INVESTIGATION OF ESSENTIAL AND POTENTIALLY TOXIC HEAVY METALS IN SOILS AND PINEAPPLE FRUIT BY USING ATOMIC ABSORPTION SPECTROSCOPY TECHNIQUE (AAST) (The Case of Teso Area in Aleta Chuko Woreda, Sidama Region)

Abstract Heavy metal toxicity arising from anthropogenic sources poses a great challenge to humans, animals, and plants. This study assessed the amounts of Mn, Cu, Pb, Cd, and Cr in soils and the pineapple in order to evaluate the health risks to humans posed by possibly harmful heavy metal contamination of the soil and pineapple fruits. Samples of soil and pineapple fruit are collected from the research site and analyzed by flame atomic absorption spectroscopy. A total of 4 pineapple fruit samples, research soil samples, and control soil samples are collected from the research site of the Teso region. The collected samples were kept in a drying oven, and 1 gm of the sample was digested by the wet digestion method using a mixture of HNO₃ (69%), HClO₄ (70%), and H₂O₂ (30%) acid to determine the optimum digestion condition and prepared solution. After preparation, the solutions were into the flame atomic absorption spectroscopy. The absorbance value of heavy metals was converted into concentration using a linear calibration curve equation. The pH of the soil samples is also measured, and data is analyzed using ANOVA. The validation procedure is performed by spiking the samples with a standard solution of each metal having a known concentration and percentage recovery values in the range of 93.69 - 98.77% for the soil samples and pineapple fruit sample. The result obtained from this study showed overall concentrations of heavy metals (Cr, Cd, Mn, Pb, and Cu) are respectively in the range of (0.0367- 0.0627), (0.035-0.047), (0.025-0.067), and (0.0785-0.0969) (mg/kg) in the edible parts of sampled pineapple fruits. The mean concentration of determined metals in pineapple fruit samples the order of Cu > Pb > Cr > Mn > Cd. Similarly, concentrations (mg/kg) of the metals in the research soil samples were found to be in the ranges of Mn (1.13-1.338), Cu (0.491-0.589), Cr (0.1188-0.1312), Cd (0.064-0.108), and Pb (0.207-0.263). The mean concentration of determined metals in agricultural soil samples the order of Mn > Cu > Pb > Cr > Cd.