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Acidification Risk Assessment

Photo of a high-elevation lake, North Cascades NP, Washington. Photo of a sugar maple tree, a plant species particularly sensitive to acidification effects. Photo of winter headwater stream, Great Smoky Mountains NP, North Carolina and Tennessee. Photo of a red spruce tree, a plant species particularly sensitive to acidification effects.
Some ecosystems and vegetation types, including
high-elevation lakes, headwater streams, sugar maple and red spruce trees, are sensitive to the effects of acidification from atmospheric nitrogen and sulfur deposition.

This report series evaluates the relative sensitivity of NPS parks and inventory & monitoring networks to potential acidification effects caused by atmospheric nitrogen (nitrate and ammonium) and sulfur (sulfate) deposition. In terrestrial ecosystems, acidification depletes soil nutrients and mobilizes aluminum, affecting plant health and growth. In lakes and streams, acidification harms fish, amphibians, and aquatic insects.

The reports provide a relative risk assessment of acidification impacts from atmospheric nitrogen and sulfur deposition for 270 parks in 32 inventory & monitoring networks. This assessment considers three factors that influence acidification risk to park resources:

  1. Nitrogen and Sulfur Pollutant Exposure
  2. Ecosystem Sensitivity
  3. Park Protection Mandates
National parks and networks are ranked according to each of these factors (themes). An overall risk ranking is then calculated based on averages of the three theme rankings.

Main Report

The main report provides background for the project, describes the assessment methods, and summarizes ranking results. It should be used in conjunction with each network report.

Inventory & Monitoring Network Reports

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Last Updated: January 08, 2014