Determination of the Level of Metallic Contamination in Irrigation Vegetables, the Soil, and the Water in Gondar City, Ethiopia

Abstract

Background: The sources of edible vegetables in Gondar, Ethiopia, are mainly from irrigation farms grown on the banks of polluted rivers. The aim of the current study was to determine the metallic contamination level of vegetables (Ethiopian kale, cabbage, Swiss chard, lettuce, onion, tomato, and potato), the soil they are grown in, and the water used for irrigation. Methods: The concentrations of copper (Cu), manganese (Mn), zinc (Zn), chromium (Cr), cadmium (Cd), nickel (Ni), and lead (Pb) were determined using flame atomic absorption spectrometry. A composite purposive sampling method was used to collect samples from the Keha river irrigation site of Gondar city, Ethiopia. Acid digestion was performed before the samples were analyzed. Microsoft Excel was used for descriptive statistical analysis, and ANOVA was employed to compare the mean difference. Results: In the vegetables samples, the mean concentrations of Cd, Ni, and Pb (0.23–6.25, 7.41–51.85, and 0–9.52 mg/kg, respectively) were found to be above the limits set by the joint WHO/FAO. Swiss chard and potato were found to contain the highest levels of Pb, while Ethiopian kale was highly contaminated with Cd and Cr. For the soil samples, the Pb (138.09–259.24), Ni (85.18–259.26), and Cd (4.63–20.37) mean concentrations (mg/kg) exceeded the recommended maximum limits set by the FAO. The mean concentrations (in mg/L) of Cr (0.5), Cd (0.046), and Cu (1.80) in the irrigated water samples were above the limit set by US EPA (2004). Conclusion: The vegetables were contaminated with heavy metals that could be unsafe for chronic human consumption. In particular, leafy vegetables showed higher heavy metals levels compared to non-leafy vegetables.