Monitoring the level of heavy metals pollution in automobile mechanic workshops using tree barks

Abstract

The level of heavy metals at automobile mechanic workshops were monitored by examining tree barks of different species and influence of sampling heights on the metals level. This was with the aim of determining the suitability of using tree barks in monitoring the level of air pollution.  Tree bark samples were collected at 2 and 4m heights from different automobile mechanic workshops around Ile-Ife metropolis and at control sites. The samples were transported to the laboratory, oven-dried at 60 ˚C to a constant weight; ground and analyzed for Pb, Cu, Cd, Fe and Zn using Atomic Absorption Spectrophotometer. Results showed that the concentration of Fe, Cu and Pb at the mechanic sites were significantly (p < 0.001) higher at 2 m than 4 m height in all the species. The concentration of Zn was significantly (p < 0.001) higher at the 2 m height in all the sites except for Gliricidia sepium. The concentration of Cd was however, significantly (p < 0.05) higher at the control site at the two heights for the species except for Gliricidia sepium and Terminalia catappa, that showed no significant difference (p > 0.05) between the sites. The correlation value of 0.94 was observed between Zn and Cd; 0.76 between Pb and Cd, and 0.50 between Zn and Pb. This study showed that different species have different affinities for air pollutants and that soil particles also acted as a source of heavy metals in our environment.

Keywords: Atmospheric, Automobile, Pollutants, Soil particle, Trace metals, Tree barks