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Seasonal variation of fractionated sea‐salt particles on the Antarctic coast
Author(s) -
Hara K.,
Osada K.,
Yabuki M.,
Yamanouchi T.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl052761
Subject(s) - sea salt , seawater , fractionation , aerosol , relative humidity , precipitation , sea salt aerosol , environmental chemistry , mineralogy , salt (chemistry) , geology , oceanography , chemistry , chromatography , meteorology , physics , organic chemistry
Aerosol sampling was conducted at Syowa Station, Antarctica (coastal station) in 2004–2006. SO 4 2− depletion by mirabilite precipitation was identified from April through November. The fractionated sea‐salt particles were distributed in ultrafine– coarse modes. Molar ratios of Mg 2+ /Na + and K + /Na + were higher than in bulk seawater ratio during winter–spring. The Mg 2+ /Na + ratio in aerosols greatly exceeded the upper limit in the case only with mirabilite precipitation. The temperature dependence of Mg 2+ /Na + ratio strongly suggested that higher ratios of Mg 2+ /Na + and K + /Na + were associated with sea‐salt fractionation by precipitation of mirabilite at −9°C, hydrohalite at ca. −23°C and other salts such as ikaite at ca. −5°C and gypsum at ca. −22°C during winter–spring. Mg‐salts with lower deliquescence relative humidity can be enriched gradually in the fractionated sea‐salt particles. Results suggests that sea‐salt fractionation can alter aerosol hygroscopicity and atmospheric chemistry in polar regions.