One brook's story of pollution


Nitrogen: A New Hampshire stream suffers from contamination that threatens many waters.

On The Bay

April 18, 2003|By Tom Horton | Tom Horton,SUN STAFF

HUBBARD BROOK, draining slopes thick with sugar maple, birches, spruce and balsam fir in central New Hampshire's White Mountains, is little known to the world, but a hallowed name in ecological science.

Half a century ago, 12 square miles of the little stream's watershed was protected for research. Today, Hubbard Brook is a national scientific treasure, one of those rare places with a long, comprehensive record of scientific observation of air and water, forest processes and bird life.

Hubbard Brook is where researchers documented acid rain for the first time in North America, a discovery that led to nationwide air-quality controls on sulfur dioxide, with huge benefits for human health, and at least partial success in restoring acidified lakes and streams nationwide.

These days Hubbard Brook is sounding another alert, one that makes common cause with the Chesapeake Bay and other polluted coastal estuaries from Texas to Maine.

Researchers have noted that decades of environmental progress haven't made a dent in Hubbard Brook's nitrogen pollution, which also happens to be the primary cause of the Chesapeake's troubles.

This week, at a news conference in Washington, Hubbard Brook scientists laid out their case -- the results of a study of nitrogen's devastating impact throughout New England and New York.

You might ask what they would have to tell us in the Chesapeake region, where for years we have been out front in trying to cope with nitrogen's impact.

While their study is interesting in its own right, perhaps the most important message is this: You are not the only ones struggling to get a handle on these problems. Nitrogen is an out-of-control pollutant of nationwide scope that demands concerted federal actions, now.

An ominous section of the Hubbard Brook study, "Nitrogen Pollution in the Northeastern United States," assesses Northeastern forest systems, which are hard hit by the nitrogen oxides in modern, polluted air.

From Maine to New York, the study finds evidence that forests are growing more slowly, that their soils are becoming less productive, even allowing toxic elements such as aluminum to escape into waterways.

It also indicates that at high levels of airborne nitrogen -- now seen across more than a third of all Northeastern forests -- woodlands cease being classic pollution "filters" that sop up nitrogen before it runs into waterways. Instead they begin to release nitrogen.

Our cleanup goals for the Chesapeake depend heavily on the watershed's 25 million acres of forests continuing to intercept and absorb nitrogen from polluted air -- an estimated 184 million pounds a year.

If, instead, they begin to leak more nitrogen (or are doing so already), that could offset billions of dollars spent on nitrogen cleanup from sewage treatment plants and other sources.

Moving downstream from mountain forests like Hubbard Brook, the study documents how nitrogen pollution is harming coastal waters from Casco Bay in Maine to Long Island Sound.

The problems there will be all too familiar to Chesapeake residents -- losses of vital seagrass habitat, declines in oxygen in the shallows and deep channels, noxious algae blooms and algae-clotted waters.

All this potentially adds powerful voices to our own in putting drastic nitrogen reductions on the nation's cleanup agenda.

The timing is right. Congress is debating major changes to airborne nitrogen controls. Also, Maryland and other states are suing the Bush administration over its plan to weaken air-quality controls on power plants.

The U.S. Environmental Protection Agency has acknowledged a funding gap of tens of billions of dollars in programs designed to take more nitrogen out of sewage.

The Hubbard Brook study concludes that only an "aggressive" scenario, in which nitrogen from power plants, vehicles, sewage treatment plants and agriculture is reduced well beyond current requirements, will restore Northeastern ecosystems from mountain streams to the coasts.

The April issue of BioScience magazine, where the Hubbard Brook study is published, has a section devoted to nitrogen.

It documents similar problems emerging throughout the Western United States and the Gulf of Mexico. It notes that of all the nitrogen fertilizer spread on farmland -- the largest single source of nitrogen pollution nationwide -- less than 15 percent makes it to human consumers of food. The rest ends up in the environment.

Nitrogen was scarce in the terrestrial and aquatic environments throughout Earth's history until the last several decades. Now, human ingenuity at extracting nitrogen from the atmosphere for fertilizer, along with liberating it by burning fossil fuels, has put the modern planet awash in this pollutant, with unintended consequences that reverberate from Hubbard Brook to the Chesapeake Bay.

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