Heavy metal pollution in marine mollusks from the coastal waters of Accra, Ghana

Abstract

Studies of heavy metals in four marine mollusks, Thais haemastoma, T. nodosa, Nerita senegalensis and P. perna, have been conducted. This involved the assessment of levels of heavy metal pollution from point sources in the Korle lagoon and the determination of the extent to which these metals are transported by longshore currents to neighbouring areas (i.e. La and Teshie). Samples were prepared following the method described in UNEP (1993) Reference methods for Marine Pollution Studies and analysed with a (Philips Pye Unicam) atomic absorption spectrophotometer for cadmium, copper, iron, lead and zinc. The results indicate that the levels of some metals notably lead, copper and cadmium exceeded the WHO recommended limits. Since coastal communites harvest at least whelks, but probably also other mulluscs for food, they are clearly under threat. No gradient patterns were detected from the Korle lagoon along the coast, suggesting that metal pollution in the study areas are from a variety of sources. There is some evidence of biomagnification of zinc and copper along the food chain. Implications on human health are discussed.


JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 1, July (1998) pp. 105-112