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African Journal of Environmental Science and Technology

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Studies on the occurrence and distribution of heavy metals in sediments in Lagos Lagoon and their effects on benthic microbial population

PO Uaboi - Egbenni, PN Okolie, O Martins, O Teniola

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 and Achromobacter sp. Fungi isolated were Saccharomyces cerevisiae, Candida utilissima and 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.



http://dx.doi.org/10.5897/AJEST09.139
AJOL African Journals Online