Gas/particle partitioning of PAHs based on equilibrium-state model and steady-state model

The gas/particle (G/P) partitioning (K_P) behavior is an important factor for the environmental fate of PAHs in atmosphere. Based on large database of log K_P, equilibrium-state and steady-state models were applied for the comprehensive study with the G/P partitioning of PAHs, including the Harner-Bidleman (H-B) model, the Dachs-Eisenreich (D-E) model, and the Li-Ma-Yang (L-M-Y) model. For different sites, the trend of regression between log K_P and log K_OA was same, however, the slopes and intercepts were different. No obvious difference was observed between northern Chinese cities and southern Chinese cities. For congeners and aromatic rings of PAHs, the difference was much more obvious for the regressions, slopes and intercepts. The prediction of the D-E model and the H-B model matched well for the regression of the 4-rings and 5-rings PAHs, with >80% of monitoring data points in the range of ±1 log unit. The L-M-Y model only predicted well with the measurement for 4-rings PAHs with special values of log K_OA. For different ranges of log K_OA, the difference with the regression between log K_P and log K_OA was also obvious. Compared with our measurement, if 1 order of magnitude difference with log K_P values between prediction and measurement was considered, the H-B model, the D-E model and the L-M-Y model can be only used when the log K_OA in the ranges from 7.65 to 13.7, 6.88 to 13.5, and 7.65 to 11.7, respectively. Therefore, further studies with prediction models should be conducted for the G/P partitioning of PAHs. The results of this study provided new insights into the research field of the G/P partitioning of SVOCs.