Influence of Air Masses Origin on Radioactivity in Aerosols

Resumen

The aim of this research is to study the influence of the air masses origin on radioactivity in aerosols at surface air, (Gross α, Gross β and 7Be activity concentration). A total of 148 samples were weekly collected from January 4th, 2011 to December 31st, 2013. The specific activity (Bq/m3) of gross alpha and gross beta was measured by α/β Low-Level counter, whereas 7Be was detected by gamma spectrometry (Eγ = 477.6 KeV, Yield = 10.42 %). Evolution of Gross α and Gross β have showed a Log-Normal distribution, while 7Be fits better a Normal distribution according to Kolmogorov Simirnov test. The air mass origings have been set using k-means clustering analysis of daily 72-h kinematic 3D backward trajectories was at altitudes of: mean altitude of Spain (500 m; 950 hPa), planetary boundary layer (1500 m; 850 hPa) and free atmosphere (3000 m; 700 hPa). Finally, Multiple Regression Analysis (MRA) have been applied to determine the influence of the air mass origin (Backward trajectory), and local meteorology on Gross α, Gross β and 7Be activity concentration. In brief, the MRA results show that the re-suspended continental particles from northern Africa and the southern part of western and central Europe transported by Mediterranean air masses at low altitude (500 m) and African air masses at high altitude (3000 m) increase the radioactivity concentration in aerosols at surface atmosphere.