Distribution Of Heavy Metals In Sediment, Suspended Particulate Matter And Bivalves (Anadara Antiquata) From The Coast Of Zanzibar:a case of malindi and fumba

The distribution of heavy metals in abiotic phases (sediment, particulate) and biotic fauna (i.e. Anadara antiquata), were studied in Malindi and Fumba coasts, Zanzibar. The aim was to determined levels of heavy metals pollution at the sites for various environmental compartments. The sediment, suspended particulate matter and tissues of Anadara antiquata were digested and analysed using Atomic Absorption Spectrometer (AAS). For the analysed metals, their concentrations in Malindi coast were generally higher than in Fumba coast. Metal burdens in the tissues of A. antiquata were higher than sediment and suspended particulate matter; this was due to the fact that marine bivalves accumulate heavy metals into their tissues at higher concentrations relative to ambient environments.The findings show that the heavy metals were present in all samples collected. The dominant metal was Cr. The total concentrations of heavy metals ranged as follows at Malindi The concentration in sediment ranged from; Cr (25.14 - 37.00 ppm), Pb (0.50-0.90 ppm) and Cu (0.10-0.33 ppm). The concentration in suspended particulate matter also followed similar trend i.e. Cr (2.50-7.50 ppm), Pb (0.23-0.25 ppm) and Cu (0.23-0.25 ppm), while concentrations in biota range from Cr (26.75-37 ppm), Pb (14.25-17.36 ppm) and Cu (12-27 ppm), at Fumba Heavy metals concentration in sediment ranged from Cr (16.88 - 40.36 ppm), Pb (1.1 - 7.23 ppm) and Cu (0.10 - 0.70 ppm). The concentration in suspended particulate matter also followed similar trend i.e. Cr (1.0 - 9.50 ppm), Pb (0.23 - 0.25) and Cu (0.23 - 0.25 ppm) while concentration in biota range from Cr (4.75 - 18.75 ppm), Pb (0.25 -2.00 ppm) and Cu (0.25 - 0.30 ppm.).The trends for all metal concentrations analysed were Cr > Pb > Cu. Copper concentrations were lowest in all compartments for all sites. The concentrations of heavy metals in suspended particulate matter were lowest in all sites among the compartments analysed. This study has found that Malindi and Fumba coasts of Zanzibar are polluted with Chromium, Copper and Lead