Thesis
Regional modeling of nitrogen, sulfur, and mercury atmospheric deposition in the Pacific Northwest
Washington State University
Master of Science (MS), Washington State University
2007
Handle:
https://hdl.handle.net/2376/101651
Abstract
Atmospheric deposition of nitrogen, sulfur, and mercury is important to the people and ecology of the Pacific Northwest (PNW). In this study, nitrogen and sulfur deposition patterns in the PNW were simulated using a numerical air quality modeling system consisting of the MM5 meteorological model and the CMAQ atmospheric chemistry and transport model. This modeling system was used as part of a separate analysis of global change and air quality to simulate current US climate conditions for ten years (1990-1999) at 36-km grid scale resolution. In the PNW, the relative contribution of nitrogen wet and dry deposition are approximately equal on an annual basis. Dry deposition processes dominate during summertime conditions, while wet deposition occurs mainly in non-summer periods. Annual nitrogen deposition ranges are 0.6--13 kg/ha. Annual sulfur deposition ranges are 0.1--14 kg/ha. Future global change conditions, consistent with the IPCC A2 "business-as-usual" scenario, are used to drive a second model simulation for the period 2045-2054. The most significant prediction for the future decade is that nitrogen deposition in the inland PNW more than doubles. Results are also presented for numerical model experiments of mercury atmospheric chemical transport and deposition. The AIRPACT-3 numerical air quality forecast system, which employs the MM5/SMOKE/CMAQ suite of models and operates on a daily basis for the PNW, was used to simulate mercury deposition. Cases studies from May, 2006 and a re-analysis covering Aug-Nov, 2004 were used for this purpose. Mercury deposition on any given day is on the order of mg/ha through much of the PNW region. Days of enhanced vertical flux and precipitation increase daily mercury deposition by 10 mg/ha or more in some locations near large mercury emission sources. Model results are compared with observations that include ambient concentration measurements conducted in southern Idaho and wet deposition measurements from the EPA National Acid Deposition Program Mercury Deposition Network. The area of highest modeled mercury deposition (34 mg/ha/day) is located near mining emission sources in northeastern Nevada; elevated mercury deposition events also occur downwind of Portland, Oregon (~2 mg/ha/day).
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Details
- Title
- Regional modeling of nitrogen, sulfur, and mercury atmospheric deposition in the Pacific Northwest
- Creators
- Matthew Kirk Porter
- Contributors
- Brian Lamb (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525044701842
- Language
- English
- Resource Type
- Thesis