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Secondary Organic A...
Secondary Organic Aerosol (SOA) from Photo-Oxidation of Toluene: 1 Influence of Reactive Nitrogen, Acidity and Water Vapours on Optical Properties
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- Mitra, Kalyan (författare)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi och molekylärbiologi,Department of Chemistry and Molecular Biology
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Mishra, Harsh Raj (författare)
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Pei, Xiangyu (författare)
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- Pathak, Ravi K. (författare)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi och molekylärbiologi,Department of Chemistry and Molecular Biology
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(creator_code:org_t)
- 2022-07-13
- 2022
- Engelska.
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:7
- Relaterad länk:
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https://gup.ub.gu.se...
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https://doi.org/10.3...
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Abstract
Ämnesord
Stäng
- Many climate models treat the light-absorbing SOA component called “brown carbon” (BrC) as non-light absorbing because its formation and transformations are poorly understood. We therefore investigated the influence of reactive nitrogen (NOx, NH3)-, acidity (H2SO4)-, and water-mediated chemistry on SOA formed by the photo-oxidation of toluene, the subsequent formation and transformation of BrC, and its optical properties. We discovered that nitrogen-poor (NP) SOA is formed when the molar ratio of NOx to reacted toluene (henceforth, [NOx/ΔHC]) is 0.15 or less, whereas nitrogen-rich (NR) SOA is formed when [NOx/ΔHC] > 0.15. NR and NP SOA have markedly different characteristics. The light absorption coefficient (Babs) and mass absorption cross-section (MAC) of the SOA increased with [NOx/ΔHC] under both the NP and NR regimes. For NP SOA, the MAC increased with [NOx/ΔHC] independently of the relative humidity (RH). However, the MAC of NR SOA was RH-dependent. Under both NP and NR regimes, acidity promoted SOA browning while NH3 increased Babs and MAC at 80% RH. The highest MAC was observed at the lowest RH (20%) for acidic NR SOA, and it was postulated that the MAC of SOA depends mainly on the pH and the [H+]free/[SOA mass] ratio of the aqueous SOA phase.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)
Nyckelord
- ammonia ramping
- nitrogen-poor (NP)
- nitrogen-rich (NR)
- NO ramping x
- photo-oxidation
- secondary organic aerosol (SOA)
- sulfuric acid
- switching optical property
- toluene
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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