ARPN Journal of Science and Technology::Determination of Physico-Chemical Parameters in Rainwater in Urban-West Region of Zanzibar Island

Rainwater samples were collected from two areas of Urban West region in Zanzibar Island. The samples were analyzed for physicochemical parameters pH, electrical conductivity (EC) and metals namely, As, Be, Ca, Cd, Co, Cr III, Cu, Fe, Li, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sr, Ti, Tl and Zn using standard procedures. The levels of As, Mn, Ni, Pb, and Sb were not detected (ND). The ranges of investigated parameters in rainwater samples are as follows: pH (6.22 – 6.92), EC (14.39 – 43.18 μS/cm). Both areas had same levels of Thallium (Tl). The ranges of concentration (μg/L) of other metals in rainwater were; Be: (4.6 – 5), Ca: (677.8 800.3), Cd: (0.2 0.4), Co: (BDL – 0.1), Cr (III): (25.6 31.5), Cu: (BDL – 0.9), Fe: (0.6 – 2.2), Li: ( 0.6 – 201.7), Mg: (116.7 – 201.7), Se: (BDL – 0.3), Sr: (6.2 -6.5), Ti: (BDL 0.1), and Zn: (5.1 – 575.4). The pH value 6.22 is below the minimum pH value recommended by WHO guideline. However, the levels of other investigated physico-chemical parameters in the rainwater samples were within the permissible limits of the World Health Organization drinking water quality guidelines.