Anthropogenic and naturally occurring radionuclide content in near surface air in Cáceres (Spain)
2016
Baeza, Antonio | Rodríguez-Perulero, Antonio | Guillén, Javier
The anthropogenic (¹³⁷Cs, ⁹⁰Sr, ²³⁹⁺²⁴⁰Pu and ²⁴¹Am) and naturally occurring radionuclide (⁴⁰K, ²³⁴,²³⁸U, ²²⁸,²³⁰,²³²Th, ²²⁶Ra and ²¹⁰Pb) content in near surface air present seasonal variations related to natural processes, such as soil erosion, resuspension of fine particles of soil and radon exhalation from soil (²¹⁰Pb). The objective is to analyze seasonal variations of their concentrations and compare with radiological events (Fukushima fallout and wild fire) in a location without any known source of anthropogenic radionuclides. The ²¹⁰Pb, ⁴⁰K, and ¹³⁷Cs presented annual variations, with maximum activity levels in summer. Solar radiation and rainfall were correlated with ²¹⁰Pb and ⁴⁰K. The ²³⁴,²³⁸U, ²²⁸,²³⁰,²³²Th, ²²⁶Ra, ¹³⁷Cs and ⁹⁰Sr presented positive correlation with monthly mean values of temperature. The ratio ⁹⁰Sr/¹³⁷Cs was within the range of those reported for soils in Spain. Finally, the maximal effective dose rate was estimated to be 37 and 88 μSv/y for infants and adults, respectively, well below 1 mSv/y reference level. The main contributor to effective dose was ²¹⁰Pb, about 92%, followed by:²¹⁰Pb ≫ ²²⁸,²³⁰,²³²Th > ²²⁶Ra, ²³⁴,²³⁸U > ⁷Be, ²³⁹⁺²⁴⁰Pu > ⁴⁰K, ⁹⁰Sr > ¹³⁷Cs > ²²Na
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