Natural and artificial radioactivity distribution in soil, rock and water of the Central Ashanti Gold Mine, Ghana
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Direct gamma spectrometry study was carried out within and around the operational area of the Central Ashanti Gold of Ghana to ascertain the baseline radioactivity levels of naturally occurring radioactive materials (NORM), prior to processing of gold ore at the mine. The average activity concentrations of 238U, 232Th, 40K and 137Cs in the soil/rock samples were 64.3, 68.4, 1243.9 and 3.5 Bqkg−1, respectively. For the water samples, the average activity concentrations were 2.5, 2.6, 14.7 and 0.7 BqL−1 for 238U, 232Th, 40K and 137Cs, respectively. The total annual effective dose to the public was estimated to be 0.141 mSv which is below the ICRP recommended level of 1 mSv for public exposure control. The average radium equivalent activity value was 257.8 Bqkg−1 in the range of 72.9–402.3 Bqkg−1. The average values of external and internal indices were 0.7 and 0.8, respectively. The concentrations of U, Th and K were variable in soil and rock samples taken from different locations in the study area with values varying in the range of 0.8–10.9, 2.4–39.4 μg/g and 0.7–6.3 %, respectively. The concentration values of gross-α and gross-β for all the water samples were below the Ghana Standards Board and Who Health Organisation recommended guideline values for drinking water quality. The results obtained in this study shows that radiation levels are within the natural background radiation levels found in literature and compared well with similar studies for other countries.
KeywordsGamma spectrometry Effective dose Radioactivity Hazard indices Radium equivalent
This work was carried out with the cooperation and support of management and staff of Central Ashanti Gold Ltd for which the authors are very grateful. All the analyses were carried out at the laboratories of the Radiation Protection Institute of the Ghana Atomic Energy Commission and the contributions from various members of staff is gratefully acknowledged. The sampling at the site of the Central Ashanti Gold Ltd was facilitated by Mr. Michael Sackey, the Manager in charge of Environment and the assistance offered by some his staff namely; Mr. Emmanuel Aidoo-Poku and Mr. Phanuel Sackey as well as Mr. Albert Quaye to gain access to various locations within the mine’s operational area is greatly appreciated.
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