Globally, aquatic ecosystems are highly polluted with heavy metals
arising from anthropogenic and terrigenous sources. The objective of
this study was to investigate the pollution of stream sediments and
possible sources of pollutants in Nakivubo Channel Kampala, Uganda.
Stream sediments were collected and analysed for heavy metal
concentration using flame atomic absorption spectrophotometer. The
degree of pollution in Nakivubo channelized stream sediments for lead,
cadmium, copper, zinc, manganese and iron was assessed using enrichment
factor, geoaccumulation index and pollution load index. The results
indicated that (1) the sediments have been polluted with lead, cadmium
and zinc and have high anthropogenic influences; (2) the calculation of
geo-accumulation index suggest that Nakivubo stream sediments have
background concentration for copper, manganese and Fe (Igeo ≤ 0);
(3) factor analysis results reveal three sources of pollutants as
explained by three factors (75.0 %); (i) mixed origin or retention
phenomena of industrial and vehicular emissions; (ii) terrigenous and
(iii) dual origin of zinc (vehicular and industrial). In conclusion,
the co-precipitation (inclusion, occlusion and adsorption) of lead,
cadmium and zinc with manganese and iron hydroxides, scavenging ability
of other metals, very low dissolved oxygen and slightly acidic to
slightly alkaline pH in stream water could account for the active
accumulation of heavy metals in Nakivubo stream sediments. These
phenomena may pose a risk of secondary water pollution under sediment
disturbance and/or changes in the geo-chemistry of sediments