Assessment of heavy metals pollution of sediments from Fosu lagoon in Ghana

Abstract

The distribution of some heavy metals, namely Cu, Pb, Zn, and Fe in sediments of Fosu lagoon of Cape Coast, Ghana was studied in the early summer (November) of 2009. The levels of the selected trace metals were determined using atomic absorption spectrophotometry. The overall mean ± RSD % of Cu, Pb, Zn, and Fe were, respectively 26.4 ± 51.0, 28.1 ± 101.0, 20.90 ± 41.90 and 1.15 × 103 ± 2.02 mg/kg. Fe recorded the highest concentration levels, the distribution of which followed the sequence Fe > Pb > Cu > Zn. Statistical analyses also showed different mean levels of trace metals at the five sites. The heavy metal burdens in the sediments revealed significant variations in the distribution of the metals, with Pb showing the greatest variation and Fe the least. Enrichment level of Fe was minimal; Cu and Zn were significantly enriched and Pb showed very high to extremely high enrichment. The average geoaccumulation values and pollution load index calculated for the five studied sites indicated that the lagoon is practically unpolluted with Fe, Cu and Zn, but moderately polluted with Pb