Model Estimates of Nitrogen and Phosphorus Deposition From Wildfires to Lakes in the US Intermountain West

Authors

Anne Barkley, U.S. Environmental Protection Agency
Nicole Olson, University of Michigan Ann Arbor
Stephen D. LeDuc, Environmental Protection Agency, Office of Research and Development
Janice Brahney, Utah State UniversityFollow
Douglas S. Stephen Hamilton, North Carolina State University
Jiahao Wen, Utah State University

Document Type

Conference Paper

Publisher

American Geophysical Union

Publication Date

12-13-2024

Keywords

Intermountain West, wildfire, nutrient concetration

Abstract

In the United States (US) Intermountain West, nutrient concentrations in many high elevation remote lakes have been increasing for the past few decades. It is currently unclear why multiple lakes across different states, which lack a common source of pollution or run-off, would simultaneously experience elevated nutrient concentrations. Many of these lakes are in Federal Class I Areas (e.g., National Parks) and are thus protected under the provisions of the Clean Air Act Amendments of 1990. It is therefore important to examine the impacts of atmospheric deposition on these aquatic ecosystems. Recent work has linked increases in phosphorus (P) in particulate matter below 2.5 microns in mean diameter (PM_2.5) emitted in wildfire smoke to algal blooms in downwind lakes in California. We expand upon that observation-based study in this modeling effort, using the Community Multiscale Air Quality (CMAQ) Model to examine nitrogen (N) and P deposition over the conterminous US at a 12-km grid resolution during 2018, a year of high wildfire activity in the western US. N deposition estimates from all sources were evaluated against observations from the National Atmospheric Deposition Program and P deposition estimates were evaluated against a recent P deposition measurement network across the Intermountain West. We then performed a sensitivity analysis to estimate N and P deposition from wildfires only, to evaluate the role of wildfires in nutrient deposition. Additionally, we sought to evaluate the link between nutrient deposition from wildfires and aquatic ecosystems. These results allow us to explore the linkage between N and P deposition and wildfire smoke emissions, and to quantify their potential impact on sensitive aquatic ecosystems.

Recommended Citation

Barkley, Anne; Olson, Nicole; LeDuc, Stephen D.; Brahney, Janice; Hamilton, Douglas S. Stephen; and Wen, Jiahao, "Model Estimates of Nitrogen and Phosphorus Deposition From Wildfires to Lakes in the US Intermountain West" (2024). Watershed Sciences Faculty Publications. Paper 1216.
https://digitalcommons.usu.edu/wats_facpub/1216