Evaluation of Heavy Metals in Water, Sediment, Fish and Flora from Six Selected Dams in Osun State, South-Western, Nigeria
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Date
2023-12
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Lead City University
Abstract
Heavy metals accumulation in consumables such as water, fish and plants are a threat to public health since their consumption is considered a primary route of human exposure to Potentially Toxic Elements (PTEs). This study investigated the physicochemical properties and concentrations of Cd, Cr, Cu, Fe, Ni, Pb Mn and Zn in a total of 204 samples comprising 60 Surface water, 60 sediments, 60 Tilapia (Oreochromis niloticus), 12 Okra (Abelmoschus
esculentus) and 12 Bitter leaf (Vernonia amygdalina) samples collected from six dams in Osun State between October and November 2019. Values obtained were subjected to descriptive, bivariate and multivariate statistical analyses and also compared with WHO permissible standards. All physicochemical values for the surface water were below the WHO permissible limit except for BOD, COD and Turb which were above the WHO limit of 10, 4 and 5 mg L-1 respectively. Elemental concentrations in surface water were below the WHO limit except for Cd (0.006 mg L-1) at one site and Ni (0.03 - 0.04 mg L-1) for approximately 67% of the sites. Also, elemental concentrations in sediments were greater than the WHO limits except for Cu and Cr. Although the average concentrations of PTEs in plants were below WHO permissible limits, average concentrations of PTEs in fish exceeded the WHO maximum permissible levels of 0.7, 0.6, 0.3 and 0.3 mg kg-1 for Cr, Ni, Cd, and Pb respectively. Generally, PTEs concentrations in fish were in the decreasing order of Ni > Cd > Pb > Cr and the mean concentrations of Cr, Ni, Pb, and Cd ranged from 1.18 to 2.31, 3.15 to 3.92, 2.36 to 3.73 and 0.41 to 14.2 mg kg -1 respectively. Furthermore, human health risk assessment data revealed that the consumption of Tilapia, Okra and Bitter leaf from these dams are not safe for consumers.
Keywords: Trace metals, Edible vegetables, Fish, Hazard quotient, Dams.
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Keywords
Trace metals, Edible vegetables, Fish, Hazard quotient, Dams.