Cleaning up old copper mines

Mines supply metals that are vital for everyday objects like cars and smartphones. But once mines are abandoned, those elements - like copper - can seep into the water and soil that surrounds them. In parts of the world where industry meets agriculture, that can make growing crops extremely problematic. That was the case for a former gold-copper mine in the Philippines that was abandoned in 1982. The mine had no significant formal rehabilitation, but indigenous people now live and farm in the area. So, how was it done? To explain, is Anne Jungblut from the Natural History Museum who has been involved in the Bio+Mine project…

Anne - Our project, Bio+Mine, is centred around a community in Northern Luzon in the Philippines. It's 1300 metres in the mountains. So it's a little bit cooler there than like in the middle of Manila, a hilly forested environment. And there was the copper mine that was closed in the eighties. It was an open pit mine. So basically they just removed the surface of the earth and then they created waste dumps where they left the mine waste. And this community is on ancestral land of the indigenous people. And so it's an area where communities have lived for for many generations and they're still now living in that area where the former mine site was.

James - Can you give an idea of the scale of the number of legacy mines we see around the world? Is this a problem in all countries or is it concentrated in particular economies?

Anne - So there are legacy mines around the world and for example, in our project in the Philippines, they have now recognised there are more than 20 legacy mines. And part of it's also in the past there was less legislation, there was less regulation for the companies to do a rehabilitation re-naturation of the sites. But with more and more guidelines in place, the number of legacy mines that will be created in the future will be a lot less.

James - So that's a positive solution for reducing the number of legacy mines that might come to exist, but that we're still stuck with the ones that do exist. Can you give me some examples of the cutting edge ways in which you are assessing these sites?

Anne - So options are, for example, like drone technology. So that allows us to image large areas across kilometres of site in 3D like the amount of vegetation, plants. Are there areas where there are no plants? Is there a risk that there could be a rockfall? Drone technology, remote sensing is very, very important. We also think DNA sequencing is very important because we can use free DNA in the water to track the biodiversity, how many species and potentially find indicator species using DNA sequencing. So I am an environmental microbiologist. My role was particular to study the microbiology and the soil and the water and the rhizosphere. A really striking result was that we found that the soil microbiology in the sites where there was the highest copper was very different to sites where agriculture was happening and the local forests. And I thought that was very striking because microbes are very small, they grow really quickly, they can change super fast. But even after 30 years, the soil microbe was really different. And we also found, say, microbes that are more common for environments where there is a lot of geochemical chemistry happening. So that was actually very striking and I've worked in the tropics and the polar regions and really didn't expect that result. So that shows even if something is green on the top, it might actually be, there is still a signal of this impact.

James - That is a very interesting finding. So using all the data you've collected and all the harms you identified, what have been the consequences, what have been the actions that have led to change for the benefit of that community?

Anne - So the first thing was we established what were the biggest concerns for the local communities. That was access to water and, in parts, agriculture. And so we are working on at the moment experimental level small scale water treatments to, for example, to remove the copper and increase the pH to make the water usable to some extent.

James - How transferable will be the techniques that you've pioneered here for other legacy mines around the world?

Anne - Yeah, so we hope that this small project potentially will be able to help in a larger way to potentially be a blueprint or create a framework to how we maybe do biodiversity assessment, identify with the community, how has the mining affected what interventions are needed.