Assessment of Selected Heavy Metals in Water and Sediment along Wami River, Tanzania

Abstract

The study was conducted to assess the heavy metal pollution in water and sediments of Wami River, Tanzania. A total of 60 water samples and sediment were collected from 15 random selected sampling points in three River sections; upstream, midstream, and downstream. All the samples were taken using standard procedures and analyzed using ASS at Ardhi University Laboratory, Tanzania for selected seven heavy metals including Pb, Zn, Cr, Cd, Ni, Co and Hg. The findings show average concentrations of studied metals in water followed the decreasing order of: Co >Pb >Zn > Ni. The mean concentration of Pb in water for dry season and rainy season observed to be 0.22 ± 0.26 mg/L and 0.17± 0.24 mg/L respectively, which was much higher than the WHO standard level (0.05 mg/L) for drinking water, while the average concentration of Zn was observed 0.10 ± 0.14 mg/L and 0.08 ± 0.13 mg/L during dry and rainy season respectively. The minimum and maximum values were found to be 0.37 and 0.41 mg/L respectively.  Environmental assessment conducted by three pollution Indices for sediment; Contamination Factor (CF), Index of Geo-accumulation (Igeo) and Pollution Load Index (PLI). The pollution indices confirmed that Wami river sediment was not contaminated with these elements. Further, the study recommends for the future systematic monitoring plans to predict and prevent any potential heavy metal loading and their effects to river water and human being.