Heavy Metals in the Sea Food from the Vicinity of the Seaport

In Zanzibar, the major source of food for a large number of populations comes from the sea like many coastal area residents. The reports show the existence of a link between seafood and toxic heavy metals in human beings. The aim of this study was to assess the metal concentration of shellfish along the Sea Port of Zanzibar. The shellfish include; oysters, mussels, clams and crabs. They were collected at the Sea Port and the concentrations were determined using Energy Dispersive X-ray Fluorescence (EDXRF). Concentrations range in clams were Cr (12.3 -21.1), Mn (235.7 -293), Fe (223.9 9 -242.0), Ni (2.13 -3.30), Cu (47.2 - 48.1), Zn (4271 -5090), Cd (4.43 - 6.61) and As (1.92 - 3.26) µg/g. The range in crabs were Zn (414.8 -1050), Fe (678.1 - 855.7), Cu (45.4 - 62.6), As (31.16 - 39.47) and Pb (1.20 -1.67)
g/g. Cd, Cr, Ni, Mn and Zn were found to be higher in clams while Fe, Pb and Cu were found to be higher in crabs. In Comparison of the data from this study and that of other regions the concentration of Cr, Cu, Zn, As and Cd in different shellfish species appears to be higher than the values reported in the literature. The concentrations of heavy metals in most different species of shellfish could be attributed to water from sewage, marine activities, paints and human activities from the ship.