An Assessment of heavy metals pollution of Mazowe river due to artisanal small-scale gold miner in Shamva district Mashonaland central province · Electronic Theses and Dissertations

Author

Gokuda, A.

Title

An Assessment of heavy metals pollution of Mazowe river due to artisanal small-scale gold miner in Shamva district Mashonaland central province

Abstract

The expansion of Artisanal Small-Scale Gold Mining (ASSGM) in Zimbabwe, particularly in Shamva District of Mashonaland Central Province, has raised significant environmental concerns due to its impact on freshwater systems. This study assessed the extent of heavy metal pollution in the Mazowe River caused by ASSGM activities, focusing on seven key metals: cadmium (Cd), chromium (Cr), copper (Cu), arsenic (As), lead (Pb), mercury (Hg) and zinc (Zn). Sampling was carried out during the summer and autumn seasons at three sites: upstream (control site) located above the mining zone; midstream (impact zone), directly adjacent to artisanal mining discharges; and downstream (recovery zone), where cumulative effects of pollution are expected. Water, sediment and fish (Oreochromis mortimeri and Protopterus annectens) samples were collected and analysed using Flame Atomic Absorption Spectrometry (FLAAS) following standardized Acid Digestion Procedures. Chi-square statistical tests revealed significant differences in cadmium, chromium, and lead concentrations between upstream and downstream sites, particularly in water and sediment samples. Lead and mercury was also found to accumulate in fish tissues, although all detected heavy metal levels in fish remained within FAO/WHO safety limits. The highest concentrations of Cd, Hg and Pb occurred downstream, indicating strong spatial influence from mining activities. The study concludes that ASSGM significantly contributes to heavy metal pollution in the Mazowe River, especially affecting sediment, aquatic life and water quality. To address this, the study recommends: (1) strengthening enforcement of environmental regulations by the Environmental Management Agency (EMA); (2) formalising artisanal mining operations to improve waste handling and reduce pollutant discharge; (3) implementing routine environmental monitoring of water bodies in mining zones; and (4) promoting community education on the health risks of consuming contaminated fish and water. These findings provide a scientific basis for guiding policy and community action to protect ecosystems and human health in mining-affected areas.

Date

JULY 2025

Publisher

BUSE

Keywords

heavy metals

artisanal small-scale gold miner

Supervisor

Dr. L. Mabhungu