Side-by-side comparison of four techniques explains the apparent differences in the organic composition of generated and ambient marine aerosol particles

TitleSide-by-side comparison of four techniques explains the apparent differences in the organic composition of generated and ambient marine aerosol particles
Publication TypeJournal Article
Year of Publication2014
AuthorsFrossard AA, Russell LM, Massoli P., Bates T.S, Quinn P.K
JournalAerosol Science and Technology
Volume48
PaginationV-X
Date Published2014/03
Type of ArticleArticle
ISBN Number0278-6826
Accession NumberWOS:000330105200011
Keywordsmass-spectrometer; size
Abstract

Characterizing the organic composition of marine aerosol particles is important for understanding the sources of marine aerosol and their impact on cloud microphysical properties (de Leeuw et al. 2011). A variety of measurement techniques have been used to measure the organic composition of both ambient atmospheric and freshly emitted sea spray aerosol (Table S1 in the online supplementary information [SI]). Using Fourier transform infrared (FTIR) spectroscopy, atmospheric aerosol particles collected in marine regions on multiple shipboard campaigns were shown to be saccharide-like based on their functional group composition, with a high ratio of oxygen to carbon (O/C) (Russell et al. 2010). Similarly, using scanning transmission X-ray microscopy with near-edge X-ray absorption fine structure (STXM-NEXAFS), Russell et al. (2010) and Hawkins and Russell (2010) found chemically distinct ambient marine particle types including saccharide-like components on sea salt particles and protein particles. Model ocean systems have been used to generate nascent sea spray aerosol (SSA) from seawater (Keene et al. 2007; Bates et al. 2012), to determine the organic composition of particles directly emitted from wave breaking and bubble bursting at the sea surface (Table S1). FTIR spectroscopy showed the organic composition of these generated nascent SSA, hereafter referred to as generated marine particles, also to be highly oxidized (Bates et al. 2012). In contrast, using high resolution time of flight aerosol mass spectrometry (HR-ToF-AMS) in the same study, Bates et al. (2012) found that generated marine aerosol particles were highly unsaturated and minimally oxidized (low O/C).
In this study, we resolve this apparent discrepancy by comparing the measured organic composition of ambient and generated marine aerosol particles using these three techniques as well as a light scattering module of the HR-ToF-AMS (LS-ToF-AMS). Each of these methods is used to calculate the level of oxidation of the organic mass (OM) and assess the differences in the composition of ambient and generated marine particles. Additionally, we consider the extent to which each method provides additional insight into the particle composition.

DOI10.1080/02786826.2013.879979
Short TitleAerosol Sci. Technol.
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