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Large Increases in Primary Trimethylaminium and Secondary Dimethylaminium in Atmospheric Particles Associated With Cyclonic Eddies in the Northwest Pacific Ocean
Author(s) -
Hu Qingjing,
Qu Keming,
Gao Huiwang,
Cui Zhengguo,
Gao Yang,
Yao Xiaohong
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd028836
Subject(s) - atmosphere (unit) , eddy , particle size , aerosol , environmental science , particle (ecology) , atmospheric sciences , oceanography , analytical chemistry (journal) , chemistry , environmental chemistry , meteorology , physics , geology , turbulence
Dimethylaminium (DMA + ) and trimethylaminium (TMA + ) ions in size‐segregated atmospheric particles are measured across the marginal seas of China and the northwest Pacific Ocean (NWPO) in March–May 2014. The concentrations of DMA + and TMA + in particles with diameters of 0.056–10 μm (PM 0.056–10 ) collected from the eutrophic seas are 0.22 ± 0.38 nmol/m 3 and 0.11 ± 0.23 nmol/m 3 , respectively. Surprisingly, an average TMA + concentration that is 1 order of magnitude higher and a slightly higher average DMA + concentration are observed across the oligotrophic NWPO. However, the concentrations of chlorophyll‐ a in the NWPO are approximately 5 times lower than those in the marginal seas. The maximum concentrations of TMA + (4.39 nmol/m 3 ) and DMA + (0.92 nmol/m 3 ) in PM 0.056–10 are observed close to the largest cyclonic eddy in the NWPO under an average wind speed of 14 m/s. The concentrations of TMA + increase with decreasing particle size in the sample, whereas those of DMA + exhibit a condensation mode at 0.2 μm and a droplet mode at 1–2 μm. The bimodal size distribution of DMA + is conventionally interpreted in terms of secondary reactions in the atmosphere. The unique size distribution of TMA + suggests that it very likely originates from sea‐spray aerosols. Based on their size distributions in other samples collected over the NWPO, these conclusions may generally apply for TMA + and DMA + . Moreover, we propose a novel conceptual model to explain how the largely increased primary TMA + and secondary DMA + are linked to emissions of sea‐spray aerosols and gaseous precursors from various cyclonic eddies.