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Airborne Observations of Reactive Inorganic Chlorine and Bromine Species in the Exhaust of Coal‐Fired Power Plants
Citation:
Lee, B., F. Lopez-Hilfiker, J. Schroder, P. Campuzano-Jost, J. Jimenez, E. McDuffie, D. Fibiger, P. Veres, S. Brown, T. Campos, A. Weinheimer, F. Flocke, G. Norris, K. O'Mara, J. Green, M. Fiddler, S. Bililign, V. Shah, L. Jaeglé, AND J. Thornton. Airborne Observations of Reactive Inorganic Chlorine and Bromine Species in the Exhaust of Coal‐Fired Power Plants. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES. American Geophysical Union, Washington, DC, 123(19):11,225-11,237, (2018). https://doi.org/10.1029/2018JD029284
Impact/Purpose:
We report on measurements of submicron pCl and pSO4, and reactive gaseous halogen species including HCl, HOCl, Cl2, ClNO2, BrCl, Br2, and BrNO2 observed in polluted air mass encounters during the WINTER campaign. A total of 50 plume encounters were identified, characterized by elevated SO2 mixing ratios observed near and downwind of power plants, located in the Northeast U.S. and also Georgia. Each of he 50 encounters were attributed to one or more operating power generation facilities using a simple wind trajectory approach. To our knowledge, this study represents the most comprehensive airborne assessment of halogen emissions from coal‐fired power plants to date.
Description:
We present airborne observations of gaseous reactive halogen species (HCl, Cl2, ClNO2, Br2, BrNO2, and BrCl), sulfur dioxide (SO2), and nonrefractory fine particulate chloride (pCl) and sulfate (pSO4) in power plant exhaust. Measurements were conducted during the Wintertime INvestigation of Transport, Emissions, and Reactivity campaign in February–March of 2015 aboard the NCAR‐NSF C‐130 aircraft. Fifty air mass encounters were identified in which SO2 levels were elevated ~5 ppb above ambient background levels and in proximity to operational power plants. Each encounter was attributed to one or more potential emission sources using a simple wind trajectory analysis. In case studies, we compare measured emission ratios to those reported in the 2011 National Emissions Inventory and present evidence of the conversion of HCl emitted from power plants to ClNO2. Taking into account possible chemical conversion downwind, there was general agreement between the observed and reported HCl:SO2 emission ratios. Reactive bromine species (Br2, BrNO2, and/or BrCl) were detected in the exhaust of some coal‐fired power plants, likely related to the absence of wet flue gas desulfurization emission control technology. Levels of bromine species enhanced in some encounters exceeded those expected assuming all of the native bromide in coal was released to the atmosphere, though there was no reported use of bromide salts (as a way to reduce mercury emissions) during Wintertime INvestigation of Transport, Emissions, and Reactivity observations. These measurements represent the first ever in‐flight observations of reactive gaseous chlorine and bromine containing compounds present in coal‐fired power plant exhaust.
URLs/Downloads:
DOI: Airborne Observations of Reactive Inorganic Chlorine and Bromine Species in the Exhaust of Coal‐Fired Power Plants