Intraurban concentrations, spatial variability and correlation of ambient polycyclic aromatic hydrocarbons (PAH) and PM_2.5

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• 作者：Angelos T. Anastasopoulos ; Am ; a J. Wheeler ; Deniz Karman ; Ryan H. Kulka
• 关键词：Air quality ; Intraurban ; Spatial variability ; Fine particulate matter (PM2.5) ; Polycyclic aromatic hydrocarbons (PAH) ; Hamilton
• 刊名：Atmospheric Environment
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：59
• 期：Complete
• 页码：272-283
• 全文大小：1683 K

文摘

To investigate the intraurban spatial variability of air toxics associated with respirable particulate matter (PM), ambient PM_2.5 and 16 polycyclic aromatic hydrocarbons (PAH) species (vapour phase plus 2.5?¦Ìm particle phase) were sampled over a dense network of sites in Hamilton, Ontario, Canada in June/July 2009 and December 2009. PM_2.5 levels ranged from 2.46 to 11.0?¦Ìg?m^?3 in the summer campaign and 6.52 to 13.4?¦Ìg?m^?3 in the winter campaign. Total sampled PAH (¦²₁₆PAH) levels ranged from 10.2 to 83.7?ng?m^?3 in the summer campaign and 8.31 to 52.1?ng?m^?3 in the winter campaign. Ambient PM_2.5 and PAH concentrations were greater below the city's escarpment with a below/above escarpment difference in concentration much greater for PAH than for PM_2.5 in both summer and winter sampling campaigns. Elevated levels of both pollutants were observed to occur near or downwind of the central business district and industrialized harbourfront area, suggesting the contribution of local sources. Ambient PAH exhibited a substantially greater degree of intraurban variability than PM_2.5 (coefficient of variation approximately three times greater in summer campaign, four times greater in winter campaign) both above and below the escarpment, particularly for heavy MW species found predominantly in the particle phase. Benzo(a)Pyrene-equivalent toxicity (BaP-TEQ) associated with ambient PAH showed a generally similar spatial distribution to ¦²₁₆PAH; however, several sites with relatively low ¦²₁₆PAH had high BaP-TEQ (enriched in more toxic heavy MW species), indicating potential hotspots for elevated PAH exposures and local source contributions. Co-located field sampling data showed that central site monitoring was a poor proxy for PM_2.5 and particularly for PAH and associated toxicity (BaP-TEQ) across the urban centre, underestimating levels at many sites, likely due to the significant number of locally distributed sources and mixed land use. The much greater intraurban variability of PAH relative to PM_2.5, particularly for toxic heavy MW species predominantly in particle phase, demonstrated variability in PM_2.5 composition and confirmed the importance of the local scale for PAH exposure health risk assessment.