Chemical characteristics and sources of water-soluble organic aerosol in southwest suburb of Beijing

Hu, Ruolan; Tian, Hezhong; Yang, Hua; Bhattarai, Noshan; Jiang, Jingkun; Song, Yu; Daellenbach, Kaspar R.; Lu, Qi; Prévôt, Andrê S. H.; Hao, Jiming

doi:10.1016/j.jes.2020.04.004

Cited by 12 publications

(10 citation statements)

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“…The mass spectrum of FFOA is characterized with relatively significant signal at m / z 115 (C 9 H 7 + ) and its concentration highly correlated with PAHs signals ( SI Figure S5 ), which is consistent with existing studies. 76 , 77 That is, the FFOA factor represents primary organic pollutant from industrial and domestic combustion and heavy diesel vehicles. COA shows a distinct mass spectral profile with prominent fragments of m / z 55 (C 4 H 7 + , C 3 H 3 O + ), and m / z 57 (C 4 H 9 + , C 3 H 5 O + ) ( SI Figure S6 ), a higher ratio of m / z 55/57 (>2), and low O/C ratio (0.13), similar to previous AMS-PMF results.…”

Section: Resultsmentioning

confidence: 99%

“…Besides, LO-OOA was related with the fragments of C 2 H 2 O 2 + and C 2 O 2 + (both R 2 = 0.90, p < 0.01, SI Figure S8C,D ) which were proved as typical fragment ions of glyoxal and methylgloxyal that are important precursors of low volatile SOA through aqueous chemistry process. 77 , 86 , 87 Other aqueous-related fragment ions were all more correlated with LO-OOA than MO-OOA ( SI Figure S9 ).The N content in LO-OOA was the highest among the four factors (N/C = 0.061) and LO-OOA concentration was correlated well with RH ( Figure 7 A) and SO 4 2– ( SI Figure S10 ), consistent with the aqueous OOA factors in the observation studies in cold seasons in Beijing. 56 , 77 The oxidation of LO-OOA (O/C = 0.67) was lower than the identified aqueous OOA factors in these previous studies, which might be because that less NO 3 radicals participated in aqueous reactions with much lower NO x concentration after lockdown.…”

Section: Resultsmentioning

confidence: 99%

“… 77 , 86 , 87 Other aqueous-related fragment ions were all more correlated with LO-OOA than MO-OOA ( SI Figure S9 ).The N content in LO-OOA was the highest among the four factors (N/C = 0.061) and LO-OOA concentration was correlated well with RH ( Figure 7 A) and SO 4 2– ( SI Figure S10 ), consistent with the aqueous OOA factors in the observation studies in cold seasons in Beijing. 56 , 77 The oxidation of LO-OOA (O/C = 0.67) was lower than the identified aqueous OOA factors in these previous studies, which might be because that less NO 3 radicals participated in aqueous reactions with much lower NO x concentration after lockdown. It seems LO-OOA concentration increased in E1 ( Figure 3 B), but Figure 5 B suggests this increase was mainly driven by a lower atmospheric boundary layer.…”

Section: Resultsmentioning

confidence: 99%

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Variations and Sources of Organic Aerosol in Winter Beijing under Markedly Reduced Anthropogenic Activities During COVID-2019

Zheng

Zhao

et al. 2021

Environ. Sci. Technol.

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The COVID-19 outbreak provides a “controlled experiment” to investigate the response of aerosol pollution to the reduction of anthropogenic activities. Here we explore the chemical characteristics, variations, and emission sources of organic aerosol (OA) based on the observation of air pollutants and combination of aerosol mass spectrometer (AMS) and positive matrix factorization (PMF) analysis in Beijing in early 2020. By eliminating the impacts of atmospheric boundary layer and the Spring Festival, we found that the lockdown effectively reduced cooking-related OA (COA) but influenced fossil fuel combustion OA (FFOA) very little. In contrast, both secondary OA (SOA) and O3 formation was enhanced significantly after lockdown: less-oxidized oxygenated OA (LO-OOA, 37% in OA) was probably an aged product from fossil fuel and biomass burning emission with aqueous chemistry being an important formation pathway, while more-oxidized oxygenated OA (MO-OOA, 41% in OA) was affected by regional transport of air pollutants and related with both aqueous and photochemical processes. Combining FFOA and LO-OOA, more than 50% of OA pollution was attributed to combustion activities during the whole observation period. Our findings highlight that fossil fuel/biomass combustion are still the largest sources of OA pollution, and only controlling traffic and cooking emissions cannot efficiently eliminate the heavy air pollution in winter Beijing.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Variations and Sources of Organic Aerosol in Winter Beijing under Markedly Reduced Anthropogenic Activities During COVID-2019

Zheng

Zhao

et al. 2021

Environ. Sci. Technol.

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“…Only the campus and residential areas fell within a 1 km radius, and no industrial point sources were within a 30 km radius. It is a representative site for the atmospheric environment in urban Beijing, where many atmospheric observation experiments have been conducted over the years ( Hu et al, 2020 ; Tang et al, 2019 ). We used atmospheric Hg monitoring system (Tekran™ 2537B/1130/1135)to monitor speciated Hg in the atmosphere, which has been widely used for atmospheric Hg observations around the world.…”

Section: Methodsmentioning

confidence: 99%

Impact of emission reductions and meteorology changes on atmospheric mercury concentrations during the COVID-19 lockdown

Tang

Wang

et al. 2021

Science of The Total Environment

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Controlling anthropogenic mercury emissions is an ongoing effort and the effect of atmospheric mercury mitigation is expected to be impacted by accelerating climate change. The lockdown measures to restrict the spread of Coronavirus Disease 2019 (COVID-19) and the following unfavorable meteorology in Beijing provided a natural experiment to examine how air mercury responds to strict control measures when the climate becomes humid and warm. Based on a high-time resolution emission inventory and generalized additive model, we found that air mercury concentration responded almost linearly to the changes in mercury emissions when excluding the impact of other factors. Existing pollution control and additional lockdown measures reduced mercury emissions by 16.7 and 12.5 kg/d during lockdown, respectively, which correspondingly reduced the concentrations of atmospheric mercury by 0.10 and 0.07 ng/m 3 . Emission reductions from cement clinker production contributed to the largest decrease in atmospheric mercury, implying potential mitigation effects in this sector since it is currently the number one emitter in China. However, changes in meteorology raised atmospheric mercury by 0.41 ng/m 3 . The increases in relative humidity (9.5%) and temperature (1.2 °C) significantly offset the effect of emission reduction by 0.17 and 0.09 ng/m 3 , respectively, which highlights the challenge of air mercury control in humid and warm weather and the significance of understanding mercury behavior in the atmosphere and at atmospheric interfaces, especially the impact from relative humidity.

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“…Specifically, Xiao et al (2011) found that 61% of the less-oxidized oxygenated OA in Guangzhou, China, is water-soluble, while Timonen et al (2013) estimated that only 14% of less-oxidized oxygenated OA is water-soluble in Helsinki, Finland, using a similar method. The water solubility of primary sources of OA, such as the biomass burning and coal combustion OA, or aqueous-oxygenated OA, were investigated in urban Beijing (Hu et al, 2020;Qiu et al, 2019). However, a more quantitative investigation of the OA from different sources has been lacking.OAs are produced both from primary emissions (e.g., primary OA or POA) and secondary formation (e.g., secondary OA or SOA).…”

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confidence: 99%

Hygroscopicity of Organic Aerosols Linked to Formation Mechanisms

Liu

Zhang

et al. 2021

Geophysical Research Letters

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Organic aerosols (OAs) account for a large fraction of tropospheric fine particulate matter, but the hygroscopicity of OA is poorly understood. Here, we show remarkably‐enhanced water uptake capacity of OA due to formation of highly‐oxidized oxygenated OA on new particle formation (NPF) events in Beijing. While non‐nucleation processes also produce oxidized OA, their hygroscopicity exhibits little enhancement. As a result, a correlation between the hygroscopicity and oxidation state is absent for OA on non‐NPF days. Further analysis reveals that the highly‐oxidized oxygenated OA is 2.5 and 5‐fold as hygroscopic as the oxidized primary OA and less‐oxidized oxygenated OA, respectively. Our results suggest that nucleation‐initiated photooxidation of volatile organic compounds to produce water‐soluble organic acids may dominate on NPF days, and the aqueous oligomerization to yield less water‐soluble products might occur on non‐NPF days.

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Chemical characteristics and sources of water-soluble organic aerosol in southwest suburb of Beijing

Cited by 12 publications

References 85 publications

Variations and Sources of Organic Aerosol in Winter Beijing under Markedly Reduced Anthropogenic Activities During COVID-2019

Variations and Sources of Organic Aerosol in Winter Beijing under Markedly Reduced Anthropogenic Activities During COVID-2019

Impact of emission reductions and meteorology changes on atmospheric mercury concentrations during the COVID-19 lockdown

Hygroscopicity of Organic Aerosols Linked to Formation Mechanisms

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