Baseline study of the water quality at industrial hotspots in the Nakivubo channel, Kampala

Abstract

Introduction: As in many other African cities, industrial activities have strongly augmented in Kampala, Uganda. To prevent chemical contamination of the city’s wastewater channel and ecosystems this study aims to generate a comprehensive understanding of industrial activities and related pollution. Methods: The study was conducted along the Nakivubo Channel, which transports a considerable portion of Kampala’s wastewater into Lake Victoria. Information on industries were obtained undertaking key informant interviews. In total, 107 water samples were collected between the 10th and 16th December 2015 at 16 sampling points. Samples were analysed for heavy metals (chromium (Cr), lead (Pb), mercury (Hg) and copper (Cu)) and physicochemical parameters (e.g. biological oxygen demand, chemical oxygen demand). Results: In water of the Nakivubo Channel contamination with Pb (<0.0045 – 0.6919 mg/L) and Hg (0.0057 – 0.0165 mg/L) exceeded national standards (<0.1 mg/L and <0.01 mg/L, respectively). The Cr and Cu levels were below the standards (<1.0 mg/L) and ranged between 0.0018 and 0.2090 mg/L and <0.0001 and 0.0627 mg/L, respectively. Weekend levels of Pb and Cu were significantly lower than on weekdays. According to the key informant interviews the effluents of 24 industries most likely contain heavy metals. Conclusions: Hg and Pb were of highest concern for the environment and public health and measured concentrations varied strongly spatially and temporally. As there is currently no heavy metals treatment in place there is an urgent need to guide polluting industries on effluent management and extend the monitoring framework to informal small-scale industries. For a sustainable environmental protection the rehabilitation of natural ecosystems (e.g. the Nakivubo wetland) and their treatment function is inevitable. Environmental epidemiology research is needed to assess heavy metal exposure and the associated public health risks for vulnerable population groups.