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Critical Loads
What is a critical load?
A quantitative estimate
of exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge.
-Nilsson
and Grennfelt, 1988
Unlike regional or national market-based cap-and-trade programs for pollutant emissions, a critical loads approach focuses on the capacity of specific ecosystems to withstand loadings of air pollutants deposited on them.
NESCAUM is undertaking a new project with a goal to "estimate critical loads of sulfur and nitrogen in atmospheric deposition for areas where sufficient knowledge, data, and methods exist." A second goal is to demonstrate the use of critical loads "as a tool for assessing environmental policies and programs and managing natural resources." NESCAUM will partner with Ecosystems Research Group (Eric Miller), U.S. Geological Survey (Greg Lawrence), and the Institute for Ecosystem Studies (Kathy Weathers) to examine possible critical loads approaches. Our plan will take the steady-state modeling approach of the New England Governors’ Conference / Eastern Canadian Premiers and extend its land-based critical load maps to New York. We will also incorporate approaches for critical loads assessments of surface waters. NESCAUM is also including Shenandoah National Park and surrounding U.S. Forest Service lands in Virginia as well as the Monongahela National Forest in West Virginia. This will be done in the context of a larger coordinated project using dynamic modeling conducted over the same region by a team headed by Tim Sullivan of E&S Environmental Services and including Jack Cosby (University of Virginia).
For more information, please contact Paul Miller, pmiller [at] nescaum.org.