GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.2 GNGTS 2024 Monitoring of the radon emission from the surface soil in the Maccalube natural reserve M. Falanga 1 , S. Mancini 1 , M. Guida 1 , P. Madonia 2 , P. Cusano 3 1 Università degli Studi di Salerno, Fisciano (SA), Italy 2 Sezione di Catania, Osservatorio Etneo – INGV, Cefalù, Italy 3 Sezione di Napoli, Osservatorio Vesuviano – INGV, Naples, Italy The reserve of Maccalube di Aragona (Ag) in Sicily (Italy) is unfortunately known because of the death of two children in 2014 due to a sudden explosion of a mud volcano. Indeed, that reserve covers a large area made of mud volcanoes which emit diferent gases with high percentage of methane, followed by liquid hydrocarbons and high salinity waters [1-3]. Such overpressure fuids migrate towards the surface across discontnuites in subsoil ofen creatng mud cones. The actvity is generally of small intensity but, suddenly, as occurred in that tragic day of 2014, it could evolve in a paroxistc phase producing fooding which, in turn, causes damages and even injuries. For these reasons, mud volcanoes consttute a geohazard problem and, thus, are currently studied. In the framework of the PROMUD Project ( htps://proget.ingv.it/it/promud ), in order to characterize the part of the reserve that is not under law restricton, in terms of environmental radioactvity, we performed measurements of radon in soil gas. Moreover, radon can be used as a naturally occurring tracer for environmental processes [4]. By means of grab-sampling or contnuous monitoring of radon concentraton, it is possible to assess several types of dynamic phenomena in the environmental matrices (air, water, etc). The preliminary survey was carried out at the end of November 2023 by using a radon and thoron detector (RAD7 Durridge) coupled with a soil probe for subsoil measurements and an accumulaton chamber for surface emission [5]. The measurement points are in Fig. 1. Not negligible values of radon actvity concentraton at surface, of the order of thousands of Bq/m 3 in concomitance with the emitng actve centers were detected, as well as values under the limit of detecton (LD) elsewhere. Such high concentraton at the only actve centers could suggest that radon likely uses gases, i.e. methane, as carrier to way out from soil whereas no escape is possible due to the presence of a compact clay layer.