環境生物学に関する専門家の意見

Assessment of Natural Radioactivity in Soil and its Contribution to Population Exposure in the Vicinity of Mkuju River Uranium Project in Tanzania

Firmi P Banzi, Peter K Msaki, Najat K Mohammed

Assessment of Natural Radioactivity in Soil and its Contribution to Population Exposure in the Vicinity of Mkuju River Uranium Project in Tanzania

The level of 226Ra, 232Th and 40K was established in soil collected in an area about 1,300 km2 in the vicinity of Mkuju uranium project in Tanzania and selected points in the concession using HPGe spectrometer and associated exposure risks to population were estimated. The radioactivity concentration in the vicinity range (Bqkg-1) for 226Ra (24.94 to 53.50), 232Th (20.86 to 47.14), and 40K (344.50 to 697.54). Whereas, radioactivity in the concession range for 226Ra (2430.00 to 4200.00), 232Th (130.00 to 220.00), and 40K (1293.30 to 1466.10). On average the radioactivity in the concession were about 89, 5 and 3 times high than those in the vicinity. Based on the measurements, the hazards attributable to use of soil from the vicinity for different purposes is marginal. However, the hazards indices indicate that soils from the concession have relatively a significantly risk by range of factors about 27 to 29 and 40 to 42 times high than in the vicinity for the external and internal hazards, respectively. Also the radium equivalent radioactivity, dose rate and effective dose tend to be significantly high in the concession than in the vicinity by range of factors from 27 to 29, 23 to 25 and 23 to 25, respectively. These findings reveals that soils in the vicinity of the project could pose less radiological risk to human health when compared to soil in the concession.