Non‐volcanic CO₂ Earth degassing: Case of Mefite d'Ansanto (southern Apennines), Italy

Abstract

Mefite d'Ansanto, southern Apennines, Italy is the largest natural emission of low temperature CO2 rich gases, from non‐volcanic environment, ever measured in the Earth. The emission is fed by a buried reservoir, made up of permeable limestones and covered by clayey sediments. We estimated a total gas flux of ∼2000 tons per day. Under low wind conditions, the gas flows along a narrow natural channel producing a persistent gas river which has killed over a period of time people and animals. The application of a physical numerical model allowed us to define the zones which potentially can be affected by dangerous CO2 concentration at breathing height for humans. The geometry of the Mefite gas reservoir is similar to those designed for sequestering CO2 in geological storage projects where huge amounts of CO2 should be injected in order to reduce atmospheric CO2 concentration. The approach which we have used at Mefite to define hazardous zones for the human health can be applied also in case of large CO2 leakages from storage sites, a phenomena which, even if improbable, can not be ruled out.

Assessing the health risks of natural CO 2 seeps in Italy

“…The greatest human mortality in one incident in this period was the death of three adults at Mefite D'Ansanto in the 1990's (7,17). Many animal fatalities of all sizes and numbers are recorded, from hundreds of toads (Galleria drenante Acquasecca) to fields of cows (Colli Albani) to lone foxes (Mefite D'Ansanto).…”

“…Density-driven accumulations can flow like a river. The paths of these gas-rivers are visible as gray scars on the landscape (7,25) where the CO 2 and H 2 S gas mixtures modify or kill the local vegetation (13,26,27). Abnormal vegetation is common at gas seeps and might assist gas hazard recognition if the animal or human is aware of such phenomena.…”

“…Public acceptance can strongly influence the fate of new technologies and onshore storage will usually be the least-cost domestic option for many countries. It is therefore crucial to assess the environmental hazards from leakage of CO 2 to the surface using analogues, models, and pilot studies (7)(8)(9)(10)(11)(12). Developing and implementing suitable risk-assessment procedures will enable the accuracy of current concerns to be evaluated.…”

Mofettes in Slovenske gorice, Slovenia

“…Maček (2013) je ugotavljala vpliv abiotskih dejavnikov okolja na biodiverziteto in strukturo združb mikrobov. Ker je vsebnost CO 2 v tleh na najožjem območju mofet tudi nad 99 vol% (weinlich et al, 1998), lahko ob njih pogosto najdemo mrtve manjše živali, včasih pa so nevarne celo za ljudi (chioDini et al, 2010).…”

High-resolution modelling of atmospheric dispersion of dense gas using TWODEE-2.1: application to the 1986 Lake Nyos limnic eruption

“…Pierret et al, 1992;Costa et al, 2005Costa et al, , 2008Chiodini et al, 2010;Costa and Chiodini, 2015;Burton et al, 2017). In particular, Costa and Chiodini (2015) have recently used the TWODEE-2.0 model (Hankin and Britter, 1999;Folch et al, 2009) to simulate the CO 2 cloud from the 21 August 1986 Lake Nyos limnic eruption by considering various scenarios for cloud volume and eruption duration estimated from previous studies (Evans et al, 1994;Kanari, 1989;Tuttle et al, 1987).…”