Size−resolved source apportionment of particulate matter from a megacity in northern China based on one-year measurement of inorganic and organic components
“…A second hump, including heavy components, is related to lubricating oils (see a and b humps in Fig. 2 ); the percent profile of vehicle emissions depends on the engine working conditions, and the relative importance of hump(s) raises at unregulated driving regimens, e.g., during cold starts (Zheng et al 2002 , Fang et al 2020 , Iakovides et al 2021a , Tian et al 2021 ). Fig.…”
Section: The State-of-the-art Of Research About Molecular Signatures ...mentioning
confidence: 99%
“…For instance, in two PAH monitoring campaigns carried out in Milan, Italy, during 1991, at a site exposed predominantly to vehicle traffic (Cecinato 1997 ), the BaP/BeP ratio reached 0.9 in the winter and was as low as 0.1 in the summer. The information obtained through molecular signatures of PAHs alone seems insufficient to quantify the contribution of each emission source to the whole of environmental particulates; however, it helps in recognizing the principal causes of pollution and can be improved through associating other markers like oxy-PAHs, sugars, and alkanes (Zheng et al 2002 ; Tian et al 2021 ; Shin et al 2022 ). Besides, this approach allows highlighting the role of oxidation processes with regard to toxicity, whenever the final products (e.g., PAH quinones and lactones) are more harmful than their parent compounds (Durant et al 1999 ).…”
Section: The State-of-the-art Of Research About Molecular Signatures ...mentioning
Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and ≥ 24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.
“…A second hump, including heavy components, is related to lubricating oils (see a and b humps in Fig. 2 ); the percent profile of vehicle emissions depends on the engine working conditions, and the relative importance of hump(s) raises at unregulated driving regimens, e.g., during cold starts (Zheng et al 2002 , Fang et al 2020 , Iakovides et al 2021a , Tian et al 2021 ). Fig.…”
Section: The State-of-the-art Of Research About Molecular Signatures ...mentioning
confidence: 99%
“…For instance, in two PAH monitoring campaigns carried out in Milan, Italy, during 1991, at a site exposed predominantly to vehicle traffic (Cecinato 1997 ), the BaP/BeP ratio reached 0.9 in the winter and was as low as 0.1 in the summer. The information obtained through molecular signatures of PAHs alone seems insufficient to quantify the contribution of each emission source to the whole of environmental particulates; however, it helps in recognizing the principal causes of pollution and can be improved through associating other markers like oxy-PAHs, sugars, and alkanes (Zheng et al 2002 ; Tian et al 2021 ; Shin et al 2022 ). Besides, this approach allows highlighting the role of oxidation processes with regard to toxicity, whenever the final products (e.g., PAH quinones and lactones) are more harmful than their parent compounds (Durant et al 1999 ).…”
Section: The State-of-the-art Of Research About Molecular Signatures ...mentioning
Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and ≥ 24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.
“…Particulate matter (PM) is primarily derived from the combustion of coal, vehicle exhausts, and diverse industrial processes. It forms secondarily in the atmosphere through intricate chemical reactions involving sulfur dioxide and nitrogen oxides [1,2]. The size of PM is commonly classified as either coarse (PM 10 < 10 µm) or fine (PM 2.5 < 2.5 µm) [3].…”
Particulate matter (PM) has deleterious consequences not only on the respiratory system but also on essential human organs, such as the heart, blood vessels, kidneys, and liver. However, the effects of PM inhalation on skeletal muscles have yet to be sufficiently elucidated. Female C57BL/6 or mt-Keima transgenic mice were randomly assigned to one of the following four groups: control (CON), PM exposure alone (PM), treadmill exercise (EX), or PM exposure and exercise (PME). Mice in the three-treatment group were subjected to treadmill running (20 m/min, 90 min/day for 1 week) and/or exposure to PM (100 μg/m3). The PM was found to exacerbate oxidative stress and inflammation, both at rest and during exercise, as assessed by the levels of proinflammatory cytokines, manganese-superoxide dismutase activity, and the glutathione/oxidized glutathione ratio. Furthermore, we detected significant increases in the levels of in vivo mitophagy, particularly in the PM group. Compared with the EX group, a significant reduction in the level of mitochondrial DNA was recorded in the PME group. Moreover, PM resulted in a reduction in cytochrome c oxidase activity and an increase in hydrogen peroxide generation. However, exposure to PM had no significant effect on mitochondrial respiration. Collectively, our findings in this study indicate that PM has adverse effects concerning both oxidative stress and inflammatory responses in skeletal muscle and mitochondria, both at rest and during exercise.
“…many important PM2.5 emission sources (such as cooking) do not have a unique composition (Zhao et al, 2015). Some organic compounds are more specific to individual PM sources and have been used as molecular markers in source apportionment models (Marmur et al, 2006;Schauer and Cass, 2000;Schauer et al, 1996;Robinson et al, 2006;Chow et al, 2007;Arhami et al, 2018;Esmaeilirad et al, 2020;Tian et al, 2021a;Mancilla et al, 2021). An organic molecular marker-based chemical mass balance (OM-CMB) method has been widely used to quantify source contributions to carbonaceous aerosols.…”
Abstract. Chemical mass balance (CMB) is one of the most popular methods to apportion the sources of PM2.5. However, the source apportionment results are dependent on the choices of measured chemical species and the source profiles. Here, we explore the sensitivity of CMB results to source profiles by comparing CMB modeling based on organic markers only (OM-CMB) with a combination of organic and inorganic markers (IOM-CMB), using organic and inorganic markers in PM2.5 samples collected in the Chinese megacity of Chengdu. OM-CMB results show that gasoline vehicles, diesel vehicles, industrial coal combustion, resuspended dust, biomass burning, cooking, vegetation detritus, SOA, sulphate, and nitrate contributed to 4 %, 10 %, 15 %, 12 %, 5 %, 3 %, 4 %, 9 %, 10 %, and 20 %, in comparison to 4 %, 11 %, 15 %, 17 %, 6 %, 2 %, 5 %, 10 %, 7 %, and 18 % from IOM-CMB modelling. The temporal variations of PM2.5 contributions from sulphate, nitrate, SOA, gasoline vehicles, and biomass burning, characterized by unique markers and low collinearity, were in good agreement between the OM-CMB and IOM-CMB results. However, resuspended dust estimates from OM-CMB had a poor correlation with that from IOM-CMB, due to the different tracers used. When replacing the source profile for industrial coal combustion with that for from residential sources, the contributions of resuspended dust and residential coal combustion were overestimated because the residential coal combustion profile contained a higher concentration of OC and organic compounds but lower crustal elements. Different source profiles for gasoline vehicles were also evaluated. Our results confirm the superiority of combining inorganic and organic tracers and using up-to-date locally-relevant source profiles in source apportionment of PM.
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