The Panarea natural CO2 seeps: fate and impact of the leaking gas (PaCO2)on marine ecosystems

2012-04-02 12:59 by Anja Reitz

The oceanographic survey PaCO2, performed aboard RV URANIA from 27 July – 01 August 2011, was conducted in and around the area of Panarea Island (Italy) where natural CO2 seeps from the sea floor into the overlying water column. This work was conducted in the context of understanding the feasibility and safety of CO2 capture and sub-seabed storage (CCS), which has been proposed as a mitigation technique against human induced climate change. Therefore, the goals of PaCO2 were to investigate the gas migration pathways in the subsurface, to test monitoring technologies, to track the fate of the CO2 as it is transferred to the water and potentially to the atmosphere, and to examine possible impacts of the enriched CO2 concentrations on water chemistry and the local ecosystem.

The ship-time, travel and logistic costs for PaCO2 were funded by the EU infrastructure project “EUROFLEETS”, while research costs were met within the Seventh Framework Programme projects “ECO2” and “RISCS”. The institutions that participated in PaCO2 are involved either in both projects (University of Rome, OGS), in ECO2 (GEOMAR, IOW), or in RISCS (CERTH). Based on the different goals of the two projects, work conducted on monitoring, migration and impact was accordingly applied to ECO2 and RISCS. In addition, four undergraduate and Masters level students participated in the cruise (three of which were women), obtaining valuable training and experience.

The methods applied included: regional seismic surveys to study gas migration pathways; high-resolution acoustic surveys to map bubble plumes; air-sea CO2-exchange survey to investigate gas transfer rates; water column sampling for biological and chemical impact studies; microbial incubation experiments to examine biological adaptation and stress indicators; high resolution temperature profiling to determine bubble plume dynamics; continuous monitoring of currents together with dissolved CO2 concentrations; continuous monitoring for heat and oxygen flux eddy correlation; and a number of exploratory dives with RV URANIA’s ROV.

While the substantial data sets collected during the cruise are still being processed and analyzed, the important initial findings include the discovery of new seeps in deep water outside of the well-known, shallow seep area, the first ever deployment of an eddy correlation system in a CO2 bubble site, detailed mapping of CO2 flux from the water to the atmosphere, and important indications of the impact of CO2 on the local aquatic biological system. All of the research goals detailed within the PaCO2 proposal were realized, and as the analyses approach the final stages, these results will be published within framework of the RISCS and ECO2 projects.

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