Transfer of CO2 from soil to karst underground atmospheres
Acronym: COSKA
Competition title: Obzor 2020 MSCA
Funding: Horizon 2020
AFZ role: coordinator
Start date: 2024/02/01
End date: 2026/07/31
Abstract
Global warming, caused by the anthropogenic increase in atmospheric CO2, is one of the major challenges that civilizations are facing. Due to their extension, karst regions have a significant contribution to the global CO2 budget, although it is unclear if they act as sinks or sources of CO2, because specific processes affecting underground CO2 fluxes are poorly understood. Most of the soil CO2 is emitted to the atmosphere through efflux, although a fraction of it propagates downwards increasing its concentration with depth. Spot measurements in wells or narrow cracks inside caves confirm that most of the underground CO2 concentrations are higher than in soils. Caves, where most underground CO2 measurements are available, are not representative of the vadose zone atmosphere dynamics because of its forced ventilation. Although decay of dissolved organic matter in vadose water is a source of CO2, this limited process alone cannot explain the exceptionally high CO2 concentrations measured in deep karst environments. Furthermore, isotope analyses exclude deep crust sources of CO2 in most cases, keeping the mystery of the high concentrations of underground karst CO2.
The goal of this project is to explore the variability of CO2 concentration of karst underground environments and establish its relationship with the soil CO2 source. Using novel techniques, coupled soil and karst vadose zone CO2 concentrations will be continuously monitored to identify the processes and dynamics of CO2 in karst (aside from caves) and to explore if natural processes could be impacted to increase the CO2 sequestration in karst. The research is conducted in Eagle Cave, Ávila (Spain) as a paradigmatic location (40°9′15′′ N, 5°4′20′′W).
Leaders
Assoc. Prof. Kristina Krklec, PhD
University of Zagreb Faculty of Agriculture