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Volume 15, issue 19
Atmos. Chem. Phys., 15, 11341–11353, 2015
https://doi.org/10.5194/acp-15-11341-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 15, 11341–11353, 2015
https://doi.org/10.5194/acp-15-11341-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 12 Oct 2015

Research article | 12 Oct 2015

Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the Arctic troposphere

J. W. Chi1, W. J. Li1, D. Z. Zhang2, J. C. Zhang3, Y. T. Lin3, X. J. Shen4, J. Y. Sun4, J. M. Chen1, X. Y. Zhang4, Y. M. Zhang4, and W. X. Wang1 J. W. Chi et al.
  • 1Environment Research Institute, Shandong University, Jinan, Shandong 250100, China
  • 2Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
  • 3Key Laboratory of the Earth' Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
  • 4Key Laboratory of Atmospheric Chemistry of CMA, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing 100081, China

Abstract. Sea salt aerosols (SSA) are dominant particles in the Arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes in physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard, in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased, the C, N, O, and S content increased. 12C- mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C- line scan further shows that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces likely determines their hygroscopic and optical properties. These abundant SSA as reactive surfaces adsorbing inorganic and organic acidic gases can shorten acidic gas lifetime and influence the possible gaseous reactions in the Arctic atmosphere, which need to be incorporated into atmospheric chemical models in the Arctic troposphere.

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Sea salt aerosols (SSA) are dominant particles in the Arctic atmosphere. Our result suggests that the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases in the Arctic. The content of organic matter increased in the aged SSA compared with the fresh SSA, which suggests organic acids (beside inorganic acids) participate in the ageing of SSA in the Arctic.
Sea salt aerosols (SSA) are dominant particles in the Arctic atmosphere. Our result suggests...
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