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Nontargeted Screening Nitrogen-Containing Organic Compounds in Frost and Wet Deposition in Rural Northeast China
Runqi Zhang1, Dongmei Cai1, Lina Wang1
1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, China.
Environmental Science & Technology
|January 8, 2025
Summary
Frost captures significant nitrogen-containing organic compounds (NOCs), impacting nitrogen deposition. Hazy conditions increase NOC deposition, particularly nitrophenols, linked to PM2.5 concentrations.
Area of Science:
- Atmospheric Chemistry and Biogeochemistry
- Environmental Science
- Organic Geochemistry
Background:
- Nitrogen-containing organic compounds (NOCs) in frost are a key pathway for atmospheric nitrogen deposition.
- The molecular composition and deposition fluxes of NOCs in frost remain understudied.
- Understanding these processes is crucial for nitrogen biogeochemical cycles.
Purpose of the Study:
- To characterize the molecular content of NOCs in frost.
- To investigate the wet deposition fluxes of NOCs in frost.
- To assess the influence of atmospheric conditions, like haze, on NOC deposition.
Main Methods:
- Frost samples were collected in rural Northeast China during winter 2023.
- Nontargeted ultrahigh performance liquid chromatography-orbitrap mass spectrometry (UHPLC-Orbitrap MS) was employed for analysis.
- Analysis covered both water-soluble (WSOM) and water-insoluble organic matter (WISOM) in electrospray ionization (ESI) modes.
Main Results:
- Hazy days showed higher numbers of assigned molecular formulas in frost compared to nonhazy days.
- CHON compounds constituted a significant proportion (35.6-51.1%) of NOCs.
- Nitrophenol and methyl nitrophenol were the most abundant NOCs, with higher deposition fluxes during haze, correlating with PM2.5.
Conclusions:
- Frost effectively captures diverse NOCs from the atmosphere.
- Hazy conditions significantly enhance the deposition of specific NOCs, like nitrophenols.
- Atmospheric particulates (PM2.5) play a role in NOC deposition via frost, impacting nitrogen cycling.
