A review of 137Cs and 40K soil-to-plant transfer factors in tropical plants

VELASCO, H.; ANJOS, R.M.

JOURNAL OF ENVIRONMENTAL RADIOACTIVITY

ELSEVIER SCI LTD

Año: 2021 vol. 235-236 p. 106650 - 106662

0265-931X

In this work we critically assess the soil-to-plant transfer factors (TF) for 137Cs and 40K in edible fleshy organs oftropical plants that are often components of the human diet. Radionuclide concentrations in soil and plants wereobtained from previous investigations developed in Brazil, after the Goi?ania radiological accident occurred in1987. Transfer factors were determined in specific plant compartments (main root, main stem, bark, old and newbranches, twig, old and new leaves, mature and green edible organs) of tropical species such as lemon (Citrusaurantifolia), orange (Citrus sinensis), guava (Psidium guajava), chili pepper (Capsicum frutescens), pomegranate(Punica granatum), papaya (Carica papaya), banana (Musa paradisíaca), and manioc (Manihot esculenta). For 137Cs,soil-to-fruit transfer factor ranged from 0.80 × 10􀀀 2 (banana) to 3.65 × 10􀀀 1 (pomegranate); for 40K, this factorwas from 4.42 × 10􀀀 1 (orange) to 1.74 (chili pepper). Considering all the plant compartments analysed, thetransfer factors for 40K are between 24.5 (guava) and 90.5 (papaya) times higher than for 137Cs. For both radionuclides,considerable differences in soil-to-plant transfer were found when new growing parts of the plant(green edible organ, leaf, and twig) are considered with respect to those older parts (mature edible organ, old leafand branches). Considering all the species analyzed, the relationship TF(40K)/TF(137Cs) does not seem to follow acharacteristic pattern. However, if we compare the value of this relationship for two organs of the same plant, theresult is approximately constant, regardless of the species considered. This confirms earlier evidence that bothradionuclides are similarly distributed in the different organs of the studied species.The differences in the transfer factors according to the ripening status of edible organs must be particularlyconsidered when estimating the dose from ingestion of fruits and their derivatives in dose assessment models.