Emission Flux of Soil Carbon Dioxide in Hydrothermal Area of the Tatun Volcano Group, Northern Taiwan

Tatun Volcano Group (TVG) is located at north of Taiwan and considered as a potential active volcano. Hydrothermal activity occurs actively along the Chinshan Fault in this area. Based on the numbers of active fumarole/venting in the area, we can classify TVG into three major groups: (I) active hydrothermal area with major fumaroles (e.g., Da-you-keng, DYK), (II) active hydrothermal area without major fumaroles (e.g., Geng-tze-ping, GTP and Liu-huang-ku, LHK), and (III) non-active hydrothermal area (e.g., Tatun Natural Park, TNP). In this study we measure the soil CO2 flux in the representative areas of TVG by closed-chamber method. Soil CO2 flux can be obtained ca. 537 g m-2 day-1 at GTP, ca. 122 g m-2 day-1 at DYK, and ca. 25 g m-2 day-1 at TNP, respectively. We can compare these values with previous measured data of soil CO2 flux at LHK, 659 g m-2 day-1, which is close to the value of GTP but much higher than that of DYK. The results show that the emission flux of soil CO2 at group-I area (DYK) is much lower than the value of group-II area (GTP and LHK). It could be explained that most CO2 gas can release to the surface through the highly permeable conduit/pathway (fumaroles) at group-I area and hence, less emission flux of soil CO2 can be observed. Furthermore, the total amount of 111 t day-1 of soil CO2 in the hydrothermal area of TVG can be estimated. It is close to the values from other active hydrothermal areas in the world.