Determination of Natural Radioactivity and Essential Elemental Concentration Levels in the Vicinity of Minjingu Mining - Tanzania
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Minjingu mining is located in the Northern part of Tanzania, the area which is known for high natural background radiation, due to the presence of phosphate mining. Tanzania has several phosphate deposits, of which Minjingu is the largest and its phosphate is exported or used in the preparation of fertilizers. In this research work, the results of studies on essential elemental concentration and activity in the vicinity of Minjingu phosphate mine in Tanzania are presented. The essential elemental concentration, outdoor dose rate and the activity levels of samples from around the mine were determined by Energy Dispersive X-ray Fluorescence and a gamma spectrometer system with a Hyper Pure germanium detector system, respectively. In all sides of the mining the concentration of P, Mn, Ti and Th is high, while Mg, K, Fe, Co, and Ni have high concentration on East, West and North. High concentration of Ba is on the South, West and North. This shows that elemental concentration for more than 50% of randomly selected elements in the vicinity of Minjingu is high. The determination of activity was made for the 238U, 228Th and 40K radio nuclides. Results show that the activities of 238U, 232Th and 40K range between 49±1 Bqkg-1 to 241±6 Bqkg-1, 51±2 Bqkg-1 to 211±5- Bqkg-1 and 666±29 Bqkg-1 to 1076±45 Bqkg-1, respectively at Minjingu. These values are above the limit average activity concentration of 40 Bqkg-1, 35 Bqkg-1 and 420 Bqkg-1 for 238U, 232Th and 40K relative to selected research sites. The dose received by the population around Minjingu is 147±3 nGyh-1which is almost three times the average limit of 50 nGyh-1. Therefore, the mean dose rate received by the population at Minjingu for each radionuclide (K, Th and U) is about 49 nGyh-1, which show that the absorbed dose rate at Minjingu is beyond the average limit of about 18.99 nGyh-1. Annual effective dose received by population at Minjingu is about 1.98 mSvy-1, which is above the average limit (1 mSvy-1). These findings suggest a radiation health risk to the population and therefore realistic quantification of the overall exposure of workers and public at Minjingu, and remedial measures for future radiation safety to be taken.