Jennifer Angel-Amaya’s research is uncovering the story of mercury in the Amazon

National Geographic Explorer Jennifer Angel-Amaya has worn many hats throughout her career as a geologist. She’s worked as a consultant in her native Colombia for the Ministry of Environment and the Comptroller General office, sits at the head of Corporación Geopatrimonio—a research non-profit co-founded by Angel-Amaya that promotes Colombian geoheritage—and is a geology professor at Universidad Nacional de Colombia, her alma mater.

But ask Angel-Amaya what brings together all the roles she’s embodied, and she’ll reveal why the title of “Explorer” perhaps describes her best. “I’ve always wanted to be in the world, free and knowing places—to explore,” she recalls. “Growing up, I didn’t even know that word, but I knew that’s what I wanted to do.” 

Choosing to explore the world as a geologist, Angel-Amaya says with a smile, “has basically been the best decision I’ve ever made.” 

Today, Angel-Amaya specializes in studying the cycle of potentially toxic metals and their impact on the ecosystem and human health. This interest began early in her career while working as an environmental consultant in Colombia. There, she saw the impacts of mercury used in alluvial gold mining firsthand as the metal infiltrated the ecosystem. 

“I did an analysis of the mercury content in my own hair. The limit, according to the World Health Organization, is 1 μg/g or one part per million; my concentration was 1.7 μg/g,” she remembers. “In the Colombian Pacific Coast, where mercury is used intensively for gold mining, communities show mercury levels that are much higher, and the effects have already been seen in the deterioration of their health.” 

The danger mercury poses to human health and the environment has been well-documented since tainted industrial wastewater was dumped into Japan’s Minamata Bay during the mid-1900s. Mercury bioaccumulated in fish and shellfish, and the local population who consumed seafood displayed symptoms of what is now known as Minamata disease, resulting in disability or death for many. An international treaty signed in 2013 committed more than 140 countries to reducing or eliminating the use and emissions of mercury in industrial activity. 

Currently, Angel-Amaya says, artisanal gold mining is one of the main sources of mercury emissions into the environment. She suggests that mining activity should be monitored in order to better understand its impacts, and better yet, remedy them. “The issue inspired me to return to academics to do a Ph.D., precisely in understanding how the mercury used to concentrate gold during the mining process is distributed downstream: where it is accumulating and what environment it is reaching.”

Her early encounters with mercury lingered with Angel-Amaya until a serendipitous meeting with hydrologist and fellow Explorer Josh West. While applying for Ph.D. programs in 2021, Angel-Amaya came across West at the University of Southern California, and his research interests in the hydrological effects of mining immediately struck a chord. She applied for his program, and the two connected over West’s burgeoning project idea for the Amazon: a team of scientists weaving together the story of artisanal gold mining and its impacts on the Amazonian landscape. “In the end, I went to Columbia University,” Angel-Amaya laughs, “but Josh was too gracious and said we could still collaborate, and that’s why I’m part of the team.”

Now, Angel-Amaya and West, along with Explorer Hinsby Cadillo-Quiroz and their team, make up a part of the National Geographic and Rolex Perpetual Planet Amazon Expedition to further understand the intricate role the Amazon River Basin plays in maintaining the entire ecosystem of the Amazon, from the Andes to the Atlantic. 

Understanding a complex story

Since July 2022, the team has traveled within the Madre de Dios region of the Peruvian Amazon to investigate gold mining’s effects on the ecosystem’s soil and water. Fully understanding this multifaceted story requires approaching it from several scientific angles. “Josh is focused on the hydrological impact, and Hinsby wants to know more about methane and carbon storage of these mining regions,” she counts off. “And I’m working on determining mercury’s impact.”

“[Artisanal gold mining] has been happening for years, and it’s a problem that is well known,” Angel-Amaya says, especially in regions along the Peruvian Amazon watershed. Because of its toxic downstream effects from mercury use and the increase in deforestation, such mining has been declared illegal in many South American countries, especially in protected areas within the Amazon River Basin.

Through natural geological processes like erosion, gold from rock and soil is transported by rivers, disseminates into river sediments, and concentrates by gravity at the bottom of sedimentary deposits. The gold here, Angel-Amaya explains, has a higher grade or greater concentration than that found in rock mines, which attracts miners in search of high profit gold. 

Thanks to the Amazon’s tropical climate and abundant rainfall, huge swaths of forest grow over flood plains. Miners must clear the forest and dredge the sediments near rivers as a first step, then wash the sediments using hydraulic pumps. The mixture of gold-bearing soil gets passed through a sluice system to trap and separate the heavier gold. Miners concentrate the gold bits using mercury, creating a mercury-gold amalgam that is then heated to evaporate the mercury portion, posing an occupational hazard to miners. What is left behind is pure gold—and mercury, now released into the environment.

Thus, mercury becomes an extremely mobile chemical, Angel-Amaya points out. Carried through the atmosphere, even areas a significant distance from the source might feel the effects of artisanal gold mining. As mercury is redeposited in sediments and finds its way back to bodies of water, it can accumulate in fish, leading to high levels of exposure in communities that consume local fish.

“That’s why it is important to address this particular issue when it comes to mercury,” Angel-Amaya emphasizes. In the Amazon, studies measuring mercury levels in Indigenous riverine communities show numbers as high as 240 μg/g. “This is high. Really high.” 

Indigenous communities in the Amazon may bear the brunt of mercury’s toxic impact because fish and shellfish remain a major food source. “In some towns it’s common that children have six fingers or similar malformations, and some studies suggest that mercury exposure in gold mining areas might lower their cognitive ability,” she says.

Another major problem is deforestation: “They need to cut the forest down to get to the minerals.” Deforestation drastically changes the morphology of the landscape, eliminates wildlife habitats, and erodes Amazonian riverways to make room for mining ponds within a desertic landscape.

There remain questions about how mercury affects other life in the Amazonian ecosystem. “What happens with animals, with the fish and birds that are presenting these high levels of mercury?” Angel-Amaya asks. It’s a growing field of research: scientists are measuring mercury levels in multiple Amazon species to gauge its effect. She points to the work of Explorer Fernando Trujillo, also participating in the Perpetual Planet Amazon Expedition: “Even his team is measuring mercury in the river dolphin. We are having this discussion about mercury everywhere along the Perpetual Planet Expedition because it’s a pervasive problem.”

But the solution is not as easy as eliminating mining or military interdictions. In fact, it’s rather difficult to definitively trace mercury back to any particular mining operation. “[Mercury is a] natural element, and some of its presence in the Amazon occurs naturally in the background or because of other sources, such as erosion from deforestation and biomass burning,” Angel-Amaya explains. “All play an important role in the release and transport of mercury. For these reasons, non-mining sources must also be carefully considered.” 

Angel-Amaya adds that the mobile nature of mercury means there is a well-spread distribution of the metal across the planet. Some regions show high levels of mercury in areas distant from mining, so it’s difficult for scientists to point to a single source of emissions.

Perhaps more importantly, Angel-Amaya notes, “Mining is a source of income for many local communities in the Amazon. Even if the people don’t want to do the work, they often don’t have other options since alternatives are much less profitable.” Artisanal gold mining is a viable industry such that “many of the miners in this area have migrated here from other territories just to carry out mining.” 

The team is well-aware that they must take these realities seriously. “We cannot be affected by our own bias,” Angel-Amaya stresses, “but also we cannot ignore mercury and its effects, because that could implicitly say that mining doesn’t have any impact.” 

So Angel-Amaya and her team are gathering concrete data. For the past year, they have been monitoring three sites with varying levels of gold mining activity every two weeks or so within the Madre de Dios region. One is a pristine control site on protected land without any activity; the team expects it to show the least disturbance from mining and serve as a baseline for comparison. Two other sites were chosen for their mid- and large-scale mining activity, where impacts are more acute. 

Angel-Amaya and team hypothesize that areas most impacted by mining will show higher amounts of suspended sediment in the water. These suspended sediments help transport mercury along the tributaries to the main Madre de Dios River and finally out to the Amazon watershed. The measurements the team collects from each site will allow them to quantify any variations in the hydrology or chemical content of water and sediments from this region. 

Their assessment is a one of a kind evaluation of mercury and carbon production in mining ponds and their subsequent impact on water flowpaths in the Amazon. 

Tricky challenges, promising prospects

One challenge with sample collection and testing is simply how long the process can take. Samples are often collected blindly and analyzed only later in a laboratory that might be miles away. A key component of Angel-Amaya’s research is developing mercury field test kits that will make taking measurements exponentially more convenient. 

Developing a proper protocol for the kits will require teasing out solutions to some tricky problems.“These kits will allow us to analyze the sediment or water in the place where it is collected without having to transport it,” Angel-Amaya explains, “The challenge we have with this idea is being able to see mercury at low concentrations. Therefore, I need to develop a method that allows us to concentrate mercury at the site using an instrument with relatively high mercury detection limits and is portable at the same time.” No sweat.

If the team is successful, these field kits will help inform the most thorough map of mercury distribution in the region to date. “The kits will allow us to simply generate a quick map—like a heat map—that indicates where we should do more detailed studies [on mercury impact] and pinpoint places where we need restorative efforts like reforestation.”

Although it is still a work in progress, the prospects look promising for Angel-Amaya: “I have already developed a pilot in the United States in a lake that is known for its mercury contamination, and I’ve gotten encouraging results that it’s possible to detect the concentration of mercury samples with portable instruments.”

In their first iteration, these kits will depend on specialized equipment, used by researchers or those with proper training for scientific research purposes. Angel-Amaya has plans for a second phase, however. “This type of field analysis tool can be made simpler and more accessible for any person to use,” she reveals, citing similar tools that analyze other chemicals like lead and arsenic as a precedent. “Ideally, anyone should be able to monitor the environment in which they live.”

Through her work, Angel-Amaya hopes to provide anyone and everyone with access to the knowledge of the land they live in. “In the future, I’d like to continue providing those tools to the people, so they can know more about their own territory through geology.” She sees it not just as an appreciation of geological heritage, but also a door to cultivating bottom-up solutions to real environmental issues. “Hopefully as we see people empowered by this knowledge, they can manage their own territory and the problems that they face.”

As for the issue of artisanal gold mining in the Amazon, Angel-Amaya does not believe stigmatizing the industry is the answer: their work can be legal, appreciated by gold-wearers around the world, and makes for a profitable livelihood. However, she holds out hope for change when considering a future of responsible mining—sans mercury. “There are other miners, ones who want to do a better job. They want to comply with the human rights and labor laws, to reforest the area they have been impacting.” 

On the other side of the world at Columbia University in New York, Angel-Amaya chips patiently away on her Ph.D. research, working to create an analytical test that detects whether or not gold was concentrated through the mercury amalgamation process. If she’s successful, such a test could usher in a new era of mercury-free gold production.

With this type of verification tool and through collaboration with economists and social scientists, she hopes there will be a way to certify and raise the market price of mercury-free gold. Producing gold without mercury is labor intensive, requires training, and takes more time; for miners, such financial incentive would be crucial for developing a more sustainable supply chain. “It has happened with diamonds, with coffee, with other commodities,” Angel-Amaya maintains. “So we believe that it's possible with gold. There are solutions if people want to be involved.”

‘Working in the Amazon means magic’

Despite working in the thorniest of situations, to Angel-Amaya, researching in the Amazon has been a special joy. “I was born and raised in the Andes in Colombia,” she says. “However, ever since I got to know the Amazon, I have always been very inclined to live and work in this territory.”  

Angel-Amaya treasures being in the field, especially the quiet moments. Out in far-flung areas of the Amazon, she sleeps on a hammock, hanging in the trees after a long day’s work. “You hear the noises of the jungle, you are far away from everyone, but you are working closely with your people, with your local fellow scientists.” Collecting samples in the middle of mining ponds, she savors the silence. “That's my favorite part, being in a boat, especially paddling in silence, no motor—that's something really nice.”

For Angel-Amaya, these singular experiences in the Amazonian wilderness are worth protecting. She never lets herself forget she’s working in a high-impact area with a story her team has yet to fully uncover. “I remind myself this is an important job, because in order to keep the jungle the way it is, we need to do research in the ‘ugly parts,’” Angel-Amaya says. 

But it’s the wonder of the place she’s in now that keeps her fire lit and burning. “When you work in the Amazon you get wrapped in its magic. When you get to know it, you are simply inclined and strengthened to work on its conservation.”

ABOUT THE WRITER
For the National Geographic Society: Melissa Zhu is a content strategy coordinator at the Society with a passion for writing. When she's not focused on advancing the nonprofit mission of Nat Geo, you might find her immersed in a good book or admiring the world around her on a long walk.