Acid Rain

Though not in the news as much as it once was, acid rain—more correctly called “acid deposition” because it also involves snow, fog, particles, and gases—remains a problem in our region.

Most of our energy needs are derived from burning fossil fuels, such as coal, oil, and gasoline. Power plants, factories, and vehicles give off sulfur and nitrogen oxide emissions, which react in the atmosphere to form sulfuric and nitric acids. These acids make their way back to the landscape in raindrops, snowflakes, fog, dew, and atmospheric particles.

Pollutants can travel hundreds of miles from their source, contaminating lakes, forests, and other natural areas. Because the Hudson Valley lies downwind of major Midwestern power plants, the region receives high levels of acid deposition.

Acid rain harms plants by stripping essential nutrients, such as calcium and magnesium, from leaves and soil. Sugar maple and red spruce are particularly vulnerable. When acid rain percolates through the soil, it releases aluminum from soil minerals. Not only does this aluminum damage plant roots, but it pollutes nearby water bodies and harms fish by interfering with the function of their gills. Other aquatic animals, such as frogs and salamanders, are also susceptible to elevated levels of acidity and aluminum.

In recent years, the acid rain problem has improved thanks to federal regulations that have reduced the emissions of the acid-forming pollutants from power plants. However, because there are still many acidified lakes and streams in the Northeast, particularly in the Catskill and Adirondack Mountains, further emission reductions will be needed to allow their recovery.

Cary Institute scientists, including Gene Likens, Kathleen Weathers, and Gary Lovett, have been conducting important research on acid rain and its effects for decades. In addition, the Cary Institute has monitored the chemistry of precipitation since 1983 as a part of its Environmental Monitoring Program. 

The Latest

gene likens 1957

Long-term Study

We often forget that some of today's obvious and formidable environmental problems were not recognized without tedious long-term studies by dedicated scientists with a hunch.


Likens receives Frontiers of Knowledge Award

Working independently, Likens and Scheffer have, says the jury, contributed to understanding and finding solutions for “gradual, abrupt and potentially irreversible ecosystem change” in response to pollution and other ecological threats. Together, the two scientists “have transformed our understanding of how human activities are changing the structure and function of natural ecosystems, and provided tools to inform ecosystem management.”

One of the largest ‘test tubes’ in science is an 8,000-acre forest in New Hampshire


The White Mountains of New Hampshire contain an unusual patch of woods known as the Hubbard Brook Experimental Forest. Hubbard Brook has been home to some of the past half-century’s biggest discoveries in forest science, particularly around acid rain and clear-cutting. 

Lessons from the forest

Since the 1960s, scientists have converged on the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire to explore how forest ecosystems work.

Related Projects


Base Cation Depletion: Organic Matter Quality & Microbial Processes

We are analyzing how changes in soil base status can influence microbial physiology, organic matter quality, and microbial activity in northern hardwood forests at Hubbard Brook.

Patterns of Atmospheric Deposition

Air pollutants are deposited not only in rain and snow, but also as gases, particles, and fog droplets. Measuring the deposition of all of these forms is difficult, especially in mountainous terrain, where deposition rates are strongly influenced by elevation and characteristics of the forest canopy. Knowing the rates and patterns of deposition is critical to evaluating ecosystem response to the pollutants

Cary Institute of Ecosystem Studies | Millbrook, New York 12545 | Tel (845) 677-5343

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