The strengthening Stromboli&#8217;s geochemical monitoring: the advanced multi parameters stations for thermal wells&#160;
Authors: Gattuso Alessandro , Scirè Scappuzzo Sergio , Lazzaro Gianluca , Traina Domenico , Federico Cinzia , Italiano Francesco , Paonita Antonio , Coltelli Mauro 
Published: February 2023

&lt;p&gt;The importance of geochemical surveillance has been demonstrated worldwide, in volcanic and/or geothermal areas. In particular, the fumarole and plume chemistry, the soil CO2 gas emission and the isotope geochemistry could give useful information about the state of the volcanic plumbing system. The role of the geochemical monitoring at Stromboli volcano has increased in the last 30 years, in order to track the phases of increased contribution of deep gas in the shallow system, which could potentially prelude to more energetic events. The ground thermal waters have been collected on a monthly basis by the National Institute of Geophysics and Volcanology - branch of Palermo (INGV-PA) since 1999 from different wells located near the NE coast of the island, where noticeable soil CO2 degassing and temperature anomalies are present. Three supplemental wells were drilled on purpose for scientific investigations: Saibbo and Limoneto in 2003, COA in 2005. Nowadays, four wells are used by INGV-PA for monitoring purposes: Limoneto, Cusolito, Fulco and Piscit&amp;#224;. In those wells, with a maximum depth of 37 metres reached at Limoneto, the temperature values range from 31 to 45 &amp;#176;C, with an electrical conductivity ranging from 4.94 to 54.6 mS/cm.&amp;#160; The COA well, in particular, located at San Vincenzo village, presents a temperature and an electrical conductivity of around 40 &amp;#176;C and 1622 &amp;#181;S/cm respectively.&lt;/p&gt;&lt;p&gt;After the recent significant paroxysmal events, occurred on July 3rd and August 28th 2019, it was perceived the need to upgrade the geochemical monitoring system in the Stromboli thermal wells, with some autonomous and technologically advanced multiparameter permanent stations capable of measuring and transferring the chemical-physical parameters collected (temperature, conductivity, phreatic level) with the dissolved CO2, in real time to the monitoring room of INGV -&amp;#160; PA.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;The long lasting station model is equipped with a CTD data logger (balanced 4-electrode cell for Conductivity, piezoresistive sensor for Pressure/Level) and a Carbon Dioxide sensor (membrane covered optical sensor) submerged straight in thermal waters. Both sensor probes, with an operational temperature range from -5 to 60 &amp;#176;C, take up a minimal amount of space in diameter and have a titanium body. A low-power single-board computer is dedicated to take samples of sensors&amp;#8217; digital output, by RS-485 serial protocol, and transmit data to INGV-PA database system and publisher service to the internet. The whole system was designed keeping in consideration low-power convenience, being not possible to have direct electricity supply for some installation, making it possible to have a configurable period of sampling that even in photovoltaic panel and battery power conditions.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;The technological innovation provided by the new installation of the advanced multiparameter permanent stations in the Stromboli thermal wells, could lead to the detection of changes in certain chemical and physical parameters eventually related to the increased contribution of magmatic-hydrothermal gases.&lt;/p&gt;