Abstract:
Leafy Vegetables widely consumed in Hirna, Western Hararghe, Ethiopia such as cabbage
(Brassica oleracea var), lettuce ( Lectuca sativa L.) and Swiss chard (Beta vulgaris L.var
.cicla) are cultivated on the main roadside soils. For this study, leafy vegetables and soil
samples up on which they grow were collected at distances of 5,6 and 7m from the main road
and the digestion procedures were optimized with a mixture of conc. 69-72 % HNO3 and
70 % HClO4 for the vegetables samples and a mixture of conc. 69 - 72 % HNO3, 36-38 %
HCl and 30 % H2O2 for soil samples and wet digestion procedure was employed to solubilized
the metals from the samples. The validation was performed by spiking the samples with a
standard solution of each metal having a known concentration and the percentage recovery
values in the ranges of 88.6–108.4 % for soil and 87.9 - 98.67 % for vegetable samples. The
samples were analyzed with the Flame Atomic Absorption Spectrophotometer (FAAS) to
determine level of selected heavy metal (Pb, Cd, Cu, Zn, Ni, Co and Fe) in leafy vegetables
and main roadside soils. The results showed that the levels of heavy metal in vegetable
samples the ranges of 0.106 - 0.130 mg/L in lead, 1.856- 3.335 mg/L in zinc, 0.902- 1.13
mg/L in copper and 3.409- 5.929 mg/L of iron. The content heavy metal in soil samples also in
the ranges of 0.137-0.179 mg/L in lead, 5.61-7.104 mg/L in zinc, 2.360-4.557 mg/L in copper
and 7.778- 10.038 mg/L of iron. The levels of cadmium, cobalt and nickel were not detected (ND) in all samples. The heavy metal contents at the same distance from the road were found in
leafy vegetables and soil samples in the following order: Fe > Zn > Cu > Pb. All these values
were small when compared to the WHO/FAO safe limit, which is an indicated that the leafy
vegetables samples in Hirna town area are safe for consumption without the risk of
environmental toxicants.
