Radon (222Rn) levels in thermal waters of the geothermally active Campi Flegrei volcanic caldera (Southern Italy): A framework study using a RAD7 radon detector

The present investigation provides measurements of radon (222Rn) concentration levels in 20 thermal waters at the Campi Flegrei volcanic caldera, an important geothermal system with hydrothermal manifestations in the Neapolitan area (Southern Italy). We used a RAD7® Radon-in-air detector equipped with Big Bottle RAD H2O and DRYSTIK accessories (Durridge Co. Inc.). Water samples with different chemical and/or physical conditions, not used as drink waters, are taken from continental thermal groundwaters, springs, lakes, pools and one submerged thermal spring. The waters are mostly chlorine to bicarbonate, except of a few sulphate types sampled at the hydrothermal discharge areas of Solfatara and Pisciarelli, central in the caldera. Water temperature and pH values range from 18.1 to 91.3 °C and from 2 to 8, respectively.