Particle bound phthalate acid esters (PAEs) and total estimated ambient air PAEs concentrations study at a mixed (commercial, urban, and traffic) site in central Taiwan

Abstract

Since there have not been any atmospheric phthalate acid ester (PAE) concentration-related studies in central Taiwan during the past few years, our first atmospheric PAE study was focused on the measurement of ambient air particle-bound PAE concentrations in central Taiwan (Fang et al., 2019). However, atmospheric PAEs in the gas phase have not yet been detected. Therefore, this study was aimed toward estimating atmospheric PAE concentrations in the gas phase from known PAE concentrations in the particle-phase. Then, the total PAE concentration in the atmosphere (estimated gas-phase concentrations and measured particle-phase concentrations) could be obtained. In this study, atmospheric PAE concentrations in the gas phase are estimated from known PAE concentrations in the particle phase, and ambient air total PAE (gas phase + particle-phase) concentrations at a mixed sampling site are estimated. Mean gas-phase and particle-phase PAE concentrations are estimated and calculated as percentages of the total estimated PAE concentrations at a mixed sampling site. The particle-bound PAE concentrations were measured using a PS-1 sampler from July to December of 2018; they were also analyzed using pyrolysis-gas chromatography/mass spectrometry. The solvent extraction method was used to determine the concentrations of the PAE species. In this study, total ambient air PAE concentrations using the known PAE concentrations in the particle phase were successfully estimated. The results indicated that the average measured P-DBP, P-DEHP, and P-DnOP concentrations were 33.94, 109.70, and 12.88 ng/m3, respectively. In addition, the average estimated gas-phase DBP, DEHP, and DnOP concentrations were 776.43, 26.11, and 2.95 ng/m3, respectively. Therefore, the average total estimated concentrations for total estimated DBP, DEHP, and DnOP concentrations were found to be 810.37, 135.81, and 15.83 ng/m3, respectively, at a mixed sampling site from July to December of 2018. In addition, the DEHP concentration was the highest when measured in the particle phase, and the DBP concentration was the highest when estimated in the gas phase; the average DEHP and DBP concentrations were highest in the autumn. DnOP had the lowest measured and estimated concentrations in the gas phase in all seasons. DnOP also had the lowest average concentration in the summer. Finally, the average particulate PAE species (DBP, DEHP, and DnOP) concentrations were highest in Taichung, Taiwan (mixed site) in the period from 2000 to 2018.