Theses and Dissertation

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Browsing Theses and Dissertation by Author "Mankala, James"

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    Investigation Of Radionuclides In Minjingu Phosphate Rock Beneficiation, Their Uptake By Spinacia Oleracea Upon Fertilizer Application, And Associated Radiological Indices
    (NM-AIST, 2025-08) Mankala, James
    Phosphate rock processing, vital for phosphorus pentoxide in blended fertilizers, raises radiological concerns due to natural radionuclides. The study investigated natural radionuclides 232Th, 226Ra and 40K in phosphate rock and greenhouse-potted Spinacia oleracea in amended soil with five phosphate fertilizers. The phosphate rock, amended soil and Spinacia oleracea were dried, grounded, sieved and sealed for over twenty-one days. Activity concentrations measured with a germanium detector showed: Phosphate rock had 232Th from 239.83 ± 23. 65 to 856. 96 ± 77.79 Bq/kg, 226Ra from 908.48 ± 84.75 to 4 525.9 ± 406.81 Bq/kg and 40K from 349.7 ± 47.34 to 1384.5 ± 129. 61 Bq/kg. Amended soil showed 232Th from 1.97 ± 0.001 to 114.30 ± 10.79 Bq/kg, 226Ra from 24.89 ± 4.77 to 114.24 ± 9.26 Bq/kg, and 40K from 546.76 ± 51.24 to 2 152.78 ± 182.34 Bq/kg. Spinacia oleracea had 232Th from 1.44 ± 0.001 to 18.21 ± 3.84 Bq/kg, 226Ra from 6.91 ± 3.29 to 110. 12 ± 11. 58 Bq/kg and 40K from 418.45 ± 51.15 to 1 880.1 ± 190.32 Bq/kg. Mean annual doses were 33. 05 msv/y for phosphate rock and 0.849 mSv/y for Spinacia oleracea. The hazard indices for phosphate rock were 8.90 (external) and 15.72 (internal); Spinacia oleracea had 0.504. The radium equivalent was 3 293.73 with a gamma index of 22.31. Results show that activity concentrations of 232Th and 226Ra are below recommended values but exceed control samples. Therefore, regular monitoring of phosphate fertilizer in soil is advised