INVESTIGATION OF TOXIC TRACE ELEMENTS IN SOILS AND COFFEE BEANS USING INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROMETRY (ICP-OES)

Abstract This research investigates the concentration levels of toxic trace elements arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb)in soils and coffee beans from Chichu Kebele, Dilla Zuriya Wereda, located within the Gedeo Zone of South Ethiopia. Utilizing Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), soil and coffee bean samples were collected and prepared through standardized microwave-assisted digestion to ensure accuracy and reliability. The study findings reveal that the mean concentrations of arsenic, cadmium, mercury, and lead in the research soil were 1.173 mg/kg, 0.879 mg/kg, 1.109 mg/kg, and 2.887 mg/kg, respectively, which exceeded those of control soil samples. Despite these elevated levels, concentrations remained below the maximum allowable limits set by the WHO/FAO, highlighting a potential contamination concern for agricultural practices. In the coffee bean samples, average concentrations of arsenic, cadmium, mercury, and lead were recorded at 0.028 mg/kg, 0.0577 mg/kg, 0.027 mg/kg, and 0.167 mg/kg, respectively. Statistical analysis further indicated significant differences in toxic trace element concentrations between research and control soil (p < 0.04).so which showed that the research soil is contaminated but the it also revealed that the research soil and coffee beans are not polluted by this toxic trace elements with confidence level of 99.9%.