Heavy metal pollution in sediment, water and fauna from Mzinga creek and rasdege mangrove ecosystem, DaresSalaam

This study examines the extent of metal pollution in Mzinga creek mangrove stand in comparison with a relatively pristine mangrove forest at RasDege in Dar es Salaam. The concentrations of Cd, Cr,Cu, Pb and Zn in sediment, water, oysters (Sacostreacecullata) and polychaete worms (Capitella capital) were analyzed by inductively coupled plasma- Atomic Emission Spectroscopy (ICP-AES), Hg was analyzed by automatic mercury analyzer. Concentrations of allmetals analyzed were higher in all samples from Mzinga creek than RasDege. The total concentrations of Cd, Cr, Cu, Pb, and Zn in suspended particulate matter from Mzinga creek ranged from 23.35±6.7 to 1427.3±21.7 µg g-1dw, whereas at RasDage the concentrations of Cd Cr, Cu,Pb, and Zn in SPM were between 1.14±0.59 and 279±30.1µg g-1dw the concentration of total Hg ranged from 4.18±1.56 to 23.05±0.002ng g-1 dw, oysters and polychaete samples from Mzinga creek accumulated higher concentrations of metals than their respective counterparts from RasDege. Sediment samples from Mzinga creek were enriched with Cu (EF=7.4), Hg (EF =5.3) and Cr (EF =3.3), but no metal was enriched in sediment samples from RasDege. The concentrations. In general, heavy metal pollution at Mzinga creek was significantly higher compared to the concentrations of metals at RasDege mangrove forest. The higher metal concentrations in Mzinga creek are associated with human activities, thus, there is a need for the determination of the exact sources of specific heavy metals in the catchment of Mzinga creek.