climate-change-2016

Volume 7, Issue 9(Suppl)

J Earth Sci Clim Change

ISSN: 2157-7617 JESCC, an open access journal

Page 15

Climate Change 2016

October 27-29, 2016

conference

series

.com

October 24-26, 2016 Valencia, Spain

World Conference on

Climate Change

‘Sizing’heterogeneous chemistry in the conversion of gaseous dimethyl sulfide to atmospheric particles

he oxidation of biogenic dimethyl sulfide (DMS) emissions is a global source of cloud condensation nuclei. The amounts

of the nucleating H

(g) species produced in such process, however, remain uncertain. Hydrophobic DMS is mostly

oxidized in the gas-phase into H

(g)+DMSO(g) (dimethyl sulfoxide), whereas water-soluble DMSO is oxidized into

(g) in the gas-phase but into SO

- + MeSO

- (methane sulfonate) on water surfaces. Thus, R=MeSO

-/non-sea-salt-

SO42- ratios would therefore gauge both the strength of DMS sources and the extent of DMSO heterogeneous oxidation if Rhet

= MeSO

-/SO

- for DMSO(aq) + ·OH(g) were known. Here we report that Rhet=2.7, a value obtained from online electro-

spray mass spectra of DMSO (aq) + ·OH(g) reaction products, which quantifies the MeSO

- produced in DMSO heterogeneous

oxidation on aqueous aerosols for the first time. On this basis, the inverse R-dependence on particle radius in size-segregated

aerosol collected over Syowa station and Southern oceans is shown to be consistent with the competition between DMSO gas-

phase oxidation and its mass accommodation followed by oxidation on aqueous droplets. Geographical R variations are thus

associated with variable contributions of the heterogeneous pathway to DMSO atmospheric oxidation, which increase with the

specific surface area of local aerosols.

Biography

Agustín J Colussi is a Senior Research Scientist at CALTECH since 1998 and has published more than 200 papers in environmental physical chemistry.

Agustin J Colussi

California Institute of Technology, USA

Agustin J Colussi, J Earth Sci Clim Change 2016, 7:9(Suppl)