Research

Research Interests

  • Atmospheric chemistry and air quality
  • Atmospheric heterogeneous/multiphase chemistry
  • Cloud-aerosol-gas interactions
  • Oxidation of VOCs and SOA formation

Research Highlights

Photochemistry of VOCs and O3 and SOA formation

The photochemical reaction of various VOCs is a significant source of O3 and SOA formation. Our research uses state-of-the-art techniques in field observations and lab experiments to probe what oxidation products are produced with different radicals and multigenerational oxidation, which precursors and oxidation products contribute to O3 and SOA formation, and how. We aim to depict a full picture of different VOCs’ evolution and oxidation and characterize the oxidation/intermediate products on the molecular level, allowing more accurate source apportionment of O3 and SOA produced by important VOCs.

Low-volatility organic vapours are critical intermediates connecting the oxidation of VOCs to SOA formation. Coordinated measurements of oxygenated organic molecules (OOMs) were performed in 4 megacities in China and demonstrated that the oxidation of anthropogenic VOCs (aromatics and aliphatic) dominates OOMs formation, and the distributions and formation pathways are largely the same across the urbanized regions. The irreversible condensation of these anthropogenic OOMs increases significantly in highly polluted conditions, accounting for a major fraction of the SOA formation.

Chang D et al., Sci. Total Environ., 2019
He Z et al., Atmos. Chem. Phys., 2019
Ling Z et al., J. Env. Sci., 2019; Atmos. Chem. Phys., 2020
Chen Y., et al., Environ. Sci. Technol., 2021
Liu Q., et al., Atmos. Res., 2022
Chen Y., et al., Sci. Total Environ., 2022
Guo J, et al., Environ. Sci. Technol., 2022
Nie, Yan, Huang, Wang et al., Nature Geoscience, 2022
Zheng P, et al., Environ. Sci. Technol., 2023
Xu Y, et al., Sci. Total Environ., 2023
Hui L., et al., Environ. Pollution., 2023
Feng X., et al., Atmos. Environ., 2023
Xu Y. et al., Trends Anal. Chem., 2023

Heterogenous N2O5/ClNO2 chemistry and impacts

Our group took the lead in field studies of heterogeneous N2O5/ClNO2 chemistry on real ambient aerosols in different regions of China. An in-situ methodology has been developed to directly measure the heterogeneous reactivity of nitrogen oxides on ambient aerosols. We developed an improved parameterization of γN2O5, which significantly improves the model prediction of NOx and secondary nitrate in the polluted regions of China. Using the observation-based chemical model, we evaluated the impacts of heterogeneous chemistry of reactive nitrogen on radical chemistry, ozone, and secondary aerosol formation, providing scientific support to mitigate regional air pollution in China.

Tham Y et al., Atmos. Chem. Phys., 2016; 2018
Wang Z et al., Atmos. Chem. Phys., 2017
Wang W et al., Atmos. Meas. Tech., 2018
Yu C et al., Atmos. Chem. Phys., 2020
Yu C et al., J. Env. Sci., 2021
Niu Y et al., J. Geophys. Res.., 2022
Li F et al., Atmos. Environ., 2023

Gas-particles-cloud interactions and multiphase process

Simultaneous measurements and chemical characterization of gas, aerosol, and cloud water have been conducted in mountain sites in different regions. The gas-aerosol-cloud interactions were investigated by combining field measurement and multiphase chemistry modeling. Semi-volatile organics formation in the in-cloud aqueous process was observed and quantified. The multiphase partitioning of carbonyls and the impacts on SOA formation were evaluated in the PRD region. The heterogeneous HO2 process on aqueous aerosol and cloud droplets and the key influencing factors were investigated and evaluated. The findings have demonstrated the importance of aqueous/heterogeneous chemical processes in secondary organic aerosol formation and atmospheric chemistry.

Wang Z et al., Atmos. Environ., 2012
Guo J et al., Atmos. Environ., 2012
Zhao W et al., Sci. Total Environ., 2019
Guo J et al., Sci. Total Environ., 2020
Li T et al., Atmos. Chem. Phys., 2020

Selected Research Projects

  1. Source, formation, and gas-particle partitioning of nitro-phenolic compounds and their environmental impacts in subtropical Hong Kong, RGC GRF (2024.1-2026.12; PI).
  2. Highly oxygenated products from aromatic VOCs oxidation in the urban environment and their impacts on air quality, RGC GRF (2023.1-2025.12; PI).
  3. Atmospheric Heterogeneous Chemistry and Secondary Pollution, NSFC Excellent Young Scientist (EYS) Fund, (2022.1 – 2024.12; PI).
  4. Investigation of local and transboundary contributions to ozone formation and pollution episodes in Hong Kong, Environment and Conservation Fund (2021.7 – 2023.12; PI).
  5. Characterization and immuno-toxicity of nanoparticles in urban aerosols in Hong Kong and France, PROCORE-FRANCE/HK-RGC Joint Research Scheme (2021.2 – 2023.1; PI).
  6. Photochemical air pollution in highly urbanized subtropical regions: from micro-environments to urban-terrestrial-oceanic interactions, Theme-based Research Scheme (2018.1-2023.12; Co-PI).
  7. The reaction mechanism of atmospheric reactive halogen species and their effects on atmospheric oxidation and secondary pollution, China NSFC Key Research Plan (2018.1-2021.12; Co-PI).
  8. Seaborne Air Monitoring Campaign within Hong Kong Waters, HKEPD (2020.11- 2022.5; PI).
  9. Determination of Volatile Organic Compounds and Oxygenated Volatile Organic Compounds in Air Samples Collected in Hong Kong and Macau, HKEPD (2020.12- 2022.6; PI).
  10. Determining the Oxygenated Volatile Organic Compound Levels in Ambient Air Samples in Hong Kong, HKEPD (2020.7- 2021.12; PI).
  11. Heterogeneous uptake of glyoxal and methylglyoxal by ambient wet aerosols and cloud droplets in a polluted subtropical environment: direct field measurement in Hong Kong, RGC GRF (2017.1-2019.12; PI).
  12. Multi-dimensional integrated measurement of air pollution along the east coast of China (MiMap) Stereoscopic Observation Technology for Air Quality Research on Mountains and Aircraft, China National Key D&R Program (2016.9-2019.8; Co-PI).
  13. Chemical characteristics of cloud/fog droplets and its roles in secondary organic aerosol formation in subtropical Hong Kong: A field and modeling study at a high-elevation site, RGC ECS (2016.1-2018.12; PI).
  14. The roles of atmospheric aqueous reactions in secondary organic aerosol formation: a field and modeling study in Pearl River Delta region, China NSFC (2016.1-2018.12; PI).
  15. Impact of Air-Sea Exchanges on Air Quality in Coastal Megacities, ANR-RGC Joint Research Scheme (2017.3-2021.2; Co-I).
  16. Heterogeneous chemistry of reactive nitrogen oxides and its impacts on atmospheric oxidative capacity and regional air pollution over North China, China NSFC Key Research Plan (2016.1-2018.12; Co-PI).
  17. Heterogeneous chemistry of atmospheric reactive nitrogen oxides: an integrative program for cutting-edge science, RGC CRF (2015.6-2018.5; Co-PI).