On December 15, the U.S. Environmental Protection Agency (EPA) proposed new emissions regulations, giving power plants up to 15 years to install pollution controls for reducing mercury emissions. Field data from common loons, including data collected by Earthwatch teams in Michigan, Wisconsin, and Maine, suggest that these regulations may not be enough to stem rising amounts of the dangerous toxin in loons and other wildlife.
The EPA rules take an "emissions trading" approach, suggesting that market forces would help spur innovation by power plants in the search for more effective and less costly emission control technologies. But while emissions trading makes sense for controlling global pollutants such as greenhouse gasses and sulfur dioxide, it is the wrong approach with pollutants like mercury that can contaminate local areas, or "point sources."
"You can have major point-source issues with mercury emissions," said Dr. David Evers, executive director of BioDiversity Research Institute in Falmouth, Maine, and former principal investigator of Earthwatch's Loons of Maine project. "The emissions trading approach will mean that some places are still going to be really dirty for a long time. You end up sacrificing parts of the country, like southeastern New Hampshire, to try to improve mercury pollution nationally."
A study published last year in the journal Ecotoxicology, co-authored by Evers, found that loon eggs in southeastern New Hampshire lakes had the highest mercury levels of any tested in eight states across the country. These data led to state-mandated changes at three municipal waste incinerators in the area, reducing mercury emissions from 600 pound per year to about 15 pounds.
The local emission controls in southeastern New Hampshire in turn led to drastic reductions in mercury loads among local fish and loons, confirming the importance of point-source emissions in this case. Emissions trading would allow local mercury emitters such as these delay emission controls by buying pollution credits from cleaner plants elsewhere.
Earthwatch teams worked for several years in the 1990s with Evers and colleague James Paruk (Feather River College), exploring the impact of mercury on population dynamics and behavior of loons in Michigan, Wisconsin, and Maine. Their data suggest that at least 22 percent of the breeding loon population is at risk in Maine, where teams conducted more than 1,500 hours of behavioral observations. Loons with blood mercury levels higher than 3 parts per million (ppm) fledged 40 percent fewer young than loons with blood levels below 1 ppm, and levels in New England loons are rising at a rate of 4 to 10 percent annually.
Mercury is a toxic byproduct of waste incineration, coal-fired power plants, and chlorine production as well as some natural processes. Human activities have doubled or tripled the amount of mercury released into the atmosphere every year, adding 2,000 to 6,000 tons globally. When rain, snow, or wind deposit mercury on water bodies, anaerobic bacteria convert it into organic methyl mercury, a powerful neurotoxin that disintegrates nerve and brain cells in humans and other vertebrates, such as loons.
Loons make an ideal indicator species for the impact of mercury on the environment, as well as human health, for several reasons. Mercury biomagnifies though the food web, growing more concentrated with each stage, so as top predator of mercury-laden fish loons get the lion's share. Loons are also long-lived and fairly easy to observe and capture, so trends in mercury contamination can be monitored over several years. Evers and colleagues have also studying mercury loads in bald eagles, otters, mink, great blue herons, and kingfishers, as well as fish and the water itself, but loons have proven to be a valuable index for mercury's impact on aquatic ecosystems.
"I think mercury is a big problem," said Evers. "The more we look at it, the more we see other animals and systems being affected by it. I think that taking mercury out of the mix, and we can take it out of the mix, will really get us ahead in many ways."
EPA's mercury emissions proposal represents a significant rollback from earlier plans, which proposed cutting mercury emissions by as much as 90 percent by the year 2008. The new rules propose a cap of 70 percent by 2018, using an emissions trading approach. Evers' findings suggest that this plan is not based on available scientific data about the impact of mercury emissions on local ecosystems.
"I have several projects with the EPA where we're building the science the best we can," said Evers. "The more solid the science, the more pressure there will be to have science-based policy. That's our goal."
Earthwatch Institute is an international nonprofit organization which supports scientific field research worldwide by offering members of the public unique opportunities to work alongside leading field scientists and researchers. The Institute's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment.