Seasonal variation in heavy metal accumulation in plants at coal mine sites and possible health risk

Abstract

Human health challenges in recent times have been attributed to consumption of food contaminated with heavy metals. Coal mining is an anthropogenic activity that releases heavy metals into the environment. This study, therefore, assessed accumulation of heavy metals (lead (Pb), cadmium (Cd), nickel (Ni), arsenic (As) and iron (Fe)) in plant species in the vicinity of Akwuke and Iva coal mine in Coal city, Enugu State. The results indicate that the highest concentration of Ni (9.02 ± 0.03 mg/kg), As (0.005 ± 0.001 mg/kg) and Cd (2.16 ± 0.07 mg/kg) was accumulated in Alchornea cordifolia while the concentration of Pb (10.37 ± 0.52 mg/kg) was highest in Andropogon gayanus and Fe (231.00 ± 1.41 mg/kg) was highest in Irvingia gabonensis. The values of Ni (9.02 ± 0.03 mg/kg), As (0.005 ± 0.00 mg/kg), Pb (10.37 ± 0.32 mg/kg), Cd (2.02 ± 0.03 mg/kg), and Fe (46.00 ± 1.41 mg/kg) accumulated in A. cordifolia, A. gayanus, D. guinense, and M. indica in wet season were significantly (P < 0.05) higher than their corresponding values (5.04 ± 0.07, 8.96 ± 0.01 and 0.003 ± 0.001 mg/kg, 1.87 ± 0.07 mg/kg, and 33.45 ± 0.21 mg/kg) in dry season, respectively. Alchornea cordifolia, Andropogon gayanus and Irvingia gabonensis consumed by animals and local inhabitants in the vicinity of the two mined sites could expose them to high levels of Pb, Ni and Cd, thus posing a serious health risk to the local people.