High nitrous oxide production from thawing permafrost

[OKIsItJustMe]

http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo803.html

Letter abstract

Nature Geoscience
Published online: 4 April 2010 | doi:10.1038/ngeo803

High nitrous oxide production from thawing permafrost

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Permafrost soils contain nearly twice as much carbon as the atmosphere1. When these soils thaw, large quantities of carbon are lost, mainly in the form of methane and carbon dioxide. In contrast, thawing is thought to have little impact on nitrous oxide emissions, which remain minimal following the summer thaw4. Here, we examined the impact of thawing on nitrous oxide production in permafrost cores collected from a heath site and a wetland site in Zackenberg, Greenland. Rates of nitrous oxide production in the heath soil were minimal, regardless of the hydrological conditions. Although rates of nitrous oxide production in the wetland soil were low following thawing, averaging 1.37 μg N h−1 kg−1, they were 18 μg N h−1 kg−1 for permafrost samples following thawing, drainage and rewetting with the original meltwater. We show that 31% of the nitrous oxide produced after thawing and rewetting a 10-cm permafrost core—equivalent to 34 mg N m−2 d−1—was released to the atmosphere; this is equivalent to daily nitrous oxide emissions from tropical forests on a mean annual basis. Measurements of nitrous oxide production in permafrost samples from five additional wetland sites in the high Arctic indicate that the rates of nitrous oxide production observed in the Zackenberg soils may be in the low range.

http://uk.reuters.com/article/idUKTRE63311Z20100404

Arctic thaw frees overlooked greenhouse gas: study

Sun Apr 4, 2010 7:26pm BST

OSLO (Reuters) - Thawing permafrost can release nitrous oxide, also known as laughing gas, a contributor to climate change that has been largely overlooked in the Arctic, a study showed on Sunday.

The report in the journal Nature Geoscience indicated that emissions of the gas surged under certain conditions from melting permafrost that underlies about 25 percent of land in the Northern Hemisphere.

Emissions of the gas measured from thawing wetlands in Zackenberg in eastern Greenland leapt 20 times to levels found in tropical forests, which are among the main natural sources of the heat-trapping gas.

"Measurements of nitrous oxide production permafrost samples from five additional wetland sites in the high Arctic indicate that the rates of nitrous oxide production observed in the Zackenberg soils may be in the low range," the study said.

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