Online chemical characterization of atmospheric fine secondary aerosols and organic nitrates in summer Nanjing, China

Xian, Jiukun; Cui, Shijie; Chen, Xingzhou; Wang, Jingyun; Xiong, Yifan; Gu, Chenjuan; Wang, Yuan; Zhang, Yunjiang; Li, Haiwei; Wang, Junfeng; Ge, Xinlei

doi:10.1016/j.atmosres.2023.106783

Cited by 4 publications

(2 citation statements)

References 91 publications

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“…Note that all these ALWC values are estimated from thermodynamic models. Xian et al [ 20 ] calculated an average ALWC of 5.33 μg m −3 in Nanjing during the summer of 2021. Considering the higher RH (69.05% vs. 63.42%) and similar PM concentration (18.88 vs. 19.50 μg m −3 ) in their study, a higher ALWC is reasonable and vice versa.…”

Section: Resultsmentioning

confidence: 99%

“…The ALWC is typically estimated based on the measured aerosol composition and concentration by using various thermodynamic models (for examples, the extended aerosol inorganic model (E-AIM) [ 18 ] and ISORROPIA II [ 19 ]). Such a methodology assumes a thermodynamic equilibrium state of the aerosols and often does not include all aerosol components (especially organics) [ 20 , 21 ]. A humidified tandem differential mobility analyzer (H-TDMA) can be used to determine the hygroscopic growth factor (HGF) of ambient aerosols under a fixed RH (typically at 90%) [ 22 ]; it can obtain the particle number size distributions [ 23 , 24 , 25 ] under both dry and humid conditions and then calculate the ALWC by comparing the volume changes before and after humidification [ 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

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Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China

Li,

Cui,

et al. 2024

Toxics

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Aerosol liquid water content (ALWC) affects the mass loading, optical properties, and toxicity of aerosols. However, the measurement of ALWC is very rare due to its requirement of sophisticated instruments and its high operational costs. In this work, we improved on our previous simple, low-cost method by using a combination of one real-time fine particulate matter (PM2.5) monitor and two turbidimeters and successfully applied these for the direct measurement of ALWC in PM2.5 in Nanjing during the summer of 2023. The average ALWC during this measurement period occupied ~1/6 of the total PM2.5 mass, and this contribution was even greater with the elevation in the PM2.5 concentration. The ALWC was, as anticipated, closely related to the relative humidity (RH) and PM2.5 concentrations, but it did not always increase with the air quality index (AQI) due to the fact that polluted periods in summer were often governed by high O3 levels, not PM2.5 levels. The ALWC also had a great impact on visibility; it could decrease the visibility rapidly to hazy conditions when the dry PM2.5 was not high (~30 μg m−3) or the AQI was “good” (75~100), indicating that the air quality classified as “good” using the dry PM2.5 concentration might actually be “lightly polluted” if the ALWC is included. We also found that the air mass originating from Northeast China had the lowest PM2.5 mass concentration yet the highest ALWC values due to its high RH. Moreover, the quantification of ALWC levels can help us understand the solubility/bioavailability and thus the toxic effects of some specific components (for example, heavy metals or organics). Moreover, the influence of ALWC on air quality classifications should also be considered in the assessment of the health effects of air pollution and in public health early warning and protection.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China

Li,

Cui,

et al. 2024

Toxics

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Chemical characteristics and formation mechanism of secondary inorganic aerosols: The decisive role of aerosol acidity and meteorological conditions

Ting,

Huang,

Cheng

et al. 2024

Environmental Pollution

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Measurement report: Impact of cloud processes on secondary organic aerosols at a forested mountain site in southeastern China

Zhang,

Xu,

Zhang

et al. 2024

Atmos. Chem. Phys.

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Abstract. Aerosol particles play critical roles in climate and human health. However, aerosol composition and evolution, particularly secondary organic aerosol (SOA), and aerosol interactions with clouds in high-altitude background areas in China remain less understood. Here, we conducted real-time measurements of submicron aerosols (PM1) using aerosol mass spectrometers at a forested mountain site (1128 m a.s.l.) in southeastern China in November 2022. The average (±1σ) PM1 mass concentration was 4.3±4.8 µg m−3, which was ubiquitously lower than that at other mountain sites in China. Organic aerosol (OA) constituted the largest fraction of PM1 (42.9 %) and was predominantly secondary, as indicated by the high oxygen-to-carbon (O / C) ratio (0.85–0.96) and carbon oxidation state (0.21–0.49). Notably, the remarkably enhanced PM1 concentrations observed during the daytime on cloudless days were identified to be likely to be produced from cloud evaporation. While more oxidized oxygenated OA was scavenged efficiently during cloud events, cloud evaporation was found to release a significant amount of less oxidized oxygenated OA from air masses transported from polluted regions. The distinct decrease in OA / ΔCO with the increase in O / C during the cloud evaporative period further demonstrates that OA remaining in cloud droplets is generally in a moderate oxidation state. Moreover, organic nitrates were also estimated and showed a higher contribution to the total nitrate during the cloudy period (27 %) than during the evaporative period (3 %). Overall, our results demonstrate the importance of SOA and the influences of cloud processes in regional mountain areas in southeastern China.

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Online chemical characterization of atmospheric fine secondary aerosols and organic nitrates in summer Nanjing, China

Cited by 4 publications

References 91 publications

Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China

Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China

Chemical characteristics and formation mechanism of secondary inorganic aerosols: The decisive role of aerosol acidity and meteorological conditions

Measurement report: Impact of cloud processes on secondary organic aerosols at a forested mountain site in southeastern China

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