Jul 22 2008
No ecosystem type in the eastern United States is free of the effects of air pollution, according to a report released today by The Nature Conservancy and the Cary Institute of Ecosystem Studies. From streams and rivers to forests and wetlands, air pollution reduces the benefits these ecosystems provide to society, and damages human health and economies. Sulfur, nitrogen, mercury and ground-level ozone not only contaminate the air we breathe, they also enter the soil and water, causing a complex set of problems.
“We have yet to fully understand all the impacts of these pollutants, but what we’ve found so far is alarming,” said Dr. Tim Tear, a Nature Conservancy scientist and co-author of the report. “The problem is extremely widespread; the more we looked, the worse it seemed to get.”
The report, Threats From Above: Air Pollution Impacts on Ecosystems and Biological Diversity in the Eastern United States (http://www.ecostudies.org/Threats_from_Above.pdf), assessed the impacts of four major pollutants on six ecosystem types in areas that receive some of the nation’s highest levels of atmospheric deposition (air pollution deposited to the landscape). These areas are often located downwind from large power plant, industrial and urban pollution sources. Among the concerns:
- Ground-level ozone reduces plants' ability to harness sunlight for growth harming both natural ecosystems and agricultural crops.
- High levels of deposited mercury have negative impacts on wildlife – from salamanders in the Appalachian Mountains to loons in the Adirondacks and bald eagles in Maine.
- Acid rain is making sensitive lakes and streams uninhabitable by fish in the mountains of the Northeast and the Southern Appalachians.
- Excess nitrogen – in part from air pollution – is harming waterways from Rhode Island's Narragansett Bay to Long Island Sound to Chesapeake Bay. Nitrogen also decreases the disease resistance of trees, leaving them more vulnerable to pests and pathogens.
Important background information from other studies on each of the pollutants includes:
- Ground level ozone has been estimated to cause $3-6 billion in reduced crop production annually.
- Current levels of mercury deposition are 4 to 6 times higher than in 1900. In one study, over 15,000 fish were sampled, and 10 of 13 recreational fish species had average mercury concentrations in the fillet that exceeded the EPA levels set to protect human health.
- More than 40 percent of the lakes in the Adirondacks of New York are chronically acidic or sensitive to episodic acidification.
- People are responsible for doubling the rate of nitrogen entering the active nitrogen cycle over the last half century.
Air quality standards in the United States are determined by direct impacts to human health, with regulations targeting emission levels – what leaves tail pipes and smoke stacks. They do not take into account where airborne pollution is actually deposited in the landscape or how this pollution compromises our soil and water resources, natural habitats or the species that live in them.
“To safeguard ecosystem health, we need a new way of thinking about air pollution – one that moves beyond measuring what is put up in the air, and captures actual impacts to natural areas, wildlife, and the services they provide,” said Dr. Gary Lovett of the Cary Institute (http://www.ecostudies.org/giving.html), lead author of the report.
The report includes a call to action for the United States to establish critical air pollution loads that are based on preserving healthy ecosystems. Critical loads identify the maximum level of pollutant deposition that ecosystems can handle before harmful effects occur. Some agencies have already established critical loads for particular landscapes, such as the nitrogen target load established at Rocky Mountain National Park (http://www.nature.org/wherewework/northamerica/states/montana/preserves/art6027.html).
It also calls for a more integrated and comprehensive national program for monitoring air pollution and its effects, including measurements of air, water, soil, habitats and wildlife.
“We need a better way of measuring our progress,” said Lovett. “We can’t assess if ecosystems are harmed by air pollution if we don’t monitor them. Our current system of monitoring is fragmented, underfunded and has serious gaps.”
The Nature Conservancy invests tens of millions of dollars each year in land protection for the purpose of conserving global biological diversity. Last month it announced the largest private land conservation sale (http://www.nature.org/wherewework/northamerica/states/montana/features/) in U.S. history, an agreement to purchase 320,000 acres of forestland for $510 million. But habitats and landscapes cannot be conserved by land protection alone – action to reduce air pollution must be part of the solution.