Abstract
Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes are important specific organic constituents in fine particulate matter (PM2.5). Seventy-five PM2.5 samples were collected in Spring Changzhou, to investigate the concentrations and sources of n-alkanes (C9–C40) and PAHs. The average concentrations of total PAHs (∑PAHs) and n-alkanes (∑n-alkanes) were 4.37 ± 4.95 ng/m3 and 252.37 ± 184.02 ng/m3, ranging from 0.43 to 22.22 ng/m3 and 57.37 to 972.17 ng/m3, respectively. The average concentrations of ∑n-alkanes and ∑PAHs were higher in severely polluted days (PM2.5 ≥ 150 μg/m3) in comparison to other days. Up to 85% of PAHs were four- and five-ring compounds, and the middle-chain-length n-alkanes (C25–C35) were the most abundant species (80.9%). The molecular distribution of n-alkanes was characterized by odd-number carbon predominance (carbon preference index, CPI > 1), with a maximum centered at C27, C29, and C31 revealing a significant role of biogenic sources. Principal component analysis suggested that the biogenic sources that contributed the most to n-alkanes and PAHs were from coal combustion (46.3%), followed by biomass burning (16.0%), and vehicular exhaust (10.3%). The variation in the concentration of n-alkanes and PAHs from different air mass transports was not agreement with the change in PM2.5 mass, indicating that regional transport had important impacts on the characterization of PM2.5. The results of our study can provide useful information for evaluating the influence of anthropogenic and biogenic activities on organic matters (n-alkanes and PAHs).
Highlights
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
There was a relative decrease in the percentages of SNA and carbonaceous species, combined with a significant increase in dust in PM2.5 on polluted days, implying that the PM2.5 concentrations might be somewhat impacted by dust storms
The four-to-five-rings Polycyclic aromatic hydrocarbons (PAHs) are dominant and occupied over 85% of the total PAHs
Summary
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China. Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes are important specific organic constituents in fine particulate matter (PM2.5 ). The average concentrations of ∑n-alkanes and ∑PAHs were higher in severely polluted days (PM2.5 ≥ 150 μg/m3 ) in comparison to other days. The variation in the concentration of n-alkanes and PAHs from different air mass transports was not agreement with the change in PM2.5 mass, indicating that regional transport had important impacts on the characterization of PM2.5. The results of our study can provide useful information for evaluating the influence of anthropogenic and biogenic activities on organic matters (n-alkanes and PAHs). The compositions of PM2.5 are very complicated, including organic carbon (OC), elemental carbon (EC), trace elements, inorganic salts, and some organic species, such as n-alkanes and polycyclic aromatic hydrocarbons (PAHs) [4]
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