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Published October 15, 2011 | Supplemental Material
Journal Article Open

Measurements of Isoprene-Derived Organosulfates in Ambient Aerosols by Aerosol Time-of-Flight Mass Spectrometry—Part 2: Temporal Variability and Formation Mechanisms


Organosulfate species have recently gained attention for their potentially significant contribution to secondary organic aerosol (SOA); however, their temporal behavior in the ambient atmosphere has not been probed in detail. In this work, organosulfates derived from isoprene were observed in single particle mass spectra in Atlanta, GA during the 2002 Aerosol Nucleation and Characterization Experiment (ANARChE) and the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS). Real-time measurements revealed that the highest organosulfate concentrations occurred at night under a stable boundary layer, suggesting gas-to-particle partitioning and subsequent aqueous-phase processing of the organic precursors played key roles in their formation. Further analysis of the diurnal profile suggests possible contributions from multiple production mechanisms, including acid-catalysis and radical-initiation. This work highlights the potential for additional SOA formation pathways in biogenically influenced urban regions to enhance the organic aerosol burden.

Additional Information

© 2011 American Chemical Society. Published In Issue October 15, 2011; Article ASAP: September 09, 2011; Received: April 09, 2011; Accepted: August 02, 2011; Revised: July 11, 2011. We gratefully acknowledge Stephanie Shaw and Eladio Knipping (EPRI) for coordinating the AMIGAS campaign. The authors thank the rest of the Prather group for extensive support throughout the studies. Additional assistance in Atlanta from Jerry Brown (ARA, Inc.) was appreciated during AMIGAS. Water-soluble organic carbon measurements were provided by Xiaolu Zhang and Prof. Rodney Weber (Georgia Institute of Technology). Michele Sipin is acknowledged for assisting with data collection during ANARChE. The authors thank anonymous reviewers for insightful comments. ANARChE was supported by the University of Rochester EPA PM Center, Grant R827354. AMIGAS was funded by the Electric Power Research Institute. L.H. has been funded by a National Science Foundation Graduate Research Fellowship (2008-2011).

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