Radionuclide Depth Profile Baseline and Radiation Hazard Indices of the Reclaimed Old Nekede Mechanic Village, Owerri, Imo State, Nigeria

摘要

Radionuclide concentration in soil samples collected at the old Nekede auto-mechanic village in Owerri were determined using gamma spectroscopy. A total of 15 soil samples were collected at depths of 10-cm, 20-cm and 30-cm at 5 different sites respectively. From the results, the mean activity concentrations of ~(40)K, ~(226)Ra, and ~(232)Th were 132.66±5.61 Bq/Kg, 26.38±3.88 Bq/Kg, and 73.24±4.91 Bq/Kg respectively for samples collected at 10cm depth. At 20cm depth the mean values obtained were 111.95±6.51 Bq/Kg, 32.63±3.48 Bq/Kg, and 89.76±5.20 Bq/Kg for ~(40)K, ~(226)Ra, and ~(232)Th respectively, while 102.88±4.62 Bq/Kg, 30.03±2.77 Bq/Kg, and 76.08±6.65 Bq/Kg were obtained at the 30 cm depth for ~(40)K, ~(226)Ra, and ~(232)Th respectively. The calculated absorbed dose rate and annual effective dose have an average value of 66.6687 nGyh~(-1) and 0.0912 mSv.y~(-1). The 10cm depth presented the lowest dose rate and annual effective dose rate with values of 61.9564 nGyh~(-1 )and 0.0847 mSv.y~(-1) respectively. While the highest values were obtained at 30cm depth with values of 64.0913 nGyh~(-1) and 0.0876 mSv.y~(-1 )respectively. The value of the annual effective dose lies within the world average value of 1.0 mSvy~(-1) annual effective dose equivalent rate. The hazard indices corresponding to the collected samples was also estimated to have a mean value of 0.142, which is below the recommended world average.