Evaluation of levels of atmospheric heavy metals in Ikeja Industrial Area of Lagos state Nigeria using Polytrichum commune as biomonitor

Abstract

This study investigates the concentrations of some heavy metals (Zn, Pb, Cu, Ni and Cd) in moss plant Polytrichum commune collected at different locations within Ikeja Industrial Area, Lagos - Nigeria. The samples of the plant were collected randomly between September and November, 2018 at 10 different locations between 2 - 2.5 m high from unplastered buildings. The samples were properly cleaned from all the debris, weighed and digested with a mixture of HNO₃ and H₂O₂ for 35 min. The concentrations of heavy metals were analyzed using Atomic Absorption Spectrophotometer (AAS). The results obtained, showed that the average concentrations of the heavy metals at Ikeja Industrial Area were: Zn 16.01944 mg/dm³, Pb 2.9485 mg/dm³, Cu 2.7843 mg/dm³, Ni 0.6653 mg/dm³ and Cd 0.095 mg/dm³ which reflects 71.16; 13.10; 12.37; 2.96 and 0.42% respectively with the most abundant pollutant heavy metal being Zn in all the sites while the least abundant was Cd. Similarly, the most polluted site was Manufacturing Production Limited (40.894mg/L; 18.1%), while the least polluted site was Kara.com.ng (9.891mg/L; 4.4%). The levels of heavy metals obtained are greater than the permissible limits prescribed by the Federal Ministry of Environment, European Communities and United Nations Environmental Programme. There was significant difference in the level of each heavy metal in the atmosphere of Ikeja Industrial Area (P_V < 0.05).The sequence of bioaccumulation and distribution follows the trends: Zn > Pb > Cu > Ni > Cd.