Studies on radioactivity in aerosols as a function of meteorological variables in Salamanca (Spain)

Ambient concentrations of aerosol radioactivity in ground-level air were me asured weekly in a low-industrialized city (Salamanca, Spain). Means of abo ut 6.9 x 10(-5) and 4.83 x 10(-4)Bq m(-3) were found for gross alpha and be ta activities, respectively, averaged over three years. The measured activi ties, which include contributions from several radionuclides in the ground atmosphere, were evaluated to determine the relationship between the meteor ology and the aerosol activities in air. We have studied the influence of d iverse meteorological parameters such as temperature, pressure and wind dir ection, as well as the effect of the less often considered terrestrial elec trostatic field. Concentrations of gross alpha and beta activities were gre atly affected by the meteorological conditions, showing pronounced differen ces between seasons. The study reveals that much of the variability (approx imately 50%) in the activities is explained by the electrostatic field, its influence being higher in winter. About 40% of the alpha and beta variabil ity is explained by both the temperature and the humidity. The influence of the wind direction is only statistically significant for alpha radioactivi ty. A simple mathematical model based on these variables is developed to de scribe globally the dynamics in air of radioactive particles enabling us to estimate the air radioactive background level. (C) 2000 Elsevier Science L td. All rights reserved.