Variations in carbon dioxide across an Arctic snowpack during spring

Carbon dioxide concentration profiles across the snowpack were monitored during spring of 1971 near Barrow, Alaska. Subnivean CO2 was continually higher than ambient CO2 throughout the period May 1-June 9. Twice during this period subnivean concentrations at the ground surface under the snow increased rapidly reaching values greater than 800 and 2100 ppm. These concentrations appeared to result from the release of gas pockets contained during fall freeze-up of the active soil layer. Maximum concentration differentials of atmospheric CO2 across the snowpack approached 2000 ppm with an average for the 40-day period greater than 150 ppm. Tundra soils of the arctic coastal plain of Alaska are apparently CO2 sources throughout the year even when temperatures are too low for significant biological activity. The CO2 from biological sources expressed by freezing the soil solution evidently leaks to the subnivean environment throughout the winter months. In spring, thermally induced physical processes may release the contained gases suddenly.