Marginal Seas as Receptors and Reactors of Marine Aerosols: A Case Study of the Yellow Sea

ANDREW LOH, Donghwi Kim, Joon Geon An, Narin Choi, Un Hyuk Yim, Korea Institute of Ocean Science and Technology

     Abstract Number: 640
     Working Group: Aerosol Chemistry

Abstract
The Yellow Sea is a marginal sea in the Western Pacific Ocean located between mainland China and the Korean Peninsula. With an escalating anthropogenic emission from both land and sea, deterioration of air quality over the Yellow Sea have been continuously reported in the past decade. Air quality over the Yellow Sea is strongly influenced by emissions from China. An air monitoring campaign was performed from February 28 to March 8, 2022, to investigate the chemical characteristics of sub-micron aerosols over the Yellow Sea. The concentrations of all aerosol mass spectrometry identified species and black carbon were highest when winds originated from China, with nitrate (NO₃^-: 38.1 ± 0.37%) dominating over sulfate (SO₄^2-: 9.77 ± 0.65%) by over four times. Elevated dinitrogen pentoxide (N₂O₅) and nitric acid (HNO₃) concentrations along with other indicators, including the ammonium-rich conditions, suggested that nighttime heterogenous hydrolysis was a potential source of particulate NO₃^- over the Yellow Sea. A positive matrix factorization (PMF) model identified one natural marine (methanesulfonic acid) and three organic aerosol sources (hydrocarbon-like organic aerosol, low-volatile oxygenated organic aerosol, and biomass burning organic aerosol). The scanning mobility particle sizer showed high particle number size distributions of ultrafine particles (Dp_{10 – 35 nm}) with winds from Mongolia and Russia, suggesting potential new particle formation events. A strong correlation between the PMF-BBOA source and sum of Dp_{>100 nm} was observed (r² = 0.94), indicating long-range transfers of BBOA over the Yellow Sea. This study is the first to investigate, comprehensively, air masses from China over the Yellow Sea, and provides field evidence of the recent changes in emission trends from SO₄^2- to NO₃^-, due to stringent emission regulations.