Plant transfer factors of naturally occurring radioactive decay series radionuclides, Be, and Cs in a semi-arid climate.

Arid and semi-arid climates give rise to drought stress in plants, implying an increased uptake of radionuclides through both leaves and roots. This study was carried out in the Tabernas Desert (Almería, Spain), classified as an arid climate. Seventeen plants were analyzed, collected from four areas of the study site. The soils in the four areas were statistically comparable and showed a chemical composition and activity concentrations characteristic of uncontaminated soils, with activity concentrations corresponding to world averages, i.e., 31 ± 4 Bq·kg for the uranium series, 37 ± 4 Bq·kg for thorium one, and 344 ± 17 Bq·kg for K. Conversely, the soils showed that Be was below the limit of detection, levels of Cs equivalent to fallout, but an average Pb of 19 ± 9 Bq·kg. The radionuclides of the three naturally occurring radioactive decay series are mainly present in the insoluble fraction, with Ra being the most abundant. The transfer factors showed the usual behaviour of Cs > Ra > U > Th. The activity concentrations of Be and Pb showed a statistically significant linear relationship, indicating greater incorporation through the plant leaves.