CHEMICAL FRACTIONATION AND BIOAVAILABILITY OF SELECTED HEAVY METALS IN SEDIMENTS OF RIVER CHALLAWA, KANO, NIGERIA

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Date
2009-08
Authors
BABALE, ABDULLAHI
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Abstract
River Challawa, Kano was divided into two parts, study and control areas. 10 sampling points were chosen as study area while 5 sampling points as control area. The point of effluent discharge from Challawa industrial area into the river demarcated the two areas. The physico-chemical parameters of the sediment were studied. The total metal (Zn, Cu, Pb, Cd and Cr) concentrations in the sediment were also determined. Sequential extraction was used to fractionate the five heavy metals into five operationally defined groups: exchangeable, carbonate, Fe-Mn oxide, organic and residual. Organic matter content of sediment ranged from 7.1 - 10.25% with the study area having the higher organic matter content. The pH of the sediment ranged from 5.0 - 5.75 in the study area while that of control area ranged from 5.25 - 6.0. pH value obtained revealed the slight acidic environment of the sediment. Other physicochemical parameters determined showed higher values in the study area than in the control area. The distribution pattern of Zn in the operationally defined phase followed: Fe-Mn oxide bound > carbonate bound > residual > organic bound > exchangeable in both the study and control areas. Chromium in different fractions were in the order: residual > carbonate bound > Fe-Mn oxide bound > organic bound > exchangeable in the study area. Chromium was associated mainly (65 ā€“ 93.3%) with the residual fractions. Pb in the river sediment showed the order of association: residual > Fe-Mn oxide bound > organic bound > carbonate bound > exchangeable. The association of Cu was dominated by the organic phase (44.88%) with Fe-Mn oxide bound (16.82%) carbonate bound 5.55% and exchangeable 2.79%. The Cd association with different sediment fraction followed the order: residual >> exchangeable > carbonate bound > Fe-Mn oxide bound > organic bound The result indicated that Cd is potential bioavailable since metals present in the exchangeable are usually readily available for plant or organism uptake. The potential bioavailablility of the metals in the sediment in this study are Cd>>Zn>>Cu>>Pb>.Cr
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A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY, ZARIA NIGERIA IN PARTIAL FULFILLMENT FOR THE AWARD OF MASTER OF SCIENCE IN ANALYTICAL CHEMISTRY DEPARTMENT OF CHEMISTRY AHMADU BELLO UNIVERSITY, ZARIA NIGERIA.
Keywords
CHEMICAL,, FRACTIONATION,, BIOAVAILABILITY,, SELECTED,, HEAVY METALS,, SEDIMENTS,, RIVER CHALLAWA,, KANO, NIGERIA
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