Source: http://www.asmscience.org/content/book/10.1128/9781555817183.chap9
Timestamp: 2019-04-21 02:19:53+00:00

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Terrestrial and submarine permafrost is identified as one of the most vulnerable carbon pools on Earth. In some areas, permafrost comprises upwards of 80% ice in the form of large features, such as massive ice sheets many kilometers in length; or on smaller scales, such as ice wedges and ice lenses, and as ice that fills soil pore space. Residual pockets of seawater, from the subsidence of the polar ocean, exist as saturated, salt-rich permafrost environments known as salt lenses or cryopegs. All of these permafrost features sustain microbial communities that contribute to carbon cycling in polar regions. The way in which gas is released from permafrost, i.e., the rate and pathway, determines the ratio of methane and carbon dioxide emitted to the atmosphere. This chapter describes the different carbon pools, carbon fluxes, and freeze-thaw stresses related to microbial activities. It then examines methane-cycling communities in Arctic active-layer and permafrost environments. The fast recovery of the microbial activity during spring suggests that carbon mineralization in thawing Arctic sediment may rapidly respond to warming, resulting in substantial changes in microbial carbon cycling and growth of microbial populations. Environmental sequences from the Laptev Sea coast consist of four specific permafrost clusters. It was hypothesized that these clusters comprise methanogenic Archaea with a specific physiological potential to survive under harsh environmental conditions. A first study on submarine permafrost of the Laptev Sea shelf demonstrated that intact DNA was extractable from late Pleistocene permafrost deposits with an age of up to 111,000 years.
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a The references cited in the table may be found in the List of Prokaryotic Names with Standing in Nomenclature (http://www.bacterio.cict.fr/index.html).
a The references cited in the table may be found in the List of Prokaryotic Names with Standing in Nomenclature ( http://www.bacterio.cict.fr/index.html).

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