Assessment of Heavy Metal Accumulation and associated potential health Risk in Green Leafy Vegetables Grown on Urban Wastewater Irrigated soil in Southern Addis Ababa, Ethiopia (case of Chromium, Lead and Cadmium).
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Date
2015-06
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Addis Ababa University
Abstract
A total of 16 Samples of wastewater, vegetable washing water, soil, root, stem, and leaf parts of the
vegetables (Ethiopian Kale, Lettuce and Chard) were collected directly from the farm. All the samples
were analyzed for the concentration of the three heavy metals lead (Pb), chromium (Cr), and cadmium
(Cd).
The concentrations of Pb, Cr and Cd in the leaves, stems and roots of Ethiopian Kale, Lettuce and Chard
were found to be in mg kg-1 Cadmium (Ethiopian Kale :0.011 }0.0000, 0.007 }0.0002 and 0.011 }0.0003;
Lettuce: 0.014 }0.0002, 0.016 }0.0003 and 0.125 }0.0003; Swiss chard: 0.014=0.0000, 0.007 }0.0000and
0.005 =0.0002, Chromium (Ethiopian Kale: 0.124 }0.0117, 0.044 }0.0137 and 0.075=0.0021; Lettuce:
0.193=0.0105, 0.033 }0.0018 and 0.112±0.0074; Swiss chard: 0.103 }0.0088, 0.067=0.0072 and
0.162=0.0000) and Lead (Ethiopian Kale: 0.620 }0.0132, 0.221 }0.0156 and 0.373 =0.0021; Lettuce:
0.019 =0.0187, 0.009 }0.0089 and 0.002 }0.0022; Swiss chard: 0.689 }+0.0093, 1.336 =0.0043 and
0.133 =0.0168) on dry matter basis, respectively.
Results showed that, all the samples contain the three heavy metals below safe value limit recommended
by FAO/WHO. Accumulation factor has the maximum value in the stem and root parts of Swiss chard
(i.e. 0.035 and 0.018 for Pb), respectively. Accumulation factor also has the maximum value in lettuce
root and chard leaf parts of the vegetable (i.e. 0.048 and 0.041 for Cr) and 0.250, 0.032 in the lettuce stem
and leaf parts for Cd, respectively. The BCF value of Pb is approximately 2- fold in stem than the root.
However, all the 3 vegetables samples can be considered excluders of the 3 heavy metals (i.e.BF< 1).
PCA (Principal Component Analyses) shows impact of wastewater irrigation and Pb contamination is
serious in wastewater-irrigated agricultural soils of the study area.
The potential health risk calculated by THQs of all three heavy metals in the three leafy vegetables were
less than 1.0 for adults , indicating that the adult residents in the Addis Ababa are not exposed to
significant health risks associated with consumption of green leafy vegetables grown around the study area.
Keywords ; Wastewater Irrigated soil; Green leafy vegetables; Heavy metals; Bio concentration factor;Target hazard quotient
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Keywords
Wastewater Irrigated soil; Green leafy vegetables; Heavy metals; Bio concentration factor;Target hazard quotient