Simulating and Quantifying Multiple Natural Subsea CO2 Seeps at Panarea Island (Aeolian Islands, Italy) as a Proxy for Potential Leakage from Subseabed Carbon Storage Sites

Carbon dioxide (CO 2 ) capture and storage (CCS) has been discussed as a potentially significant mitigation option for the ongoing climate warming. Natural CO 2 release sites serve as natural laboratories to study subsea CO 2 leakage in order to identify suitable analytical methods and numerical models to develop best-practice procedures for the monitoring of subseabed storage sites. We present a new model of bubble (plume) dynamics, advection-dispersion of dissolved CO 2 , and carbonate chemistry. The focus is on a medium-sized CO 2 release from 294 identified small point sources around Panarea Island (South-East Tyrrhenian Sea, Aeolian Islands, Italy) in water depths of about 40-50 m. This study evaluates how multiple CO 2 seep sites generate a temporally variable plume of dissolved CO 2 . The model also allows the overall flow rate of CO 2 o be estimated based on field measurements of pH. Simulations indicate a release of ∼6900 t y -1 of CO 2 for the investigated area and highlight an important role of seeps located at >20 m water depth in the carbon budget of the Panarea offshore gas release system. This new transport-reaction model provides a framework for understanding potential future leaks from CO 2 storage sites.