Published: March 21, 2016

Saving a River from Poison

Kate Golembiewski, PR and Science Communications Manager, Public Relations


The Putumayo River is home to some of the purest water in the Amazon basin—but maybe not for long. The huge Amazon tributary forms the border between Colombia and Peru, draining from giant Amazonian forests, orchid-covered peatlands, and, most presciently, soil bearing traces of gold. But mining that gold has the unfortunate side-effect of poisoning the water with mercury.

“To extract the gold, you dig a huge pit and dive down, breathing compressed air from a tube. Then, when you find gold, you extract the gravel that contains it and add mercury to process it,” explains Ashwin Ravikumar, a social scientist at the Field Museum, who recently returned from a scientific inventory of the region. “It’s a hugely dangerous process in and of itself—the sand pit can collapse, the miners can get the bends, and they’re exposed to toxic mercury.”

But it’s not just dangerous for the miners—the mercury seeps into the soil and the water, wreaking havoc on the plants and animals in the area.

“Mercury is a poison that bioaccumulates as you go up the food chain—it starts in the water and then gets ten times more concentrated in each link of the chain,” says Ravikumar. Little fish get eaten by bigger fish that get eaten by even bigger fish, and by the time that the poison’s worked its way up to the huge arapaima fish that indigenous people in the area rely on as their major source for protein, the mercury is highly concentrated. “There are huge implications for both human health and biological systems,” says Ravikumar.

But Ravikumar and his colleagues, led by the Museum’s Corine Vriesendorp, hope to be part of the solution. For the past seventeen years, the museum’s scientists have led international teams on what they call “rapid inventories,” four-week-long trips into remote, unexplored wilderness. Their mission is three-fold: to document all the types of plant and animal life that they see in the area, to understand how local peoples use the land, and to argue for the long-term protection of those areas.

“The main thing we’re aiming for is the creation of a regional conservation area. If the people that live there are successful in lobbying their government, then they’ll have a stronger legal basis to organize against illegal gold mining,” says Ravikumar. “There is an opportunity to act now, while the gold mining is still small-scale.”

Protecting the land would also keep the massive natural carbon stores in the area intact, which can help mitigate global climate change. And, according to Ravikumar, it would have a major impact on the people living there.

“Conserving the land around the Putumayo would allow indigenous people to continue living the kinds of lives they want to live—it’s a matter of environmental justice,” says Ravikumar.