| Popis: |
The atmospheric deposition of some heavy metals was investigated using lichen (Parmelia caperata) and moss (Polytrichum juniperinum, Calymperes erosum and Racopilum africanum) samples collected from two oil-producing host communities viz Eket and Ibeno Local Government Areas of Akwa Ibom State, Nigeria. Lichen and moss samples were analysed using atomic absorption spectrometry equipped with flame and graphite furnace after decomposition using acid digestion technique. The concentrations of heavy metals in lichen and moss samples ranged from 0.001 - 0.092 μg g −1 for cadmium (Cd); 0.004 - 8.793 μg g −1 for chromium (Cr); 0.989 - 1.950 μg g −1 for cobalt (Co); 2.350 - 110.760 μg g −1 for copper (Cu); 10.530 - 153.320 μg g −1 for manganese (Mn); 1.425 - 21.730 μg g −1 for nickel (Ni); 0.001 - 17.380 μg g −1 for lead (Pb), and 23.530 - 130.600 μg g −1 for zinc (Zn). The statistical significance of correlations between Cu-Pb, Cu-Zn, Pb-Ni and Mn-Zn concentrations confirmed anthropogenic sources mainly due to emissions from vehicular traffic, fossil fuel combustion, solid waste disposal and other local anthropogenic activities. In a direct comparison, some of the target heavy metals such as Cd, Cr, Mn, Ni and Zn were accumulated at higher concentrations in moss samples compared to lichen from the same sampling site. The results obtained reveal important contributions towards understanding of heavy metal deposition patterns and provide baseline data that can be used for potential identification of areas at risk from atmospheric heavy metals contamination in the region. The use of epiphytic lichens and mosses provides a cost-effective approach for monitoring regional atmospheric heavy metal contamination and may be effectively used in large scale air pollution monitoring programmer. |
