Assessment of heavy metal concentrations in water and sediments from shallow wells in Kilwa Masoko

Kilwa Masoko depends mainly on groundwater for consumption and other activities. Most of the groundwater wells are shallow with high possibility of being contaminated with Heavy metal due to the characteristics of soil and circulation of groundwater through rock types in the region which is enclosed by Indian Ocean are added to the wells. Also the industrial sewage system (wastes), domestic wastes and agriculture residue (pesticides & herbicides) are other factors expected to add heavy metal in these shallow wells of Kilwa Masoko. This study aimed to assess heavy metal concentrations in water and sediment from shallow wells of Kilwa Masoko. A short-term field survey was conducted in August 2014. Ten (10) water and twenty (20) sediments samples were collected at Kilwa Masoko. The measurements of heavy metal concentrations in water samples were conducted using the Atomic Absorption Spectrometer while those of sediments were analysed using WDXRF spectrometer. Heavy metals such as Fe, Cr, As, Cu, Ti, Zn, K, Hg, Al, Cd, Pb, Zr, Sr and Mn were detected in water and sediment samples. In water, the concentrations of Fe (3.70 mg/l), Mn (0.6 mg/l), K (35 mg/l) and Pb (0.702mg/l) were obtained in SM/SE 3, were above the international standard of drinking water as prescribed by TBS and WHO. In sediments the concentrations of Fe (2.7 g/g) and Al (12.6 g/g) were above the international standard of drinking water prescribed by TBS and WHO. This study has shown high concentrations of heavy metals in the shallow wells of Kilwa Masoko. Therefore, water should be treated and education on environmental protection should be given to the communities surrounding these shallow wells in order to control the quality of the groundwater in Kilwa Masoko. It is highly recommended that other studies on physical and chemical properties of the water and the soil effect from these shallow wells should be conducted. In view of metals being found in water as compounds, such studies should include other areas in the Southern part of Tanzania, such as Kilwa Kivinje and Kisiwani.