Evaluation of Natural Radionuclides in Selected Dumpsites in Gboko, Makurdi and Otukpo Towns of Benue State North Central Nigeria

Abstract

The activity concentrations of some radionuclides in dumpsites samples were collected from 8selected locations in Gboko, selected locations each in Makurdi and  Otukpo metropolis respectively of Benue State have been determined using the Gamma ray Spectroscopy (model T35240K). The soil activity from Gboko ranges from 13.10±0.25 Bq/Kg to 22.56±0.32 Bq/Kg for ⁴⁰K, 0.35±0.00 Bq/Kg to 0.71±0.00 Bq/Kg for ²³⁸U and 0.12±0.00 Bq/Kg to 1.20±0.00 Bq/Kg for 232Th respectively with mean value of 19.15±0.29Bq/Kg for ⁴⁰K, with the mean value of 0.60±0.00 Bq/Kg for ²³⁸U, and with the mean value of 0.14±0.00Bq/Kg for ²³²Th respectively in Gboko. The soil activity from Makurdi ranges from 12.88±0.24 Bq/Kg to 22.23±0.32 Bq/Kg for ⁴⁰K, 0.37±0.00 Bq/Kg to 0.66±0.00 Bq/Kg for ²³⁸U and 0.09±0.00 Bq/Kg to 0.21±0.00 Bq/Kg for ²³²Th respectively with the mean value of 18.76±0.29Bq/Kg for ⁴⁰K, mean value of 0.52±0.00 Bq/Kg for²³⁸U and with mean value of 0.15±0.00 Bq/Kg for ²³²Th respectively in Makurdi. The soil activity from Otukpo ranges from 10.42±0.22 Bq/Kg to 23.59±0.33 Bq/Kg for ⁴⁰K, 0.41±0.00 Bq/Kg to 0.68±0.00 Bq/Kg for ²³⁸U and 0.14±0.00 Bq/Kg to 0.20±0.00 Bq/Kg for ²³²Th with the mean value of 17.86±0.36 Bq/Kg for ⁴⁰K, with the mean value of 0.54±0.00 Bq/Kg for ²³⁸U and with the mean value of 0.17±0.00 Bq/Kg for ²³²Th respectively in Otukpo. The mean absorbed dose rate in air from Gboko ranges from 0.91±0.00  to 1.35±0.00 , the mean absorbed dose rate in air from Makurdi ranges from 0.80±0.00  to 1.17±0.00and the mean absorbed dose rate in air from Otukpo ranges from 0.74±0.00 to 1.28±0.00while the annual effective dose for Gboko varied from 0.0011±0.00  to 0.0016±0.00 , the annual effective dose for Makurdi varied from 0.0009±0.00  to 0.0016±0.00  and for Otukpo varied from 0.0009±0.00 to 0.0015±0.00 .The results showed that, dose rate are lower than the safe limit of 0.07mSv/y...