Size-resolved gas-particle partitioning of polycyclic aromatic hydrocarbons in a large temperature range of 50 ℃.

Size-resolved gas-particle partitioning of semi-volatile organic compounds (SVOCs) can affect their environmental behaviors and health effects, which has not been widely studied in comparing with the gas-total suspended particle partitioning. Herein, the size-resolved gas-particle partitioning quotient (K) of polycyclic aromatic hydrocarbons (PAHs) in a large temperature range (-20.6 ℃ ∼ 29.4 ℃) was firstly comprehensively studied. The log K values of PAHs related to fine particles were significantly higher than those related to coarse particles. When the logarithm of subcooled liquid-vapor pressure (log P) ∈ [-7, -1), the regression slopes of log K vs log P related to the particle size > 1.0 µm were shallower than those with the particle size range of 0.10-1.0 µm, which indicated the influence of particle size on K. Among the three previous prediction equations of gas-particle partitioning quotient, the empirical equation based on the ambient temperature matched better with the measured log K. Therefore, a new prediction equation including ambient temperature and particle size as the two major parameters was established. For most particle size ranges, the new equation showed better prediction performance than the three previous equations. In summary, this study provided new insights for the size-resolved gas-particle partitioning mechanism and quotient.