Post Flooding Assessment of the Heavy Metal Pollution of Water and Fish of Rivers Niger and Benue in Lokoja, Nigeria
Post Flooding Assessment of the Heavy Metal Pollution of Water and Fish of Rivers Niger and Benue in Lokoja, Nigeria
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Date
2016
Authors
OMONIYI, Kehinde Israel
EKWUMEMGBO, Adamma Patricia
BAWA, Isuwa
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Abstract
The study reports the water quality and heavy metal concentrations in Clarias gariepinus, Oreochromis niloticus and Synodontis nigrita obtained from rivers Niger and Benue in Lokoja, Nigeria following the 2012 flooding in Nigeria. The chemical oxygen demand, dissolved oxygen, turbidity and biological oxygen demand of the water ranged: 98.25-141.73 mg/L, 2.26-14.39 mg/L, 5.33-23.13 NTU, 5.56-15.59 mg/L respectively in 2013. Cd, Co, Cr, Cu, Pb and Zn in the water ranged from 0.0082-0.0276, 0.0042-0.0279, 0.0480-0.1391, 0.0979-1.8037, 0.0003-0.0047 and 0.7671-2.8510 mg/L respectively. There was significant difference in the metal levels of the rivers and by sampling periods (P < 0.05). The bio-accumulation of Cd, Co, Cr, Cu and Pb by the fish follows the ranking: bone > brain > flesh. Cd and Pb accumulated in the order O. niloticus > C. gariepinus > S. nigrita. The results indicate pollution of the rivers, so enforcement of environmental laws is imperative. Enokela and Salifu (2012) reported the pH, turbidity, DO and BOD of River Niger water in Lokoja, Nigeria to be 7.42, 42.75.60 NTU, 8.73 mg/L and 2.24 mg/L respectively for River Niger; with Na+, Ca2+, Mg2+, Cl- and SO42- found within the tolerable limit set by WHO [5]. The metal concentration in the water of River Niger in Lokoja was in the sequence Mn > Zn > Cu > Cr > Ni > Cd > Pb [6]. On the other hand, water from River Benue at Makurdi, Nigeria recorded pH (5.00 - 9.00), TDS (6.81 - 521.33 mg/L), turbidity (3.00 - 258 NTU), conductivity (9.90 - 1071.00 μS/cm) and copper (0.00 - 1.45 mg/L) and the ranking for heavy metals was Cd < Cu < Zn < Mn < Pb < Cr < Fe [7], [8].
Tukura et al. (2005) stated that except for chromium, metal levels in water were higher than in Clarias gariepinus and Tilapia zilli and that zinc and lead bio-accumulate most in the gills of the fish species studied [9]. Heavy metals accumulate more in the visceral tissues (liver, kidney, intestines etc) than in other organs and least in the muscles of Tilapia and shrimps [10].his work is aimed at furnishing scientific data on the quality of the water and fish from River Niger and River Benue in Lokoja, Nigeria, since these rivers supply bulk of fish for commercial purpose and serve as source of water for municipal and industrial utilization.
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preprint journal article
Keywords
Bio-accumulation,, Fish,, Flooding,, Rivers,