CENPERM seminar – University of Copenhagen

CENPERM seminar

Methane oxidation in the dry mineral soils of Greenland.
Ludovica D'imperio, Postdoc, CENPERM

The distribution of dry tundra and barren soils covers the majority of the ice-free areas of Greenland and an increasing number of studies have demonstrated that these areas are significant sinks of atmospheric methane (CH4). Soil water content (SWC) is a main driver controlling CH4 uptake rates in upland Arctic soils.

We hypothesized that the drier the soil hydrological regime the larger the response of CH4 oxidation to increased SWC. Hence, we expect that the response of potential net CH4 oxidation in upland tundra soils to SWC increase is inversely proportional to the mean annual precipitation.

To test this hypothesis we investigated the potential net CH4 oxidation capacity of upland tundra and barren soil microcosms at field and elevated SWC conditions in a laboratory experiment. Intact soil samples (0-5 cm) were collected at 11 sites across a latitudinal gradient ranging from the low Arctic in the area of Nuuk (64°) to the high Arctic at Kap Morris Jesup (83°) in July 2016. Within this latitudinal gradient is nested a soil hydrological gradient with decreasing mean annual precipitation by latitude. The intact soil cores were first incubated at 7°C and field SWC (0.20 – 28 % vol.) in closed jars. Subsequently, the soil water content (SWC) of the samples was adjusted to 10-15 vol % for all sites as this has been shown to be optimal SWC for CH4 oxidation in similar upland tundra soils of Disko Island. All gas samples were analyzed using an Ultra-portable Greenhouse Gas Analyzer.

Preliminary results showed consistent net CH4 oxidation across sites, also after SWC manipulation; hence emphasized the strong potential role that these largely distributed dry areas of Greenland may have in counterbalancing CH4 emissions from the wetlands

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