Source Apportionment Coupled with Gas/Particle Partitioning Theory and Risk Assessment of Polycyclic Aromatic Hydrocarbons Associated with Size-Segregated Airborne Particulate Matter

Abstract

Polycyclic aromatic hydrocarbons (PAHs) were measured in airborne particulate matter (PM) collected by an eight-stage (S0, S1, …, S7, and SF) particle sizing sampler in three sampling periods, 85 h (85-h) each period. The measured particle-phase PAHs (P-only) data set and the sum of predicted gas-phase and measured particle phase PAHs (predicted G + P) data set considering the effect of gas/particle partitioning were used in positive matrix factorization (PMF) for source apportionment. Benzo[a]pyrene equivalent concentration (BaPeq) and incremental life cancer risk (ILCR) model were utilized for risk assessment of PAHs. The average concentrations of 85-h PM10 and PM2.1 were 292.729 and 142.642 μg/m3, respectively. The average concentration of 15 PAHs was 480.777 ng/m3 in PM10 and 254.464 ng/m3 in PM2.1. PAHs showed unimodal distribution among the nine sampling stages and S5 collected the most concentrations of PAHs and PM. PAHs with over four aromatic rings tended to accumulate in fine PM especially in S5 and S6 while PAHs with less than four rings preferred to stay in coarse PM especially in S0. A four source profiles for P-only were identified by PMF as follows with their source contributions: biomass burning (BB) (9.580 %), coal combustion (CC) (10.600 %), “air-surface exchange” (20.160 %), and vehicle emission (VE) (59.660 %). However, three source profiles for predicted G + P only identified including BB (93.330 %), CC (0.0600 %), and VE (6.610 %). The average 85-h average total BaPeq of 15 PAHs was 5.226 g/m3. S4, S5, and S6 had BaPeq concentrations greater than domestic standard concentration and ILCR value higher than 10−6.