Gold and mineral mining has deteriorated waterways in 49 countries across the tropical region, according to a study at Dartmouth College.
Impacts of Alluvial Mining
River mining usually involves intensive excavation that leads to deforestation and increased erosion. Most excavated materials are dumped into the rivers, disrupting aquatic life in the nearby ecosystems. The inorganic particles of sand, clay, and silt are carried by rivers as suspended sediments and transmit the environmental effects of mining downstream.
Previous studies have reported that the suspended sediment may also carry toxins like mercury used in river mining. Although mining has been taking place for thousands of years in the tropics, it has never been on a scale like we have seen over the past two decades.
In the first part of the study, assistant professor Evan Dethier from Occidental College and his colleagues conducted a comprehensive evaluation of river mining across the tropical region from 1984 to 2021. They obtained data from media, mining company reports, aerial images from public sources, and satellite images from Landsat 5 and 7 through the NASA/United States Geological Survey Landsat program.
The team has identified an estimated 400 individual mining districts in 49 countries across the tropical region. More than 80% of the mining facilities are in Africa, South America, Oceania, and Asia. The study's findings revealed a major increase in mining during the 21st century, particularly during the global financial crisis, and has continued even through the COVID-19 pandemic.
In the second part of the study, the research team evaluated the impact of mining operations in producing suspended sediment in 173 tropical rivers. It was found that global gold and mineral mining has affected over 35,000 kilometers of tropical rivers. Furthermore, the mining activities also increased the amount of suspended sediment concentrations to 80%.
To understand the environmental impact of river mining in the tropics, the team investigated the ecological management guidelines used in the U.S. and other parts of the world. These guidelines are then used as standards for their research data.
Meeting the Global Demand for Gold and Minerals
Gold has diverse uses in jewelry, technology, central banks, and investments. It also has emotional and cultural value and is purchased by different people across the globe for various reasons. Because of this, gold serves as a major target of miners and accounts for almost 80% of global mining sites.
Meanwhile, mining activities in central and west-central Africa make diamond the second most mined mineral in the tropical region. Other precious minerals are mined, such as nickel, excavated in Southeast Asian countries.
Other minerals have increased in demand due to their role as components of cell phones and electric car batteries. This includes coltan, tantalite, cobalt, and tungsten, mined in the Democratic Republic of the Congo. According to Dethier, such minerals have become increasingly necessary as our society shifts from fossil fuels to sustainable energy sources. In addition, gold mining also has the potential to lift people out of poverty, especially those from remote tropical areas.
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