Mnium hornum Hedw moss as bioindicator of atmospheric pollution of heavy metals in the University of Lagos, Akoka Campus

Abstract

This study investigated the presence of heavy metals pollutants in the University of Lagos, Akoka campus using the moss (Mnium hornum Hedw.) as a bioindicator. Samples of M. hornum. were collected in 2019 from four different locations within the University of Lagos campus: Faculty of Engineering (FE), Lagoon Front (LF), Main Library (ML) and Akintunde Ojo Library (AKT). A control sampling was done at First Estate, Amuwo-Odofin LGA (CL). The concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were determined using the Atomic Absorption Spectrophotometer (AAS). Results confirmed the presence of heavy metals in the following order Fe > Zn > Mn > Cu > Pb > Ni > Co > Cr > Cd. The concentrations of the examined heavy metals across the locations were lowest in CL except Ni which was lowest in FE and LF (0.03mg/kg). While there were no significant differences in the concentrations of Cd, Co, Cr, Cu, Mn, Ni, and Pb among the locations, both Fe (66.00mg/kg) and Zn (64.33mg/kg) were significantly higher in ATK than in the other locations. The contamination factor suggests that ML (C2), FE (C3) and LF (C3) were moderately contaminated while AKT (C5) was highly contaminated. The index of geo-accumulation revealed that FE (I_geo4) and ML (I_geo4) are moderate to severely polluted, LF (I_geo5) was severely polluted while AKT (I_geo7) was extremely polluted with the assayed metals. The difference in the occurrence of anthropogenic activities was believed to be the major factor responsible for the variations in the concentration of heavy metals accumulated by the mosses.