Mine ponds enhance mercury threats in Peru’s Amazon


IMAGE: Countless synthetic ponds like this one, developed when rainwater filled out a deserted gold mining pit, are enhancing threats of mercury direct exposure for people and wildlife in the Peruvian …
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Credit: Melissa Marchese

DURHAM, N.C. – The expansion of pits and ponds developed recently by miners digging for little deposits of alluvial gold in Peru’s Amazon has actually drastically changed the landscape and increased the threat of mercury direct exposure for native neighborhoods and wildlife, a brand-new research study programs.

” In greatly mined watersheds, there’s been a 670% boost in the degree of ponds throughout the landscape considering that 1985. These ponds are practically totally synthetic lakes developed as countless previous mining pits fill out with rainwater and groundwater in time,” stated Simon Topp, a doctoral trainee in geological sciences at the University of North Carolina at Chapel Hill, who co-led the research study.

Landscapes previously controlled by forests are now progressively dotted by these ponds, which, the research study discovers, offer low-oxygen conditions in which immersed mercury – a poisonous leftover from the gold mining procedure – can be transformed by microbial activity into a much more hazardous type of the component, called methylmercury, at net rates 5-to-7 times higher than in rivers.

” Methylmercury presents specifically high threats for people and big predators since it bioaccumulates in body tissue as it goes up the food cycle. That’s especially worrying provided the high biodiversity and the a great deal of native populations that reside in the Peruvian Amazon,” stated Jacqueline Gerson, a doctoral trainee in ecology at Duke University, who likewise co-led the research study.

These increased threats most likely likewise take place in other areas where uncontrolled artisanal small gold mining happens, consisting of Asia, sub-Saharan Africa and other parts of South America, she stated.

Topp, Gerson and their coworkers released their peer-reviewed research study Nov. 27 in Science Advances

Artisanal gold miners utilize mercury, a powerful neurotoxin, to separate their gold ore from soil and sediments, frequently without sufficient security preventative measures to secure themselves or the environment.

Mercury poisoning can trigger a vast array of health effects, consisting of tremblings, muscle weak point, vision and hearing disabilities, and loss of coordination and balance. In serious cases, it can cause abnormality or death.

A few of the mercury utilized by the miners is burnt into the air or spilled into close-by rivers, producing significant ecological and human health threats that have actually been well recorded in previous research studies. The brand-new research study is the very first to record how the mining has actually changed the landscape and at the same time magnified the threats of mercury poisoning through the production of ponds and the microbial processing of mercury into methylmercury that happens there.

To perform the research study, the researchers gathered water and sediment samples at websites upstream and downstream of artisanal gold mining websites along Peru’s Madre de Dios River, its tributaries, surrounding lakes, and mining ponds throughout the dry season in July and August of 2019. They determined each sample for overall mercury material and for the percentage of that mercury that remained in the more hazardous type of methylmercury.

By integrating these measurements with more than 3 years of high-resolution satellite information from the area, they had the ability to figure out the degree of synthetic ponding and mercury contamination at each website and determine causal links.

” You can plainly see that the boost in synthetic lakes and ponds in greatly mined locations sped up after 2008, when gold costs drastically increased in addition to mining activity,” Topp stated. By contrast, the overall area of ponds in locations without heavy mining increased by approximately just 20% over the whole research study duration.

” We anticipate that this pattern, and the ecological and human health threats it triggers, will continue as long as gold costs stay high and artisanal small gold mining is a lucrative activity,” he stated.


Co-authors of the brand-new research study were John Gardner, Xiao Yang and Tamlin Pavelsky of UNC-CH; Emily Bernhardt of Duke; and Claudia Vega and Luis Fernandez of Wake Forest University’s Center for Amazonian Scientific Development in Peru.

Financing originated from Duke University.

CITATION: “Artificial Lake Growth Enhances Mercury Contamination from Gold Mining,” Jacqueline R. Gerson, Simon N. Topp. Claudia M. Vega, John R. Gardner, Xiao Yang, Luis E. Fernandez, Emily S. Bernhardt and Tamlin M. Pavelsky. Science Advances, Nov. 27, 2020. DOI: 10.1126/ sciadv.abd4953 .

Disclaimer: AAAS and EurekAlert! are not accountable for the precision of press release published to EurekAlert! by contributing organizations or for making use of any details through the EurekAlert system.

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