Single-particle investigation of summertime and wintertime Antarctic sea spray aerosols using low-Z particle EPMA, Raman microspectrometry, and ATR-FTIR imaging techniques

Hyo-Jin Eom, Dhrubajyoti Gupta, Hye-Rin Cho, Hee Jin Hwang, Soon Do Hur, Yeontae Gim, Chul-Un Ro
2016 Atmospheric Chemistry and Physics  
<p><strong>Abstract.</strong> Two aerosol samples collected at King Sejong Korean scientific research station, Antarctica, on 9 December 2011 in the austral summer (sample S1) and 23 July 2012 in the austral winter (sample S2), when the oceanic chlorophyll <i>a</i> levels on the collection days of the samples were quite different, by ∼ <span class="thinspace"></span>19 times (2.46 vs. 0.13<span class="thinspace"></span>µg<span class="thinspace"></span>L<sup>−1</sup>, respectively), were
more » ... vely), were investigated on a single-particle basis using quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-<i>Z</i> particle EPMA, Raman microspectrometry (RMS), and attenuated total reflection Fourier transform infrared (ATR-FTIR) imaging techniques to obtain their characteristics based on the elemental chemical compositions, molecular species, and mixing state. X-ray analysis showed that the supermicron summertime and wintertime Antarctic aerosol samples have different elemental chemical compositions, even though all the individual particles analyzed were sea spray aerosols (SSAs); i.e., the contents of C, O, Ca, S, and Si were more elevated, whereas Cl was more depleted, for sample S1 than for sample S2. Based on qualitative analysis of the chemical species present in individual SSAs by the combined application of RMS and ATR-FTIR imaging, different organic species were observed in samples S1 and S2; i.e., Mg hydrate salts of alanine were predominant in samples S1 and S2, whereas Mg salts of fatty acids internally mixed with Mg hydrate salts of alanine were significant in sample S2. Although CaSO<sub>4</sub> was observed significantly in both samples S1 and S2, other inorganic species, such as Na<sub>2</sub>SO<sub>4</sub>, NaNO<sub>3</sub>, Mg(NO<sub>3</sub>)<sub>2</sub>, SiO<sub>2</sub>, and CH<sub>3</sub>SO<sub>3</sub>Mg, were observed more significantly in sample S1, suggesting that those compounds may be related to the higher phytoplankton activity in summer.</p>
doi:10.5194/acp-16-13823-2016 fatcat:ehhmsijrqjehxdjwtonw3nz664