CCS (Carbon Capture and Storage) is a technical process to capture CO2 from industrial and energy-based sources, to transfer and sequestrate impressed CO2 in geological formations, oceans, or mineral carbonates. However, potential CO2 leakage exists and causes environmental problems. Thus, this study was conducted to analyze the spatial and temporal variations of CO2 fluxes and concentrations after artificial CO2 release. The Environmental Impact Evaluation Test Facility (EIT) was built in Eumseong, Korea in 2015. Approximately 34kg CO2 /day/zone were injected at Zones 2, 3, and 4 among the total of 5 zones from October 26 to 30, 2015. CO2 fluxes were measured every 30 minutes at the surface at 0m, 1.5m, 2.5m, and 10m from the CO2 releasing well using LI-8100A until November 13, 2015, and CO2 concentrations were measured once a day at 15cm, 30cm, and 60cm depths at every 0m, 1.5m, 2.5m, 5m, and 10m from the well using GA5000 until November 28, 2015. CO2 flux at 0m from the well started increasing on the fifth day after CO2 release started, and continued to increase until November 13 even though the artificial CO2 release stopped. CO2 fluxes measured at 2.5m, 5.0m, and 10m from the well were not significantly different with each other. On the other hand, soil CO2 concentration was shown as 38.4% at 60cm depth at 0m from the well in Zone 3 on the next day after CO2 release started. Soil CO2 was horizontally spreaded over time, and detected up to 5m away from the well in all zones until CO2 release stopped.
Also, soil CO2 concentrations at 30cm and 60cm depths at 0m from the well were measured similarly as 50.6±25.4% and 55.3±25.6%, respectively, followed by 30cm depth (31.3±17.2%) which was significantly lower than those measured at the other depths on the final day of CO2 release period.
Soil CO2 concentrations at all depths in all zones were gradually decreased for about 1 month after CO2 release stopped, but still higher than those of the first day after CO2 release stared. In conclusion, the closer the distance from the well and the deeper the depth, the higher CO2 fluxes and concentrations occurred. Also, long-term monitoring should be required because the leaked CO2 gas can remains in the soil for a long time even if the leakage stopped.