The Environmental Price of Gold

open-pit gold mine

Open-pit gold mines change an environment significantly. (Photo credit: Corbis)

In January 2013, the price of gold reached over $1,660/ounce, up from just over $400/ounce just ten years earlier. The high price of gold has led to a global rush for the precious yellow metal. But the true price of gold, paid in damage to ecosystems and compromised health of miners, their communities, and possibly the global population, is little reported. If more people knew the true price of gold, it would quickly lose its luster.

Few people are aware that metal mining is the top polluter of all the world’s industries. Mines are often in remote areas, out of public view. However, in 2010, an estimate 3.93 billion pounds of toxic chemicals were released from metal mines. And don’t forget the huge displacement of earth itself necessary for these large mining operations.

The gold deposits that are mined from the earth today are not big, shiny nuggets that can be panned from a stream. They are tiny deposits distributed across vast areas of rock. Today’s processing methods, combined with the high gold price and lack of accountability for cleanup, make the extraction of such small amounts of gold financially worthwhile to gold companies.

Now that much of the gold in the United States has been depleted, U.S. gold companies and those of other developed countries have moved on to other countries, including Ghana and Peru. Some countries have little regulation regarding gold mining. Others, like Peru, have strict mining laws, but lack enforcement.

The method of extraction used by large-scale gold mining companies is called open-pit mining. The process is similar for many types of metals. In open-pit mining, mountain-sized portions of land are blasted and the rubble piled into masses, some as tall as a 30-story building. As much as 60 tons of rock may be destroyed to yield just a single ounce of gold. One crater produced by a gold mine operation in Utah is two and a half miles wide and a mile deep! It can literally be seen from space.

After blasting, natural substances in the rock, including arsenic, cadmium, mercury, copper, and lead, enter the environment in quantities much higher than those found naturally. Sulfur in the blasted rock forms sulfuric acid once it is exposed to air and water. Sulfuric acid is commonly known as the pollutant found in acid rain. However, the acid waste from mining, known as AMD (acid mine drainage), is 20-300 times more concentrated than acid rain. AMD travels to streams and rivers where it kills aquatic life for miles.

Once in the environment, the substances become a permanent part of ecological cycles. In this way, substantial lead and mercury have entered human food webs. Both mercury and lead are well-known neurotoxins. Fish in northern California are still contaminated from AMD even though a mine there shut down 50 years ago. Hundreds of thousands of acres of land just in the U.S. alone have been similarly affected from past gold mines. The full impact of AMD on ecosystems and human health is not yet known. However, in a recent study of thousands of fish from hundreds of streams across the U.S., mercury was found in every single fish.

To extract the gold from the rock pile, the ore undergoes a process called leaching. In leaching, a solution containing the poison cyanide is sprayed over the rock piles. Cyanide binds to gold ions, carrying them to the base of the heap over the course of a few months, where the gold and solution is collected in pipes. Some mines use several tons of cyanide a day. The cyanide solution can leak, joining the minerals and sulfuric acid in the pollution of ground and surface water.

The semi-solid mixtures of rock and liquid waste that are left after gold has been removed are called tailings. Although they continue to accumulate, no good method of disposing tailings exists as of yet. Tailings are often bulldozed into dams, but the dams can fail. Sometimes tailings are dumped into rivers, changing their flow and killing wildlife. Such “riverine tailing disposal” practices have been banned in most developed countries but still happen illegally and continue to occur in developing countries. Other mines dump tailings directly into the ocean, devastating coastal ecosystems. Newer practices involve pumping tailings deeper into the ocean so as to avoid coral reef communities. These practices, however, may do more to hide problems from view than prevent them.

Gold mining also consumes an incredible amount of energy and fresh water. It is estimated that as much energy is used in gold mining as would supply over 25 million average American homes for a year.

In addition to the large-scale mining of gold, the phenomenon of small-scale gold mining has exploded globally. About 25 percent of the world’s gold presently comes from small-scale mining. This type of mining, known as “artisanal mining” is happening in some of the poorest corners of the world, often illegally, by people with few other options for employment.

The methods used in artisanal mining are even cruder than those of large-scale mining. In a process known as amalgamation, gold is extracted from silt by heating it with mercury. Sometimes amalgamation is done by families, even children, in their own homes, using the same pots they use for cooking. When mercury enters the food chain, it bioaccumulates. Like the other pollutants of gold mining, once mercury has entered an ecosystem, it doesn’t go away.

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