l.) in NE Slovenia (Central Europe), within the area of Radenci Spa, which is famous for its springs of mineral water containing dissolved CO2 and for the occurrence of CO2 mofettes. The CO2, compressed in Miocene and Pliocene porous sediments under a pressure of 100 to 110 bars, results from post-volcanic activity (Titek, 1999).
The mofettes often release CO2 in fluctuating bursts and in similar locations in Slovenia, soil [CO2] has varied by as much as almost 30% (Vodnik et al., 2006; 2009).
The gas vent was a mofette, which presented as a small hole flooded by rain water, giving it a puddled appearance.
The Romanian spa resorts, spreading over all forms of relief, were established in order to exploit the spa valences of natural resources, especially hydro and thermal, all types of mineral waters, mofettes, organic and inorganic sludge, as well as the climate specific of the seaside (thalassotherapy, heliotherapy, mud therapy), of the mountains and hilly areas (shelter climate), or of the microclimate of salt mines and caves etc.
Traditionally, mofettes are specific to Covasna, Sugas, Balvanyos (Covasna County) and Baile Tusnad (Harghita county), in the so-called "mofette aureola".