Variability of polycyclic aromatic hydrocarbons and their oxidative derivatives in wintertime Beijing, China

Abstract

<p><strong>Abstract.</strong> Ambient particulate matter (PM) can contain a mix of different toxic species derived from a wide variety of sources. This study quantifies the variation in diurnal and nocturnal abundance of 16 Polycyclic Aromatic Hydrocarbons (PAHs), 10 Oxygenated PAHs (OPAHs) and 9 Nitrated PAHs (NPAHs) in ambient PM in central Beijing during winter. Target compounds were identified and quantified using Gas Chromatography – time of flight mass spectrometry (GC-Q-TOF-MS). The total concentration of PAHs varied between 18 and 297 ng m<sup>−3</sup> over 3 h daytime filter samples and from 23 to 165 ng m<sup>−3</sup> in 15 h night-time samples. The total concentrations of PAHs over 24 h varied between 37 and 180 ng m<sup>−3</sup> (mean: 97 ng m<sup>−3</sup>). The total daytime concentrations during high particulate loading conditions for PAHs, OPAHs and NPAHs were 224, 54, and 2.3 ng m<sup>−3</sup>, respectively. The most abundant PAHs were fluoranthene (33 ng m<sup>−3</sup>), chrysene (27 ng m<sup>−3</sup>), pyrene (27 ng m<sup>−3</sup>), benzo(a)pyrene (27 ng m<sup>−3</sup>), benzo[b]fluoranthene (25 ng m<sup>−3</sup>), benzo[a]anthracene (20 ng m<sup>−3</sup>) and phenanthrene (18 ng m<sup>−3</sup>). 9,10-Anthraquinone (18 ng m<sup>−3</sup>), 1,8 Naphthalic anhydride (14 ng m<sup>−3</sup>) and 9-Fluorenone (12 ng m<sup>−3</sup>) were the three major OPAHs species, while 9-Nitroanthracene (0.84 ng m<sup>−3</sup>), 3-Nitrofluoranthene (0.78 ng m<sup>−3</sup>) and 3-Nitrodibenzofuran (0.45 ng m<sup>−3</sup>) were the three most abundant NPAHs. ∑PAHs and ∑OPAHs showed a strong positive correlation with the gas phase abundance of NO, CO, SO<sub>2</sub>, and HONO indicating that PAHs and OPAHs can be associated with both local and regional emissions. Diagnostic ratios suggested emissions from traffic road and coal combustion were the predominant sources for PAHs in Beijing, and also revealed the dominant source of NPAHs was secondary photochemical formation rather than primary emissions. PM<sub>2.5</sub> and NPAHs showed a strong correlation with gas phase HONO. 9-Nitroanthracene appeared to undergo a photodegradation during the daytime and has shown a strong positive correlation with ambient HONO (R = 0.90, P < 0.001). The lifetime excess lung cancer risk for the species with available toxicological data (16 PAHs, 1 OPAH and 6 NPAHs) was calculated to be in the range 10<sup>−5</sup> to 10<sup>−3</sup> (risk per million people range from 26 to 2053).</p>

Introduction to the special issue “In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-Beijing)”

“…During the intensive campaigns, the project measured the fluxes of particulate and gaseous air pollutants from groundlevel sources by sampling on the meteorological tower (325 m) at the IAP site, which is compared with emissions estimates taken from the inventory for Beijing. This was complemented by top-down fluxes inferred from satellite data for nitrogen dioxide, sulfur dioxide and formaldehyde, the latter indicative of volatile organic compound (VOC) oxidation processes (Palmer et al, 2003;Fu et al, 2007). Through these means, the emissions inventory is being tested, allowing revisions which are being incorporated into the atmospheric modelling work.…”

Atmospheric conditions and composition that influence PM<sub>2.5</sub> oxidative potential in Beijing, China

“…Briefly, the following composition data was collated: total organic and elemental carbon (OC, EC), soluble inorganic ions (K + , Na + , Ca 2+ , NH4 + , NO3 -, SO4 2and Cl -) measured using ion chromatography (IC), low-oxidised organic aerosol and moreoxidised organic aerosol (LOOOA/MOOOA) fractions using aerosol mass spectrometry (AMS), biomass burning markers (galactosan, mannosan and levoglucosan), 16 polycyclic aromatic hydrocarbons (PAHs) (see Elzein et al, 2019Elzein et al, , 2020, C24-C34 n-alkanes, aerosol cooking markers (palmitic acid, stearic acid, cholesterol), vehicle exhaust markers (17a(H)-22, 29,30trisnorhopane (C27a) and 17b(H)-21a-norhopane (C30ba)), isoprene SOA markers (2-methylglyceric acid, 2-methylerythritol, 2-methylthreitol, 3-hydroxyglutaric acid), C5-alkene triols (cis-2-methyl-1,3,4-trihydroxy-1-butene, 3-methyl-2,3,4trihydroxy-1-butene, trans-2-methyl-1,3,4-trihydroxy-1-butene), α-pinene SOA tracers (cis-pinonic acid, pinic acid, 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), 2,3-dihydroxy-4-oxopentanoic acid, aged α-pinene SOA marker), β-caryophyllene SOA tracer (β-caryophyllinic acid) and an aromatic volatile organic compound (VOC) SOA tracer (3-isopropylpentanedioic acid) (Liu et al, 2020). The following additional data was obtained from the Centre for Environmental Data Analysis (CEDA) archive : concentrations of inorganic elements Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Sb, Ba and Pb in PM2.5 using X-ray fluorescence (XRF) (Xu et al, 2020a), gas phase concentrations of methanol, acetonitrile, acetaldehyde, acrolein, acetone, isoprene, methacrolein, methyl ethyl ketone, benzene, toluene, C2-benzenes and C3-benzenes measured using proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) (Acton et al, 2018), gas phase concentrations of O3, CO, NO, NO2, NOy and SO2 as well as relative humidity (RH) and air temperature measurements (Shi et al, 2019), photolysis rates for singlet oxygen and nitrogen dioxide (J O 1 D and J NO2) (Whalley et al, 2020) and gas phase concentrations of hydroxyl radicals (OH), peroxy radicals (HO2) and organic peroxy radicals (RO2) measured using fluorescence assay gas expansion (FAGE) (Whalley et al, 2020).…”