White on green: under-snow microbial processes and trace gas fluxes through snow,Niwot Ridge,Colorado Front Range |
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Authors: | Mark W Williams Detlev Helmig Peter Blanken |
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Institution: | (1) Institute of Arctic and Alpine Research, University of Colorado at Boulder, UCB 450, Boulder, CO 80309, USA;(2) Department of Geography, University of Colorado at Boulder, UCB 260, Boulder, CO 80309, USA |
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Abstract: | The importance of snow and related cryospheric processes as an ecological factor has been recognized since at least the beginning
of the twentieth century. Even today, however, many observations remain anecdotal. The research to date on cold-lands ecosystems
results in scientists being unable to evaluate to what extent changes in the cryosphere will be characterized by abrupt changes
in local and global biogeochemical cycles, and how these changes in seasonality may affect the rates and timing of key ecological
processes. Studies of gas exchanges through snow have revealed that snow plays an important role in modulating wintertime
soil biogeochemical processes, and that these can be the driving processes for gas exchange at the snow surface. Previous
research has primarily focused on carbon dioxide, and resulted from episodic experiments at a number of snow-covered sites.
Here we report new insights from several field sites on Niwot Ridge in the Colorado Rocky Mountains, including a dedicated
snow gas flux research facility established at the 3340 m Soddie site. A novel in situ experimental system was developed at
this site to continuously sample trace gases from above and within the snowpack for the duration of seasonal snow cover. The
suite of chemical species investigated includes carbon dioxide, nitrous oxide, nitrogen oxides, ozone, and volatile inorganic
and organic gases. Wintertime measurements have been supplemented by soil chamber experiments and eddy covariance measurements
to allow assessment of the contribution of wintertime fluxes to annual biogeochemical budgets. This research has resulted
in a plethora of new insight into the physics of gas transport through the snowpack, and the magnitude and the chemical and
biogeochemical processes that control fluxes at the soil-snowpack and the snow-atmosphere interface. This article provides
an overview of the history and evolution of this research, and highlights the findings from the ten articles that constitute
this special issue. |
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Keywords: | Snow Winter Microbes Respiration Isotopes Carbon dioxide Nitrous oxide Nitrogen oxides Volatile inorganic and organic gases |
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