This is a brief description of studies that exemplify the methods and approaches that have been developed and used by Oak Ridge National Laboratory (ORNL) researchers in conducting integrated assessments. See the complete list of Integrated Assessment Briefs to find out more about ORNL's efforts in integrated assessment. Contact Mike Farrell ( for more information.

Sensitivity of Aquatic Systems to Acidic Deposition

(a) Percent of modeled target population in each subregion with ANC < 0 µeq liter-1 after 50 years, based on MAGIC projections. (b) Percent of waters potentially supporting brook trout projected to become unsuitable for brook trout because of changes in acid-base chemistry versus median change in sulfur deposition for each deposition scenario (-50, -30, -20, 0, +20, +30%) and subregion. Values in parentheses after the region name indicate the simulated conditions at the start of the 50-year projection.

How sensitive are eastern U.S. lakes and streams and brook trout populations to alternative rates of continuing acidic deposition?

A weight-of-evidence approach was used by Oak Ridge National Laboratory researchers in collaboration with other scientists in the National Acid Precipitation Assessment Program to assess the sensitivity of the chemistry and biology of lakes and streams to hypothesized changes in sulfate deposition over the next 50 years. The analyses focused on the projected effects of the magnitude and timing of changes in sulfate deposition in the northeastern United States, the Mid-Appalachian Highlands, and the Southern Blue Ridge Province.

The sensitivity of water chemistry and brook trout resources to the hypothesized changes in deposition was found to be greatest in the Adirondacks of New York and the Mid-Appalachian Highlands. Several chemical and biological models, field observations, and paleolimnological findings were used to evaluate uncertainty in the projections.

The findings of these studies were used as input by the administration and by Congress in the formulation of the 1990 Clean Air Act Amendments.

Turner, R. S., P. F. Ryan, D. R. Marmorek, K. W. Thornton, T. J. Sullivan, J. P. Baker, S. W. Christensen, and M. J. Sale. 1992. Sensitivity to change for low-ANC eastern U.S. lakes and streams and brook trout populations under alternative sulfate deposition scenarios. Environmental Pollution 77:269-277.

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Integrated Assessment Briefs. 1995. ORNL/M-4227. Oak Ridge National Laboratory, Oak Ridge, TN.