Speciation of lead, chromium, cadmium, copper and zinc in sediments and plants along Msimbazi river in Dar es Salaam, Tanzania

The speciation of lead, chromium, cadmium, copper and zinc in sediments and plants (pumpkin) along Msimbazi River in Dar es Salaam were determined using Atomic Absorption Spectrophotometry. Results in sediments indicated that the heavy metal contents (mg/kg) in the form of total trace metals ranged from 50.34 to 161.63 for Pb, 68.38 to 501.85 for Zn, 18.43 to 66.61 for Cu, 20.93 to 76.46 for Cr and BDL to 0.23 for Cd. The contents (mg/kg) in the form of metals bound to organic matter ranged from 18.24 to 46.58 for Pb, 27.64 to 228.62 for Zn, 3.55 to 16.76 for Cu, 1.37 to 4.10 for Cr whereas Cd was not detected. In plant samples results in forms of total labile heavy metals ranged from 0.86 to 1.46 for Pb, 2.68 to 4.59 for Zn, BDL to 0.41 for Cu and from not detected to 0.21 mg/kg for Cr. In the form of total heavy metals, the ranges were from 19.62 to 36.68 for Pb, 33.56 to 68.80 for Zn, 3.33 to 13.06 for Cu while Cr and Cd were not detected. It was generally found that the levels of lead in plant samples along Msimbazi River were above the permissible levels recommended by WHO and TBS.