SU-led study pinpoints nitrogen pollution sources and solutions
Nitrogen pollution is harming forests, streams and coastal waters but can be alleviated, reports a team of 12 leading scientists in a study released April 15 in a special issue of the journal BioScience. The authors of the study, including lead author Charles Driscoll, University Professor and chair of the Department of Civil and Environmental Engineering in the L.C. Smith College of Engineering and Computer Science, pinpoint air pollution and wastewater effluent as the leading causes of nitrogen pollution to forests and estuaries of the Northeastern U.S. Driscoll discussed the study during a press briefing at the National Press Club in Washington, D.C. on April 15.
Despite the reductions in sulfur emissions that have been achieved by the 1990 Clean Air Act, little progress has been made in reducing total emissions of nitrogen. So unfortunately, we weren’t surprised that airborne nitrogen pollution continues to be a serious problem for Northeast forests and streams,” says Driscoll.
The authors report that the current Clean Air Act (as amended in 1990) will not reduce nitrogen emissions enough to prevent damage to northeast forests and reverse acid rain impacts to lakes and streams. The analysis shows that additional reductions in total nitrogen emissions of 30 percent or more would be needed to reduce nitrogen runoff to less harmful levels.
The report provides a scientific basis for evaluating clean air proposals currently before Congress including a new bill introduced by Sen. Judd Gregg (R-NH) earlier this month and two bills introduced by Sen. James Jeffords (I-VT) and James Inhofe (R-OK) in February of this year. “In clear and decisive terms, this report confirms the need for cuts in nitrogen oxides similar to those outlined in my multi-pollutant bill if we want to see healthier people and ecosystems in the next 50 years,” says Jeffords, ranking member of the U.S. Senate Environment and Public Works Committee.
Driscoll and his colleagues synthesized data on the effects of nitrogen pollution and evaluates possible solutions. Impacts on forests and watersheds cited by the authors include diminished forest productivity (up to 14 percent in some areas) due to nitrogen-induced ozone, and nitrogen-driven pulses of acidity that impact approximately 41 percent of lakes in the Adirondack region of New York and 15 percent in New England.
“In all the watersheds we examined, airborne emissions of nitrogen and nitrogen discharged from wastewater treatment plants were the overwhelming sources of nitrogen pollution to forests and coastal waters in the Northeast,” says co-author Dr. David Whitall of the Hubbard Brook Research Foundation, the group that organized the new study.
The study also assesses nitrogen pollution in estuaries – the ultimate receiving waters for much of the nitrogen produced in the regions watersheds – and confirms that excess nitrogen can lead to over-enrichment of coastal waters, depleting oxygen levels and degrading critical sea grass habitat.
The study demonstrates that upgrades to wastewater treatment plants using currently available technology could reduce nitrogen loading to coastal waters, such as Long Island Sound, by as much as 57 percent — a level that would improve the low oxygen conditions experienced in the Sound annually.
This study adds to the growing body of evidence concerning the severity of nitrogen pollution nationwide and the need for policy reform to address the problem. Despite the pressing nature of nitrogen pollution, initiatives to address the problem appear to have stalled or been rolled back.
“Solving the nitrogen problem nationally will require a multi-pronged approach. We now know that in the Northeast, two of these approaches must be reduced air emissions and improved wastewater treatment,” said Kathy Fallon Lambert, executive director of the Hubbard Brook Research Foundation.
The paper “Nitrogen Pollution in the Northeastern United States: Sources, Effects and Management Options” can be downloaded from the BioScience Web site at http://www.aibs.org/bioscienceonline/. A summary of the BioScience article and lay report for the general public can be found at www.hubbardbrook.org/hbrf/nitrogen.
The Hubbard Brook Research Foundation is a nonprofit organization established in 1993 to provide support for the Hubbard Brook Ecosystem Study and develop new initiatives linking ecosystem science and public policy. The HBRF Science Links program was created to increase the exchange of information among scientists, land managers, and policy-makers. It focuses on identifying important policy issues that can benefit from increased access to scientific research.