BASELINE RADIATION IN GOLD MINING AREAIN ERINMO OSUN STATE, NIGERIA.

Abstract

The mining of gold facilitates the release of radioactive minerals from the host rock into the environment and the gold miners would be exposed to gamma radiation due to radionuclide contaminants associated with the gold. Twenty samples of soil were collected from different illegal gold mining locations in Erinmo in Osun State of Nigeria and were counted using the high purity germanium detector. The radionuclide’s identified in all the samples with reliable regularity are 238U ,232Th and 40K. The 238U concentrations in soil range from 9.01 ± 1.7 – 35.4 ± 3.7 BqKg-1 with an average of 21.9 ± 2.1 BqKg-1 . The mean specific activities
for 232Th range from 10.9 ± 2.8 – 37.5 ± 4.6 BqKg-1 with an average of 23.4 ± 2.9 BqKg-1 and the mean specific activities for 40K in soil ranged from 99.0 ± 12.3 – 182.8 ± 18.5 BqKg-1 with a mean of 136.5 ± 18.2 BqKg-1 . The uranium and thorium specific activities fall within the earth crustal mean for normal environmental, hence no uranium or thorium deposit could be said to be in Erinmo. The total absorbed dose rate in air for Erinmo in Osun State ranged between 15.4 nGyh-1 and 47.2 nGyh-1 with an average of 30.7
nGyh-1 . The average value of the absorbed dose rate obtained in this work represents 55.8% of the world average of value of 55.0 nGyh-1 . The external hazard indices are in the range of 0.10 to 0.29 with an average of 0.19. The annual effective doses are in the range of 0.019 mSvy-1 to 0.058 mSvy-1 with an average value of 0.038 mSvy-1 which is lower compared with the world average value of 0.07 mSvy-1 .