College of Natural and Computational Sciences
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Item Assessment of Heavy Metal Levels in Soil, Vegetables and Wastewater used for Irrigation in Wukro, Tigray, Ethiopia(Mekelle University, 2025-09-25) Nigisti GirumFresh vegetables and fruits are the most common foods of human diet all around humankind often used for balanced diet, prevention and treatment of various diseases. However, if these vegetables and fruits grow in a polluted environment they can be a major public concern due to their toxic property which leads to acute and chronic health effects. The aim of this study was to determine the level of manganese, chromium, copper, zinc and lead and to estimate their health risks associated with their daily intake in vegetables grown in Wukro town, Tigray. FAAS was used to determine concentrations of those heavy metals in selected vegetables (cabbage, onion, spinach, lettuce and tomato). 1 gm of each sample was digested by wet digestion method using a mixture of HNO3 (69%), HClO4 (70%) and H2O2 (30%) until a clear solution was prepared. After proper dilutions, the solutions were aspirated into the FAAS. The absorbance value of heavy metals was converted in to concentration using linear calibration curve equation. Finally, the concentration of each metal was expressed in mg/Kg of dry weight of each sample and health risk was estimated by using estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) for selected heavy metals. The validity of the method was checked by the analysis of spiked samples whose recovery was found in the range of 90.8-107.0% and %RSD value in the range of 0.03-7.7%. The average concentrations of Cr and Cu in all of the selected vegetables were lower than the maximum limit of normal values. However, concentrations (mg/kg) of Pb in cabbage (2.05), spinach (2.47), and lettuce (1.56) had exceeded the safe limit, 0.3 mg/Kg set by FAO/WHO. Hence, consuming plant products grown from contaminated water sources such as municipal wastes, industrial effluents, engine fuels, garages disposals, constructions and car washes are potentially toxic to plants, animals and humans. Therefore, people and concerned bodies should take care of the sources of water for irrigationItem Comparative Assessment of Heavy Metal Levels in the Soil and Some selected Edible Fruits (Orange and Papaya) Grown in the Addiha Irrigational site, Kola Tembien-Woreda Tigray, Ethiopia(2025-03-25) Gebremeskel Welegebrial HagosEdible fruits (orange and papaya) are source of vitamins, minerals and organic acids which provide an excellent health promoting nutrients. Heavy metals are natural constituents of the Earth's crust and their excessive consumption levels can be damaging to the organisms. The objective this study was compartive assessement of heavy metals (Fe, Zn, Cu, Cr and Mn) in the soil and selected edible fruits (Orange and Papaya). The sampling methods of this study were randomly and targeted methods.The chemicals used in this study were HNO3, HClO4, HCl and distilled water and the materials used inthis study were cutters, sample containers (plastic bags), gloves, hot plates, beakers, test tubs, electrical balance, spoon, stirrer, sample cells, oven, sample holder, volumetric flask and digester. The study was assessed heavy metal (Zn, Cu, Cr, Mn, and Fe) in both soil and selected edible fruits (orange and papaya) grown in the Addiha irrigation site Kola Tembien woreda central zone of Tigray, Ethiopia. Soil analysis revealed that Zn, Cu, and Mn were below established WHO (2011) safe limits, while Cr and Fe exceeded them. In contrast, all heavy metal levels in the selected edible fruits (orange and papaya) were below the established WHO (2012) safe limits. T-tests showed statistically significant differences (p<0.05) for the concentration level of heavy metals Zn, Cr, Mn, and Fe, but the heavy metal Cu is not statistically significant (p>0.05), while the analysis using ANOVA showed significance for all elements when comparing soil to fruit which between soil and orange and between soil and papaya were statistically significant differences (p<0.05). Transfer factors between soil and edible fruits (orange and papaya) varied, with Zn being highest in both. Strong positive correlations were also observed between heavy metal levels in soil and those in the selected edible fruits. The correlation coefficients of soil and orange are (0.9877) and soil and papaya is (0.99932). ANOVA revealed statistically significant differences (p<0.05) between orange and papaya fruits for the mean concentration of heavy metals except Cu at (p<0.05) for Zn, Cu, and Fe, but not for Cr and Mn (p>0.05). Furthermore, ANOVA comparisons between orange and soil, as well as papaya and soil, showed statistically significant differences for all heavy metals (Zn, Cu. Cr. Mn and Fe) (p<0.05). Keywords: Heavy metals, Edible Fruits, Soils, Permissible levels