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Published April 16, 2015 | Published + Supplemental Material
Journal Article Open

Airborne measurements of organosulfates over the continental U.S.


Organosulfates are important secondary organic aerosol (SOA) components and good tracers for aerosol heterogeneous reactions. However, the knowledge of their spatial distribution, formation conditions, and environmental impact is limited. In this study, we report two organosulfates, an isoprene-derived isoprene epoxydiols (IEPOX) (2,3-epoxy-2-methyl-1,4-butanediol) sulfate and a glycolic acid (GA) sulfate, measured using the NOAA Particle Analysis Laser Mass Spectrometer (PALMS) on board the NASA DC8 aircraft over the continental U.S. during the Deep Convective Clouds and Chemistry Experiment (DC3) and the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). During these campaigns, IEPOX sulfate was estimated to account for 1.4% of submicron aerosol mass (or 2.2% of organic aerosol mass) on average near the ground in the southeast U.S., with lower concentrations in the western U.S. (0.2–0.4%) and at high altitudes (<0.2%). Compared to IEPOX sulfate, GA sulfate was more uniformly distributed, accounting for about 0.5% aerosol mass on average, and may be more abundant globally. A number of other organosulfates were detected; none were as abundant as these two. Ambient measurements confirmed that IEPOX sulfate is formed from isoprene oxidation and is a tracer for isoprene SOA formation. The organic precursors of GA sulfate may include glycolic acid and likely have both biogenic and anthropogenic sources. Higher aerosol acidity as measured by PALMS and relative humidity tend to promote IEPOX sulfate formation, and aerosol acidity largely drives in situ GA sulfate formation at high altitudes. This study suggests that the formation of aerosol organosulfates depends not only on the appropriate organic precursors but also on emissions of anthropogenic sulfur dioxide (SO_2), which contributes to aerosol acidity.

Additional Information

© 2015 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Received 1 AUG 2014; Accepted 26 FEB 2015; Accepted article online 28 FEB 2015; Published online 3 APR 2015. The majority of the study is supported by the NASA grant NNH12AT29I from the Upper Atmosphere Research Program, Radiation Sciences Program, and Tropospheric Chemistry Program and by NOAA base funding. The GA sulfate standard is based upon work supported by the National Science Foundation under grant CHE-1213723. IEPOX and ISOPOOH measurements were supported by NASA NNX12AC06G. PTR-MS measurements were supported by BMVIT/FFG-ALR (Austrian Space Applications Programme, ASAP), the NASA Postdoctoral Program (NPP), and the National Institute of Aerospace (NIA). NO and O3 measurements were supported by NASA grant NNH12AT30I. AMS measurements were supported by NASA NNX12AC03G, NSF AGS-1243354, and NOAA NA13OAR4310063. We thank Barbara Ervens at NOAA and University of Colorado, Boulder for helpful discussion. We also would like to thank all the NASA DC8 crew for their assistance to integrate, maintain, and deintegrate the instrument on the airplane. The data are publicly available at NASA data achieve https://www-air.larc.nasa.gov/cgi-bin/ArcView/dc3-seac4rs and http://www-air.larc.nasa.gov/missions/seac4rs/index.html. The analysis results are available upon requested from jin.liao@noaa.gov and karl.froyd@noaa.gov.

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Supplemental Material - jgrd52049-sup-0001-supplementary.doc

Published - jgrd52049.pdf


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August 22, 2023
August 22, 2023