| Abstrakt: |
The impact of human activities on some physicochemical parameters and heavy metals was studied in Lagos Lagoon, an eastern arm of the Gulf of Guinea. For ease of description, the 21 study stations were categorized into 6 regions. The mean surface and subsurface concentrations for water physicochemistry are temperature (27.34 ± 0.47 °C and 27.04 ± 0.67 °C), pH (7.86 ± 0.27 and 7.90 ± 0.29), dissolved oxygen (DO) (7.93 ± 1.11 mg/l and 6.95 ± 0.54 mg/l), Salinity (12.80 ± 12.74 ppt and 14.20 ± 13.80 ppt), turbidity (59.53 ± 43.94 NTU and 71.63 ± 49.96 NTU), nitrate (0.88 ± 0.35 mg/l and 0.82 ± 0.19 mg/l), phosphate (2.47 ± 1.55 mg/l and 1.96 ± 1.53 mg/l), silicate (2.13 ± 1.55 mg/l and 2.15 ± 1.95 mg/l). While the mean surface concentrations (µg/l) for the metals in decreasing order are Fe (162.22 ± 63.12), Pb (81.52 ± 48.56), Cu (74.19 ± 52.09), Zn (17.95 ± 16.27), Cd (15.33 ± 10.48), Ni (13.24 ± 8.60), the subsurface levels (µg/l) are Fe (179.88 ± 64.00), Cu (108.71 ± 66.64), Pb (54.43 ± 36.61), Ni (26.33 ± 18.28), Zn (25.48 ± 13.41), Cd (20.81 ± 16.81). Except for Pb and Cd, all the metals concentrations at both surface and subsurface are within the FEPA permissible limits. Contamination factor (CF) of the study area ranged from low contamination (0.1) to considerable contamination (3.08). Nemerow’s pollution index (NPI) the study area is within the good water quality (NPI < 1). Based on the outcome of this study, periodic assessment of Lagos lagoon is hereby suggested; this is with the view of ensuring adequate conservation of the lagoon system, particularly in maintaining the ecosystem services it provides within the region. There should be periodic review of the extant regulations controlling the dumping of chemical contaminants into the lagoon systems, especially in the aspects of their enforcement by the regulatory agencies, and compliance by the general public. Enlightenment programs for the public on the dangers associated with marine pollution are equally considered necessary. |
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