Assessment of nutrient enrichment and heavy metal pollution of headwater streams of Bulawayo, Zimbabwe

• Published in: Physics and chemistry of the earth. Parts A/B/C 2021-06, Vol.122, p.102912, Article 102912
• Main Authors: Siziba, N., Mwedzi, T., Muisa, N.
• Format: Article
• Language: English
• Subjects: Bulawayo; Degradation of rivers; Heavy metal contamination; Nutrient enrichment; Umguza river
• ISSN: 1474-7065; 1873-5193
• DOI: 10.1016/j.pce.2020.102912

The continuing degradation of riverine ecosystems by the discharge of poorly treated and untreated urban-wastewater (together referred to as partly treated urban-wastewater in this study) is a major problem in developing countries. This study assessed water and sediment quality of headwater streams radiating from the Bulawayo area including Umguza and Khami Rivers that drain wastewater from the City. Seventeen study sites were a priori selected from different land use types: City sites (5 sites), downstream communal sites (4), upstream communal sites (3) and for reference five sites were selected upstream of the City within the buffer zones of protected areas. Water and sediment samples were collected during the hot-wet, cold-dry and hot-dry seasons from these site categories and were analysed for selected physicochemical water parameters and heavy metals. The City sites were the most degraded as indicated by significantly highest levels of dissolved oxygen deficiency, embeddedness by particulates, turbidity, conductivity, total dissolved solids (TDS), salinity, total nitrogen (TN) and total phosphorus (TP) and chemical oxygen demand (COD) (ANOVA, p