Abstract
High concentrations of CO2 in soil air affect subsurface water quality and weathering reactions; however, few simple methods have been proposed for the collection of soil air from deep soils. Therefore, we have developed a gas sampler that enabled soil air collection and soil temperature measurement at several depths using commercially and reasonably available materials. The sampler was then used at a headwater hillslope that had a thick soil layer (a maximum depth of approximately 5 m). The soil temperature showed typical seasonal changes, whereas the CO2 concentration in soil air reached the maximum and formed a peak near the ground surface in summer. The depth of the peak then moved downward from autumn to winter. The sampler developed in this study can be used to clarify the characteristics of CO2 dynamics in deep soils and its effect on groundwater quality and basal weathering.
