Distribution and risk assessment of heavy metals in Peri-urban areas of Kumasi
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Date
2018-08
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Publisher
KNUST
Abstract
The occurrence of heavy metals in urban soil is of great environmental concern due to
the effects associated with excessive exposure. The main purpose of the work was to
measure the levels and determine possible health risks due to excessive exposure to
some selected metals. A total of 73 soil samples were collected from the top soil of
Peri- Urban areas of Kumasi at a depth of 0-10 cm and subjected to the X - ray
fluorescence spectroscopy analysis. Soil pH, conductivity and total organic content
were also determined. pH and electrical conductivity were in a range of 6.5 - 8.5 and
153 S/cm - 8990 S/cm respectively for all samples. The mean concentrations of
metals analyzed were Pb (18.60 0.53 mg/kg), Cu (20.20 2.34 mg/kg), Ni (29.33
2.0mg/kg), Cr (77.97 4.35 mg/kg), Zn (49.27 3.56 mg/kg), Fe (23031 10.56
mg/kg), Mn (158.688.56 mg/kg) ,V (78.215.34 mg/kg), Sn (8.834.85 mg/kg), Cd
(12.9152 mg/kg) and As (10.112.93 mg/kg). The enrichment factor (0.2090.004),
contamination factor (0.4830.003) and Pollution Load Index (0.0570.004) indicated
that soil in the study area is not polluted. The Potential Ecological Risk Index projected
low risk effect whereas Hazard Index and Carcinogenic Risk Index indicated no human
health risk associated with exposure to these metals. Bioaccessibility of surface soil
samples was estimated using the modified in vitro physiologically based extraction test
(PBET), with the results indicating that the bioaccessibility of the metals were all below
100%. However, to regulate bioaccumulation effect, constant monitoring is required
Description
A thesis submitted to the Department of Chemistry. Faculty of Physical and Computational Sciences, Kwame
Nkrumah University of Science and Technology, in partial fulfilment of the requirements of the Degree of
Master of Philosophy (Environmental Chemistry)