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Synthesizing the effects of N and S deposition on terrestrial biodiversity to inform air quality standards

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  • Overview
Atmospheric deposition of nitrogen (N) and sulfur (S) impacts terrestrial biodiversity in the United States (U.S.) and much of the developed world.  There have been dramatic improvements from the deposition levels of the past, but in many areas N and S deposition remains above levels known to impact ecosystems.  Here, we synthesize research from the U.S. on the sensitivity of different taxonomic groups (e.g., trees, lichen, herbs) to N and S deposition, and we put this in the context of federal decision-making to protect ecosystems from the effects of air pollution.  Air pollution is regulated through the National Ambient Air Quality Standards (NAAQS), which are standards based on atmospheric concentrations.  This can pose a challenge when assessing deposition impacts and relating those impacts to air concentrations.  We will review the current science on the ecosystem impacts from S and N deposition and identify challenges and potential future research opportunities to help improve our understanding of these relationships.  Although we continue to make progress in cleaning the air to protect ecosystems, we have more to do and will discuss the path forward from a scientific perspective.

Impact/Purpose

Atmospheric deposition of nitrogen (N) and sulfur (S) has significantly declined in recent decades.  However, current levels of N and S deposition are still above levels known to have effects in the environment.  This presentation is an overview for the American Geophysical Union 2024 Conference that synthesizes research from the U.S. on the sensitivity of different taxonomic groups (e.g., trees, lichen, herbs) to N and S deposition, and put this in the context of the most recent rulemaking to protect against effects from atmospheric deposition.  We show that many taxonomic groups and species are still impacted at level recommended by the Clean Air Science Advisory Committee (CASAC).  These findings suggest that many sensitive species remain at risk in the U.S. and has implications for air quality managers at the EPA, National Park Service, US Forest Service and State air quality offices. 

Citation

Clark, C., M. Bell, J. Coughlin, L. Pardo, L. Geiser, N. Pavlovic, AND T. Greaver. Synthesizing the effects of N and S deposition on terrestrial biodiversity to inform air quality standards. American Geophysical Union, Washington DC, DC, December 09 - 13, 2024.
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Last updated on December 16, 2024
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