To Assess the Level of Heavy Metal Pollution in Groundwater in Ilala Dar es salaam

Addo , Michael Ndimbo (2016) To Assess the Level of Heavy Metal Pollution in Groundwater in Ilala Dar es salaam. Masters thesis, The Open University of Tanzania.

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Abstract

This study aimed at evaluating the level of heavy metal pollution in the groundwater in Ilala Dar es Salaam. The potential sources of heavy metals in Dar es Salaam city include: auto-repair shops, informal sector activity premises, small to large scale industries, on-site sanitation systems, poor solid wastes management and fuel filling stations all of which have potential for groundwater pollution. A total of 54 water samples were collected from bore holes in Ilala district, Dar es Salaam region. The samples were collected in two seasons: the dry and wet seasons of September to October 2014 and March to May respectively. The samples were collected in clean and sterile glass bottles soaked overnight in 0.5% (v/v) analytical grade nitric acid. Physical parameters such as pH and EC were measured in-situ while heavy metals were analyzed in the laboratory by using atomic absorption spectrophotometer (AAS). Results show that pH of groundwater ranged between 7.3±0.04 to 5.2±2, EC ranged between 2470±28 to 256.5±43 (µS/cm). Chromium concentration in water samples from different locations in the study area ranged from below the detection limits to 1.1±0.01 mg/L for samples collected near petrol stations. These concentrations are above TZS and WHO standard (0.05mg/l). Lead (Pb) ranged from 0.34±0.2 to 0.15±0.1 (mg/l) which were above the TZS standard (0.01mg/l). On the other hands Cu and Zn were below the TZS and WHO standards. Dumpsite and the fuel filling stations have shown to have a major contribution of the heavy metal pollution to the groundwater. The heavy metal concentration varies with season whereby the concentration was low during the rainy season as a result of dilution by rain water. Users of this polluted groundwater are at risk of contracting various health problems including cancers.

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