Plant transfer factors of naturally occurring radioactive decay series radionuclides, 7Be, and 137Cs 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−1 for the uranium series, 37 ± 4 Bq·kg−1 for thorium one, and 344 ± 17 Bq·kg−1 for 40K. Conversely, the soils showed that 7Be was below the limit of detection, levels of 137Cs equivalent to fallout, but an average 210Pbex of 19 ± 9 Bq·kg−1. The radionuclides of the three naturally occurring radioactive decay series are mainly present in the insoluble fraction, with 226Ra being the most abundant. The transfer factors showed the usual behaviour of Cs > Ra > U > Th. The activity concentrations of 7Be and 210Pb showed a statistically significant linear relationship, indicating greater incorporation through the plant leaves. © 2024 Elsevier Ltd