Browsing by Author "Ndai, Kelvin Didas"

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    Evaluation of toxic metals and radionuclide levels in root vegetables grown in the vicinity of Bahi uranium deposit
    (The University of Dodoma, 2022) Ndai, Kelvin Didas
    The presence of large uranium deposit in Kisalalo area in Bahi district has raised concerns on the contamination of food groups grown in the vicinity. This study has assessed the levels of concentration of toxic metals including arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg) and Lead (Pb) and radionuclides including Thorium (232Th), Radium (226Ra) and Potassium (40K) in cassava (Manihot Esculenta) and sweet potatoes (Ipomoea Batatas) from Bahi district.Characterisation of toxic metals and radionuclides was done using Energy Dispersive X-Ray Fluorescence and Gamma Ray Spectrometries respectively. Cassava and sweet potatoes from Bahi ward were found to accumulate higher concentration of toxic metals than in other areas. The highest mean concentration of Cd, Cr, Hg and Pb were found to be 7.91 𝑚𝑔/𝑘𝑔, 34.68 𝑚𝑔/𝑘𝑔, 2.19 𝑚𝑔/𝑘𝑔, and 2.78 𝑚𝑔/ 𝑘𝑔respectively and were approximately 80, 34, 22, and 28 times higher than their respective maximum tolerable limits.Cr levels in cassava and sweet potatoes were highest than other toxic metals due to presence of Cr in the soil and its higher soil to plant transfer factor while As levels were the least almost around tolerable limit.Furthermore, the highest mean activity concentration of 232Th was found to be 9.98 𝐵𝑞/𝑘𝑔in sweet potatoes from Bahi ward while that of 226Ra was 6.63 𝐵𝑞/𝑘𝑔 in sweet potatoes from Bahi ward and that of 40K was 528.43 𝐵𝑞/𝑘𝑔 in cassava from Bahi ward. The highest total annual effective dose due to consumption of cassava and sweet potatoes was found to be 0.0133 mSv/year from Bahi ward but this was within the recommended limit of 1 mSv/year set by FAO/WHO.The results show that cassava and sweet potatoes grown in Bahi ward which is closest to the Kisalalo Uranium deposit site had the highest accumulation of toxic metals.It is thus suggested that the root vegetables are not suitable to be grown in this place as they contribute to exposing consumers to toxicity of heavy metals. On the other hand, despite the presence of the above mentioned radionuclides, the annual effective dose due to consumption of radionuclides is very low and this suggests that the root vegetables do not contribute much in exposing consumers to radiation toxicity.