摘要：The objective of the study was to establish the key point sources of heavy metals (lead, cadmium and chromium) to River Sosiani. This study was a scientific design involving sample collection, preparation and laboratory work to determine Pb, Cd and Cr concentrations in wastewater from point sources. The units of analysis used study were wastewater samples sampled from nine sampling locations (WW1 – WW9) in the Sosiani catchment. Data for wastewater was obtained using AAS to determine the concentrations levels of the heavy metals lead, cadmium and chromium. Data analysis was done using the statistical program for social sciences (SPSS) version 23. The results show that wastewater from solid waste dumpsite (WW6), MTRH (WW5) and steel mills (WW7) had higher values of lead during both the wet and dry seasons which were above the WHO thresholds of 1.0. All sites had lead values above the NEMA thresholds for both wet and dry seasons. WW6 also had the highest values for all the heavy metals (Pb, Cd and Cr) in both seasons. Regarding Cadmium, the values for all sites and during both the dry and wet seasons was below the NEMA thresholds of 0.1 but were ≤ the world Health Organizations thresholds of 0.03. All sites had a mixed trend for chromium values during both seasons. They fluctuated above and below the thresholds of NEMA and WHO standards. It is also noted that generally, all the wastewater sites registered higher concentrations in heavy metals during the wet season as opposed to the dry season. These sites require mandatory measures to ensure that the discharge of wastewater into the environment meets the recommended effluent standards. Some of the measures include, improved Technology in designing the wastewater treatment Works that can remove all the macro and micro heavy metals. The sewer system and drainage lines should also be improved on so as to reduce flooding and raw wastewater flow into the river.
关键词：wastewater; lead; chromium; cadmium; heavy metals; pollution; river Sosiani
