Project No: 16302626

Title: Sources and formation mechanisms of organic aerosol in coastal environments: the roles of multiphase chemistry and marine-continental interactions

Principal Investigator: Dr. Yan ZHENG

Co-Investigator: Prof. Qi CHEN, Prof. Zhe WANG

Abstract:

Organic aerosols (OA) exert significant impacts on air quality, radiative forcing, and human health. However, their sources, formation pathways, and chemical evolution remain poorly constrained, particularly in coastal environments where marine and continental emissions strongly interact. These regions are characterized by complex and rapidly changing air masses, high humidity, and variable chemical regimes, all of which complicate current understanding and modeling of secondary organic aerosol (SOA) formation. In particular, the roles of multiphase chemistry and marine-continental interactions in controlling SOA composition and variability remain among the least understood aspects of atmospheric chemistry. This project aims to unravel the sources and formation mechanisms of OA in Hong Kong, a subtropical coastal environment located at the dynamic interface between the South China Sea and the Pearl River Delta. With its persistently high humidity, frequent air-mass shifts, and abundant anthropogenic, biogenic, and marine precursors, Hong Kong provides an ideal natural laboratory to investigate how multiphase processes and air-mass interactions shape SOA formation and transformation. The study adopts a fully integrated approach combining year-round field observations, in-situ oxidation experiments with ambient air, laboratory simulations, and regional chemical transport modeling. A suite of advanced mass spectrometers, including several chemical ionization mass spectrometers and a high-resolution aerosol mass spectrometer, will be deployed to achieve near full-volatility coverage of organic compounds. These instruments will enable the molecular-level characterization of key precursors, intermediates, and oxidation products, offering direct insights into SOA chemistry. Field observations will capture the temporal and seasonal variability of OA sources under varying marine and continental influences, while laboratory experiments will simulate representative multiphase processes under controlled humidity, oxidant, and temperature conditions to validate field-based interpretations and identify dominant chemical pathways. By integrating observational and experimental findings with chemical transport model simulations, this project will establish a mechanistic and quantitative framework for predicting coastal OA behavior under current and future climatic conditions. The results will elucidate the contribution of multiphase chemistry and marine-continental interactions to OA variability, reduce uncertainties in the parameterization of SOA processes in regional and global models, and provide scientific evidence to support air-quality management and climate-mitigation strategies. The outcomes will also advance our broader understanding of how coastal environments respond to simultaneous changes in anthropogenic emissions and climate, offering implications for air-pollution control across East and Southeast Asia.