Gold mining is becoming an increasingly dangerous threat to the Amazon. A new study has found that barely any trees or plants grow where mines once sat. This is bad news for the wildlife that depends on vegetation for habitat. Without trees or vegetation, though, the Amazon also can’t store as much carbon to prevent further global warming.
The study, published Sunday in the Journal of Applied Ecology, found that abandoned mining pits and tailing ponds in Guyana saw nearly no recovery of vegetation three to four years after mining ended. The recovery rates are among the lowest ever recorded for tropical forests. This lack of regrowth has reduced the forest’s carbon sequestration by about 21,000 tons of carbon a year, the study found. While previous research has used satellite imagery to measure the impact of gold mining on the environment, this study involves on-the-ground investigation with thorough measurements. It’s the first study to offer a full picture of what gold mining may be doing to the Amazon.
“Gold mining has much longer-lasting consequences on forests than other drivers of deforestation,” authors Michelle Kalamandeen, a postdoctoral researcher at Cambridge University, and David Galbraith, an associate professor at the University of Leeds, wrote in an email statement to Gizmodo. “Our study indicates that active restoration will be required in order to recover forests from mining.”
Mining activity has been growing in northern Amazonian countries such as Guyana and Venezuela. Small-scale mines are the main drivers of the devastation, which can also contaminate the broader environment if toxic contaminants travel spill into waterways waterways or leach into the soil. This is of particular concern for the Indigenous communities that live in and rely on the forest’s resources to survive.
The study authors installed nine monitoring plots in two central gold mining areas in Guyana from January to March 2016. They then checked back in on them between June and August 2017 to look for saplings, individual trees, or seedlings. They had to ultimately exclude nearly half of the plots because miners had already begun to re-mine them by 2017, which is another issue altogether and may have an even bigger impact on mercury concentrations.
The study found both high mercury and low nitrogen levels in the soil affect the ability for vegetation to regrow, with nitrogen a particularly good predictor. Compared to the control plots on both sites the team examined, the previously mined plots saw depleted nitrogen levels. Without the necessary nutrients, the forest struggled to grow. Where nitrogen levels were higher but biomass accumulation was still low compared to the control plots, the team noticed mercury levels were still high. However, the amount of mercury measured was much lower than what is found on active mining sites, which suggests that mercury is quickly leaching into the surrounding soils and waterways.
“Not only does this have serious consequences for our battle against global warming by limiting Amazonian forests’ ability to capture and store carbon, but there is also a larger implication of contaminating food sources especially for indigenous and local communities who rely on rivers,” Kalamandeen said in a statement.
The authors would like to expand this research into Brazil or Peru and do long-term monitoring to better understand the true extent of ecological damage as well as what it could mean for the climate. Natural carbon sinks like the Amazon are an invaluable resource in global efforts to pull carbon out of our atmosphere and prevent further global warming. However, the forest needs its own protection from deforestation for agriculture, mining, and other extractive activities. Otherwise, there will be no trees left to absorb our excess carbon emissions, and we’ll be left suffering.