Mining operation in Peru. (Photo by R. Butler)
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ENVIRONMENTAL IMPACT OF MINING IN THE RAINFOREST
By Rhett Butler | Last updated July 27, 2012
Gold, copper, diamonds, and other precious metals and gemstones are important resources that are found in rainforests around the world. Extracting these natural resources is frequently a destructive activity that damages the rainforest ecosystem and causes problems for people living nearby and downstream from mining operations.
In the Amazon rainforest most mining today revolves around alluvial gold deposits. Due to the meandering nature of Amazon rivers, gold is found both in river channels and on the floodplains where rivers once ran. These deposits are actively mined by large-scale operators and informal, small-scale miners. Both operators rely heavily on hydraulic mining techniques, blasting away at river banks, clearing floodplain forests, and using heavy machinery to expose potential gold-yielding gravel deposits. Gold is usually extracted from this gravel using a sluice box to separate heavier sediment and mercury for amalgamating the precious metal. While most of the mercury is removed for reuse or burned off, some may end up in rivers. Studies have found that small-scale miners are less efficient with their use of mercury than industrial miners, releasing an estimated 2.91 pounds (1.32 kg) of mercury into waterways for every 2.2 pounds (1 kg) of gold produced.
While there is no scientific consensus on mercury contamination in the Amazon, according to biologist Michael Goulding, there is evidence of mercury causing problems in other ecosystems. Elemental or inorganic mercury can be transformed (methylated) into organic forms by biological systems and enter food chains. Not only are methylated mercury compounds toxic, but highly bioaccumulative, meaning that mercury concentrations increase up the food chain. Top predators, including otters, birds of prey, and humans, will have the highest levels of mercury in their systems. Those who eat large amounts of fish are at the greatest risk.
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Location of the Grasberg mine.
A Giant Mess on New Guinea
Freeport-McMoRan, based in New Orleans, has operated the Grasberg gold, silver, and copper mine in Indonesian New Guinea (formerly Irian Jaya), since 1972, converting Mount Ertsberg into a 600-meter hole. As documented by the New York Times and dozens of environmental groups, the mining company has dumped substantial amounts of waste into local streams, rendering downstream waterways and wetlands "unsuitable for aquatic life." Relying on large payments to military officials, the mining operation for most of its history was protected by a virtual private army that were implicated in the deaths of an estimated 160 people between 1975 and 1997 in the mine area.
Freeport estimates that it generates 700,000 tons of waste a day and that the waste rock stored in the highlands—900 feet deep in places—now covers some three square miles. Government surveys have found that tailings from the mines have produced levels of copper and sediment so high that almost all fish have disappeared from nearly 90 square miles of wetlands downstream from the operation.
Cracking down on the Freeport's environmental abuses and questionable human-rights practices has proved a challenge since the mine is one of the largest sources of revenue for the Indonesian government. An Indonesian government scientist wrote that "the mine's production was so huge, and regulatory tools so weak, that it was like 'painting on clouds' to persuade Freeport to comply with the ministry's requests to reduce environmental damage," according to a December 27, 2005, article in the New York Times.
For more take a look at "Below a Mountain of Wealth, a River of Waste" in the New York Times. The article was written by JANE PERLEZ and RAYMOND BONNER.
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Other toxic compounds are used and generated in the mining process as well. Mining exposes previously buried metal sulfides to atmospheric oxygen causing their conversion to strong sulfuric acid and metal oxides, which run off into local waterways. Oxides tend to more soluble in water and contaminate local rivers with heavy metals.
Cyanide, a highly toxic compound, is also often used to separate gold from sediment and rock. While cyanide is supposed to be carefully monitored to prevent its escape into the surround environment, spills do occur—especially when there's no one around to enforce mining regulations. The effects of poisoning can be widespread, especially when a waste-holding pool overflows or breaks, as it did in Guyana in August 1995.
The Guyana spill made international headlines for its magnitude—over one billion gallons (four billion liters) of cyanide-laced waste water was released into a tributary of the Essequibo— and its effects, causing widespread die-offs of aquatic and terrestrial plant and animal life, poisoning floodplain soils used for agriculture, polluting the main source of drinking water for thousands of people, and striking a blow to the emerging eco-tourism industry on the river. The mine, run by Golden Star Resources of Denver and Cambior of Montreal, at first tried to cover up the spill by burying fish carcasses. Six days after the spill, after locals found dead wildlife, the mine reported the accident to the Guyana government. Despite the damage inflicted by the spill, the government granted additional mining concessions on the New River shortly thereafter.
Large-scale mining operations, especially those using open-pit mining techniques, can result in significant deforestation through forest clearing and the construction of roads which open remote forest areas to transient settlers, land speculators, and small-scale miners. These settlers and miners are probably a greater threat to the tropical rainforest environment than industrial mining operations. Wildcat miners enter regions rumored to have gold deposits and clear forest in search of riches. They hunt wildlife, cut trees for building material and fuelwood, and trigger erosion by clearing hillsides and detonating explosives. Miners can also bring diseases to local indigenous populations (where they still exist) and battles over land rights. One well-documented example is the conflict between the Yanomani Indians of Northern Brazil and Venezuela and garimpeiros—illegal Brazilian miners. Reports indicated that Yanomani populations have fallen significantly since the first incursion of miners in the 1980s.
While deforestation and chemical pollution from mining can impact the rainforest environment, downstream aquatic habitats fare worse. Increased sediment loads and reduced water flows can seriously affect local fish populations.
Photos of a mining operation in the Peruvian Amazon >>
Articles on rainforest mining >>
Review questions:
- How does mining affect the rainforest and local rivers?
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WEEKLY NEWSLETTER
INTERACT
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Recent news
Top Indonesian official calls out misinformation in environmental campaign
(05/20/2013) Indonesia's top REDD+ official confirmed there is no plan to open 1.2 million hectares of forest in Sumatra's Aceh Province, calling into question numbers used by environmentalists in their bid to stop reclassification of the province's forest land.
NGO: conflict of interests behind Peruvian highway proposal in the Amazon
(05/16/2013) As Peru's legislature debates the merits of building the Purús highway through the Amazon rainforest, a new report by Global Witness alleges that the project has been aggressively pushed by those with a financial stake in opening up the remote area to logging and mining. Roads built in the Amazon lead to spikes in deforestation, mining, poaching and other extractive activities as remote areas become suddenly accessible. The road in question would cut through parts of the Peruvian Amazon rich in biodiversity and home to indigenous tribes who have chosen to live in "voluntary isolation."
Petition targeting plan to open protected forests in Indonesia for mining, logging reaches 1M signatures
(05/15/2013) An AVAAZ petition calling upon Indonesian officials to put a stop to a proposal to open tens of thousands of hectares of protected rainforest to mining, logging, and oil palm plantations has surpassed one million signatures.
Uranium mine at edge of Grand Canyon National Park approved
(05/08/2013) Uranium mining on the doorstep of the Grand Canyon national park is set to go ahead in 2015 despite a ban imposed last year by Barack Obama. Energy Fuels Resources has been given federal approval to reopen its old Canyon Mine, located six miles south of the canyon's popular South Rim entrance, that attracts nearly 5 million visitors a year.
Health effects of toxic waste sites in developing countries could rival malaria, air pollution, new study shows
(05/07/2013) Exposure to dangerous chemicals from toxic waste sites may be creating a public health crisis in developing countries comparable to that caused by malaria or even air pollution, a new study suggests, highlighting the urgent need to clean up toxic waste. In a study published on Saturday in Environmental Health Perspectives, researchers calculated the number of 'healthy years of life lost' due to ill-health, disability or early death in individuals at risk of exposure to chemicals at 373 toxic waste sites in India, the Philippines and Indonesia.
More news on mining
More rainforest news
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(10/11/2011) As the price of gold inches upward on international markets, a dead zone is spreading across the southern Peruvian rain forest. Tourists flying to Manu or Tambopata, the crown jewels of the country’s Amazonian parks, get a jarring view of a muddy, cratered moonscape ... and then another ... and another in what the country boasts is its capital of biodiversity. While alluvial gold mining in the Amazon is probably older than the Incas, miners using motorized suction equipment, huge floating dredges and backhoes are plowing through the landscape on an unprecedented scale, leaving treeless scars visible from outer space. Sources close to the Peruvian Environment Ministry say the government is considering declaring an environmental emergency in the region, but emergency measures passed two years ago were not enough to contain the destruction, and some observers doubt that a new decree would have any more impact.
(04/19/2011) Deforestation is on the rise in Peru's Madre de Dios region from illegal, small-scale, and dangerous gold mining. In some areas forest loss has increased up to six times. But the loss of forest is only the beginning; the unregulated mining is likely leaching mercury into the air, soil, and water, contaminating the region and imperiling its people. Using satellite imagery from NASA, researchers were able to follow rising deforestation due to artisanal gold mining in Peru. According the study, published in PLoS ONE, Two large mining sites saw the loss of 7,000 hectares of forest (15,200 acres)—an area larger than Bermuda—between 2003 and 2009.
(03/01/2010) Guyana has banned gold dredging in the Rewa Head region of the South American country after pressure from Amerindian communities in the area. A recent expedition to Rewa Head turned up unspoiled wilderness and mind-boggling biodiversity. The researchers, in just six weeks, stumbled on the world's largest snake (anaconda), spider (the aptly named goliath bird-eating spider), armadillo (the giant armadillo), anteater (the giant anteater), and otter (the giant otter), leading them to dub the area 'the Land of the Giants'. "During our brief survey we had encounters with wildlife that tropical biologists can spend years in the field waiting for. On a single day we had two tapirs paddle alongside our boat, we were swooped on by a crested eagle and then later charged by a group of giant otters."
(01/21/2009) One of the world's largest nickel mines will have adverse impacts on a threatened and biologically-rich forest in Madagascar, say conservationists. The $3.8 billion mining project, operated by Canada's Sherritt, will tear up 1,300 to 1,700 hectares of primary rainforest that houses nearly 1,400 species of flowering plants, 14 species of lemurs, and more than 100 types of frogs. Many of the species are endemic to the forest. While Sherritt says on its web site that is working to minimize its environmental impact, including moving endangered wildlife, replanting trees, and establishing buffer zones near protected areas, conservationists say that efforts are falling short.
(11/09/2006) Troubles are mounting in one of Earth's most beautiful landscapes. Deep in the Venezuelan Amazon, among ancient forested tabletop mountains known as tepuis, crystalline rivers, and breathtaking waterfalls, illegal gold miners are threatening one of world's largest remaining blocks of wilderness, one that is home to indigenous people and strikingly high levels of biological diversity. As the situation worsens -- a series of attacks have counted both miners and indigenous people as victims -- a leading scientific organization has called for the Venezuelan government to take action.
