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Filters: Tags: Biogeochemistry (X) > Types: Journal Citation (X) > partyWithName: Chowanski, Kurt (X)

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An experimental system for sampling trace gas fluxes through seasonal snowpack was deployed at a subalpine site near treeline at Niwot Ridge, Colorado. The sampling manifold was in place throughout the entire snow-covered season for continuous air sampling with minimal disturbance to the snowpack. A series of gases (carbon dioxide, water vapor, nitrous oxide, nitric oxide, ozone, volatile organic compounds) was determined in interstitial air withdrawn at eight heights in and above the snowpack at ~hourly intervals. In this paper, carbon dioxide data from 2007 were used for evaluation of this technique. Ancillary data recorded inlcuded snow physical properties, i.e., temperature, pressure, and density. Various vertical...
The soil emission rates (fluxes) of nitrous oxide (N2O) and nitrogen oxides (NO + NO2 = NOx) through a seasonal snowpack were determined by a flux gradient method from near-continuous 2-year measurements using an automated system for sampling interstitial air at various heights within the snowpack from a subalpine site at Niwot Ridge, Colorado. The winter seasonal-averaged N2O fluxes of 0.047-0.069 nmol m-2 s-1 were ~15 times higher than observed NOx fluxes of 0.0030-0.0067 nmol m-2 s-1. During spring N2O emissions first peaked and then dropped sharply as the soil water content increased from the release of snowpack meltwater, while other gases, including NOx and CO2 did not show this behavior. To compare and contrast...
Fluxes of CO2 during the snow-covered season contribute to annual carbon budgets, but our understanding of the mechanisms controlling the seasonal pattern and magnitude of carbon emissions in seasonally snow-covered areas is still developing. In a subalpine meadow on Niwot Ridge, Colorado, soil CO2 fluxes were quantified with the gradient method through the snowpack in winter 2006 and 2007 and with chamber measurements during summer 2007. The CO2 fluxes of 0.71 ?mol m?2 s?1 in 2006 and 0.86 ?mol m?2 s?1 in 2007 are among the highest reported for snow-covered ecosystems in the literature. These fluxes resulted in 156 and 189 g C m?2 emitted over the winter, ~30% of the annual soil CO2 efflux at this site. In general,...