Water-soluble species in the marine aerosol from the northern South China Sea: High chloride depletion related to air pollution

Shih Chieh Hsu, Shaw Chen Liu, Shuh Ji Kao, Woei Lih Jeng, Yi Tang Huang, Chun Mao Tseng, Fujung Tsai, Jien Yi Tu, Yih Yang

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Dichotomous (PM2.5-10 and PM2.5 modes) and size-resolved marine aerosols collected during the northeastern monsoon on two wintertime cruises in the subtropical South China Sea (SCS) were analyzed for water-soluble ions. During the sampling periods the study region was under the influence of strong pollution originating primarily from the Asian continent. Elevated levels of non-sea-salt sulfate and ammonium ions of up to 4.5 and 1.2 μ/m3, respectively, were observed, indicating that the SCS is now substantially contaminated by massive amounts of air pollutants most likely from China and South/ Southeast Asia. The non-sea-salt sulfate to nitrate mass ratios reaching 3.8 ± 1.9 are much larger than those (approximately 2) in and around East Asia and the western Pacific Ocean, suggesting that the Asian outflow aerosols measured in the SCS experienced different traveling history from those in the vicinity of source regions. High chloride depletion (Cl-depletion) measured in the SCS marine aerosols was, on average, 30% for coarse-mode particles and nearly 90% for fine-mode particles. Cl-depletion is size-dependent, and maximizes in submicrometer particles (i.e., Cl has almost been completely lost). Acid displacement is responsible for the observed high Cl-depletion: nitrate substitution accounts for the coarse-mode depletion, whereas sulfate substitution accounts for the fine-mode depletion. The acid displacement of sea salt aerosols may be related to a variety of factors, especially the substantial air pollution, which is discussed in detail in this paper. On cloudy/rainy days, fine-mode aerosol samples have moderate Cl-depletion (i.e., ∼40-50%), in contrast to nearly complete Cl loss on sunny days, presumably indicating that photochemical reactions would play a key role in the Cl-deficit; however, it merits further investigation as the available samples were limited.

Original languageEnglish
Article numberD19304
JournalJournal of Geophysical Research Atmospheres
Volume112
Issue number19
DOIs
Publication statusPublished - 2007 Oct 16

Fingerprint

air pollution
South China Sea
aerosols
Aerosols
Air pollution
Chlorides
China
chlorides
depletion
atmospheric pollution
chloride
aerosol
Water
sulfates
Salts
water
sulfate
salts
Nitrates
Sulfates

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

Hsu, Shih Chieh ; Liu, Shaw Chen ; Kao, Shuh Ji ; Jeng, Woei Lih ; Huang, Yi Tang ; Tseng, Chun Mao ; Tsai, Fujung ; Tu, Jien Yi ; Yang, Yih. / Water-soluble species in the marine aerosol from the northern South China Sea : High chloride depletion related to air pollution. In: Journal of Geophysical Research Atmospheres. 2007 ; Vol. 112, No. 19.
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abstract = "Dichotomous (PM2.5-10 and PM2.5 modes) and size-resolved marine aerosols collected during the northeastern monsoon on two wintertime cruises in the subtropical South China Sea (SCS) were analyzed for water-soluble ions. During the sampling periods the study region was under the influence of strong pollution originating primarily from the Asian continent. Elevated levels of non-sea-salt sulfate and ammonium ions of up to 4.5 and 1.2 μ/m3, respectively, were observed, indicating that the SCS is now substantially contaminated by massive amounts of air pollutants most likely from China and South/ Southeast Asia. The non-sea-salt sulfate to nitrate mass ratios reaching 3.8 ± 1.9 are much larger than those (approximately 2) in and around East Asia and the western Pacific Ocean, suggesting that the Asian outflow aerosols measured in the SCS experienced different traveling history from those in the vicinity of source regions. High chloride depletion (Cl-depletion) measured in the SCS marine aerosols was, on average, 30{\%} for coarse-mode particles and nearly 90{\%} for fine-mode particles. Cl-depletion is size-dependent, and maximizes in submicrometer particles (i.e., Cl has almost been completely lost). Acid displacement is responsible for the observed high Cl-depletion: nitrate substitution accounts for the coarse-mode depletion, whereas sulfate substitution accounts for the fine-mode depletion. The acid displacement of sea salt aerosols may be related to a variety of factors, especially the substantial air pollution, which is discussed in detail in this paper. On cloudy/rainy days, fine-mode aerosol samples have moderate Cl-depletion (i.e., ∼40-50{\%}), in contrast to nearly complete Cl loss on sunny days, presumably indicating that photochemical reactions would play a key role in the Cl-deficit; however, it merits further investigation as the available samples were limited.",
author = "Hsu, {Shih Chieh} and Liu, {Shaw Chen} and Kao, {Shuh Ji} and Jeng, {Woei Lih} and Huang, {Yi Tang} and Tseng, {Chun Mao} and Fujung Tsai and Tu, {Jien Yi} and Yih Yang",
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Water-soluble species in the marine aerosol from the northern South China Sea : High chloride depletion related to air pollution. / Hsu, Shih Chieh; Liu, Shaw Chen; Kao, Shuh Ji; Jeng, Woei Lih; Huang, Yi Tang; Tseng, Chun Mao; Tsai, Fujung; Tu, Jien Yi; Yang, Yih.

In: Journal of Geophysical Research Atmospheres, Vol. 112, No. 19, D19304, 16.10.2007.

Research output: Contribution to journalArticle

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T1 - Water-soluble species in the marine aerosol from the northern South China Sea

T2 - High chloride depletion related to air pollution

AU - Hsu, Shih Chieh

AU - Liu, Shaw Chen

AU - Kao, Shuh Ji

AU - Jeng, Woei Lih

AU - Huang, Yi Tang

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AU - Tsai, Fujung

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AU - Yang, Yih

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