EFFECTS OF AGING AND FLOODING ON SORPTION OF PAHS IN MANGROVE SEDIMENT

Polycyclic aromatic hydrocarbons (PAHs) pollution in mangroves has drawn much attention, but knowledge of the sorption of PAHs in mangrove sediment is limited. For the first time, this study investigated the sorption of three typical polycyclic aromatic hydrocarbons (PAHs), naphthalene, anthracene and benze[a]pyrene, in mangrove sediment of Jiulong River Estuary and the effects of aging and flooding on the sorption. Our study confirmed that aging can strengthen the sorption of PAHs in the sediment and found that flooding had great influence on PAHs sorption both in aged and unaged sediments. The influence in unaged sediment was more significant than those in 100d aged sediment. Our research also showed that the effects of aging and flooding on PAHs sorption had relationship with the physical and structural properties of the mangrove sediment. It was observed that the main sorbents of mangrove sediment were carbonized particles and clays. The porous structure of carbonized particles made it easy to sequestrate the PAHs, and the aging made the PAHs come into deeper sites of the carbonized particles, thereby causing the PAHs was difficult to be desorbed after aging; clays had good PAHs-fixing capacities and they always combined by organic matters and formed aggregates; we demonstrated that flooding damaged the aggregate stabilities to some extent, thereby causing the PAHs to be released as the flooding was done.