Samples were collected from a hollow probe at 0. 75-m depth and from a plastic hemisphere on the ground surface. Soil temperature, air temperature, percent humidity, and barometric pressure were also measured. Soil moisture was measured only indirectly as amount of rain or snowfall. Higher concentrations of CO//2 in both the 0. 75-m and surface samples correlated with higher soil and air temperatures, which suggests that CO//2 was produced by bacteria. Lower concentrations of helium in both the 0. 75-m and surface samples correlated with higher soil and air temperatures. Rain and snowfall appear to affect helium concentrations.
Additional publication details
EFFECTS OF METEOROLOGICAL CHANGES ON CONCENTRATIONS OF HELIUM, CARBON DIOXIDE, AND OXYGEN IN SOIL GASES.