Sources of PM2.5-Associated PAHs and n-alkanes in Changzhou China

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).

Molecular Composition, Seasonal Variation, and Size Distribution of n-Alkanes, PAHs, and Saccharides in a Medium-Sized City of Guanzhong Plain, Northwest China: Evaluation of Control Measures Executed in the Past Decade

“…According to the homologue percent profile, there are two main sources of alkanes, which were natural plant wax emission and fossil fuel combustion [ 21 , 22 ]. n-Alkanes from plant waxes usually present the odd carbon number predominance, while those from fossil fuel combustion show no odd/even preference [ 23 ].…”

Assessing anthropogenic contribution to PM2.5 from an urban residential area of Lagos, Nigeria using aliphatic hydrocarbon compounds as indicators

“…Atmospheric particulate matter (PM) with an aerodynamic diameter of 2.5 μm or less (PM 2.5 ) is considered a major contributor to severe air pollution and has significant impacts on human health, atmospheric visibility and climate (Russell and Brunekreef, 2009;Javed et al, 2019;Tian et al, 2020;Sun et al, 2021). The composition of PM 2.5 is very complicated and includes organic carbon (OC) and elemental carbon (EC), often referred to as carbonaceous components, trace metals, inorganic salts and some specific organic compounds such as aliphatic hydrocarbons including n-alkanes, steranes and hopanes, n-alkanoic acids and polycyclic aromatic hydrocarbons (PAHs) (Mandalakis et al, 2002;Javed et al, 2019;Sun et al, 2021). However, the most prevalent and significant class of organic compounds in the atmosphere are the aliphatic hydrocarbons (Fu et al, 2008;Ren et al, 2016;Boreddy et al, 2018).…”

“…However, the most prevalent and significant class of organic compounds in the atmosphere are the aliphatic hydrocarbons (Fu et al, 2008;Ren et al, 2016;Boreddy et al, 2018). Due to their specificity, hydrophobicity, and prolonged persistence in the environment, these aliphatic hydrocarbon compounds have been used as organic molecular markers for pollution source identification Mudge and Duce, 2005;Andreou et al, 2007;Javed et al, 2019;Sun et al, 2021). For example, n-alkanes primarily come from both anthropogenic and biological sources, such as petroleum residue, diesel engine exhaust (Simoneit,1984), and biomass burning Elias, 2000, 2001), and also from terrestrial plant wax, fungi, bacteria, algae, and plankton (Brown et al, 2002).…”

“…Aliphatic hydrocarbon compounds have been used in other parts of the world to identify the main sources of PM 2.5 pollution and to understand the important impact of regional transport on the characterisation of PM 2.5 (Andreou et al, 2007;Javed et al, 2019;Sun et al, 2021). For instance, Andreou et al (2007) investigated the organic chemical composition of PM 2.5 in Athens to determine the emission sources.…”

“…Vehicular emissions were the main source of aliphatic hydrocarbon compounds, with biogenic sources contributing less. Recently, Sun et al (2021) determined the sources of PM 2.5associated PAHs and n-alkanes in Changzhou, China. Their results showed that biogenic sources are the main source of n-alkanes and PAHs in PM 2.5 .…”