Gamma spectroscopy study of soil-plant transfer factor characteristics of 40K, 232Th and 226Ra in some crops cultivated in southwestern region of Nigeria

Soil-plant transfer factor (TF) is one of the vital variables employed in assessing plants uptake of radionuclides and their transfer to food chain for predictive ingestion dose and risk evaluation. To further this goal, the TF characteristics of natural 40K, 232Th and 226Ra were thus investigated in some crops (yam, cassava, rice, maize, groundnut, cowpea, okra, pumpkin leaf, banana and pawpaw) cultivated in southwestern part of Nigeria using HPGe gamma spectroscopy. The obtained results of activity concentration (AC) of the radionuclides across all the cultivated soil samples indicated average values that are less than the global average, whereas in the crops, average values of 226Ra and 232Th, were higher than reference values for different crops group. The overall range of the calculated TF of 40K, 232Th and 226Ra across all the crops was 0.05 (in maize and cowpea) to 15.01 (in banana), 0.01 (in pumpkin leaf and groundnut) to 19.80 (in pawpaw), and 0.04 (in cassava) to 21.30 (in cowpea), respectively. Overall arithmetic mean and geometric mean were estimated as 2.66 and 1.60, 1.11 and 0.43, and 1.10 and 0.54 for 40K, 232Th and 226Ra, respectively. TFs mostly correlated negatively with soil radionuclides, while positive correlation was mostly noticeable in the case of crop. Log normal transform of the TFs data indicated a near normal distribution as against the calculated data. The derived results of this study is here presented as a baseline data suggested for possible radiological risk assessment of food chain of the local population.