CMAQ Estimates of Nitrogen and Phosphorus Deposition From Wildfires to Lakes in the US Intermountain West
Document Type
Conference Paper
Publisher
Community Modeling and Analysis System (CMAS) Conference
Publication Date
10-21-2024
Keywords
Intermountain West, wildfire, particulate matter, 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, and it is therefore important to examine impacts to these lakes from atmospheric deposition. Recent work has linked increases in phosphorus (P) in particulate matter below 2.5 microns in mean diameter (PM2.5) emitted in wildfire smoke to harmful algal blooms in downwind lakes in California. We expand upon that observation-based study in this modeling effort, using the Community Multiscale Air Quality Model (CMAQ) to examine nitrogen (N) and P deposition for the entirety of 2018 from wildfires over the conterminous US at a 12-km grid resolution. As P is not included in the emissions inputs to CMAQ, we estimate total P deposition using elemental carbon (EC) deposition from CMAQ as a proxy, along with the ratio of P to EC obtained from a previous modeling study with the Community Earth System Model. These results provide a baseline total N and P deposition estimates from all sources and are evaluated against observations from a P deposition measurement network across the Intermountain West. Differences between the baseline estimate and the results of a CMAQ sensitivity simulation without wildfire emissions yield an estimate of N and P deposition from wildfires. 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; Shankar, Uma; Olson, Nicole; Pavlovic, Irena; LeDuc, Stephen; Brahney, Janice; Wen, Jiahao; and Hamilton, Douglas, "CMAQ Estimates of Nitrogen and Phosphorus Deposition From Wildfires to Lakes in the US Intermountain West" (2024). Watershed Sciences Faculty Publications. Paper 1217.
https://digitalcommons.usu.edu/wats_facpub/1217