Assessment of Heavy Metal Pollution in Sediment and Polychaete Worms from the Mzinga Creek and Ras Dege Mangrove Ecosystems, Dar es Salaam, Tanzania

Abstract

Metal pollution in the Mzinga creek mangrove stand was assessed and compared with a
relatively pristine mangrove forest at Ras Dege in Dar es Salaam. The concentrations of cadmium,
chromium, copper, lead and zinc in sediment and polychaete worms (Capitella sp.) were analyzed
by ICP-AES and mercury was analyzed by a semi-automatic analyzer. Concentrations of most of
the metals analyzed were higher in samples from Mzinga creek than from Ras Dege. Sediment
samples from the Mzinga creek were enriched with Cu (EF = 7.4), Hg (EF = 5.3) and Cr (EF
= 3.3) relative to sediment samples from Ras Dege, which were mostly at natural background
levels. Polychaete worm samples from the Mzinga creek also accumulated high amounts of metals
when compared to samples from Ras Dege. The data show perturbation of the Mzinga creek from
human activities in the catchment.