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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Gas monitoring at volcanic fields outside Naples, Italy, exposes   
   multiple sources of carbon dioxide emissions    
      
     Date:   
         March 7, 2023   
     Source:   
         Geological Society of America   
     Summary:   
         The Phlegraean volcanic fields just west of Naples, Italy, are   
         among the top eight emitters of volcanic carbon dioxide in the   
         world. Since 2005, the Solfatara crater -- one of many circular   
         depressions in the landscape left by a long history of eruptions   
         --has been emitting increased volumes of gas. Today it emits   
         4,000-5,000 tons of carbon dioxide each day, equivalent to the   
         emissions from burning ~500,000 gallons of gasoline.   
      
         Researchers estimate that as much as 20%--40% of the current carbon   
         dioxide emissions are from the dissolution of calcite in the rocks,   
         while 60%--80% is from underground magma.   
      
      
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   FULL STORY   
   ==========================================================================   
   The Phlegraean volcanic fields just west of Naples, Italy, are among the   
   top eight emitters of volcanic carbon dioxide in the world. Since 2005,   
   the Solfatara crater -- one of many circular depressions in the landscape   
   left by a long history of eruptions -- has been emitting increased   
   volumes of gas. Today it emits 4,000-5,000 tons of carbon dioxide   
   each day, equivalent to the emissions from burning ~500,000 gallons of   
   gasoline. In a new paper published ahead of print in Geologyon Thursday,   
   researchers estimate that as much as 20%- 40% of the current carbon   
   dioxide emissions are from the dissolution of calcite in the rocks,   
   while 60%-80% is from underground magma.   
      
      
   ==========================================================================   
   "Estimating the source of the carbon dioxide is important to   
   properly reconstruct what is happening in the magmatic system and the   
   hydrothermal system," says Gianmarco Buono, a volcanologist at Italian   
   National Institute of Geophysics and Volcanology and lead author of   
   the study. "Our aim is to provide a tool to better discriminate the   
   contribution of magmatic and non-magmatic carbon dioxide that can   
   also be applied to other systems."  When magma moves toward Earth's   
   surface, the decreasing pressure on the magma results in degassing --   
   the release of gases that were previously trapped inside the magma --   
   including water vapor, carbon dioxide, and sulfur dioxide.   
      
   Scientists monitor volcanoes for unrest and possible eruptions using   
   a variety of observations -- detecting earthquakes and tremors related   
   to magma movement, taking detailed measurements of ground deformation,   
   and assessing the types and volumes of gases released at the surface   
   from fumaroles -- openings in the earth that emit steam and other gases.   
      
   Eruptions are often preceded by increased fluxes of gas, but that does   
   not mean that every increase in gas emissions will be followed by an   
   eruption. It is also possible for carbon dioxide to come from sources   
   besides magma.   
      
   Interaction between hot underground fluids and host rocks can also   
   release carbon dioxide.   
      
   The Italian National Institute of Geophysics and Volcanology has been   
   monitoring gas emissions from Solfatara crater since 1983, providing   
   a long record of the changes in volume and composition of the gases   
   released there. By comparing ratios of nitrogen, helium, and carbon   
   dioxide in the emissions, researchers had previously established that   
   the gases were coming from deep sources of magma.   
      
   "We focused mainly on geochemical variation, especially for carbon   
   dioxide, helium, and nitrogen, because they are non-reactive species. They   
   contain information about what is happening in the magma," explains Buono.   
      
   But when the region started experiencing increased unrest in 2005, the   
   data began to deviate from the chemical fingerprints of the magmas, a   
   trend that continued to increase over time alongside rising temperatures   
   in the shallow hydrothermal system. The unrest continued, and in 2012   
   the alert level was raised from green to yellow, indicating that there   
   is heightened activity but not an imminent threat of eruption.   
      
   In addition to small earthquakes and higher gas emissions, the region also   
   experienced deformation of the ground surface. Circulation of hot fluids   
   underground could explain the rising temperatures, ground deformation,   
   and increased gas emissions -- interaction of hot acidic fluids with   
   calcite in the rocks also releases carbon dioxide. Drill cores of the   
   rocks from previous studies reveal that calcite in the rocks has similar   
   composition to the gas emissions. The researchers estimate that 20%-40%   
   of the carbon dioxide at the Solfatara crater site was from removal of   
   the calcite in the host rock.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Global_Warming # Volcanoes # Air_Quality # Climate #   
                   Forest # Natural_Disasters # Geochemistry # Air_Pollution   
       * RELATED_TERMS   
             o Carbon_dioxide o Fossil_fuel o Carbon_monoxide o   
             Ocean_acidification o Forest o Carbon_dioxide_sink o   
             Greenhouse_gas o Caldera   
      
   ==========================================================================   
   Story Source: Materials provided by Geological_Society_of_America. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Gianmarco Buono, Stefano Caliro, Antonio Paonita, Lucia Pappalardo,   
         Giovanni Chiodini. Discriminating carbon dioxide sources during   
         volcanic unrest: The case of Campi Flegrei caldera (Italy). Geology,   
         2023; DOI: 10.1130/G50624.1   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230307144354.htm   
      
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