Mapping the bedrock K2O, U and Th concentration in Italy - Towards the European Atlas of Natural Radiation

The Joint Research Center, the European Commission’s science and knowledge service, started the European Atlas of Natural Radiation project with the objective of gathering all the data related to natural radioactivity from the European countries. The estimate of the terrestrial natural radioactivity is one of the priority of the project and it includes the realisation of concentration maps of the radioactive elements naturally occurring in the environment, that are the elements of the U and Th families together with 40K. The aim of this work is to study the methodology to develop the first complete K2O, U and Th concentration maps of the bedrock in Italy through the creation of geological units identified on a pre-compiled basis and the collection of geochemical data from scientific literature. The geological units were determined based on litho-, chrono- and tectono-stratigraphic features of the bedrock. The dataset was created using global open-access database and peer-reviewed articles; the data, more than 15000 in total, was checked for outliers and representativeness and then studied with statistical analysis, in order to evaluate the methodology and to assign an average K2O, U and Th concentration to the geological units. The results confirm that the methodology is reliable and allows to create K2O, U and Th concentration maps at 1:1M scale. The main sources of errors come from the high lithological variability of the units, which implies a high variability in the distribution of the concentration values, and from the heterogeneity of the data coverage. Focusing on these problems, it’s still possible to improve the methodology, especially by increasing the amount of available geochemical data and, subsequently, by realising more accurate maps on a smaller scale.