Radioactivity And Earth Cycle: Characterization Of The Maccalube Nature Reserve

key indicators of mud volcano activity and potential precursors of paroxysmal events, aim of this study is to explore the potential of natural radioactivity as tracer for analysing long and short-term variation at Maccalube di Aragona Nature Reserve (Sicily, Italy). In order to define a “past status” (status zero) of the environment from which starting to analyse, in the future, variations of the global environmental system at specific times and space scale through also correlations with environmental factors, experimental campaigns were conducted between November 2023 and July 2025, including a specific sampling phase, on September 2025, after a paroxysmal overturning event, registered on August 2025. The ‘baseline’ for the radiological characterization of the site was performed, by using gamma spectrometry, by measuring the content of 226Ra and 232Th and 40K and 137Cs in soil, mud and water samples, alongside in situ measurements of surface 222Rn and 220Rn emissions were completed for tracing short-term environmental variations. The experimental results reveal a concentration of 226Ra and 232Th and 40K lower than the global average and coherent with the expected geology of the area, as well as 137Cs concentrations below the detection limit was registered, indicating the absence of anthropogenic radiocesium contamination within the sensitivity limits of the applied method. On the other side, the 222Rn surface emissions from soil registered high activity concentrations in well localized points coherent with the active surface manifestations of the sedimentary volcanism which characterizes the study area, whereas the scarcity of surface 220Rn is best explained by the combined effect of rapid radioactive decay during upward migration and the low permeability of the compact clay-rich upper layer, rather than by a simple absence of shallow thoron in the system.