Elaborazione della mappa del degassamento profondo di CO2 nella regione alpina partendo da dati aperti e GIS open source

Carbon migrates within a closed system consisting of atmosphere, oceans, biosphere and landmass. Earth's climate is linked to atmospheric CO2 concentration, so it's critical the estimation of CO2 involved in the processes. Chiodini et al. (2004) presented the map of CO2 degassing for central and southern Italy, where CO2 released is globally significant, ~ 10% of the total CO2 discharge from subaerial volcanoes (Kerrick, 2001). There is an underestimation on CO2 released by the Earth: processes of CO2 degassing affect tectonically active areas and metamorphic environments. Here we show the map of deep-CO2 degassing of Alps, starting from a database (DB) of more than 1000 chemical analyses of springs from open data (scientific publications, books, web sites...) and new fieldworks. The DB was prepared using open source software: GRASS (Neteler & Mitasova, 2008), QGIS, and PostgreSQL linked with PostGIS. Using a publicly available software - PHREEQC (Parkhurst, 1999), for each point of the DB we estimated the total dissolved inorganic carbon (TDIC). We considered that (Chiodini et al., 2000): TDIC = Ccarb + Cinf + Cdeep, (Ccarb = C from carbonate dissolution, Cinf = C form rainwater infiltrating in the soil, Cdeep = deeply derived CO2). Through mass-balance equations we estimated the mean amount of Cinf. Ccarb was estimated for sprigs hosted in carbonate aquifers, localized by a simplified geo-lithological map of Alps elaborated trough publicly available geological maps and open sources GIS (GRASS and QGIS). Using values of effective infiltration of alpine region estimated by open data and open source software, we prepared the CO2 degassing map using a publicly available software - GSLIB (Deutsch and Journel, 1998). The results show that using open data and open source GIS software, is possible to elaborate the map of deep-CO2 degassing of Alps, useful to localize areas of high CO2 degassing where more detailed investigations shall be performed. References Chiodini, G., Frondini, F., Cardellini, C., Parello, F., Peruzzi, L. 2000 "Rate of diffuse carbon dioxide Earth degassing estimated from carbon balance of regional aquifers: The case of central Appennini, Italy". Journal of Geophysical Research, 105, 8423-8434 Chiodini, G., Cardellini, C., Amato, A., Boschi, E., Caliro, S., Frondini, F., Ventura, G. 2004 "Carbon dioxide Earth degassing and seismogenesis in central and southern Italy". Geophysical Research Letters, 31, L07615 Deutsch C. V., Journel A. G., 1988 "GSLIB: Geostatistical Software Library and User Guide". 369 pp, Ed Oxford Univ. Press, New York Neteler, M., Mitasova, H., 2008 "Open Source GIS. A GRASS GIS approach. Third edition". Springer, New York Kerrick, D.M., 2001 "Present and past nonanthropogenic CO2 degassing from the solid Earth". Reviews of Geophysics, 39 (4), 565-585 Parkhurst, D.L., Appelo C.A.J., 1999 "User's guide to PHREEQC (version 2), a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations". Ed. U.S. Geological Survey, 312 pp. Reston, Va