Project No: 16211824

Title: Investigating the formation and impact of atmospheric di-carbonyls in Hong Kong and the Greater Bay Area

Principal Investigator: Prof. Zhe WANG

Co-Investigator: Prof. Tzung-May FU

Abstract:

Atmospheric carbonyls are crucial oxygenated volatile organic compounds (OVOCs) with significant implications for air quality, human health, and the environment. They play vital roles in tropospheric photochemistry and oxidation capacity, particularly affecting radical cycling and formation of ozone (O3) and secondary organic aerosol (SOA). Di-carbonyls, such as glyoxal, methylglyoxal, and diacetyl, are key carbonyl species with two carbonyl groups in the molecule and exhibit higher reactivity. These di-carbonyls are usually formed through complex chemical reactions involving precursors from both anthropogenic and natural sources. While studies have reported varying but generally high concentrations of di-carbonyls in different urban and rural areas, their formation mechanisms, especially the interplay between anthropogenic and biogenic precursors, remain incompletely understood. Air quality models also face challenges in simulating their production to match the ambient measurements. Furthermore, much is uncertain about the phase distribution and aerosol uptake of di-carbonyls, as well as their subsequent impacts on photochemistry and SOA formation. This research proposal aims to investigate the characteristics, sources, formation, chemical processing, and impacts of atmospheric di-carbonyls in the Hong Kong-Macau-Guangdong Greater Bay Area (GBA) in South China. This region, characterized by rapid urbanization and industrialization, is susceptible to high photochemical pollution given its unique geographical and meteorological conditions. The combination of ambient sampling at different locations followed by laboratory analysis and the real-time intensive campaigns at paired supersites will be conducted to characterize the abundance, distribution, and evolution of di-carbonyls in this region. Field in-situ and laboratory experiments will be performed to examine the formation and yield of different di-carbonyls from ambient and various precursors, as well as gas-particle partitioning and photolysis of those di-carbonyls. Observation-based photochemical model simulations will be performed for comprehensive budget analysis to quantify the formation and loss pathways of di-carbonyls, and to evaluate their impacts on the atmospheric radical cycling and formation of O3 and SOA. This proposed study endeavors to advance our understanding of the complex atmospheric chemistry and environmental impacts of di-carbonyl compounds. The results will provide valuable insights to policymakers to develop effective control measures on critical organic precursors to mitigate photochemical O3 and haze pollution in this economically vital but environmentally challenged region.