– by Susan Leavitt
At a recent meeting of the Society of American Foresters, I attended a session presented by Christopher Eagar from the Hubbard Brook Research Foundation in NH on acid deposition and its effects on the New England woodlands. The last time I seriously considered the effects of acid rain was about 15 years ago when I visited an elementary school in north-central Vermont and heard many presentations by children expressing their concerns about acid rain. John, my husband, worked with limiting air emissions from coal burning power plants in the early 90s, but, I didn’t’t make the association between what he was working with and the impact it might have on our forest land. I found this session particularly enlightening, although somewhat frightening, as it helped me begin to make the connection between industrial emissions elsewhere in our country and their impact on our forest in New England. The following is an attempt to synthesize some of what I learned at the session.
Acid rain has been around since the industrial revolution 150 years ago and we became aware of its serious effects as long ago as the 1960s. Rain becomes acidic from the combustion of atmospheric moisture with sulfate and nitrate particles and gases resulting from the combustion of fossil fuels (coal, oil and, to a lesser extent, natural gas) forming dilute sulfuric and nitric acid. Principal sources of sulfates are the combustion of coal in power plants and other heavy industries. At the present nitrates are produced by the combustion of coal, oil and gas, foremost among which are the emissions from vehicles and other gasoline engines.
The Hubbard Brook Research Foundation (HBRF) is a non-profit organization established to provide support for the Hubbard Brook Ecosystem Study (HBES). The HBES is a long-term ecological research project which occupies a 3,160 hectare reserve in the White Mountain National Forest. It was established as a major center for hydrologic research in New England. The HBRF was created to be a link between science and policy, which could provide scientific input to policy making.
An important question was raised as part of the lecture – “Is acid rain still a problem?” In very graphic diagrams, the magnitude of the sulfate (SO2) emissions was shown in the early 90s and then again in the year 2000. Following the passage of the Clean Air Act of 1990, there was significant reduction in SO2 emissions in the mid-west, but it was clear that the air in the northeast is still significantly impacted by these emissions. Despite the reductions in SO2, there has been only a modest improvement in the acidity of precipitation and surface waters, there is little to no improvement in acid neutralizing capacities and there is increased impact on soils. The pH levels show very little improvement in the year 2000 and it are still 100 times more acidic than they should be.
Environmental effects of the emissions from the combustion of fossil fuel contribute to many issues: acidic deposition, coastal eutrophication, oxygen depletion, mercury contamination, tropospheric ozone, visibility impairment and climate change. Acid deposition impacts negatively by altering the soil, causing stress on forest vegetation and acidification of surface water. The soil can suffer a loss of calcium, the mobilization of toxic aluminum compounds, accumulation and release of sulfur and accumulation of nitrogen.
In the forest, 25-50% of canopy spruce have died at high elevation sites in the Adirondacks, and the Green and White Mountains, which are most impacted by long-distance transport of pollutants. There also has been greater frequency of winter injury of red spruce observed throughout an elevational range in the Northeast. Studies also show documented loss of calcium in the wood. It is often found that aluminum is usually tied up with that loss, since its presence inhibits the uptake of calcium and it damages the roots. Aluminum is also responsible for damaging the aquatic system. There is also documentation that sugar maple are dying at higher elevations.
Acid rain from the combustion of fossil fuels is also leaching calcium from foliage. This loss of foliar calcium has reduced cold tolerance and increases freeze injury to red spruce. Acid rain also leaches calcium from the soil, making many sites less fertile for many species.
More information may be acquired from the Hubbard Brook Research Foundation’s website at www.hubbardbrook.org.
It is important that as forest land owners we are aware of the impact of these issues upon our forest. We can’t go out and treat our many acres in the same way we would treat an ailing houseplant, but certainly, through our awareness, we may be able to help make a difference in the policies that have significant impact on our environment. The old adage of “Think globally, act locally” has a vibrant ring and is appropriate to this issue.
This article originally appeared in the March 2003 ECFLA/WDLT Newsletter.
Note: noted that the sulfur content in mid-western (Pa/KY/WV/Va/OH) is much higher than western coal.