Assessment of Atmospheric Metal Depositions in the Industrial Areas of the Southwest of Nigeria

Abstract

Industrial wastes and discharges have been reported to cause environmental pollution. Lagos and Ogun states house many industries which are assumed to have impacted the states. It is in respect of these that the atmospheric metal deposit of Lagos and Ogun industrial areas, southwest Nigeria were assessed to determine the extent of air pollution of these areas. 100 moss samples were collected from the industrial areas of these two states and were digested using Nordic guidelines and the As, Cd, Cr, Pb, Ni, Cu and Ag contents determined by Atomic Absorption Spectrophotometeric method. Data generated were statistically analysed with Analysis of Variance and the means separated with Duncan Multiple Range Test. It was found that Ogun state was more polluted with Cd, Ni and Cu, Lagos state had more of Pb while the Cr, Ag and As concentrations of the two areas were statistically the same. Moreover, the concentrations of Ag, As and Cr were less than 1mg/l while those of Cd, Cu, Ni and Pb were less than 10mg/l. These metals contributed differently to the pollution of the study areas. It was further found that the highest concentrations of Pb (9.16mg/l), Ag (0.07mg/l), Cr (0.32mg/l) were found in Mile 2, Ojota and Mile 2 respectively in Lagos while the least concentrations were found in Aiyepe, Ogun state. In the same vein, the highest concentration of As (0.31mg/l), Ni (98.32mg/l), Cu (7.76mg/l) and Cd (8.70mg/l) were recorded in Agbara, Attan-tta, Sagamu and Aiyepe respectively, all in Ogun state. The least values were found in Aiyepe (0.04mg/l), Ikeja (6.54mg/l), Mile 2 (5.83mg/l) and Ojota (1.85mg/l) respectively. However, all these heavy metals were present in concentrations greater than the recommended limits of Federal Environmental Protection Agency and European Communities and this suggest that the study areas are highly polluted. It is hoped that the results of this study would inform the Government and the citizens of the study areas that their environments are polluted with heavy metals. This would certainly help in taking proactive steps that will help to reduce the pollution load.

Keywords: Air quality, biomonitors, anthropogenic, environment, passive biomonitoring, exudates