Modelling CO2 dynamic in the karst critical zone

An essential component of the global carbon cycle is the carbonate pool hosted in the karst critical zone. In fact, carbonate landscapes comprises around 15% of the Earth's land surface and karst ecosystems are one of the main carbon sinks in the terrestrial environment, not only because carbon dioxide (CO2) of biogenic origin is stored inside the caves, but above all the karst development itself is capable of sequestering atmospheric CO2, seasonally moves it and occasionally unbalances its release. Moreover, many karst processes have a shorter response-time to impact of global change that has not yet been sufficiently addressed by the carbon cycle models. Even though the weathering of carbonate rocks is recognized as part of the C-cycle, the contribution of karst critical zone to the C-budget remains mostly indeterminate. Karst studies therefore play a non-negligible role in understanding the global carbon cycle in terms of climate change. One of the methods for estimating the volumes involved in the regulation of this cycle in carbonate environments is the analysis of the carbon flux between underground air masses and the atmosphere. In this study, the modelling of CO2 dynamics has been performed in a Sardinian karst area at the geosphere-atmosphere interface based on data provided by a continuous monitoring system optimized for the measurement of CO2 concentrations in cave atmosphere with the aim to improve the knowledge of its migration in response to climate change.