Spatiotemporal Variation, Source Analysis, and Health Risk Assessment of Particle-bound PAHs in Urumqi, China

Received: May 7, 2018
Revised: July 22, 2018
Accepted: July 24, 2018
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2018.04.0151  

Cite this article:
Simayi, M., Yahefu, P. and Han, M. (2018). Spatiotemporal Variation, Source Analysis, and Health Risk Assessment of Particle-bound PAHs in Urumqi, China. Aerosol Air Qual. Res. 18: 2728-2740. https://doi.org/10.4209/aaqr.2018.04.0151

HIGHLIGHTS

• Size-segregated aerosols were collected and analyzed for 16 PAHs‎.
• PAHs in PM showed notable seasonal variation with higher levels in the heating period.
• Particle bound PAHs pollution was more serious in the north of the Urumqi.
• PAHs mainly originated from vehicle exhaust and natural gas/coal combustion.
• BaP and DbA dominated the ƩBaP_eq levels, varying with the seasons and space.

ABSTRACT

The purpose of the present study was to evaluate the polycyclic aromatic hydrocarbons (PAHs) in fine (PM_2.5) and coarse (PM₁₀) particles in five functional areas, namely, the traffic, industrial, residential, commercial, and educational areas, in Urumqi, a megacity in northwest China. Airborne PM₁₀ and PM_2.5 samples were collected from the five areas during heating (November 2015–March 2016) and non-heating (July–September 2016) periods, and 16 priority PAHs (Ʃ₁₆‎PAHs) in the samples were quantified and analyzed. Over the study period, the average Ʃ₁₆PAHs in the PM₁₀ and PM_2.5 were 116.97 ± 41.44 ng m^–3 and 88.57 ± 31.22 ng m^–3, respectively. During the heating period, Ʃ₁₆PAHs in both of the fractions were more than 2.5 times those during the non-heating period, with the highest values found in the industrial area during the heating period and in the traffic area during the non-heating period. The northern part of the city had more PAH pollution than the southern part. The compositions of the particle-bound PAHs varied temporally and spatially, with 4-ring PAHs contributing more during the heating period than during the non-heating period and with 5- and 6-ring PAHs exhibiting the opposite trend. In addition, 4-ring PAHs contributed more in the industrial area, whereas 5- and 6-ring PAHs contributed more in the traffic area, reflecting the variety of emission sources. Principal component analysis and diagnostic molecular ratios showed that vehicular exhaust was the major source of PAHs during both periods at the traffic and central urban sites, while heavy-duty vehicular emissions and natural gas/biomass/coal combustion emissions dominated in the industrial area. The average Benzo[a]pyrene equivalent toxicity (BaP_eq) ranged from 4.4 to 37.9 ng m^–3, showing a generally similar spatiotemporal distribution with the Ʃ₁₆PAHs.‎ The results showed that the lifetime excess cancer risk (LCR) during the heating period was higher than during the non-heating period and that people who lived around the industrial and traffic areas had a higher likelihood of getting lung cancer than residents in other parts of the city.

Keywords: Polycyclic aromatic hydrocarbons; Particulate matter; Spatiotemporal variations; Source apportionment; Health risk.