Radiological Implications of Coal-Mining Activities in Maiganga Coalfield of North-Eastern Nigeria

Abstract

Maiganga coalfield is a newly discovered coal deposit in the north-eastern Nigeria that is currently receiving considerable attention from coal stakeholders. The deposit is also a prime target for power generation by the Nigerian government. Protection of man and the environment from excessive radiation exposures due to anthropogenic activities is, therefore, important. The main objective of this study is the assessment of natural radioactivity in the Maiganga coalfield environment of north-eastern Nigeria, with particular emphasis on their environmental and human health implications. Samples of soil, coal, and mine tailings from Maiganga coalfield were assessed for 40K, 226Ra, and 232Th activity concentrations using HPGe γ-ray spectrometry. Mean activity concentrations of 40K, 226Ra, and 232Th in coal were 17.8 ± 1.2, 7.6 ± 0.5, and 5.5 ± 0.4, Bq kg−1, respectively, which were below world mean values of 50, 20, and 20 Bq kg−1, respectively, for coals. Mean specific activities of 40K, 226Ra, and 232Th for mine tailings were 91.2 ± 4.3, 20.2 ± 1.0, and 25.7 ± 1.3 Bq kg−1, respectively, while mean values for soil were, respectively, 83.5 ± 4.0, 17.7 ± 0.9, and 27.3 ± 1.3 Bq kg−1. The mean specific activities were below their respective world mean values of 400, 35, and 30 Bq kg−1. Calculated average gamma dose for soil, coal, and mine tailings were 28.1, 7.6, and 28.7 nGy h−1, respectively, with average annual effective dose equivalent of 0.03, 0.01, and 0.03 mSv year−1 in sequence. These were all below their respective world average values. Computed average values for other radiation hazard indices were lower than the recommended limits set for radiation protection. Radiation load on mine workers, environment, and the public due to coal-mining operations in Maiganga coalfield is insignificant.