Distribution of organophosphate esters between the gas phase and PM2.5 in urban Dalian, China
2020
Wang, Yan | Bao, Meijun | Tan, Feng | Qu, Zhenping | Zhang, Yuwei | Chen, Jingwen
We investigated the concentrations and seasonal variations of organophosphate esters (OPEs) in the gas phase and PM₂.₅ (particulate matter with an aerodynamic diameter <2.5 μm) in an urban area of Dalian, China, as well as their gas-particle partitioning. The total concentrations of OPEs in the gas phase were in the range of 0.056–6.38 ng/m³ with the mean concentration of 0.83 ± 1.24 ng/m³, while the concentrations of OPEs in the PM₂.₅ were in the range of 0.32–3.46 ng/m³ with the mean concentration of 1.21 ± 0.67 ng/m³. Tris-(1-chloro-2-propyl) phosphate (TCIPP) was the dominant congener in the gaseous phase, followed by tris-(2-chloroethyl) phosphate (TCEP) and tri-n-butylphosphate (TNBP), whereas TCEP was the dominant species in the PM₂.₅, followed by TCIPP and triphenyl phosphate (TPHP). Seasonality was discovered for OPEs in both gas phase and PM₂.₅ with their concentrations higher in hot seasons, which may due to the temperature-driven emission or gas-particle partitioning. The PM₂.₅-bound fractions of OPEs varied significantly between seasons. Tricresyl phosphate (TMPP), tri(2-ethylhexyl) phosphate (TEHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and TPHP were mostly adsorbed onto fine particles, while TNBP, TCEP, TCIPP, and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) distributed in both gas and fine particle phases. The predicted PM₂.₅-bound fractions by Kₒₐ-based model were closer to the measurements for TCIPP, TDCIPP, and TPHP, whereas the predictions by Junge-Pankow model were closer to the measurements for TMPP and tris (2-butoxyethyl) phosphate (TBOEP). However, the predictions of both models cannot accurately match the measured gas-particle partitioning of TNBP and TCEP.
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