Behavior of ambient concentrations of natural radionuclides Be-7, Pb-210, K-40 in the Mediterranean coastal city of Malaga (Spain)

摘要

During a 4-year period (January 2009-December 2012), the Be-7, Pb-210, and K-40 activity concentrations in airborne particulate matter were weekly determined at the Malaga (Spain) located in the southern Iberian Peninsula. Totally 209 polypropylene filters were analyzed in the mentioned period. In 100 % of the filters, Be-7 and K-40 activity concentrations were detected while Pb-210 activity concentration was detected in 96 % of the filters. The results from individual measurements of Be-7, Pb-210, and K-40 concentrations were analyzed to derive the statistical estimates characterizing the distributions. Principal components analysis (PCA) was applied to the datasets and the results of the study reveal that aerosol behavior is represented by two principal components which explain 73.2 % of total variance. Components PC1 and PC2 respectively explain 46.0 and 27.2 % of total variance. PC1 was related positively to dust content, Be-7 and K-40 concentrations and negatively to sunspot numbers. In contrast, PC2 was related positively to temperature and Pb-210 activity and negatively to precipitation and relative humidity. The Be-7 levels showed a significant correlation with sunspot numbers due to the cosmogenic origin. K-40 activities showed a good correlation with dust deposition in filters mainly because it was transported to the air as resuspended particle from the soil. An inverse relationship was observed between the Pb-210 concentrations and monthly rainfall, indicating washout of atmospheric aerosols carrying these radionuclides and a pronounced positive correlation with the average monthly temperature of air.