Decreasing effect and mechanism of FeSO 4 seed particles on secondary organic aerosol in α -pinene photooxidation

Chu, Biwu; Li, Junhua; Takekawa, Hideto; Liggio, John; Li, Shao-Meng; Jiang, Jingkun; Hao, Jiming; He, Hong

doi:10.1016/j.envpol.2014.06.018

Cited by 28 publications

(30 citation statements)

References 52 publications

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“…(HaloSOA, halogenated SOA or halogenations of pre-existing secondary organic aerosol; XOA, halogen-induced organic aerosol; VOX, volatile organohalogens; low VOC, low volatile organic compounds; AqSOA, SOA formed in the aqueous phase; Gas SOA, SOA formed in the gas phase.) consistent with recent work by Chu et al, [46] who observed reduced SOA formation in the presence of FeSO 4 in their experiments under wet conditions (50 % relative humidity) in a-pinene-NO x and a-pinene-HONO photooxidation systems. They propose oxidation processes on the wet surface of the SOA layer by OH radicals breaking down the organic oxidation products into smaller molecules, which may be released into the gas phase, thereby reducing the aerosol mass concentration.…”

Section: Discussionsupporting

confidence: 81%

“…the standard Fe II concentration in C1, the maximum particle number concentration was 8.3 Â 10 4 cm À3 , whereas the maximum particle number concentration was much lower for increased Fe II concentrations in C2 (2.2 Â 10 4 cm À3 ), and higher without Fe II in C3 (1.9 Â 10 5 cm À3 ). This finding is consistent with recent work by Chu et al, [46] who observed reduced SOA formation in the aqueous phase with increased FeSO 4 concentrations. Ultrahigh-resolution mass spectrometry of aerosol samples also shows a loss of CHO oligomers (CH 2 homologous series) from iron-free experiment C3 to C1 and C2, and an increase of the chemical diversity in C1 and C2 with a maximum in experiment C1 (cf.…”

Section: Effect Of Fe II Concentration On New Particle Formationsupporting

confidence: 83%

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New particle formation above a simulated salt lake in aerosol chamber experiments

Kamilli¹,

Ofner²,

Lendl³

et al. 2015

Environ. Chem.

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Environmental context. Deforestation in Western Australia beginning in the mid-19th century led to a considerable change of the land surface, and Western Australia is now suffering more often from droughts. Particle formation induced by salt lakes has been identified as a potential control factor for changed precipitation patterns. This study aims to determine key factors involved in the particle formation process by simulating a simplified salt lake in an aerosol chamber in the laboratory.Abstract. In recent field experiments, particle formation has been observed above salt lakes in Western Australia and related to changes in regional precipitation patterns. This work investigates the particle formation potential above a simulated salt lake in aerosol chamber experiments under various conditions. The salt lake mixture comprised fixed concentrations of NaBr, NaCl and Na 2 SO 4 , and varying concentrations of FeSO 4 and FeCl 3 . Further, an organic mixture of 1,8-cineol and limonene was added under dark and light conditions. Both the presence of organic compounds and of light were found to be essential for new particle formation in our experiments. There were clear indications for conversion of Fe II to Fe III , which suggests a Fenton-like reaction mechanism in the system. Contrary to the idea that a Fenton-like reaction mechanism might intensify the oxidation of organic matter, thus facilitating secondary organic aerosol formation, the observed particle formation started later and with lower intensity under elevated Fe II concentrations. The highest particle number concentrations were observed when excluding Fe II from the experiments. Chemical analysis of the formed aerosol confirmed the important role of the Fenton-like reaction for particle formation in this study. Ultrahigh-resolution mass spectrometry and Raman spectroscopy provide analytical proof for the formation of organosulfates and halogenated organic compounds in the experiments presented. Even though halogens and organic precursors are abundant in these experimental simulations, halogen-induced organic aerosol formation exists but seems to play a minor overall role in particle formation.

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Section: Discussionsupporting

confidence: 81%

Section: Effect Of Fe II Concentration On New Particle Formationsupporting

confidence: 83%

New particle formation above a simulated salt lake in aerosol chamber experiments

Kamilli¹,

Ofner²,

Lendl³

et al. 2015

Environ. Chem.

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“…Time variations of concentration of the generated PM in these experiments are shown in Figure 1(a). Particle density was assumed to be 1.4 g cm 3 in this study, following previous work [10,[34][35][36]. We also measured the chemical composition of the generated aerosols after 6 h of photooxidation in each experiment with the AMS as shown in Figure 1(b).…”

Section: 3mentioning

confidence: 99%

“…Wall deposition of particles in the chamber was similarly corrected as in the first chamber by using a regression equation to describe the dependence of deposition rate on the particle size [15]. And the detailed information about the equation was described in our previous studies [10,32]. Using the regression equation had very limited influence on particle concentrations (less than 1% for mean value).…”

Section: 1mentioning

confidence: 99%

“…The production of sulfate and nitrate depends on the concentration of the precursors as well as the levels of oxidants (or oxidation capacity) [9]. The characteristics of preexisting seed particles [10][11][12][13][14], and meteorological conditions [10,15] were also found to play important roles in secondary aerosol formation, resulting in a highly non-linear relationship between PM formation and precursors [16,17]. It is important to understand how these factors individually and collectively affect the production of secondary aerosols under different conditions [9].…”

Section: Introductionmentioning

confidence: 99%

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Secondary aerosol formation and oxidation capacity in photooxidation in the presence of Al2O3 seed particles and SO2

et al. 2015

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To investigate the sensitivity of secondary aerosol formation and oxidation capacity to NO x in homogeneous and heterogeneous reactions, a series of irradiated toluene/NO x /air and -pinene/NO x /air experiments were conducted in smog chambers in the absence or presence of Al 2 O 3 seed particles. Various concentrations of NO x and volatile organic compounds (VOCs) were designed to simulate secondary aerosol formation under different scenarios for NO x . Under "VOC-limited" conditions, the increasing NO x concentration suppressed secondary aerosol formation, while the increasing toluene concentration not only contributed to the increase in secondary aerosol formation, but also led to the elevated oxidation degree for the organic aerosol. Sulfate formation was suppressed with the increasing NO x due to a decreased oxidation capacity of the photooxidation system. Secondary organic aerosol (SOA) formation also decreased with the presence of high concentration of NO x , because organo-peroxy radicals (RO 2 ) react with NO x instead of with peroxy radicals (RO 2 or HO 2 ), resulting in the formation of volatile organic products. The increasing concentration of NO x enhanced the formation of sulfate, nitrate and SOA under "NO x -limited" conditions, in which the heterogeneous reactions played an important role. In the presence of Al 2 O 3 seed particles, a synergetic promoting effect of mineral dust and NO x on secondary aerosol formation in heterogeneous reactions was observed in the photooxidation. This synergetic effect strengthened the positive relationship between NO x and secondary aerosol formation under "NO x -limited" conditions but weakened or even overturned the negative relationship between NO x and secondary aerosol formation under "VOC-limited" conditions. Sensitivity of secondary aerosol formation to NO x seemed different in homogeneous and heterogeneous reactions, and should be both taken into account in the sensitivity study. The sensitivity of secondary aerosol formation to NO x was further investigated under "winter-like" and NH 3 -rich conditions. No obvious difference for the sensitivity of secondary aerosol formation except nitrate to NO x was observed. secondary aerosol, oxidation capacity, synergetic promoting effect, Al 2 O 3 seed particles, sensitivity

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Photooxidation of Methacrolein in Fe(III)-Oxalate Aqueous System and Its Atmospheric Implication

et al. 2021

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Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex (Fe(III)-Ox). The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(III)-Ox under solar irradiation. Although the photolysis mechanisms of Fe(III)-Ox have been investigated extensively, information about the oxidation of volatile organic compounds (VOC), specifically the potential for Secondary Organic Aerosol (SOA) formation in the Fe(III)-Ox system, is lacking. In this study, a ubiquitous VOC methacrolein (MACR) is chosen as a model VOC, and the oxidation of MACR with Fe(III)-Ox is investigated under typical atmospheric water conditions. The effects of oxalate concentration, Fe(III) concentration, MACR concentration, and pH on the oxidation of MACR are studied in detail. Results show that the oxidation rate of MACR greatly accelerates in the presence of oxalate when compared with only Fe(III). The oxidation rate of MACR also accelerates with increasing concentration of oxalate. The effect of Fe(III) is found to be more complicated. The oxidation rate of MACR first increases and then decreases with increasing Fe(III) concentration. The oxidation rate of MACR increases monotonically with decreasing pH in the common atmospheric water pH range or with decreasing MACR concentration. The production of ferrous and hydrogen peroxide, pH, and aqueous absorbance are monitored throughout the reaction process. The quenching experiments verify that • OH and are both responsible for the oxidation of MACR. MACR is found to rapidly oxidize into small organic acids with higher boiling points and oligomers with higher molecular weight, which contributes to the yield of SOA. These results suggest that Fe(III)-Ox plays an important role in atmospheric oxidation.

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Decreasing effect and mechanism of FeSO 4 seed particles on secondary organic aerosol in α -pinene photooxidation

Cited by 28 publications

References 52 publications

New particle formation above a simulated salt lake in aerosol chamber experiments

New particle formation above a simulated salt lake in aerosol chamber experiments

Secondary aerosol formation and oxidation capacity in photooxidation in the presence of Al2O3 seed particles and SO2

Photooxidation of Methacrolein in Fe(III)-Oxalate Aqueous System and Its Atmospheric Implication

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