222Rn behavior at the Latera geothermal field (Northern Latium,Italy)

Permanent probes to sample soil gases were placed at the Latera geothermal field, located in the Volsini Mts., Latium, Italy. Due to high uranium concentrations in the area's alkali-potassic volcanics outcropping, quite high²²²Rn values, ranging from 9,260 up to 753,000 Bq/m³, were found. The highest radon activities match tectonic structures such as fractures and faults, and a deep high structure which constitutes the geothermal reservoir. These high radon values also conform to a major amount of⁴He and CO₂. The latter gases are enriched in the gaseous phase of the geothermal fluids, and their migration is also controlled by structural features. This suggests that the enrichment of²²²Rn in the soil gases, can be linked to a direct contribution of²²⁶Ra, carried by deep-seated fluids from the reservoir itself.