Observation of sea-salt fraction in sub-100 nm diameter particles at Cape Grim

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Luke T. Cravigan
  • Zoran Ristovski
  • Robin L. Modini
  • Melita D. Keywood
  • John L. Gras

Detail(s)

Original languageEnglish
Pages (from-to)1848-1864
Journal / PublicationJournal of Geophysical Research D: Atmospheres
Volume120
Issue number5
Publication statusPublished - 16 Mar 2015
Externally publishedYes

Abstract

Volatility-hygroscopicity tandem differential mobility analyzer measurements were used to infer the composition of sub-100 nm diameter Southern Ocean marine aerosols at Cape Grim in November and December 2007. This study focuses on a short-lived high sea spray aerosol (SSA) event on 7-8 December with two externally mixed modes in the Hygroscopic Growth Factor (HGF) distributions (90% relative humidity (RH)), one at HGF > 2 and another at HGF∼1.5. The particles with HGF > 2 displayed a deliquescent transition at 73-75% RH and were nonvolatile up to 280°C, which identified them as SSA particles with a large inorganic sea-salt fraction. SSA HGFs were 3-13% below those for pure sea-salt particles, indicating an organic volume fraction (OVF) of up to 11-46%. Observed high inorganic fractions in sub-100 nm SSA is contrary to similar, earlier studies. HGFs increased with decreasing particle diameter over the range 16-97 nm, suggesting a decreased OVF, again contrary to earlier studies. SSA comprised up to 69% of the sub-100 nm particle number, corresponding to concentrations of 110-290 cm-3. Air mass back trajectories indicate that SSA particles were produced 1500 km, 20-40 h upwind of Cape Grim. Transmission electron microscopy (TEM) and X-ray spectrometry measurements of sub-100 nm aerosols collected from the same location, and at the same time, displayed a distinct lack of sea salt. Results herein highlight the potential for biases in TEM analysis of the chemical composition of marine aerosols.

Research Area(s)

  • Cape Grim, deliquescence, entrainment, hygroscopic growth, marine aerosol, sea spray

Citation Format(s)

Observation of sea-salt fraction in sub-100 nm diameter particles at Cape Grim. / Cravigan, Luke T.; Ristovski, Zoran; Modini, Robin L.; Keywood, Melita D.; Gras, John L.

In: Journal of Geophysical Research D: Atmospheres, Vol. 120, No. 5, 16.03.2015, p. 1848-1864.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review