Article

Biogeochemistry and microbial ecology of methane oxidation in anoxic environments: a review

Scripps Institution of Oceanography, University of California at San Diego, 92093-0202, USA.
Antonie van Leeuwenhoek (Impact Factor: 2.14). 09/2002; 81(1-4):271-82. DOI: 10.1023/A:1020587206351
Source: PubMed

ABSTRACT Evidence supporting a key role for anaerobic methane oxidation in the global methane cycle is reviewed. Emphasis is on recent microbiological advances. The driving force for research on this process continues to be the fact that microbial communities intercept and consume methane from anoxic environments, methane that would otherwise enter the atmosphere. Anaerobic methane oxidation is biogeochemically important because methane is a potent greenhouse gas in the atmosphere and is abundant in anoxic environments. Geochemical evidence for this process has been observed in numerous marine sediments along the continental margins, in methane seeps and vents, around methane hydrate deposits, and in anoxic waters. The anaerobic oxidation of methane is performed by at least two phylogenetically distinct groups of archaea, the ANME-1 and ANME-2. These archaea are frequently observed as consortia with sulfate-reducing bacteria, and the metabolism of these consortia presumably involves a syntrophic association based on interspecies electron transfer. The archaeal member of a consortium apparently oxidizes methane and shuttles reduced compounds to the sulfate-reducing bacteria. Despite recent advances in understanding anaerobic methane oxidation, uncertainties still remain regarding the nature and necessity of the syntrophic association, the biochemical pathway of methane oxidation, and the interaction of the process with the local chemical and physical environment. This review will consider the microbial ecology and biogeochemistry of anaerobic methane oxidation with a special emphasis on the interactions between the responsible organisms and their environment.

3 Followers
 · 
208 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study presents geochemical evidence for biogenic methane formation (methanogenesis) in the shallow sediments of the oligotrophic SE Mediterranean continental shelf at water depths between 46 and 88 m. Depth-profiles of methane concentrations and related chemical parameters such as dissolved sulfate, dissolved inorganic carbon (DIC), and the stable carbon isotope composition of DIC and methane (δ13CDIC, δ13CCH4, respectively) were measured in six sediment cores (each 4.2–5.4 m long) in order to characterize the processes that involve methane production and decomposition. All the sediment cores reached the consumption depth of the entire sulfate pool and the in-situ microbial methane production (methanogenesis) zone. Methane concentrations reached saturation levels in one of the cores, but not in the others, probably because the zone of maximum methanogenesis was at a greater depth. Although the sediments exhibit a low TOC content of ~1%, the biogenic methane formation indicates a relatively high organic carbon lability capable of sustaining all redox microbial activity potential. Anaerobic oxidation of methane (AOM) was also evident in the sulfate–methane transition zone, showing a distinct isotope signature in diffusion limited conditions.
    Continental Shelf Research 04/2015; 101. DOI:10.1016/j.csr.2015.04.001 · 2.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Multiple-sulfur isotope compositions (32S, 33S, 34S and 36S) were analyzed for paired carbonate-associated sulfate (CAS) and disseminated pyrite (PY) from the ∼1.6-Ga Gaoyuzhuang Formation of the North China Craton to reconstruct the history of sulfate levels in Proterozoic oceans. The 200-m-thick study interval yielded relatively constant values for δ34SCAS (13.0 ± 1.8‰), δ34SPY (8.0 ± 2.3‰), and Δ34SCAS-PY (∼5‰), as well as relatively constant Δ33S (0 ± 0.05‰) and Δ36S (0.35 ± 0.15‰) for both CAS and pyrite. Limited variation in δ34SPY and slightly lower Δ33S of pyrite relative to CAS suggest water-column precipitation of pyrite. Limited fractionation of sulfur during microbial sulfate reduction (as documented by Δ34SCAS-PY) implies low seawater sulfate concentrations in the early Mesoproterozoic ocean. We quantitatively constrained paleo-seawater [SO42−] using a novel modeling approach based on measured values of Δ34SCAS-PY and ∂δ34SCAS/∂t(max). For the study unit, Δ34SCAS-PY is 5.4 ± 1.4‰ (n = 17), and ∂δ34SCAS/∂t(max) is 6.8–34‰ Myr−1 based on sedimentation rates of 30–150 m Myr−1. These data indicate early Mesoproterozoic seawater [SO42−] of ∼<0.1 to 0.35 mM (with a maximum possible concentration of 1.8 mM), a range that is lower and more tightly constrained than earlier estimates for the Mesoproterozoic. Compilation of published data suggests that low seawater sulfate concentrations began about ∼1.7 Ga and persisted until at least the mid-Mesoproterozoic (∼1.4 Ga), documenting a distinct early Mesoproterozoic perturbation in ocean chemistry that may have been related to a decline in atmospheric pO2 after Great Oxidation Event I.
    Precambrian Research 03/2015; 258. DOI:10.1016/j.precamres.2014.12.014 · 6.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present the first universal calibration of the clumped isotope thermometer for calcites of various mineralizing types. These are an eggshell of an ostrich, a tropical bivalve, a brachiopod shell, cold seep carbonate, and three foraminifera samples that grew between 9 and 38 °C. CaCO3 was digested at 90 °C using a common acid bath. Considering a difference in phosphoric acid fractionation factors between reaction at 25 and 90 °C of 0.069‰ (Guo et al., 2009), the function between growth temperature T and the excess of 13C-18O bonds in the evolved CO2 is expressed by a linear regression between 1/T2 and absolute Δ47 (R2 = 0.9915):

Preview

Download
6 Downloads
Available from