Measuring Mercury

Researchers Study Sources Of The Toxic Metal In The Northwest Environment And What Can Be Done About It

By Ben Raker

While searching for mercury and other toxic chemicals deep in the backcountry of the American West, Dixon Landers' team of researchers does not travel light.

The researchers typically hike in with pack trains and camp for three days to get all the samples they need. They haul their monitoring instruments, coolers, dry ice, and sample containers with them–about 2,000 pounds of equipment in all.

"You're looking at probably twelve to sixteen horses or mules to get our gear in,” says Landers, a senior research environmental scientist for the U.S. Environmental Protection Agency (EPA) in Corvallis, Ore.

Landers directs the Western Airborne Contaminant Assessment Program (WACAP), a consortium of government and university scientists conducting a three-year study of sites in national parks from California to Alaska.

The group, which expects to release preliminary findings in early 2005, is measuring mercury and other contaminants in the snow, soils, fish, water, and air of these sensitive areas. "What we're trying to do with the science is actually get some facts on the table,” says Landers.

The WACAP study is one of several projects launched in recent years that may aid understanding about how mercury moves through the region, what put it there in the first place, and what can be done about it. Meanwhile, debate remains about the main sources of the mercury, including natural and manmade sources, and the severity of its threat.

The fact that these studies are taking place in the Northwest backcountry is significant. In recent years, unexpectedly high levels of mercury have been reported in fish from lakes and streams both urban and remote. These findings have led to an increasing number of advisories about eating fish from these waters.

In 2002, for example, the Seattle Times reported on tests of bass, a frequently eaten game fish, in 20 Washington waterways from Olympia to Spokane that had previously been little studied ["State investigators go fishing for leads on mercury's menace,” Seattle Times, Oct. 27, 2002]. Almost a year later, state ecologists warned of high levels in the fish from most of these study locations.

In 2003, Montana and Washington became the two most recent states to issue fish advisories for all lakes and rivers. Meanwhile, Oregon and Idaho have advisories for at least some lakes and streams. Alaska and Wyoming remain the last two states in the country not to have issued any advisories.

In the Northwest, which has fewer sources of manmade mercury than other regions, scientists are trying to determine how mercury gets into fish in areas without an obvious nearby source. They are determining background levels, gaining understanding about natural sources, and looking at the influence of airborne transport from distant sources, such as in Asia.

"We've got the manmade sources fairly well figured out; we don't have the natural sources figured out,” says Michael Abbott, a scientist at the Idaho National Engineering and Environmental Laboratory in Idaho Falls. Abbott recently completed a study showing unexpectedly high mercury at some sites in Yellowstone National Park.

"If you get out anywhere in the Pacific Northwest, the ambient air concentrations are as low as they are anywhere in the world,” says Abbott. "The problem is, we're seeing mercury fish advisories in all these supposedly background, low, isolated areas.”

Over the past few years, high mercury levels have been found in lakes and streams often thought of as pristine and remote.

Despite the increased number of advisories, mercury levels in Northwest states are not generally as high as in other regions of the country. This is in part due to lower levels of emissions in these states than in states like Texas and Ohio, which have a greater concentration of coal-fired power plants.

Washington state, for example, with its heavy reliance on hydroelectric power, has only one coal-fired power plant: the TransAlta plant in Centralia. Yet it still has mercury, and it still has advisories.

The big question in areas without an obvious source of pollution is: How is mercury getting into the fish? Increasingly, scientists are looking at distant sources to explain this phenomenon, a concept important to explaining mercury in the Northwest.

"Let's say you're fishing in a lake downstream from Centralia and you catch bass,” says Dan Jaffe, professor of environmental science at the University of Washington's Bothell campus. "What you'd really like to know is how much of the mercury in that fish is coming from Centralia versus how much is coming from much farther away.”

Jaffe is currently studying transport of mercury and other contaminants coming to the Northwest from Asia. He is taking air samples from a high-pollutant site in Okinawa off the Asian mainland and comparing them to samples from Chica Peak on Washington state's northwest corner and Oregon's Mt. Bachelor. If the samples share particular combinations of chemical isotopes, or chemical "signatures,” it will suggest influx of mercury from Asia.

Although Jaffe says it's too early in his study to say anything yet, he hopes that tracking the input from Asia ultimately will help his team figure out what can and can't be attributed to local sources.

The form of mercury transported in the atmosphere is mostly gaseous elemental mercury, though there is some particulate mercury in the air as well. Elemental mercury also occurs naturally in rocks, soils, water, and air. Volcanic eruptions can spread mercury into the air, as can forest and range fires–significant in some areas of the Northwest–and even geothermal heating such as at Yellowstone.

Human activities, including the burning of coal and fossil fuels, mining, and the production of some household, medical, and industrial products, also increase the load in the atmosphere.

The reactive form of mercury that collects in fish, methylmercury, is a toxin that has been shown to cause developmental delays and other health effects in human fetuses. This is why the fish advisories focus on children and women of childbearing age.

Mercury takes on its toxic form when it is methylated by microorganisms in the soil and water. Larger organisms need to eat many of these smaller organisms, so the toxin concentrates or as it moves up the food chain, a process known as bioaccumulation.

"Mercury's generally not a problem directly,” says Abbott. "But once you get to the food chain, the aquatic food chain, and it's bioaccumulated by a factor of a million, that's where it becomes a problem.”

According to John Stein, the salmon science coordinator at Seattle's Northwest Fisheries Science Center, your intake of mercury can depend on the type of fish you eat. Larger fish tend to have higher levels of methylmercury, as do predatory fish like swordfish that feed higher on the food chain. Older fish and fish that spend more time in heavily polluted areas also tend to have higher levels of toxins due to increased exposure.

The questions of how much mercury is in Northwest fish, and more importantly where it is coming from, have implications in the debate about how much to regulate manmade mercury in the region.

According to the EPA's National Emissions Inventory, coal-fired power plants account for about 40 percent of all manmade U.S. emissions, but there are relatively few of these facilities in the Northwest.

Although it remains to be seen how much mercury can be attributed to regional sources and how much to the global loading phenomenon, many suggest caution. "The fact that that there are global sources should not be used as an excuse that we should not be reducing our own,” says Jaffe.

Some states, such as Oregon and Washington, are stepping up with comprehensive action plans to reduce man-made mercury emissions through monitoring, curbing manufacturing processes that use mercury, and recycling or properly disposing of products that contain mercury, like fluorescent bulbs and thermometers.

"It's important to pick that low-hanging fruit: to clean up where we can clean up,” says Rob Duff, director of the Washington State Department of Health (DOH), Office of Environmental Health Assessments in Olympia, the office responsible for DOH fish advisories in the state. "But we recognize that it's going to be up to the federal government and in fact the international community to get together to have even more meaningful impacts on mercury in the environment.”

In Dec. 2003, the EPA proposed a plan to reduce mercury emissions from coal-fired power plants by 70 percent by the year 2018. The plan, if approved, will be enacted in March 2005. It favors a "cap-and-trade” approach, which would set a national emission limit and then allow plants that pollute more to buy credit from lesser-polluting plants.

Environmental groups have called the plan inadequate. They say it does not satisfy the requirements of a 1990 Clean Air Act amendment. The amendment calls for all power plants built before 1980 to cut mercury emissions by 90 percent by the year 2007. The environmentalists note that power plants built after 1980 already have the technologies that could reduce emissions up to 90 percent in the older plants.

For their part, energy industry representatives point to the fact that mercury levels have already decreased 50 percent since 1990, based on EPA data. They also note the EPA's August 2004 finding that emissions are decreasing even as advisories are increasing. Industry representatives say that further reductions would not produce noticeable results for its costs because of global mercury sources and natural background levels. Also, retrofitting the old plants may incur costs that would ultimately raise electricity prices for everyone.

Environmental groups dismiss these claims and express particular concern about rules on new, proposed power plants.

"In the Northwest I think the particular concern is that it [the new EPA emission reduction proposal] also comes at a time when there are a slew of new coal-fire power plants proposed for development,” says David Ponder, director of the Montana Public Interest Research Group in Missoula.

This camp argues that since coal plant emissions are a known, identifiable source, they should be dealt with.

"We know that there are natural sources of mercury that we can most likely never do anything about, including volcanoes and forest fires,” says Mo McBroom of the Washington Public Interest Research Group in Seattle. "We don't really have that kind of power over volcanoes. So it really is a question of addressing the problems you can address.”

Dori Gilels, a board member at Women's Voices for the Earth in Missoula and mother of two, has a more personal perspective: "In a place like Montana, where you would think that we would be able to fish from our beautiful streams and eat the fish we catch, we can't,” she says. "As a mom, I'm a little worn out on all of the various choices I have to make to stay away from environmental pollution.”

Duff notes the conflicting impulses health officials face when advising caution on fish. They want people to be aware of the risks, but fish are also an important dietary source of protein, and low in unhealthy fats. "You're seeing federal, state, and local health departments starting to take action and starting to take fish off people's plates, which is the real tragedy here. Because we don't want to do that.”

Ben Raker is a freelance writer and editor who has studied science writing at the University of Washington.

Images:

Top: Michael Abbott, a scientist at the Idaho National Engineering and Environmental Laboratory (INEEL), takes mercury measurements in Yellowstone National Park. Photo: INEEL

A fish is weighed before being measured for mercury and other contaminants at a WACAP field site in the Rocky Mountains. Photo: EPA/WACAP

Bottom: Researchers with the Western Airborne Contaminant Assessment Program (WACAP) clean fish to measure contaminants at a backcountry field site. Photo: EPA/WACAP