Metal mine wastes - from solid form to river pollutant

What is it about?

Pollution from metal mining has led to severe environmental damage worldwide. Mine drainage is a significant problem for riverine ecosystems, it is commonly acidic, but neutral mine drainage can also occur. One example is the lead and zinc mines in North Yorkshire (UK) where limestone bedrock makes the local streams and rivers neutral or slightly alkaline. In this work we aimed to define to main chemical process controlling how mine wastes end up in the surrounding waters.

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Why is it important?

Chemical analysis showed that the extracted minerals had changed form since being mined due to exposure to oxygen. This means that it is the dissolving of these "secondary" minerals that is resulting in continuous leaching into the stream. Loose spoil results in elevated metal in local streams due to solid metals being exposed to rainwater.