Large Increases in Primary Trimethylaminium and Secondary Dimethylaminium in Atmospheric Particles Associated With Cyclonic Eddies in the Northwest Pacific Ocean. Issue 21 (6th November 2018)

• Record Type: Journal Article
• Authors: Hu, Qingjing; Qu, Keming; Gao, Huiwang; Cui, Zhengguo; Gao, Yang; Yao, Xiaohong
• Is Part Of: Journal of geophysical research. Volume 123:Issue 21(2018)
• Page Start: 12, 133
• Page End: 12, 146
• Publication Date: 2018-11-06
• Subjects: aminium salts -- sea‐spray aerosols -- chlorophyll‐a -- salinity -- cyclonic eddies; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2018JD028836
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: 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 (PM0.056–10 ) 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 PM0.056–10 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. Key Points: Unexpected increases in aminium ions in atmospheric particles are observed over the oligotrophic open ocean The maximum concentrations of particulate aminium ions are observed close to the largest observed cyclonic eddy at high wind speeds We construct a novel conceptual model to interpret the unexpected increases in particulate aminium ions related to cyclonic eddies