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Scientists in a new study have found that gold mining in South America makes restoration of the Amazon rainforest impossible.
The researchers found that gold mining not only destroys the soil, but also sucks all the moisture out of it, retaining heat. In such extreme conditions, young seedlings simply cannot grow.
«It’s like trying to grow a tree in an oven», — notes the co-author of the study, Professor of Earth and Environmental Studies at the University of Southern California’s Dornsife College of Letters, Arts and Sciences, Josh West.
In the Amazon, gold mining leads to the deforestation of 10% of the rainforest, and these figures continue to grow. The area of land used for gold mining has doubled since 2018 due to the rapid increase in prices for the precious metal. As of 2023, the estimated area of gold mining in the Amazon was 13 thousand square kilometers.
As a result, the soil temperature rises to 60°C. The layer of dry sand already reaches several meters. Natural soil regeneration becomes almost impossible.
As part of the study, the researchers analyzed two abandoned mining sites in the region Madre de Dios in southeastern Peru. For mining and quarrying in these areas, dredges were used — floating technological units with mining and processing equipment to extract minerals from under the water layer.
These installations used large volumes of water for pumping sludge and sand from riverbeds and streams in search of gold particles. According to the lead author of the study Abra Atwood, such dredges wash away the top layer of soil, which is rich in clay and nutrients. After that the landscape becomes deserted in the environment sand mounds up to 7 meters high.
Scientists used remote sensing, electrical resistance analysis — a method to determine how easily moisture moves through the soil, measuring soil properties and using thermal imaging cameras to assess the impact of mining on the land. It turned out that mining waste work like a sieve, allowing water to infiltrate much faster than in the original forest soils. The rate of water seepage reached 15 meters per day, while in the forest it was only 0.074 meters per day.
As a result, the soil retains much less moisture and more heat. This is exacerbated by the lack of shade caused by the felling of trees, which makes it almost impossible for new ones to grow. Transplanted seedlings simply die in such conditions. Assessing the scale of the disaster, the researchers found that between 1980 and 2017, 950 square kilometers of rainforest were cut down in this area.
«The current landscape in the alluvial mining areas where we have worked provides very little in terms of ecosystem services other than gold production. The loss of habitat will also impact long-term biodiversity», — explains Abra Atwood.
Instead, the researchers propose a number of specific measures to redesign the landscape and improve water retention in areas affected by mining. They propose to fill in the dried-up ponds that were used for mining to restore the flat terrain. This will bring tree roots closer to groundwater, increase moisture retention and stimulate plant regeneration. After that, it will be necessary to restore the topsoil.
Meanwhile, Abra Atwood predicts that these measures will face significant financial, logistical and political challenges Illegal gold mining affects many regions of the Amazon, including Peru, Brazil, Suriname, and Guyana.
The results of the study were published in the journal Communications Earth & Environment
Source: LiveScience