ASSESSMENT OF PHYSICOCHEMICAL PARAMETERS AND HEAVY METALS CONTAMINATION IN KORLE AND KPESHIE LAGOONS

ABSTRACT Lagoons are highly productive coastal systems that provide natural services to the ecosystem, however, their pollutions cause adverse changes to the natural environment. Korle and Kpeshie Lagoons in Ghana, both receive wastes from industries and municipal sewage. Controlling and monitoring of contaminants in these systems is very important to environmental protection. The study examined the presence of heavy metals (arsenic, cadmium, chromium, copper, lead and zinc) in sediments, crabs (Callinectes amnicola), and in fish (Sarotherodon melanotheron) at Kpeshie and Korle Lagoons and compared the concentrations against the environmental standards set by international organisations such as WHO and US EPA. The sediments of Korle and Kpeshie lagoons showed traces of contamination in the order cadmium, lead, copper, zinc, chromium and arsenic, the following metal concentrations in Sarotherodon melanotheron in mgkg-1: As, 0.397 ± 0.07; Cd, 1.10 ± 1.31; Cr, 5.895 ± 9.76; Cu, 3.494 ± 4.56; Pb, 1.227 ± 5.77; Zn, 23.225 ± 10.93, and in Callinectes amnicola : As, 0.288 ± 0.07 mgkg-1; Cd, 4.60 ± 2.69 mgkg-1; Cr, 39.521 ± 55.89 mgkg-1; Cu, 31.085 ± 16.26 mgkg-1; Pb, 10.902 ± 12.95 mgkg-1; Zn, 36.042 ± 17.8 mgkg-1. The pollution indices such as contamination factor (Cf), pollution load index (PLI) and potential ecological risk index (RI) calculated indicated that the sediments are highly polluted with Cd and Pb. Cadmium, chromium and lead concentrations in Callinectes amnicola, and Sarotherodon melanotheron exceeded the permissible limit by FAO/WHO. The estimated target hazard quotient (THQ) of Cd, Cr, and Pb of fishery examined in Kpeshie Lagoon resulted in less than 1, indicating that the daily consumption of Callinectes amnicola and Sarotherodon melanotheron do not pose potential non-carcinogenic health risk to individuals.