Airborne Trace Metals Heavy Metal Pollution Biomonitoring Environmental Pollution Trace Metal Accumulation Atomic Absorption Spectrometry AAS Psidium guajava Mangifera indica Chromium Cr Iron Fe Nickel Ni Lead Pb

The importance of tree plant species as biological components in the ecosystem is significant. These plants are used as shade, beautification, and even food. Urban locations are also bound to face numerous human activities that cause the introduction of many pollutants, including trace (heavy) metals into the environment. This research work is designed to determine the level of airborne trace metals (Cr, Fe, Ni, and Pb) present in the environment using Psidium guajava and Mangifera indica. The bark and leaf samples of these trees were collected, digested and analyzed using the Atomic Absorption Spectrometer (AAS). The bark samples of Mangifera indica gave a mean concentration of Cr – 0.24mg/kg, Fe – 15.85mg/kg, Ni – 0.11mg/kg, and Pb – 0.04mg/kg while the leaf samples gave a mean concentration of Cr – 0.28mg/kg, Fe – 15.70mg/kg, Ni – 0.09mg/kg, and Pb - 0.03mg/kg. Also, the data obtained from Psidium guajava bark samples gave a mean concentration of Cr – 0.19mg/kg, Fe – 2.25mg/kg, Ni – 0.03mg/kg, and Pb – 0.02mg/kg while the leaf samples resulted in a mean concentration of Cr – 0.15mg/kg, Fe – 2.70mg/kg, Ni – 0.06mg/kg, and Pb – 0.04mg/kg. The leaf and bark samples of Mangifera indica accumulated the highest level of trace metals, indicating that they are good biomonitors of airborne trace metals in Ugbowo Campus. The level of chromium (Cr) is above the permissible limit in all the plant species suggesting the contamination of the study area. The levels of other trace metals reported in this study are below the permissible limit. The findings of this work therefore shows that the study area is unsafe in Cr levels but safe and clean in the levels of other airborne heavy metals (Fe, Ni, and Pb).