Premium
Snowpack fluxes of methane and carbon dioxide from high Arctic tundra
Author(s) -
Pirk Norbert,
Tamstorf Mikkel P.,
Lund Magnus,
Mastepanov Mikhail,
Pedersen Stine H.,
Mylius Maria R.,
Parmentier FransJan W.,
Christiansen Hanne H.,
Christensen Torben R.
Publication year - 2016
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2016jg003486
Subject(s) - snowpack , tundra , permafrost , snow , atmospheric sciences , environmental science , carbon dioxide , atmosphere (unit) , methane , arctic , growing season , flux (metallurgy) , snowmelt , greenhouse gas , hydrology (agriculture) , geology , chemistry , geomorphology , ecology , oceanography , meteorology , geography , geotechnical engineering , organic chemistry , biology
Measurements of the land‐atmosphere exchange of the greenhouse gases methane (CH 4 ) and carbon dioxide (CO 2 ) in high Arctic tundra ecosystems are particularly difficult in the cold season, resulting in large uncertainty on flux magnitudes and their controlling factors during this long, frozen period. We conducted snowpack measurements of these gases at permafrost‐underlain wetland sites in Zackenberg Valley (NE Greenland, 74°N) and Adventdalen Valley (Svalbard, 78°N), both of which also feature automatic closed chamber flux measurements during the snow‐free period. At Zackenberg, cold season emissions were 1 to 2 orders of magnitude lower than growing season fluxes. Perennially, CH 4 fluxes resembled the same spatial pattern, which was largely attributed to differences in soil wetness controlling substrate accumulation and microbial activity. We found no significant gas sinks or sources inside the snowpack but detected a pulse in the δ 13 C‐CH 4 stable isotopic signature of the soil's CH 4 source during snowmelt, which suggests the release of a CH 4 reservoir that was strongly affected by methanotrophic microorganisms. In the polygonal tundra of Adventdalen, the snowpack featured several ice layers, which suppressed the expected gas emissions to the atmosphere, and conversely lead to snowpack gas accumulations of up to 86 ppm CH 4 and 3800 ppm CO 2 by late winter. CH 4 to CO 2 ratios indicated distinctly different source characteristics in the rampart of ice‐wedge polygons compared to elsewhere on the measured transect, possibly due to geomorphological soil cracks. Collectively, these findings suggest important ties between growing season and cold season greenhouse gas emissions from high Arctic tundra.