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Methanogenic archaeal community in the sediment of an artificially partitioned acidic bog lake (2002)

Chan, On Chim ; Wolf, Matthias ; Hepperle, Dominik ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology ecology 42 (2002), S. 0

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ISSN: 1574-6941

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The methanogenic archaeal communities in the sediment of two basins of an artificially partitioned acidic bog lake were studied. In the northeast basin, which was separated from a peat bog, a high methane production rate was measured only in the upper layers of the sediment. In contrast, methane production was detected at various depths of the sediment in the southwest basin, which continuously receiving humic acids from the bog. Ten bands were observed in the denaturing gradient gel electrophoresis (DGGE) fingerprint of the 16S rDNA archaeal amplicons from the NE basin top (0–5 cm) sediment layer, which reflected the presence of at least 10 ribotypes. Seventy clones of the 16S rDNA amplicons were obtained from the NE basin top sediment layer, and were grouped into 10 operational taxonomy units (OTUs) according to their positions on the DGGE gel. Seven of these OTUs could be matched with the bands of the community fingerprint. Phylogenetic analyses indicated that the sequences clustered into three groups: five of the OTUs were related to Methanosaeta, four OTUs to Methanomicrobiales and one OTU to Methanobacterium. Among the OTUs, sequences with high similarities (〉96%) were retrieved. The sequence data suggested that the diversity of the methanogenic archaeal community was limited. Bands corresponding to those three phylogenetic groups were found in the DGGE fingerprints of both NE and SW basins, which reflected the presence of the same dominant methanogenic archaeal groups in both basins. However, differences in the distribution of the ribotypes that had high 16S rRNA sequence identities were observed in the fingerprints between the two basins at various depths. The microdiversity decreased along the sediment depth in the NE basin, and vice versa in the SW basin. The greater variety of the archaeal ribotypes, apparently, correlated with the higher methanogenesis rate.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6941.2002.tb01001.x

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Fluxes of methane and carbon dioxide from a small productive lake to the atmosphere (2000)

Casper, Peter ; Maberly, Stephen C. ; Hall, Grahame H. ; [et al.]

Springer

Biogeochemistry 49 (2000), S. 1-19

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ISSN: 1573-515X

Keywords: carbon dioxide ; diffusion ; ebullition ; emission ; freshwater ; hypertrophic lakes ; methane

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Geosciences

Notes: Abstract The fluxes of CH4 and CO2 to the atmosphere, and the relative contributions of ebullition and molecular diffusion, were determined for a small hypertrophic freshwater lake (Priest Pot, UK) over the period May to October 1997. The average total flux of CH4 and CO2 (estimated from 7 sites on the lake) was approximately 52 mmol m−2 d−1 and was apportioned 12 and 40 mmol m−2 d−1 toCH4 and CO2 respectively. Diffusion across the air-water interface accounted for the loss of 0.4and 40 mmol m−2 d−1 of CH4 and CO2 respectively whilst the corresponding figures for ebullition losses were 12.0 (CH4) and 0.23 (CO2) mmol m−2 d−1. Most CH4 (96%) was lost by ebullition, and most CO2 (99%) by diffusive processes. The ebullition of gas, measured at weekly intervals along a transect of the lake, showed high spatial and temporal variation. The CH4 content of the trapped gas varied between 44 and 88% (by volume) and was highest at the deepest points. Pulses of gas ebullition were detected during periods of rapidly falling barometric pressure. Therelevance of the measurements to global estimates ofcarbon emission from freshwaters are discussed.