Characterizing the parent and oxygenated polycyclic aromatic hydrocarbons in mangrove sediments of Hong Kong

• Parent and oxygenated PAHs were ubiquitous in mangrove sediments of Hong Kong.
• The contamination of parent and oxygenated PAHs were at the middle-to-high level.
• Parent and carbonylic PAHs were originated from petroleum combustion in sediments.
• The source of hydroxylated PAHs was more complicated.
• TOM was an important factor for regulating the spatial distribution of oxygenated PAHs.

Parent and oxygenated polycyclic aromatic hydrocarbons (PAHs) were investigated in mangrove sediments of Hong Kong. Most of the analytes were detected, and the dominant carbonylic and hydroxylated PAHs in mangrove sediments were 9-fluorenone and 2-hydroxy fluorene, respectively. The concentration of 9-fluorenone and 9,10-anthraquinone was higher than their parent PAHs. Moreover, the concentration of total organic matter (TOM) related with those of the parent PAHs and carbonylic PAHs, except for hydroxylated PAHs, which indicated that TOM was not the only factor regulating the distribution of oxygenated PAHs. Nevertheless, the parent PAHs in mangrove sediments was correlated positively with carbonylic PAHs which demostrated not only the similar source but also the fate of these two compound class. However, hydroxylated PAHs had different source by comparing with parent PAHs and carbonylic PAHs, they were probably originated from biodegradation and accumulated in mangrove sediments.