Characterizing sources and health risks of airborne Carbonyl compounds in a subtropical coastal atmosphere in South China

Carbonyl compounds are critical air pollutants with adverse impacts on regional air quality and human health. This study presents a pioneering analysis of spatiotemporal distribution, source appointment, and health risk assessments of carbonyl compounds in the coastal marine atmosphere. By combining ship-borne and groundbased sampling followed with enhanced chemical analysis, 39 carbonyls were identified and quantified in the coastal Hong Kong. Carbonyl concentrations were generally higher in late summer/autumn with lower levels in winter, correlating with their secondary formation rates from precursors. Most species exhibited higher concentrations in open waters than in the fairway and sea channels, due to prominent photochemical formation from regional outflows in the Pearl River Estuary. In contrast, alpha, beta-unsaturated aliphatic aldehydes and acetone were elevated in harbor areas, highlighting the influence of ship emissions on these compounds. Source analysis further indicated a notable contribution from ocean emissions to long-chain aldehydes (C >= 6), acetone and dialdehydes. Health risk assessment demonstrated that carbonyl compounds pose substantial carcinogenic and non-carcinogenic risks to maritime workers and other exposed populations, even exceeding risks faced by road workers. These findings underscore the necessity of considering carbonyl compounds in occupational exposure risk assessments. Overall, this study provides a comprehensive overview of carbonyl compounds in the coastal marine atmosphere, shedding light on the interactions among ship emissions, ocean activities and coastal urban emissions on airborne carbonyls and emphasizing the associated health implications.