Abstract

An investigation was conducted to assess the concentration of heavy metals in sediments in three selected locations along Lagos lagoon comprising University of Lagos, Ebute Metta and Ijora zones and correlate the effect of metal concentrations on benthic microbial population vis a vis the open water bacterial population. Physiochemical analysis revealed a pH of 8.94, 11.98 and 7.82 of University of Lagos, Ebute Metta and Ijora zones respectively. The concentration of lead was more in Ebute Metta zone (Oko Oba) with a value of 22.75 mg/100 g, while the concentration of iron was more in Ijora zone with a value of 45.31 mg/100 g. The concentration of Cadmium was higher than other zones in Ebute Metta with a value of 14.63 mg/100 g. Mercury was more concentrated in University of Lagos zone with a value of 7.83 mg/100 g, while the value for chromium was more in Ebute Metta sediments with a value of 6.81 mg/100 g. Levene’s statistical analysis shows there is no significant difference in the variances for all metals across the three locations understudy. However, ANOVA analysis shows that mean measurements for all metals across the three locations are significantly different at 5% level of significance except for mercury where the mean measurements were not significantly different at 5% level of confidence. The benthic population (bacteria) was less than that of surface water (control). University of Lagos had the highest bacterial mean cfu/ml determined by log₁₀ with a value 6.81 for control and 3.51 for sediments. The cfu value for fungi for control samples for University of Lagos zone, Ebute Metta and Ijora were 1.7, 1.54 and 1.6 respectively. The bacteria isolated and identified were Bacillus subtilis, Bacillus licheniformis, Arthrobacter sp andAchromobacter sp. Fungi isolated were Saccharomyces cerevisiae, Candida utilissimaand Sporobolomyces sp. The values for heavy metals for all zones are of public health significance and pose a threat to the survival of both humans and aquatic life. An immediate attention from concerned authorities is required in order to protect the Lagos lagoon and its dependants from further pollution and diseases.

Key words: Heavy metals, benthic, sediment, Bacillus, Candida, Achromobacter,Sporobolomyces