Distribution and composition of polycyclic aromatic hydrocarbons in the surface microlayer and the subsurface microlayer from the Guangzhou Section of the Pearl River

Polycyclic aromatic hydrocarbons (PAHs) in water from the surface microlayer and the subsurface microlayer of the Guangzhou section of the Pearl River were studied in March 2009. The dissolved concentrations of 16 PAHs ranged from 622.0 to 2132.2 ng·L-1,and there was a positive correlation between the concentrations of PAHs and the DOC. The particulate concentrations of PAHs ranged from 316.7 to 639.5 ng·L-1,which were approximately linearly related to the concentrations of the particulates. Most of the PAHs contained 2 to 3 aromatic rings,and they accounted for 86.0% to 95.7% of the total PAHs in the dissolved phase. This was much higher than those observed in the particulate phase (68.8% to 84.0%). The octanol-water partition coefficients and physicochemical properties of the PAHs contributed to the difference. The PAHs were found to be enriched in the microlayers and enrichment factors (EF) ranged from 1.1 to 1.5 (1.2 to 1.5 for dissolved and 1.1 to 1.3 for particulate).