Savanna Journal of Basic and Applied Sciences 2(1):1-14
Spatial Distribution and Contamination Assessment of Heavy Metals in Surface Sediments of Badagry Creek, southwest Nigeria
Phillips, O. A. ; Abubakar, A.S., Adebayo, A. J.

Heavy metals in surface sediments from Badagry Creek in southwest Nigeria were studied to evaluate their spatial distributions, degree of contamination and possible ecological risk. Aqua regia technique was used for digestion of the pulverized sediments (< 63 m) and, inductively coupled plasma-optical emission spectrometer (ICP-OES) was used for quantification of the heavy metals. Contamination indices including modified degree of contamination (mCd), pollution load index (PLI), geoaccumulation index (Igeo) and enrichment factor (EF) were used to assess the extent of contamination of the creek sediments. The results showed that the overall average concentrations (ppm) of heavy metals of concern are 14.6 (Cu), 9.8 (Pb), 49.9 (Zn), 19.3 (Ni), 18.9 (Co), 702.5 (Mn), 1.8 (As) and 0.7 (Cd). The decreasing order of heavy metal enrichment in sediments is Cd > As > Co > Zn > Pb > Cu ≥ Ni. The resulting Pearson’s correlation matrix and dendrograms from cluster analysis identified aluminium as a conservative tracer to differentiate natural (lithogenic) and anthropogenic components. Also, the values of threshold effect level (TEL) and probable effect level (PEL) were used to assess the ecotoxicological potential of heavy metal concentrations in sediments. Results indicated that metal concentrations are below the threshold effect level (TEL), except, cadmium in all stations and; Ni, in western segment and 33.3 % of stations in eastern segment of the creek. Interestingly, Cd and Ni are not near the probable effect level (PEL), therefore, all the heavy metals examined are not likely to produce harmful effects on sediment-dwelling organisms.