Introduction
Despite significant improvement of ambient air quality in China over the past decade, it still presents to be a major challenge to control ground-level ozone (O3) pollution and to further reduce PM2.5 concentrations. The positive correlations between PM2.5 and O3 in the Greater Bay Area demonstrate the necessity and feasibility of coordinated control of the two air pollutants. However, there is a significant lack of scientific evidence to support the relevant control strategies. This project focuses on the photochemical secondary organic aerosol (SOA), an important constituent of PM2.5, and aims to reveal the complex relationships between photochemical SOA and O3 and their sensitivities to the common precursors and environmental conditions. The project is dedicated to answering three key scientific questions: (1) How to identify the photochemical SOA? (2) Can photochemical SOA and O3 in the ambient air be explained by conventional sources of air pollution and conventional precursors? and (3) What is the dominant mechanism of the complex interactions between photochemical SOA and O3? An integrated research method combining field observation, aging experiments, and in-situ modelling will be adopted. Notably, thermal desorption aerosol gas chromatography mass spectrometry and two-dimensional gas chromatography orbitrap mass spectrometry will substantially improve the temporal and chemical resolution of measuring molecular tracers of photochemical SOA, respectively. The mechanism-extended box model will unravel the photochemical effects of unconventional precursors and the formation processes of typical photochemical SOA. The project breaks through the traditional research paradigm of single air pollutants and aims to establish a theoretical framework for the coordinated control of O3 and photochemical SOA. The research findings will provide reference for complex photochemical air pollution control under the 'dual carbon' targets.
近十年來我國空氣品質顯著改善，然而控制臭氧（O3）污染和持續降低PM2.5濃度仍面臨巨大挑戰。大灣區PM2.5和O3的正相關性突顯了二者協同控制的必要性和可行性，而相關策略的科學支持明顯不足。本計畫重點關注光化學二次有機氣溶膠（SOA）這一PM2.5的重要組成，致力於揭示光化學SOA與O3的複雜關係及二者對共同前驅物及環境條件的敏感度。計畫旨在回答三個關鍵科學問題：1、如何辨識大氣中的光化學SOA？ 2.傳統源/前驅物能否完全解釋大氣中的光化學SOA和O3？3、光化學SOA和O3相互作用的主導機制為何？將採用外場觀測、氧化流動管實驗和機制擴展的盒子模型模擬相結合的研究方法。除廣州的外場觀測外，團隊累積的香港多站點觀測資料也將作為專案的基礎資料。綜上，計畫突破傳統單污染物研究範式，致力於建立O3-光化學SOA協同控制理論架構。研究結果可望為「雙碳」目標下的光化學複合污染的深化治理提供參考。