Impacts of Artisanal Gold Mining on Water Quality in Uganda

By Dr. Noopur JainReviewed by Laura ThomsonNov 8 2024

In a recently published article in the journal Earth, researchers investigated the environmental consequences of artisanal and small-scale gold mining (ASCGM) on the water quality and sediment characteristics of Kitengure Stream, located in the Buhweju Plateau of Western Uganda.

ASCGM is prevalent in many developing nations, providing livelihoods for numerous communities. However, this form of mining often leads to significant environmental degradation, particularly affecting water resources.

The study aims to assess the concentrations of potentially toxic elements (PTEs) in both water and sediment samples, evaluate the associated health risks, and contribute to a better understanding of the environmental impacts of ASCGM in the region. By focusing on the Kitengure Stream, the research seeks to inform strategies for mitigating the adverse effects of mining activities on local ecosystems and public health.

Background

Artisanal and small-scale gold mining has become increasingly common in Uganda, where it is reported to account for a substantial portion of the country’s gold production. The Buhweju Plateau, rich in mineral deposits, has seen a rise in ASCGM activities, which, while economically beneficial, pose serious threats to environmental integrity.

The mining processes often release harmful substances, including heavy metals, into nearby water bodies, leading to contamination that can adversely affect aquatic life and human health.

Previous studies have documented the negative impacts of mining on water quality, emphasizing the need for comprehensive assessments to understand the extent of contamination and its implications. This research builds on existing knowledge by specifically examining the Kitengure Stream, providing localized data on PTE concentrations and their potential risks to the environment and communities.

The Current Study

The study employed a systematic sample collection and analysis approach, focusing on water and sediment from three distinct sections of Kitengure Stream: upstream, midstream, and downstream. Between October 2021 and January 2022, 94 surface water samples and 36 sediment samples were collected.

Water samples were gathered in pre-cleaned Teflon bottles, while sediment samples were obtained using a grab sampler at 0-5 cm depth. The sampling locations were carefully selected to ensure a minimum distance of 10 meters between points to avoid contamination overlap.

In situ measurements were taken using calibrated meters for various physicochemical parameters, including pH, turbidity, total dissolved solids (TDS), and electrical conductivity. The concentrations of selected PTEs—zinc, cadmium, lead, copper, and arsenic—were determined through inductively coupled plasma-optical emission spectrometry (ICP-OES) following appropriate sample digestion. Statistical analyses were conducted to compare the mean concentrations of PTEs across the different sampling sites, allowing for the identification of significant differences in contamination levels.

Results and Discussion

The study results revealed concerning levels of PTEs in both water and sediment samples, particularly in the midstream and downstream sections of Kitengure Stream. The analysis indicated that turbidity levels in these areas exceeded the World Health Organization (WHO) guideline of 5 NTU, suggesting significant contamination likely linked to mining activities. Among the analyzed PTEs, cadmium and copper were detected in water samples, with cadmium concentrations surpassing the permissible limit of 0.003 mg/L for potable water. This finding raises serious health concerns for local communities that rely on the stream for drinking water.

Sediment samples also exhibited elevated concentrations of various PTEs, with geoaccumulation indices indicating no significant enrichment of these elements in the sedimentary phase. However, the potential ecological risks associated with the detected concentrations were highlighted, particularly for aquatic organisms. The study found that the mean concentrations of PTEs were significantly higher in the midstream and downstream samples compared to upstream, underscoring the impact of ASCGM on water quality as pollutants accumulate downstream.

Statistical analyses further confirmed the significant differences in PTE concentrations across the sampling sites, with downstream areas showing the highest contamination levels. This trend emphasizes the need for immediate action to address the environmental and health risks posed by ASCGM activities.

Conclusion

In summary, the study provides critical insights into the environmental impacts of artisanal and small-scale gold mining on the water quality and sediment composition of Kitengure Stream in Buhweju Plateau, Uganda.

The elevated levels of potentially toxic elements pose significant risks to aquatic ecosystems and the health of local communities dependent on this water source.

The research highlights the necessity for effective regulatory frameworks and sustainable mining practices to mitigate contamination and protect public health. Raising community awareness about the environmental consequences of mining activities is essential for promoting responsible practices among miners. The findings serve as a valuable resource for policymakers and stakeholders, laying the groundwork for future research and intervention strategies to address the challenges associated with ASCGM.