A hybrid modeling approach for estimating reactive nitrogen deposition in Rocky Mountain National Park. (February 2016)

• Record Type: Journal Article
• Authors: Malm, William C.; Rodriguez, Marco A.; Schichtel, Bret A.; Gebhart, Kristi A.; Thompson, Tammy M.; Barna, Michael G.; Benedict, Katherine B.; Carrico, Christian M.; Collett, Jeffrey L.
• Is Part Of: Atmospheric environment. Volume 126(2016)
• Page Start: 258
• Page End: 273
• Publication Date: 2016-02
• Subjects: Nitrogen deposition -- Receptor model -- Rocky Mountain National Park -- Source apportionment; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2015.11.060
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Changes in ecosystem function at Rocky Mountain National Park (RMNP) are occurring because of nitrogen deposition associated with emissions of nitrogen from sources in Colorado as well as other areas of the North American continent and beyond. Nitrogen species are in both reduced and oxidized forms. A year-long monitoring program was initiated to better understand their origins as well as the complex chemistry occurring during transport from source to receptor. Specifically, the goals of the study were to characterize the atmospheric concentrations of nitrogen species in gaseous, particulate, and aqueous phases in RMNP and to identify the emission sources of these various species. The apportionment strategy was designed to focus on differentiating between sources within and outside the state of Colorado and then further differentiate between sources along the Front Range of Colorado and the rest of Colorado. It was also desirous to identify the relative contributions to atmospheric nitrogen species from mobile sources, agricultural activities, and large and small point sources within the state of Colorado. The Particle Source Apportionment Technology (PSAT) module available in the chemical transport model, the Comprehensive Air quality Model with extensions (CAMx), is used to develop first-principle estimates of the contributions from different areas of North America. The CAMx_PSAT results are combined with measured species concentrations in a receptor modeling approach to develop final estimates of source apportionment of the various species' concentrations and deposition. Highlights: Total nitrogen deposition at Rocky Mountain National Park (RMNP) is modeled. Only a few percent of nitrogen deposition originates from eastern United States. 40% of total deposition at RMNP is from sources within that state of Colorado. 27% of nitrogen disposition is from the Front Range. Reduced nitrogen, other than the WON, makes up 66% of the deposition budget.