Karst cave, a seasonal carbon dioxide exchanger: an example of Sloup-Šošůvka Caves (Moravian Karst)

Part of the gaseous carbon dioxide (CO 2 ) produced in karst soils / epikarst is transported into underground cavities / caves during the growing season by advective flux, diffusive flux, and flux associated with degassing of seeping water. In dynamic caves, accumulated CO 2 is released into the outside atmosphere during the autumn-winter period through advective flux associated with ventilation of the cave in the upward airflow mode. This case study from the Moravian Karst (MK) showed that the net weight of CO 2 released annually from the Sloup-Šošůvka Caves (total volume of 131,580 m 3 and a total area of 17,950 m 2 ) into the external atmosphere was 348 kg. Extrapolating this value to all known MK caves (area about 352,080 m 2 ) yielded a total of CO 2 flux of 6820 kg yr −1 . This flux is representing only 0.024‰ of the annual soil respiration from entire MK area (about 2.81 × 10 8 kg CO 2 yr −1 ).