Preprints
https://doi.org/10.5194/acp-2021-258
https://doi.org/10.5194/acp-2021-258

  12 May 2021

12 May 2021

Review status: this preprint is currently under review for the journal ACP.

Mapping gaseous amines, ammonia, and their particulate counterparts in marine atmospheres of China’s marginal seas: Part 1 – Differentiating marine emission from continental transport

Dihui Chen1, Yanjie Shen1, Juntao Wang1, Yang Gao1,2, Huiwang Gao1,2, and Xiaohong Yao1,2 Dihui Chen et al.
  • 1Key Laboratory of Marine Environment and Ecology, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ministry of Education, Ocean University of China, Qingdao 266100, China
  • 2Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China

Abstract. To study sea-derived gaseous amines, ammonia, and primary particulate aminium ions in the marine atmospheres of China's marginal seas, an onboard URG-9000D Ambient Ion Monitor-Ion chromatography (AIM-IC, Thermo Fisher) was set up on the front deck of the R/V Dongfanghong 3 to semi-continuously measure the spatiotemporal variations in the concentrations of atmospheric trimethylamine (TMAgas), dimethylamine (DMAgas), and ammonia (NH3gas) along with their particulate matter (PM2.5) counterparts. In this study, we differentiated marine emissions of the gas species originating from continental transport using data obtained from December 9 to 22, 2019 during the cruise over the Yellow and Bohai Seas, facilitated by additional measurements collected at a coastal site near the Yellow Sea during summer 2019. The data obtained during the cruise and the coastal site demonstrated that the observed TMAgas and protonated trimethylamine (TMAH+) in PM2.5 over the Yellow and Bohai Seas overwhelmingly originated from marine sources. During the cruise, there was no significant correlation (P > 0.05) between the simultaneously measured TMAH+ and TMAgas concentrations. Additionally, the concentrations of TMAH+ in the marine atmosphere varied around 0.28 ± 0.18 μg m−3 (average  ±  standard deviation), with several episodic hourly average values exceeding 1 μg m−3, which were approximately one order of magnitude larger than those of TMAgas (approximately 0.031 ± 0.009 μg m−3). Moreover, there was a significant negative correlation (P < 0.01) between the concentrations of TMAH+ and NH4+ in PM2.5 during the cruise. Therefore, the observed TMAH+ in PM2.5 was overwhelmingly derived from primary sea-spray aerosols. Using the TMAgas and TMAH+ in PM2.5 as tracers for sea-derived basic gases and sea-spray particulate aminium ions, the values of non-sea-derived DMAgas and NH3gas, as well as non-sea-spray particulate DMAH+ in PM2.5, were estimated, and the estimated average values of each species contributed to 16 %, 34 %, and 65 % of the observed average concentrations, respectively. Uncertainties remained in the estimations as TMAH+ may decompose into smaller molecules in seawater to varying extents. The non-sea-derived gases and non-sea-spray particulate DMAH+ likely originated from long-range transport from the upwind continents, according to the recorded offshore winds and increased concentrations of SO42− and NH4+ in PM2.5. The lack of a detectable increase in the particulate DMAH+, NH4+, and SO42− concentrations in several SO2 plumes did not support the secondary formation of particulate DMAH+ in the marine atmosphere.

Dihui Chen et al.

Status: open (until 07 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-258', Anonymous Referee #3, 31 May 2021 reply
  • RC2: 'Comment on acp-2021-258', Anonymous Referee #2, 08 Jun 2021 reply
  • RC3: 'Comment on acp-2021-258', Anonymous Referee #1, 16 Jun 2021 reply

Dihui Chen et al.

Dihui Chen et al.

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Short summary
The study provides solid evidences to demonstrate that atmospheric trimethylamine (TMAgas) and particulate trimethylaminium in PM2.5 (TMAH+) observed in marine atmospheres were uniquely derived from sea-water emissions. As sea-derived TMAgas correlated significantly with DMAgas and NH3gas, sea-derived DMAgas and NH3gas can be estimated and quantify the contribution to the observed species in the marine atmosphere. Similarly, the contributions of primary DMAH+ have also been estimated.
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