Publication date: November 2017
Source:Journal of Environmental Radioactivity, Volumes 178–179
Author(s): C. Dueñas, E. Gordo, E. Liger, M. Cabello, S. Cañete, M. Pérez, P. de la Torre-Luque
The monthly bulk depositional fluxes of three natural radionuclides (
7Be,
210Pb and
40K) were measured at a Mediterranean coastal station (Málaga) over an 11-year period from 2005 to 2015. The mean annual depositional fluxes of
7Be,
210Pb and
40K were 1215, 144 and 67 Bq m
−2 year
−1 respectively, showing a clear seasonal trend with minimum values recorded during summer and maximum values in winter. The rainfall regime with dry summers allows estimating the dry deposition. Assuming constant dry deposition through each year,
7Be,
210Pb and
40K would account for 12.5, 26.5 and 33% of the bulk fallout respectively which indicates that deposition for
210Pb and
40K are significantly higher than
7Be. The precipitation-normalized enrichment factor alpha used to explain seasonal variations in the depositional fluxes of radionuclides with respect the rainfall, indicates higher depositional fluxes during spring and summer than expected from the amount of rainfall. Despite their different origin,
210Pb and
7Be monthly depositional fluxes have strong correlation. The atmospheric deposition fluxes of
7Be,
210Pb and
40K were controlled mainly by the amount of rainfall (r = 0.89, 0.91 and 0.66 respectively). Moreover, principal component analysis was applied to the datasets and deposition of radionuclides and rainfall in the same component highlighting the importance of the washout mechanism. The mean depositional velocity of aerosols evaluated using
7Be and
210Pb are similar and are compared to other published values.
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