Tree Rings Bear Witness to Illegal Gold Mining Operations in the Amazon, New Study Finds
Mercury concentrations in fig trees could provide useful information about mining activity in the rainforest over time
Sara Hashemi - Daily Correspondent
April 15, 2025
An aerial view of dredges at an illegal gold mining area in the Amazon region of Peru. Ernesto Benavides / AFP via Getty Images
Gold mining has ramped up across the Amazon rainforest in recent years, leaving devastated landscapes behind. Small-scale—and usually illegal—mining operations dredge the mineral from subsoil or river sediment. Then, to separate the gold, miners will pour liquid mercury into the soil, forming a hard coating around the coveted mineral. Then, they’ll burn off the mercury to get pure gold.
This process unleashes toxic mercury into the air, making small-scale gold mining worldwide responsible for nearly two-fifths of the planet’s mercury pollution. While these operations provide an important source of income to many locals, they also poison the surrounding environment and negatively impact people’s health.
That mercury also finds its way into trees, according to a study published in the journal Frontiers in Environmental Science last week. Tracking the mercury content in tree rings, the research suggests, can offer insight into mining operations over time.
“We could potentially see whether mining is starting to ramp up,” says Jacqueline Gerson, an environmental engineer at Cornell University and the study’s lead author, to James Dinneen at New Scientist.
. . .
Fernandez tells New Scientist that his research consortium, the Center for Amazonian Scientific Innovation, which focuses on rainforest restoration and mercury pollution, has had its funding from the United States Agency for International Development (USAID) terminated. He calls that decision counter-productive. “Artisanal gold mining is something that threatens borders,” he says. “It corrupts societies. It is a global source of mercury pollution.”
More:
https://www.smithsonianmag.com/smart-news/tree-rings-bear-witness-to-illegal-gold-mining-operations-in-the-amazon-new-study-finds-180986390/
(My bolding)