The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

The coastal sea is a special zone where terrestrial and oceanic atmospheric components interact, the spatial and temporal variations in atmospheric components will seriously affect ambient air quality and marine ecosystems. The present study explored sources and interactions of marine atmospheric aerosol between anthropogenic and oceanic emissions based on physico-chemical observations obtained at several coastal stations, islands and shipping cruises of China.
We have established a high-resolution in-situ observation system for water-soluble brown carbon (WS-BrC), statistical analysis indicated ambient temperature and relative humidity as well as total oxidized nitrogen (NO2 + NO3-) and reduced nitrogen (NH4+ + NH3) were the dominant factors promoting secondary WS-BrC. Moderate aerosol pH (>2.5) also facilitated the formation of secondary WS-BrC while no obvious dependences of secondary WS-BrC on gas-particle partitioning of ammonia, O3, and sulfur precursors were found. Further, with non-target analysis by mass spectrometry, the DBE, O/C, H/C and OSc parameters of molecular composition from different pollution processes were compared, and the key components contributing to the absorbance of organic aerosols were identified.
Amines, sugars, sugar alcohols, organic acids and other components in marine organic aerosols were discussed. Methylamine, dimethylamine, ethylamine and diethylamine were found to show higher enrichment with less anthropogenic influence and showed significant correlation with methanesulphonic acid (MSA), suggesting that secondary production associated with marine biogenic sources should be an important source of organic amines and that acid-base neutralization in liquid phase was a key process for secondary formation. Trimethylamine showed correlation with Na+ in TSP, suggesting that it was mainly emitted from the bursting of seawater bubbles in the surface layer of the ocean and then enriched in aerosol particles. It is worth emphasizing that the organic nitrogen reservoirs in seawater are an important source of atmospheric organic amines over the Bohai Sea, while the contribution of marine phytoplankton is relatively weak.
Molecular characteristics of organic aerosol in the East China Sea and the Bohai Sea were characterized, and it was found that marine emissions are stable contributed to marine organic aerosol. Strong heterogeneous processes occurring on dust surface during the dust transport processes resulted in the rapid decomposition of long-chain organic acids, while higher water vapor during sea-fog condition promoted the rapid liquid-phase formation of organic acids and organosulfates.

Marine aerosol, atmospheric chemistry, sources