Assessment of levels of heavy metals in spring water in Nsooba/Mulago 3, Kampala District, Uganda

Abstract

Due to the rapid urbanization that has occurred in Nsooba-mulago III over the last few decades, metals have been continuously emitted into the urban environment and now pose a serious threat to human health. Indeed, there is a growing concern over the potential for pollution of spring waters with heavy metals. Therefore, this study was conducted in this region, to evaluate the current status of heavy metal contamination in the spring waters and their seasonal variations and to assess the community awareness about heavy metals and their toxicity in domestic water given that springs are the major water sources in this community. A total of 24 samples of water from the three selected springs were collected using random probability sampling strategy in which one sample was collected from every spring per week. Samples were analyzed analyzed by direct absorption with atomic absorption spectrometry, except for mercury which was done by cold vapor generation in a special accessory. The results indicated that there was a seasonal variation of heavy metals as it was observed that heavy metal levels were higher in dry than the wet season. Cadmium and chromium levels were below detectable limits (BDL) in both seasons in all samples. The lead levels in all samples were above the WHO, UNBS and NEMA maximum limits of 0.01mg1, 0.05 and 0.05mg-1 respectively in both seasons. The levels of manganese were also generally high in all samples than the recommended levels of 0.01 and 0.03mg-1 by and UNBS.Lead metal was found to be the leading contaminant among the heavy metals with mean concentration of 0.245 ± 0.062 mg-1 in the dry month and mean concentrations of 0.230 ± 0.021mg-1 in the wet month as compared to other mean concentration of heavy metals like mercury 0.001 ± 0.0004 mg-1 , 0.001 ± 0.0006 mg-1 and manganese 0.113 ± 0.072mg-1 , 0.112 ± 0.072mg-1 in the dry and wet month respectively in spring water of Nsooba Mulago III area..A paired t test was performed to compare the concentrations of heavy metals in the dry and wet seasons.The findings concluded that There was a seasonal variation of heavy metals as it was observed that heavy metal levels were generally higher in dry than the wet season.It was also noted that human activities i.e., increased population, welding workshops, garages, septic tanks also had a significant effect on heavy metal levels in the spring water and generically people in Nsooba village have limited knowledge on heavy metals and their toxicity in domestic water.