Analysis of ground-based 222Rn measurements over Spain: Filling the gap in southwestern Europe

Harmonized atmospheric Rn-222 observations are required by the scientific community: these data have been lacking in southern Europe. We report on three recently established ground-based atmospheric Rn-222 monitoring stations in Spain. We characterize the variability of atmospheric Rn-222 concentrations at each of these stations in relation to source strengths, local, and regional atmospheric processes. For the study, measured atmospheric Rn-222 concentrations, estimated Rn-222 fluxes, and regional footprint analysis have been used. In addition, the atmospheric radon monitor operating at each station has been compared to a Rn-222 progeny monitor. Annual means of Rn-222 concentrations at Gredos (GIC3), Delta de l'Ebre (DEC3), and Huelva (UHU) stations were 17.32.0Bqm(-3), 5.80.8Bqm(-3), and 5.10.7Bqm(-3), respectively. The GIC3 station showed high Rn-222 concentration differences during the day and by seasons. The coastal station DEC3 presented background concentrations typical of the region, except when inland Rn-222-rich air masses are transported into the deltaic area. The highest Rn-222 concentrations at UHU station were observed when local recirculation facilitates accumulation of Rn-222 from nearby source represented by phosphogypsum piles. Results of the comparison performed between monitors revealed that the performance of the direct radon monitor is not affected by meteorological conditions, whereas the Rn-222 progeny monitor seems to underestimate Rn-222 concentrations under saturated atmospheric conditions. Initial findings indicate that the monitor responses seem to be in agreement for unsaturated atmospheric conditions but a further long-term comparison study will be needed to confirm this result.