Quantitative Assessment of Heavy Metals Contamination in Nigerian Coal Using Instrumental Neutron Activation Analysis

Abstract

The mining, processing and use of coal result in the accumulation of coal and coal ash, posing environmental and human health risks. In this study, the concentration of heavy metal distribution in the coal samples from selected coal mining sites (Maiganga, Gboko, Onyeama, Okobo, Opoko-Obido, Odagbo and Ofugo) in Nigeria were determined using the Instrumental Neutron Activation Analysis. The concentrations (mg/kg) of heavy metals ranged from 4.69 ± 0.92 to 18.40 ± 1.10 for V, 4.82 ± 0.29 to 185 ± 2 for Mn, 0.11 ± 0.01 to 0.33 ± 0.04 for As, 0.19 ± 0.04 to 0.74 ± 0.05 for U, 7.14 ± 1.62 to 16.60 ± 1.80 for Cr, 1.49 ± 0.16 to 9.10 ± 0.33 for Co, 312 ± 71 to 383 ± 107 for Sr, 0.12 ± 0.03 to 296 ± 23 for Sb, 92 ± 25 to 296 ± 22 for Ba, and 0.26 ± 0.04 to 2.39 ± 0.11 for Th. The concentrations of Mn, Sr, and Sb were slightly higher than the permissible limits given by the Nigerian National Environmental Standards and Regulations Enforcement Agency (NESREA) and the United States Environmental Protection Authority (USEPA). The study revealed that the coal from the mines was contaminated with heavy metals especially Mn and Ti thereby posing stern environmental and health concerns. The study therefore recommends that regulations and emission control technologies should be implemented to mitigate the release of these toxic metals during coal mining, processing, combustion, and waste management into the environment. In addition, the study suggests that workers should receive regular training on the proper use, maintenance, and disposal of personal protective equipment such as respirators, gloves, and eye protectors to maximize its effectiveness in reducing exposure.