With concern mounting that Nevada gold mines are belching clouds of toxic mercury downwind to neighboring states, officials are being urged to tighten regulations regarding the dangerous pollutant.
Environmentalists insist a stricter system to measure, monitor and reduce airborne discharge of mercury from mines must be put in place and say they're ready to force the issue.
"Your state is doing something of such scale that it's affecting health and quality of life in our state," said Justin Hayes of the Idaho Conservation League. The group, concerned over mercury-contaminated fish found in Idaho, has threatened to sue the U.S. Environmental Protection Agency over "excessive, unhealthy amounts" of mercury emissions from Nevada mines. "This is not a pressing health issue for the people in Reno. For the people in Idaho and Utah, this absolutely is a human health issue," Hayes said. "Nevada's at the point where they need to address this or they're going to lose control of this issue."
But officials from the Nevada Division of Environmental Protection, the EPA and mining industry representatives counter that a voluntary program launched in 2001 has significantly cut back on mercury emissions by the state's four largest gold mining companies. They say the program should soon be improved and likely will expand to other, smaller mining operations.
"I think it's been a tremendous success," said Leo Drozdoff, NDEP administrator. "There's a clear recognition that we want to reduce mercury emissions."
Substance poses risks
Nevada is the world's third-largest gold producer behind South Africa and Australia and in 2004, produced nearly 7 million ounces of gold worth more than $2.8 billion. With gold often comes mercury, which is naturally occurring in ore harvested from many Nevada mines. Mercury is released into the air during roasting or other refining processes used to extract gold.
Elemental mercury discharged from mine smokestacks can then settle over the landscape, entering streams and lakes. Through interaction with microbes and other chemical processes, elemental mercury can change into methylmercury, the organic form of the element that can easily enter the food chain and is particularly toxic. Readily absorbed by living tissues, methylmercury affects the central nervous system and in severe cases irreversibly damages the brain. Children and developing fetuses are especially sensitive to mercury's dangerous effects, which recent research suggests also include diminished intelligence and autism.
Nevada's neighbors are increasingly concerned over mercury being found in their states. In Idaho, health officials have issued fish consumption advisories because of mercury contamination at four popular fishing reservoirs, including Salmon Falls Creek Reservoir near the Nevada border. The fact mercury is showing up in Idaho's eating fish is of particular concern, said Hayes of the Idaho Conservation League.
"It's really a human health issue for us," Hayes said. "We're trying to get this mercury pollution stopped."
Early this year, federal researchers in Utah discovered in the Great Salt Lake some of the highest levels of mercury ever measured anywhere. Concentrations of methylmercury found in the lake's water were at levels 25 times those where fish consumption advisories are sometimes considered justified, according to the Associated Press. Mercury concentrations also were discovered in eared grebe, a bird that eats brine shrimp found in the lake.
Although there are no fish in the Great Salt Lake, its presence is still of profound concern, conservationists said. Millions of waterfowl that migrate through the area could be at risk of contamination as well as offer a means to pass mercury to people who might eat them, said Ivan Weber, a Salt Lake City environmentalist.
"To me, that's enough (for concern)," Weber said. "I think what we're looking at here is an immense concentrator of mercury. It's not a pretty picture."
Maunsel Pearce of the Great Salt Lake Alliance said the issue currently poses "more unanswered questions than facts," but that the threat posed by mercury pollution in Utah clearly warrants additional study.
Program shows results
The scope of mercury pollution associated with Nevada's gold mining industry wasn't discovered until the EPA changed rules in 1998 to add mercury to the list of toxic discharges required to be reported. When the first numbers were released in 2000, Nevada mines reported the release of 13,576 pounds in 1998. Those numbers have since been revised upward to an estimated 21,098 pounds, or more than 10 tons, to make Nevada the nation's No. 1 source of mercury emissions at the time.
One mine alone, Jerritt Canyon, 60 miles northwest of Elko, reported discharging nearly 8,000 pounds of mercury. "We were actually surprised to see these air emissions at the levels they were at," said Dave Jones, an associate director for the EPA. "We were surprised at the magnitude."
Following release of the 1998 data, EPA and NDEP officials met with representatives of the mining industry to discuss ways to reduce mercury emissions. Rather than adopt new Clean Air Act regulations -- a process officials agreed could take six years or more -- a voluntary program was agreed upon in 2001 that officials hoped could produce quicker results.
Participating were four mining companies operating seven mines that combined were responsible for more than 90 percent of mercury emissions from Nevada mines. The participating companies are Newmont Mining Corp., Barrick Gold Corp., Queenstake Resources Ltd. and Placer Dome Inc.
Through the installation of smokestack scrubbers and similar technology, the goal was to reduce the amount of mercury released into the environment by 50 percent within three years. That goal has in fact been surpassed, officials said.
From the more than 21,000 pounds the EPA said was released annually from 1998 to 2001, emissions in 2003 were cut to an estimated 5,396 pounds, a reduction of about 74 percent. "I'd say those are pretty fantastic results," said Russ Fields, president of the Nevada Mining Association. "What we've done is yielding results and they're positive results."
Numbers suspect? At least one Nevada environmental researcher isn't sure the estimates of mercury produced and released into the air by the state's gold mines are accurate.
While Nevada's voluntary program is definitely resulting in reduced mercury emissions, a stronger program is needed, said Glenn Miller, a professor of environmental sciences at University of Nevada, Reno. Miller is concerned much of the mercury being released into the environment isn't being measured.
Now preparing a final report on the emissions program expected to be released to the EPA later this month, Miller was surprised to learn the 1998 emissions estimate had been increased by the agency by almost 50 percent. That's a symptom of a problem, Miller said, adding that the latest EPA estimates may also be off, with some mines under-reporting mercury releases and others over-reporting.
"Right now, they're using very, very crude estimates and some mines don't measure anything at all," Miller said. "I don't know that (the numbers) are necessarily wrong, but they're suspect." Miller said it is critical the mines adopt a uniform system to measure how much mercury goes into the gold refining process, how much is recovered and how much is emitted into the air. The state also should regularly inspect mercury monitoring systems, he said.
"They need to require measurements that meet some kind of reliability standard," Miller said. "Once mercury is reliably measured, everything else will fall into place." Miller, who serves on the board of the conservationist Great Basin Mine Watch, insists the hazards presented by mercury make a strengthened regulatory program particularly important. "Mercury is probably one of the most insidious substances we release into the air," Miller said. "If we're going to measure anything, it should be mercury."
Fields, of the Nevada Mining Association, said mine operators will meet this month to discuss "technology transfer" possibilities that could reduce mercury emissions from mines not currently participating in the voluntary program.
Rick Sprott, director of the Utah Division of Air Quality, said officials there are concerned about mercury emissions from Nevada mines but are generally satisfied with steps now being taken to address the problem. "What EPA and the state of Nevada have done is the prudent thing to do," Sprott said. "It appears to us there's been a significant amount of progress made."
NDEP's Drozdoff said that since last November, officials have been discussing ways to improve the existing program and that some changes are likely, with draft recommendations expected by next October. "We're moving pretty fast," Drozdoff said. "Although the program has been a tremendous success, there are questions. It's not perfect."
Elemental mercury discharged from mine smokestacks can settle over the landscape, entering streams and lakes. Through interaction with microbes and other chemical processes, elemental mercury can change into methylmercury, the organic form of the element that can easily enter the food chain and is particularly toxic.
Ã¢â¬ËPolitically, it's not something the state can afford to ignore. It's a serious problem that requires a serious solution. Are we going to wait for a downwind state's posse to come after us or are we going to take care of it ourselves?' --- ELYSSA ROSEN Executive Director, Great Basin Mine Watch
Mercury and the food chain
For most aquatic ecosystems, atmospheric deposition, both natural and human-related, is the primary source of mercury. Natural sources include outgassing from the oceans, volcanoes, and natural mercury deposits. Coal combustion, waste incineration, chloralkai production, and metal processing are the dominant human-related sources. Mining activity is under increasing scrutiny as a source of mercury. When mercury falls in rain or snow, it may flow into lakes and streams. Bacteria in soils and sediments convert mercury to methylmercury. In this form, it is taken up by tiny aquatic plants and animals. Fish eat these organisms and build up methylmercury in their bodies. As bigger fish eat smaller ones, the methylmercury is concentrated further up the food chain, ultimately reaching humans.
- 183 Environment
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