DETERMINATION OF SOME HEAVY METALS IN SELECTED FISHES IN THE VICINITY OF CONFLUENCE OF RIVERS NIGER AND BENUE IN LOKOJA, NIGERIA
DETERMINATION OF SOME HEAVY METALS IN SELECTED FISHES IN THE VICINITY OF CONFLUENCE OF RIVERS NIGER AND BENUE IN LOKOJA, NIGERIA
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Date
2016-02
Authors
BAWA, Isuwa
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Abstract
The study assessed the physicochemical parameters of the water and concentrations of Cd, Co, Cr, Cu, Pb and Zn in the water, sediments and organs (bones, brain and flesh) of Clarias gariepinus, Oreochromis niloticus and Synodontis nigrita obtained from River Niger, River Benue (close to their confluence) and after the confluence point at Lokoja, Nigeria during the months of March, June, September and December 2013. By using standard procedures, the chemical oxygen demand, dissolved oxygen, turbidity, biological oxygen demand, total dissolved solids, total hardness, conductivity and pH of the water were determined. The ranges of these parameters were 98.25 - 141.73 mg/L, 2.26 - 14.39 mg/L, 5.33 - 23.13 NTU, 5.56 - 15.59 mg/L, 457.91 - 781 mg/L, 48.85 - 245.83 mg/L, 65.61 - 233.39 μs/cm and 6.77 - 8.07 respectively. All the parameters were above the acceptable limits set by World Health Organisation (WHO), except pH. The concentrations (mg/L) of Cd, Co, Cr, Cu, Pb and Zn in the water samples were in the range of 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 respectively. Only Pb and Zn were in levels within the permissible limit set by WHO and the concentrations recorded between the rivers and across sampling periods were significantly different. The concentrations of Cd, Co, Cr, Cu, Pb and Zn in the sediments were in the range of 0.2026 - 2.0203, 2.1567 - 20.5421, 13.1767 - 33.0976, 7.0832 - 23.4040, 0.1054 - 2.5593 and 12.9263 - 32.8418 mg/kg respectively. The mean concentration of Cd in the sediment was above the ISQG (Interim Freshwater Standard Quality Guidelines) limit of 0.6000 mg/kg. The pollution load index for the heavy metals indicates low to moderate pollution state of the sediments while the geoaccumulation index for Cd, Co, Cr, Cu, Pb and Zn also suggest low to moderate
pollution of the sediments by Cd, Co and Cr. The organs of the three fish species bio-accumulate Cd, Co, Cr, Cu and Pb above their respective permissible limit. The bone accumulated the metals more than the brain and the level was least in the flesh for all the metals. However, Zn was below the acceptable limit in all the species and organs. Cd and Pb accumulate more in O. niloticus followed by C. gariepinus and least in S. nigrita. Generally, the parameters for the water samples obtained in March 2013 were the highest. The results indicate pollution of the rivers, so enforcement of environmental laws that will minimize anthropogenic activities is imperative
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A MASTER DEGREE OF SCIENCE IN ANALYTICAL CHEMISTRY DEPARTMENT OF CHEMISTRY, FACULTY OF SCIENCE AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
DETERMINATION,, HEAVY METALS,, SELECTED FISHES,, VICINITY,, CONFLUENCE,, RIVERS NIGER,, BENUE,, LOKOJA,, NIGERIA,