Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 3701-3715, 2018
https://doi.org/10.5194/acp-18-3701-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
13 Mar 2018
Ubiquitous influence of wildfire emissions and secondary organic aerosol on summertime atmospheric aerosol in the forested Great Lakes region
Matthew J. Gunsch1, Nathaniel W. May1, Miao Wen2, Courtney L. H. Bottenus2,3, Daniel J. Gardner1, Timothy M. VanReken2,a, Steven B. Bertman4, Philip K. Hopke5,6, Andrew P. Ault1,7, and Kerri A. Pratt1,8 1Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
2Department of Civil and Environmental Engineering, Washington State University, Pullman, WA, USA
3Pacific Northwest National Laboratory, Richland, WA, USA
4Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
5Center for Air Resources, Engineering and Science, Clarkson University, Potsdam, NY, USA
6Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
7Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA
8Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
anow at: National Science Foundation, Alexandria, VA, USA
Abstract. Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5–2.0 µm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 µm (PM1) was measured with a high-resolution aerosol mass spectrometer (HR-AMS). The field site was influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire-influenced periods, 0.5–2.0 µm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O∕C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon–organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models underpredicting organic carbon in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest, United States, particularly considering increasing intensity and frequency of Canadian wildfires.
Citation: Gunsch, M. J., May, N. W., Wen, M., Bottenus, C. L. H., Gardner, D. J., VanReken, T. M., Bertman, S. B., Hopke, P. K., Ault, A. P., and Pratt, K. A.: Ubiquitous influence of wildfire emissions and secondary organic aerosol on summertime atmospheric aerosol in the forested Great Lakes region, Atmos. Chem. Phys., 18, 3701-3715, https://doi.org/10.5194/acp-18-3701-2018, 2018.
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Short summary
During summer 2014, atmospheric particulate matter in northern Michigan was impacted by wildfire emissions under all air mass conditions (Canadian wildfires, US urban, and Canadian forest influences). Biomass burning particles coated with secondary organic aerosol contributed the majority of the submicron aerosol mass. Given increasing wildfires, the impacts of biomass burning on air quality must be assessed, particularly for downwind areas impacted by long-range transport.
During summer 2014, atmospheric particulate matter in northern Michigan was impacted by wildfire...
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