Occurrence, hydrolysis and photodegradation of phthalate esters in urban atmospheric aqueous aerosol in Wuhan City

A gas chromatography-flame ionization detection method was developed to investigate the occurrence and transformations of phthalate esters (PAEs) in atmospheric aqueous aerosol in Wuhan City. Six of PAEs were detected in collected aerosol samples and their concentrations in atmosphere were followed the order of diallyl phthalate (0.244 μg m⁻³) > diethyl phthalate (0.235 μg m⁻³) > di(2-ethylhexyl) phthalate (0.176 μg m⁻³) > dimethyl phthalate (0.110 μg m⁻³) > di-n-octyl phthalate (0.081 μg m⁻³) > dipropyl phthalate (0.024 μg m⁻³). The Redundancy analysis results indicated that, compared to humidity and wind speed, temperature had the most important influence on the occurrence of PAEs in aqueous aerosol. The hydrolysis of selected PAEs in aqueous extracts of aerosol samples was examined under different conditions, determining that hydrolysis of PAEs is most susceptible to the ambient temperature at typical atmospheric aqueous pH of 3–5. In addition, photodegradation results suggested that indirect photodegradation played a key role in photodecomposition of PAEs under sunlight irradiation. The photo-generated reactive species including triplet water-soluble organic matter (³WSOM∗) and reactive oxygen species (ROS) mainly contribute to the degradation of PAEs in atmospheric aqueous aerosol. This study provides an important reference for better understanding the occurrence and transformations of PAEs in ambient urban atmospheric aqueous aerosol.