CO2 Degassing in Sicily (Central Mediterranean) as Inferred from Groundwater Composition

The circulation of groundwater is influenced by several factors, including permeability changes due to the dynamics of the stress field acting along tectonic discontinuities. Open faults can act as preferential pathways for the escape of crustal and subcrustal gases, such as CO2, towards the surface, allowing their chemical interaction with meteoric fluids. Here, we present the first map of dissolved CO2 partial pressure in the groundwater of Sicily, Italy. Based on the chemical analysis of 557 samples of groundwater, which were collected in wells and springs, we calculated the related CO2 partial pressure (PCO2) using PHREEQC software. The spatial distribution of the calculated PCO2 values highlights a general homogeneity at the regional scale, interrupted by positive anomalies linked to the main seismogenic or volcanic areas. Faults work as preferential escape pathways for deep CO2. The subsequent CO2–water–rock interaction determines the chemical composition of circulating water. As a consequence, groundwater composition can be successfully used to identify anomalous degassing areas.

[1]  I. Arienzo,et al.  Tracing the circulation of groundwater in volcanic systems using the 87Sr/86Sr ratio: Application to Mt. Etna , 2017 .

[2]  M. Camarda,et al.  Temporal and spatial correlations between soil CO2 flux and crustal stress , 2016 .

[3]  M. Liotta,et al.  Volcanic plume fingerprint in the groundwater of a persistently degassing basaltic volcano: Mt. Etna , 2016 .

[4]  Mario Locati,et al.  CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes , 2016 .

[5]  D. Luzio,et al.  A regional‐scale discontinuity in western Sicily revealed by a multidisciplinary approach: A new piece for understanding the geodynamic puzzle of the southern Mediterranean , 2015 .

[6]  M. Loddo,et al.  Active upper crust deformation pattern along the southern edge of the Tyrrhenian subduction zone (NE Sicily): Insights from a multidisciplinary approach , 2015 .

[7]  Alessandro Bonforte,et al.  Geological and geodetic constraints on the active deformation along the northern margin of the Hyblean Plateau (SE Sicily) , 2015 .

[8]  F. Guglielmino,et al.  Geodetic and geological evidence of active tectonics in south-western Sicily (Italy) , 2014 .

[9]  P. Fiannacca,et al.  Late Triassic tholeiitic magmatism in Western Sicily: A possible extension of the Central Atlantic Magmatic Province (CAMP) in the Central Mediterranean area? , 2014 .

[10]  M. Camarda,et al.  Magma-ascent processes during 2005–2009 at Mt Etna inferred by soil CO2 emissions in peripheral areas of the volcano , 2012 .

[11]  M. Liotta,et al.  Dissolved gases in brackish thermal waters: an improved analytical method , 2012 .

[12]  C. Cardellini,et al.  The geochemical signature caused by earthquake propagation in carbonate-hosted faults , 2011 .

[13]  M. Camarda,et al.  Long-term continuous monitoring of the dissolved CO2 performed by using a new device in groundwater of the Mt. Etna (southern Italy). , 2011, Water research.

[14]  P. Madonia,et al.  Chemical composition of precipitation at Mt. Vesuvius and Vulcano Island, Italy: volcanological and environmental implications , 2010 .

[15]  D. Hilton,et al.  The effects of volatile recycling, degassing and crustal contamination on the helium and carbon geochemistry of hydrothermal fluids from the Southern Volcanic Zone of Chile , 2009 .

[16]  G. Dongarrà,et al.  Geochemical characteristics of waters in mineralised area of Peloritani Mountains (Sicily, Italy) , 2009 .

[17]  C. Cardellini,et al.  Natural trace elements baselines and dissolved loads in groundwater from carbonate aquifers of central Italy , 2009 .

[18]  F. Frondini.  Geochemistry of regional aquifer systems hosted by carbonate-evaporite formations in Umbria and southern Tuscany (central Italy) , 2008 .

[19]  Maria Stella Giammarinaro,et al.  Ground motion phenomena in Caltanissetta (Italy) investigated by InSAR and geological data integration , 2008 .

[20]  G. D. Guidi,et al.  The migration of plate boundaries in SE Sicily: Influence on the large-scale kinematic model of the African promontory in southern Italy , 2008 .

[21]  Mauro Coltelli,et al.  Geological evolution of Mount Etna volcano (Italy) from earliest products until the first central volcanism (between 500 and 100 ka ago) inferred from geochronological and stratigraphic data , 2008 .

[22]  Fedora Quattrocchi,et al.  Insights into stress-induced variations in water chemistry , 2008 .

[23]  P. Madonia,et al.  Flow Changes and Geochemical Anomalies in Warm and Cold Springs Associated with the 1992–1994 Seismic Sequence at Pollina, Central Sicily, Italy , 2007 .

[24]  Paolo Baldi,et al.  Kinematics of the Western Africa-Eurasia plate boundary from focal mechanisms and GPS data , 2007 .

[25]  Luigi Marini,et al.  Geological Sequestration of Carbon Dioxide: Thermodynamics, Kinetics, and Reaction Path Modeling , 2006 .

[26]  M. Martelli,et al.  New insights into magma dynamics during last two eruptions of Mount Etna as inferred by geochemical monitoring from 2002 to 2005 , 2006 .

[27]  S. Inguaggiato,et al.  Chemical and Isotopic Composition of Waters and Dissolved Gases in Some Thermal Springs of Sicily and Adjacent Volcanic Islands, Italy , 2006 .

[28]  Salvatore Barba,et al.  Database of Individual Seismogenic Sources (version 3.0.2): A compilation of potential sources for earthquakes larger than M 5.5 in Italy and surrounding areas. , 2006 .

[29]  C. Federico,et al.  Trace metal modeling of groundwater-gas-rock interactions in a volcanic aquifer: Mount Vesuvius, Southern Italy , 2005 .

[30]  F. Italiano,et al.  Active geodynamics of the central Mediterranean Sea: Tensional tectonic evidences in western Sicily from mantle‐derived helium , 2005 .

[31]  I. Finetti,et al.  CROP PROJECT : Deep Seismic Exploration of the Central Mediterranean and Italy , 2005 .

[32]  G. Martinelli,et al.  Geochemical evidence of seismogenic‐induced anomalies in the dissolved gases of thermal waters: A case study of Umbria (Central Apennines, Italy) both during and after the 1997–1998 seismic swarm , 2004 .

[33]  Enrico Serpelloni,et al.  Convergence vs. retreat in Southern Tyrrhenian Sea: Insights from kinematics , 2004 .

[34]  F. Italiano,et al.  Evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at Mount Etna (Italy): Assessment of the magmatic reservoir pressure , 2003 .

[35]  M. Liotta.  Geochemical Processes Governing Groundwater Composition in North-Western Sicily: isotopic model and water rock interaction , 2003 .

[36]  B. Capaccioni,et al.  Hydrogeochemistry of groundwaters from carbonate formations with basal gypsiferous layers: an example from the Mt Catria–Mt Nerone ridge (Northern Appennines, Italy) , 2001 .

[37]  L. Marini,et al.  Use of stream sediment chemistry to predict trace element chemistry of groundwater. A case study from the Bisagno Valley (Genoa, Italy) , 2001 .

[38]  S. Inguaggiato,et al.  Hydrogeochemistry and stable isotopes of thermal springs: earthquake-related chemical changes along Belice Fault (Western Sicily) , 2001 .

[39]  L. Marini,et al.  Water-rock interaction in the Bisagno valley (Genoa, Italy): application of an inverse approach to model spring water chemistry , 2000 .

[40]  Giovanni Chiodini,et al.  Quantification of deep CO2 fluxes from Central Italy. Examples of carbon balance for regional aquifers and of soil diffuse degassing , 1999 .

[41]  F. D'amore,et al.  Geochemical and hydrogeological characterization of thermal springs in Western Sicily, Italy , 1998 .

[42]  L. Petronio,et al.  Crustal image of the Ionian basin and its Calabrian margins , 1996 .

[43]  S. Carbone,et al.  Main structural domains of the Central Mediterranean region and their Neogene tectonic evolution , 1994 .

[44]  R. Klusman,et al.  Soil gas and related methods for natural resource exploration , 1993 .

[45]  I. Moretti,et al.  Late cenozoic subduction complex of Sicily , 1990 .

[46]  J. Dewey,et al.  Kinematics of the western Mediterranean , 1989, Geological Society, London, Special Publications.

[47]  E. Stolper,et al.  Experimental determination of the solubility of carbon dioxide in molten basalt at low pressure , 1988 .

[48]  F. Ghisetti,et al.  Thin-skinned deformations of the western Sicily thrust belt and relationships with crustal shortening; mesostructural data on the Mt. Kumeta-Alcantara fault zone and related structures , 1984 .

[49]  H. Takeda,et al.  Origin of Hydrogen and Carbon Dioxide in Fault Gases and Its Relation to Fault Activity , 1983, The Journal of Geology.

[50]  I. Barnes,et al.  Tectonic relations of carbon dioxide discharges and earthquakes , 1980 .

[51]  J. J. Morgan,et al.  Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters , 1970 .

[52]  R. Garrels,et al.  Evaluation of irreversible reactions in geochemical processes involving minerals and aqueous solutions—II. Applications , 1969 .

[53]  H. Helgeson,et al.  Evaluation of irreversible reactions in geochemical processes involving minerals and aqueous solutions - I. Thermodynamic relations , 1968 .