Assessment of Foliose Epiphytic Lichen (Parmelia sulcata) as Bioindicators of Atmospheric Trace Metals Pollution in Lapai Metropolis, Niger State

Abstract

The levels of atmospheric trace metals were determined using foliose epiphytic lichens (Parmelia sulcata) samples collected in eight (8) different locations within the residential areas and two control locations outside the residential area of Lapai town in Lapai local government of Niger State. A stratified random sampling technique was adopted and the analysis of the samples with atomic absorption spectrophotometer (AAS) gives the concentration (mg/kg) range of the metals as follows; 1.123-7.837 for Fe, 4.579-6.62 for Pb, 0.210-2.152 for Cr, 0.491-1.171 g for Ni, 0.018-0.983 for Cd, 0.057-1.471 g Zn, 0.198-1.287 for Mn, and 0.098-2.583 for Cu but Selenium was not detected in all the samples. The levels of some of these metals were slightly higher than the recommended USEPA (1993) limits but lower than FEPA (1991) limits. However, the distribution of these metals was not uniform across the samples, though their level was still at the background and very low compared to the reports on similar studies from industrialized areas of South-south and South-west Nigeria and other European countries. The variation in concentration of these metals at p≤0.05 indicates their source is mainly anthropogenic in origin. Epiphytic lichens validate the cost-effectiveness of this method for evaluating, assessing, and identifying depositional sources of the metals in the environment. The study revealed the atmospheric trace metal concentration of the area under study to be at a threshold level and hence the environment is still very safe from atmospheric trace metal pollution.