Assessment of Heavy Metal Contamination in Edible Fruit Seeds from Dar es Salaam City, Tanzania.

Machibya, Ziliwa Peter (2020) Assessment of Heavy Metal Contamination in Edible Fruit Seeds from Dar es Salaam City, Tanzania. Masters thesis, The Open University of Tanzania.

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Abstract

Rivers are the most vital freshwater resources in the world. In Dar es Salaam city, anthropogenic activity stresses the quantity and quality of water resources especially in heavy metal levels. The heavy metals contamination of rivers, soil and hence consumable food materials remains a global threat to biodiversity and humans. This study was carried out to assess the heavy metals contamination in Mpiji River water, soil and pumpkin, which are irrigated with respective river water. Selected heavy metals (Cd, Cu, Fe, Pb and Zn) were analyzed using an inductively-coupled plasma optical emission spectrometer after HNO3/HCl/H2O (1:2:3) digestion. The mean concentration of cadmium (Cd) at sampling sites ranges from < 0.001 - 0.03 mg/kg (pumpkin), < 0.001 – 0.04 mg/L (river water) and < 0.001 – 0.06 mg/kg (sediment) while quantity of zinc was detected in ranges from 0.02 – 0.07 mg/L, 2.86 – 2.97 mg/kg and 41.07 – 45.63 mg/kg in water, sediment and pumpkin seeds respectively. The allowable limits for Lead in food by WHO and TZS is 0.01mg/kg and 0.05mg/kg respectively. Two samples (0.1mg/kg and 0.14mg/kg) of pumpkin seeds deviated from the allowable limits. All Iron values in pumpkin seeds, water and soil deviated from the allowable limits by WHO and TZS. Three samples of pumpkin seeds deviated from the allowable limits for Zinc. So continued uses of products contaminated with such heavy metals could be significant sources of human exposure and may be linked with harmful effects. Therefore, recommends there must be regular monitoring of heavy metals in sediment, river water and foodstuffs to prevent excessive accrual in food chain. Keywords: Heavy metals, contamination, food chain, fruit seeds, consumption habit

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