Determination of the levels of selected essential and toxic metals in soil collected from the flower farm in Roshara Roses PLC (Bishoftu) of Ethiopia and assessment of associated human health risks

Abstract

Abstract The overuse of pesticides and fertilizers to grow high-quality roses unintentionally introduces heavy metals into the soil which is detrimental to the human health. Thus, the aim of the current study is to examine the concentrations of the essential (Ca, Mg, Zn, Fe, Cu, Fe, Mn and Ni) and toxic metals (Cd and Pb) in the soil samples from the flower farm using Flame atomic absorption spectrometry (FAAS) and to assess the risk that heavy metals pose to human health. To obtain an optimum condition for the wet digestion of soil samples, the volume ratio of reagents, reflux time and temperature were optimized. The concentrations of Ca, Fe, Mn, Mg, Zn, Cr, Ni, Cu were found to be 3468, 4926, 450, 255, 74, 70,48.5 and 25 and 2150, 4862,472, 241, 71, 58, 37 and 12.5 mg/kg for the soil samples collected from the flower farm and road side, respectively. Cadmium and lead were not detected in the studied soil samples. Statistical analysis of variance (ANOVA) showed the concentrations of Ca and Cu in the two soil samples are significantly different. Correlation analysis showed there was strong positive association for Fe with Zn, Cr and Ni, Mg with Ca, Cu, Ni and Cr, Zn with Cr and Cu and Ni with (Cu, Zn and Cr). Values of hazard quotient (HQ) and hazard index (HI) for the heavy metals under the study in the all exposure pathways are below 1.0 indicating that none of them could be harmful to human health.