The Xiamen Symposium on Marine Environmental Sciences

2027 Xiamen Symposium on Marine Environmental Sciences

January 12-15, 2027

Spatiotemporal Variation on Dry Deposition Fluxes of pNH₄⁺-N and pNO₃⁻-N in PM2.5 at Islands in East Asia
ID:471 Poster Presentation

2027-01-15 18:00 (China Standard Time)

Session:Session 69 - The nitrogen cycle in a changing ocean: from the process level to basin scale

Abstract
This study investigated the dry deposition fluxes of particulate inorganic nitrogen in PM2.5 at four islands in East Asia, including Penghu, Dongsha, Okinawa, and Green Islands. Consecutive seven-day 24-h PM2.5 per season were initially sampled in four seasons. The nitrate (NO3-) and ammonium (NH4+) in PM2.5 were further analyzed to estimate pNH₄⁺-N and pNO₃⁻-N in PM2.5. The dry deposition fluxes of particulate nitrogen at the islands in East Asia ranged from 0.140-0.674 mg N m⁻² day⁻¹. Seasonally, the highest deposition fluxes of particulate nitrogen were observed in winter, and followed by fall and spring, while the lowest fluxes were found in summer. In winter, strong northeastern monsoons and high atmospheric stability both elevated PM2.5 concentrations, secondary inorganic species, and particulate nitrogen deposition fluxes. In summer, clean marine air, better air dispersion, and rain washout reduced particulate nitrogen deposition fluxes to the lowest level. Spatially, Penghu Island had higher dry deposition fluxes of particulate nitrogen than those at other three islands. The highest seasonal particulate nitrogen flux of 0.674 mg N m⁻² day⁻¹ was observed at Penghu Island in winter, showing that the western channel was strongly influenced by long-range transport (LRT) via channel effect in the Taiwan Strait. Dongsha Island showed the second highest fluxes of 0.444 mg N m⁻² day⁻¹ in fall and 0.500 mg N m⁻² day⁻¹ in winter, respectively. It suggested that Dongsha Islands were affected by Asian continental outflow, regional transport over the South China Sea, and ship emissions. The winter nitrogen deposition flux at Green Island increased up to 0.507 mg N m⁻² day⁻¹, showing that the eastern channel was affected by LRT during the strong northeastern monsoon periods, even though it was influenced by clean marine air. In contrast, Okinawa Island had lower fluxes with particulate nitrogen deposition fluxes of 0.172-0.338 mg N m⁻² day⁻¹, suggesting lower input from anthropogenic sources. In terms of nitrogen species, dry deposition flux of pNO₃⁻-N was higher than pNH₄⁺-N at most islands and in most seasons. Overall, the dry deposition of particulate inorganic nitrogen at four islands showed similar spatiotemporal variation trend. The western channel, especially Penghu Island, is a high-flux area of particulate nitrogen dry deposition. It showed that the Taiwan Strait is an important pathway for LRT during the northeastern monsoon seasons. The results provided valuable scientifical information for understanding particulate nitrogen input, biogeochemical cycles, and nutrient loading to marine ecosystems in East Asia, showing the strong influences of LRT on atmospheric deposition of particulate nitrogen over islands and nearby seas.
 
Speaker
Chung-Shin Yuan Institute of Environmental Engineering; National Sun Yat-sen University

Author
Chung-Shin Yuan Institute of Environmental Engineering; National Sun Yat-sen University

    Important Dates

    • Jan 30

      2026

      Session / Event proposals open

    • Mar 31

      2026

      Session / Event proposals close
      (Extended to April 7)

    • Apr 30

      2026

      Session acceptance notifications

    • Apr 30

      2026

      Abstract submissions & registration open

    • Jun 30

      2026

      Abstract submissions close
      (Extended to July 21)

    • Aug 31

      2026

      Abstract acceptance notifications

    • Sep 15

      2026

      Scientific program released

    • Oct 15

      2026

      Early bird registration closes

    • Jan 12–15

      2027

      XMAS 2027