Temporal variability of heavy metal content in the atmosphere of Mushin Area of Lagos - State, southwestern - Nigeria using <i>Barbulaindica</i> (Hook) <i>spreng.var.indica</i> as bioindicator

Abstract

This research reports the results of some heavy metal content (Zn, Pb,Cd, Ni and Co) in Mushin area of Lagos - State using the moss plant Barbulaindica (Hook) spreng.var.indica as bioindicator. The samples of the Moss plant were collected randomly from September to November, 2016 at ten different locations at Mushin area between 2 to 2.5 metres high from unplastered buildings in Lagos state and analysed for their heavy metal contents as at the time of sampling. The samples were properly cleaned from all the debris then weighed and digested with a mixture of HN03 and H2O2 for 35 min. The concentrations of the five heavy metals were determined using Atomic Absorption Spectrophotometer (AAS). Results of the analysis, shows that the average concentration of the heavy metals at Mushin are: Zn 23.477mg/l,53.9%; Pb 4.240mg/l,9.74%; Cd 0.195mg/l,0.45%; Ni 4.418mg/l, 10.15% and Co 11.191mg/l,25.71%. The most abundant pollutant heavy metal was Zn in all the sites while the least abundant was Cd. Levels of some of the heavy metals were present in concentrations greater than WHO (2001) threshold limiting values. The most polluted site is Olorunshogo 11.809mg/l while the least polluted is Shoremekun 1.2765mg/l. The sequence of bioaccumulation and distribution follows the pattern: Zn > Co > Ni > Pb > Cd. The concentrations of heavy metals obtained exceeded the recommended limits of the Federal Ministry of Environment (FME), European communities (EC) and United Nations Environmental Programme (UNEP) permissible level for heavy metals in the atmosphere which suggests that the study area is polluted with heavy metals. There is a significant high level of each heavy metal in the atmosphere of Mushin areas (Pvalue< 0.05).

Keywords: Anthropogenic, bioaccumulation, bioindicator, concentrations, pollution, spectrophotometer