Concentration of Heavy Metals in Water, Soil, and Vegetables Irrigated with Industrial Wastewater in Oromia Special Zone Surrounding Finfinne, Ethiopia

Abstract

Background: This study sought to determine the spatial distribution of heavy metal concentrations in water, soil, and vegetables that were irrigated with industrial wastewater in Ethiopia’s Oromia Special Zone. We aimed to make recommendations for corrective actions that would reduce the negative environmental effects of untreated waste. Methods: Five sampling sites were meticulously chosen within the Sululta, Laga Tafo Laga Dadi, Galan, Sabata, and Burayu regions, taking into account the varying stressors across the upper stream, middle stream, and downstream segments of the rivers. These sampling sites were strategically selected to capture a comprehensive understanding of heavy metal aggregation within the area. The sampling encompassed the collection and analysis of 25 water and wastewater samples, 13 soil samples, and 8 vegetable samples. The distribution of sampling efforts was tailored to reflect the availability of irrigation sites within the respective areas, resulting in a harmonized amalgamation of 5, 3, and 1 samples for water and wastewater, soil, and vegetable matrices, respectively. Results: The lettuce in the Gelan area had the greatest quantity of lead, suggesting higher cancer risk. The sites of Gelan and Burayu had significant levels of chromium contamination in their lettuce, followed by their cabbage, according to the WHO/FAO and USEPA. As a result, those who eat vegetables that have high levels of heavy metal contamination may be at risk for developing cancer. Conclusion: The concerned institutions and stakeholders must work to mitigate the high concentration of heavy metals in water, soil, and vegetables by the installation of treatment plant.