Methyl halides in surface seawater and marine boundary layer of the northwest Pacific

Atsushi Ooki, Atsushi Tsuda, Sohiko Kameyama, Shigenobu Takeda, Sachihiko Itoh, Toshio Suga, Hirofumi Tazoe, Ayako Okubo, Yoko Yokouchi

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16 Citations (Scopus)

Abstract

The partial pressures of methyl halides (CH3X; X = Cl, Br, or I) and of CHClF2 (HCFC-22), which are all volatile organic compounds (VOCs), were measured in the air of the marine boundary layer (pVOC air) and in surface seawater (pVOCwater) during a cruise from the subarctic to subtropical regions of the northwest Pacific in summer of 2008. In the northern transition water (TWN) with high biological activity, high levels of the three CH3Xs in surface seawater were frequently observed, probably owing to their enhanced production by phytoplankton. Supersaturation of CH3Br was only present in TW N water, with a saturation anomaly (SCH3Br) of 0.95 [SCH3X = (pCH3Xwater - pCH3X air)/pCH3Xair]. The highest saturation anomalies for CH3Cl (SCH3Cl = 1.6) and CH3I (SCH3I = 91) were found in the southern subtropical water (ST S) with low biological production south of the subtropical front. We found that the molar concentrations of CH3Cl (CCH3Cl) and CH3I (CCH3I) sharply increased with increasing sea surface temperature (SST) in the subtropical waters. The maximum CCH3Cl (144 pmol l-1) was present in STS water at SST = 30°C and is 1.5 times the value extrapolated from the previously reported relationship between CCH3Cl and SST. Photochemical production might have contributed to the production of CH3Cl and CH3I in ST S water.

Original languageEnglish
Article numberC10013
JournalJournal of Geophysical Research: Oceans
Volume115
Issue number10
DOIs
Publication statusPublished - 2010

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Oceanography

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