Temporal Distribution and Gas/Particle Partitioning of Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere of Strasbourg, France

Abstract

Gas and particulate phase ambient air concentrations of polycyclic aromatic hydrocarbons (Ʃ16PAHs) were determined in Strasbourg, a large city located in the Alsace region of northeastern France, from May 2018 to March 2020, to study the evolution of their temporal variations and their potential origins. The analysis of PAHs was performed using a global analytical method permitting the quantification of pesticides, PAHs, and polychlorobiphenyls (PCBs). Filters and Carbon doped silicon carbide NMC@SiC foams were extracted by accelerated solvent extraction (ASE) followed by a solid-phase extraction (SPE). Afterwards, extracts were analyzed using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Prior to analysis, a pre-concentration step based on solid-phase microextraction (SPME) was used with a polydimethylsiloxane (PDMS) 100 µm fiber. The average total (gas plus particulate) concentration of Ʃ16PAHs varied from 0.51 to 117.31 ng m−3 with a mean of 16.87 ng m−3, with higher concentrations in the cold season of more than 2.5-fold and 6-fold that in the warm season for the gas and particulate phases, respectively. Moreover, low molecular weight (LMW) (2-ring and 3-ring) and medium molecular weight (MMW) (4-ring) PAHs contribute dominantly to the gas phase, while the particulate phase is associated with MMW (4-ring) and high molecular weight (HMW) (5-ring and 6-ring) PAHs. Gas/particle partitioning coefficient (log Kp) was calculated, and values varied between −4.13 and −1.49. It can be seen that the log Kp increased with the molecular weight of the PAHs and that the log Kp is different between cold and warm seasons for HMW PAHs but not for LMW PAHs. Diagnostic ratios of PAHs, which were employed to estimate the primary source of PAHs in Strasbourg, indicate that fuel combustion and biomass/coal burning are the possible origins of PAHs in Strasbourg’s atmosphere.

Compositional and seasonal differences of gas and particle phase polycyclic aromatic hydrocarbons (PAHs) over the southern Baltic Sea coast

“…These results suggest photodegradation processes of PAHs in the particulate phase by ozone that could significantly affect PAH transformations, especially during summer and spring, when concentrations of O 3 are high (mean = 76.3 and 66.8 µg m −3 , respectively) 29 . Similar photochemical effects of ozone on particulate PAHs during the warm study period have been demonstrated in previous studies 13 , 15 , 16 , 49 .…”

“…In this study, the BaP/BghiP ratio was more than 2 times higher during the cold season compared to the warm one. Therefore, vehicular exhaust emission is expected to play an important role in high-molecular-weight PAH pools, depending on season and meteorological conditions, as observed in many previous studies 4 , 6 , 7 , 11 , 49 .…”

“…In this study, the BaP/BghiP ratio was more than 2 times higher during the cold season compared to the warm one. Therefore, vehicular exhaust emission is expected to play an important role in high-molecular-weight PAH pools, depending on season and meteorological conditions, as observed in many previous studies 4,6,7,11,49 . S2 shows Spearman's rank correlation analysis (Rs) performed to assess the statistically significant dependences between concentrations of individual PAH isomers in the gas (only Naph, Acy, Ace) and particle phases, and other parameters at the 95% confidence level (p < 0.05).…”

Impact of Atmospheric Conditions and Source Identification of Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) during a Smoke Haze Period in Upper Southeast Asia

“…For example, gaseous PAHs produced by primary emissions (i.e., vehicle emission and fuel evaporation) might be photo-oxidized and react with various high-potential oxidants (i.e., ozone, nitrate radical, and hydroxyl radical) in the atmosphere. Therefore, the difference in high traffic congestion could be the reason for the significant reactivity of those compounds because of widely detected gaseous PAH concentrations [ 7 ].…”

“…Several studies found two- to three-ring PAHs are a gaseous phase, while five- to seven-ring PAHs are a particulate phase. However, both phases are found in four-ring PAHs [ 7 , 8 , 9 ]. Although gaseous PAHs are less carcinogenic/mutagenic, there are many in the atmosphere and they can interact with other pollutants to produce derivatives through processes such as sulfonation, nitration, and photo-oxidation [ 10 , 11 , 12 ].…”