An investigation about natural radioactivity, hydrochemistry, and metal pollution in groundwater from Calabrian selected areas, southern Italy

The increasing interest in radioactivity has brought about the need for an assessment of human exposure to radiation. It is, therefore, necessary to examine naturally occurring radioactivity in the environment, especially its occurrence in groundwater. The aim of this work was then to study the levels and behavior of the most significant natural radionuclides, also in order to improve the knowledge of the hydrochemical processes involved in the selected groundwater systems. Natural radioactivity in fifteen Calabrian groundwaters for human use was investigated through high-resolution gamma spectrometry (with a negative-biased Ortec HPGe detector) and liquid scintillation measurements. Particular attention was given on those radionuclides (3H, 238U, 226Ra, and 228Ra), which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The activity concentration of 238U varied from 1 to 51 mBq/L, as a result of the geology of the investigated area and of the oxidizing conditions that favored U dissolution. 226Ra presented a broad range of activity concentrations (0.011–0.14 mBq/L), lower than uranium ones because radium occurs in groundwater under reducing conditions. Some heavy metals (Cd, Pb, Be, Hg, Ag, As, Tl, Sb, Se, and Ni) were also investigated through ICP-MS measurements and compared with the limits set by the Italian Legislation. Metals are released into the environment by both natural and anthropogenic sources; they leach into underground waters, moving along water pathways and eventually depositing in the aquifer.