Monitoring of 7Be and gross beta in particulate matter of surface air from Mallorca Island, Spain

Abstract

Measurements of airbone radionuclides 7Be and gross beta (Aβ) jointly with atmospheric aerosols, i.e. particulate matter (PM) were routinely carried out for 10 years (2004–2014) at the University of the Balearic Islands, Spain. A total of 728 filter (0.8 μm pore size) samples were collected, and in all of them 7Be and Aβ specific activities were detected. The maximum and minimum specific activities monitored were 0.73 ± 0.41 – 15.8 ± 1.26 mBq m−3 of 7Be and 0.14 ± 0.02 – 2.55 ± 0.04 mBq m−3 of Aβ. PM concentrations were also determined, showing seasonal behavior with the highest concentration in summer and the lowest one in winter. Several meteorological parameters have been considered to explain this intra-annual variation. Principal component analysis (PCA) was applied to the dataset indicating that it is well represented by two principal components that explain 76.6% of total variance. Additionally, a second study with preliminary results of the specific activities of two natural radiotracers (7Be and 210Pb) in PM10 samples was carried out. They were monitored for two years (2013–2015) in air of Mallorca Island. 7Be and 210Pb were detected in most of the PM10 filters, in 100% and 93% of them, respectively. The relationship between activities of both radionuclides and several relevant meteorological parameters was established at 95% confidence level. As a common result to PM and PM10 samples, a strong positive correlation between the evaluated radionuclides and temperature was found.