PAH Profiles of Emitted Ashes from Indoor Biomass Burning across the Beijing-Tianjin-Hebei Region and Implications on Source Identification

Sixty-four bottom ash (BA) samples from indoor burning of eight bio-fuels (BFs) including cotton (COT), corn (COR), millet (MIL), soybean (SOY), sorghum (SOR) and sesame (SES), firewood walnut (WAL), and corn cob (COC) were collected across the Beijing-Tianjin-Hebei (BTH) region. Each BA was divided into five differently sized parts for the analysis of eighteen PAHs using the GC/MS system. The Σ18PAHs values for all the BAs varied from 65.0 ± 10.6 to 1310 ± 129 ng g–1. SOR had the highest PAH level, and COC produced the lowest level. The Σ18PAHs for SOY, WAL, COT, COR, COC, and SES were negatively correlated with the BA sizes. The NA, PHE, ACL, AN, FA, PY, FL, and AC dominated in all the BAs except for SES. All the BAs were dominated by 2, 3-ring PAHs. The PAH profiles for differently sized BAs within MIL, SOR, COC, COR, and SES were similar based on lower coefficient of divergence values, while the other three BFs did not exhibit this trend. All the BF pairs except for SOR vs. SES and COC vs. COR had the different PAH profiles. No series of coincident diagnostic ratios (DRs) could represent all BFs based on their significantly varied DRs. AN/(AN + PHE) and BA/BgP might be used in identification of combustion sources of different types of BFs. SOR and SES had higher potential toxicity risk based on higher TEQ, BaPE, and CPAHs values. BgF and BgP were the indicatory PAHs for SOY, MIL, COR, SOR, and COC, while they were AC and FL for the remaining three BFs.