Assessment of Heavy Metals Pollution in Sediments from Ologe Lagoon, Agbara, Lagos, Nigeria

Abstract

This study was carried out to assess the level of heavy metals pollution in Ologe Lagoon, Agbara, Lagos, Nigeria. The Lagoon receives effluents from industries in the Agbara Industrial Estate. Cored Soft sediments were retrieved from six random sampling points within the Lagoon and labeled (S1, S2, S3, S4, S5 and S6). Subsamples of the sediments were prepared and analyzed for heavy metal concentration. The result from the heavy metal analysis of the sediments shows that average concentration of Mn, Zn, Cr, Ni, Cr, Ni, Co, Cu and Pb in the samples was 278.1 ppm, 21.7 ppm, 14.2 ppm, 6.6 ppm, 6.4 ppm, 6.4 ppm and 4.4 ppm, respectively. The correlation between the heavy metals varies from 0.71 to 0.98 shows that they have a strongly positive degree of association which suggests that they are from the same source. The geo-accumulation values for Cu in all stations ranged between (1-2.8 ppm) and it can be deduced that the sediments are moderately to strongly polluted. Pb varies between 1 and 2.1 suggesting that the sediments are moderately polluted. Zn exhibits strong pollution levels with a range from 2.5 and 3.5 ppm. Co is moderately polluted with 1.5-2.4 while Mn shows the highest level of pollution in all stations with I geo values ranging between 4.1 and 5.8. This study showed that the Lagoon accumulates heavy metals as a result of anthropogenic activities evident in the dumping of municipal, sewage, industrial waste in the environment and domestic activities such as auto mobile transportation and mechanic repair workshop. Based on sediment quality guidelines, the Ologe Lagoon level of pollution ranged from Cu > Pb > Zn > Ni > Co > Mn > Cr > Al with Mn having the highest level of pollution.