Snow scavenging and phase partitioning of nitrated and oxygenated aromatic hydrocarbons in polluted and remote environments in central Europe and the European Arctic

Abstract

Abstract. Nitrated and oxygenated polycyclic aromatic hydrocarbons (N/OPAHs) are emitted in combustion processes and formed in polluted air. Their environmental cycling through wet deposition has hardly been studied. Fresh snow samples at urban and rural sites in central Europe, as well as surface snow from a remote site in Svalbard, were analysed for 17 NPAHs, 8 OPAHs, and 11 nitrated mono-aromatic hydrocarbons (NMAHs), of which most N/OPAHs as well as nitrocatechols, nitrosalicylic acids, and 4-nitroguaiacol are studied for the first time in precipitation. In order to better understand the scavenging mechanisms, the particulate mass fractions (θ) at 273 K were predicted using a multi-phase gas-particle partitioning model based on polyparameter linear free energy relationships. ∑NPAH concentrations were 1.2–17.6 and 8.8–19.1 ng L−1 at urban and rural sites, whereas ∑OPAHs were 79.8–955.2 and 343.3–1757.4 ng L−1 at these sites, respectively. 9,10-anthraquinone was predominant in snow aqueous and particulate phases. NPAHs were only found in the particulate phase with 9-nitroanthracene being predominant followed by 2-nitrofluoranthene. Among NMAHs, 4-nitrophenol showed the highest abundance in both phases. The levels found for nitrophenols were in the same range or lower than those reported in the 1980s and 1990s. The lowest levels of ∑N/OPAHs and ∑NMAHs were found at the remote site (3.5 and 390.5 ng L−1, respectively). N/OPAHs preferentially partitioned in snow particulate phase in accordance with predicted θ, whereas NMAHs were predominant in the aqueous phase, regardless of θ. It is concluded that the phase distribution of non-polar N/OPAHs in snow is determined by their gas-particle partitioning prior to snow scavenging, whereas that for polar particulate phase substances, i.e. NMAHs, is determined by an interplay between gas-particle partitioning in the aerosol and dissolution during in- or below-cloud scavenging.

Composition and mass size distribution of nitrated and oxygenated aromatic compounds in ambient particulate matter from southern and central Europe – implications for origin

“…These trends are in good agreement with other studies, where 4-NC, MNCs and 4-NP were the most abundant NMAHs (Kitanovski et al, 2012b;Chow et al, 2016). However, we previously found different concentration trends in snowscavenged atmospheric particles collected in MZ, where 4-NC and MNCs were the second most abundant NMAH species following NPs (Shahpoury et al, 2018). ∑NMAH winter concentrations at TK were higher than those found in winter PM2.5 and PM10 from Hong Kong (China; Chow et al, 2016) and rural Belgium (Kahnt et al, 2013), respectively, but lower than NMAH concentrations in winter PM10 samples from Ljubljana (Slovenia; Kitanovski et al, 2012b) MZ were among the lowest values reported so far (Iinuma et al, 2010;Kitanovski et al, 2012b;Kahnt et al, 2013;Mohr et al, 2013;Chow et al, 2016;Li et al, 2016;Teich et al, 2017;Wang et al, 2019).…”

“…N/OPAHs were extracted from PM samples following a QuEChERS method with slight modifications (Albinet et al, 2014;Shahpoury et al, 2018). Briefly, each filter paper was placed inside a glass centrifuge tube (Duran, Schott, Mainz, Germany) and spiked with a mixture of internal standards containing 60 ng of each 1-nitronaphthalene-d7, 2-nitrofluorene-d9, 9nitroanthracene-d9, 3-nitrofluoranthene-d9, 1-nitropyrene-d9, 6-nitrochrysene-d11, 9,10anthraquinone-d8, and 9-fluorenone-d8.…”

“…Polycyclic aromatic hydrocarbons (PAHs) and their nitrated and oxygenated derivatives (NPAHs and OPAHs), as well as hydroxy derivatives (OH-PAHs), are ubiquitous in the atmosphere (Walgraeve et al, 2010;Lammel, 2015;Bandowe and Meusel, 2017;Shahpoury et al, 2018). They are primarily emitted from incomplete combustion of fossil fuels (Zielinska et al, 2004;Karavalakis et al, 2010;Pham et al, 2013;Inomata et al, 2015), wood, coal and biomass burning (Ding et al, 2012;Shen et al, 2012Shen et al, , 2013aShen et al, and 2013bHuang et al, 2014;Vicente et al, 2016).…”

Composition and mass size distribution of nitrated and oxygenated aromatic compounds in ambient particulate matter from southern and central Europe – implications for the origin

“…Considering the PM 0.97 size fraction (Table S11), the correlation with K + was only significant for 1-NPYR at TK, whereas both BaOFLN and 1-NPYR correlated with WSOC and HULIS in this size fraction. 1-NPYR is the predominant congener among NPAHs found in diesel engine exhaust particles and was proposed as a tracer for diesel emission (Bamford et al, 2003;IARC, 2013), but it may also be emitted with relatively small quantities from biomass-fuelled combustion (Shen et al, 2012;Orakij et al, 2017). These findings suggest the importance of primary emission sources including BB and diesel exhaust in the TK study area.…”

“…Polycyclic aromatic hydrocarbons (PAHs) and their nitrated and oxygenated derivatives (NPAHs and OPAHs), as well as hydroxy derivatives (OH-PAHs), are ubiquitous in the atmosphere (Walgraeve et al, 2010;Lammel, 2015;Bandowe and Meusel, 2017;Shahpoury et al, 2018). They are primarily emitted from the incomplete combustion of fossil fuels (Zielinska et al, 2004;Karavalakis et al, 2010;Pham et al, 2013;Inomata et al, 2015) and wood, coal, and biomass burning (Ding et al, 2012;Shen et al, 2012Shen et al, , 2013aHuang et al, 2014;Vicente et al, 2016). The PAH derivatives are secondarily formed by the reaction of parent PAHs with atmospheric oxidants such as OH, NO x and O 3 .…”