicarbonate and H2 resulted in the strongest stimulation of DMS production, and MT levels declined slightly. Addition of methyl-group donors such as methanol and syringic acid or methyl-group acceptors such as hydrogen sulfide did not enhance further accumulation of DMS and MT. The addition of 2-bromoethanesulfonate inhibited DMS formation and caused a slight MT accumulation. MT and DMS had average Г13C values of -55‰ and -62‰, respectively. Labeling with NaH13CO3 showed that incorporation of bicarbonate into DMS occurred through methylation of MT. H352 S labeling demonstrated a microbially-mediated, but slow, process of hydrogen sulfide methylation that accounted for <10% of the accumulation rates of DMS. Our data suggest: (1) methanogens are involved in DMS formation from bicarbonate, and (2) the major source of the 13C-depleted MT is neither bicarbonate nor methoxylated aromatic compounds. Other possibilities for isotopically light MT, such as demethylation of 13C-depleted DMS or other organic precursors such as methionine, are discussed. This DMS-forming pathway may be relevant for anoxic environments, such as hydrothermally influenced sediments and fluids and sulfatemethane transition zones in marine sediments.
- Subjects
GERMANY; DISSOLVED organic matter; COMPOSITION of water; WATER analysis; ANOXIC zones; LAKE sediments; LAKES
- Publication
Biogeosciences Discussions, 2010, Vol 7, Issue 2, p2569
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-7-2569-2010