Nature 325, 244 - 246 (15 January 1987); doi:10.1038/325244a0

Decrease in precipitation acidity resulting from decreased SO^2-₄ concentration

Lars O. Hedin^*†, Gene E. Likens^† & F. Herbert Bormann^‡

^*Department of Biology, Yale University, New Haven, Connecticut 06511, USA
^†Institute of Ecosystem Studies, The New York Botanical Garden, Box AB, Millbrook, New York 12545, USA
^‡School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA

The effect of decreases in SO₂ emissions on precipitation acidity has received much attention^1–10, but there has been no direct quantification of how recent decreases in SO₂ emissions in the northeastern and midwestern United States have affected precipitation acidity at a local site. Yet such quantification is an Simportant step in assessing the effectiveness of control measures for SO₂ emissions. It is thought that recent decreases in SO^2- ₄ concentration in precipitation at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, result from decreases in SO₂ emissions. The effect of the SO^2- ₄ decrease on precipitation acidity is obscured by long-term trends in other ions, which also influence acidity. Here we show that, given the observed trends in concentration of other ions, the H+ concentration in 1983 would have been nearly two-thirds higher than the measured values if the SO^2- ₄ concentration had not decreased.

References

1.	Ableson, P. H. Science 230, 617 (1985).
2.	Ableson, P. H. Science 226, 1263 (1984).
3.	Oppenheimer, M. et al. Science 227, 1155−1156 (1985).
4.	Hidy, G. M. et al. APCA Jl 31, 333−354 (1984).
5.	Katzenstein, A. W. Science 228, 390−391 (1985).
6.	Katzenstein, A. W. Wall Street J., 28 June 1984.
7.	Oppenheimer, M., Epstein, C. B. & Yunkhe, R. E. Science 229, 859−862 (1985). | ISI | ChemPort |
8.	Ad Hoc Committee on Acid Rain: Science and Policy Is there Scientific Consensus on Acid Rain? (Institute of Ecosystem Studies, Millbrook, New York, 1985).
9.	Lewis, D. & Davis, W. Joint Report of the Special Envoys on Acid Rain, Report to the President, 8 Jan. 1986.
10.	National Research Council Acid Deposition: Atmospheric Processes in Eastern North America (National Academy Press, Washington, DC, 1983).
11.	Gschwandtner, G., Gschwandtner, K. C. & Eldridge, K. Historic Emissions of Sulfur and Nitrogen Oxides in the United States from 1900 to 1980, USEPA Project Summary EPA/600/S7-85/009 (1985).
12.	Schertz, T. L. & Hirsch, R. M. Trend Analysis of Weekly Acid Rain Data—1978−83, USGS Water Resources Investigation Report 85-4211 (1986).
13.	Rodhe, H. & Granat, L. Atmos. Environ. 18, 2627−2639 (1984). | ChemPort |
14.	Munn, R. E. et al. A Climatological Analysis of the Hubbard Brook (New Hampshire) Precipitation Chemistry Data (Institute for Environmental Studies, Univ. Toronto, 1982).
15.	Likens, G. E. et al. Ecology 48, 772−785 (1967). | ChemPort |
16.	The Acidic Deposition Phenomenon and Its Effects: Critical Assessment Review Papers, Vols I and II, USEPA Report EPA-600/8-83-016A (1984).
17.	National Research Council Atmospheric-Biosphere Interactions: Toward a Better Understanding of the Consequences of Fossil Fuel Combustion (National Academy Press, Washington DC, 1981).
18.	Report of the Acid Rain Peer Review Panel (Office of Science and Technology Policy, Washington DC, 1984).
19.	Acid Rain and Transported Air Pollutants: Implications for Public Policy, Report OTA-O-204 (Office of Technology Assessment, US Congress, Washington DC, 1984).
20.	Likens, G. E. et al. Biogeochemistry of a Forested Ecosystem (Springer, New York, 1977).
21.	Likens, G. E. et al. Atmos. Environ. 18, 2641−2647 (1984). | ChemPort |
22.	Galloway, J. N. & Likens, G. E. Atmos. Environ. 15, 1081 (1981). | ChemPort |
23.	Munger, J. W. & Eisenreich, S. J. Environ. Sci. Technol. 17, 32A−42A (1983). | ChemPort |
24.	Gorham, E. et al. Science 225, 407−409 (1984). | ISI | ChemPort |
25.	Galloway, J. N., Likens, G. E. & Hawley, M. E. Science 226, 829−831 (1984). | ISI | ChemPort |