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October 2012 Volume 1 Issue
7
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Gobal Advanced Research Journal
of Environmental Science and Toxicology (GARJEST) ISSN:
2315-5140
October 2012 Vol. 1(7), pp.
183-189
Copyright © 2012 Global Advanced Research Journals
Full Length
Research Paper
Heavy metal
concentration in some fishes (Chrysichthys nigrodigitatus,
Clarias gariepinus and Oreochromis niloticus) in the
Great Kwa River, Cross River State, Nigeria
Fidelis Bekeh Ada1*,
Edet Ekpenyong2 and Bayim Peter-Robins Bayim3
1Department
of Fisheries and Aquatic Sciences, Faculty of Agriculture
and Forestry, Cross River University of Technology, Obubra
Campus, Cross River State, Nigeria.
2Department
of Zoology and Environmental Biology, Faculty of Sciences,
University of Calabar, Cross River State, Nigeria.
3Department
of Chemical Science, Faculty of Sciences, Cross River
University of Technology, Calabar Campus, Cross River
State, Nigeria.
*Corresponding Author E-mail:
fbekehada@yahoo.com
Accepted 13 October, 2012
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Abstract |
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Heavy
metal concentration in the tissues of three
important food fishes namely: Chrysichthys
nigrodigitatus, Clarias gariepinus and Oreochromis
niloticus were investigated. This was aimed at
finding their fitness for consumption become fish is
usually at the apex of aquatic food chain capable of
bioaccumulating heavy metals. Specimens were
purchased once a month from the local fishers at
Ekpene Esuk Essighi and Esuk Mba landing sites.
Gills, kidney, liver, stomach and muscles were
washed and oven dried at 105 0C until constant
weight. Heavy metals concentrations were obtained
spectophotometrically using Perkin-Elmer Analyst 300
Atomic Absorption spectroscopy (AAS). A one way
Analysis of variance (ANOVA) was used to test the
difference in concentrations of heavy metals in the
different tissues. Differences in means were
separated by the use of Duncan’s multiple range
tests (DMRT). In Chrysichthys, zinc was highest in
stomach (177.70+1.48 mg/kg) and lowest in muscle
(32.37+1.00 mg/kg) Chromium was not detected in
muscle but highest in gills (0.34+0.01 mg/kg).
Cadmium ranged from 0.004+0.001 mg/kg in muscle to
0.02 in kidney. Nickel was 0.00+0.00 mg/kg in kidney
to 0.012+0.001 mg/kg in liver. Lead was high in the
gills of Chrysichthys. Clarias has the highest
concentration of zinc in gut (99.43+ 0.87 mg/kg and
lowest in muscle. Chromium and Nickel were the least
concentrated metal in tissues of Clarias. Cadmium
was high in the gills (0.06+0.01 mg/kg) and lowest
in muscle (0.002+0.001 mg/kg). Lead had the highest
concentration in gills (0.044+0.014 mg/kg) and
0.001+0.001 mg/kg in muscle. In Oreochromis, lowest
zinc was in muscle (28.41+0.58 mg/kg) highest in
kidney (66.48+ 0.002 mg/kg) Chromium was not
detected in any tissue. Cadmium was found in gills
(0.002+0.001mg/kg), kidney (0.05+0.001 mg/kg) and
liver (0.273+0.01mg/kg). Nickel was found in liver
in trace amount only. Lead was not present in muscle
but highest in gills (0.213+0.025 mg/kg). Of all the
tissues, muscle was the one with least concentration
of metals. These concentrations were allowable in
food fish.
Keywords: Chrysichthys, Clarias, Oreochromis,
Heavy metals, Great Kwa River.
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