Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

Kroll, J. H.; Donahue, Neil M.; Jimenez, José L.; Kessler, Seymour; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, J. D.; Kolb, C. E.; Worsnop, Douglas R.

doi:10.1038/nchem.948

Cited by 970 publications

(1,120 citation statements)

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“…2b). The secondary nature of organic coatings observed in the afternoon peak was supported by the diurnal cycles of O / C, H / C, and average carbon oxidation state (OS c ≈ 2O / C -H / C; Kroll et al, 2011) of total OA (Fig. 2d).…”

Section: Chemical Characteristics Of Rbc Coating Materialsmentioning

confidence: 86%

Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

Lee

Chen

et al. 2017

Atmos. Chem. Phys.

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Abstract. Black carbon (BC) emitted from incomplete combustion can result in significant impacts on air quality and climate. Understanding the mixing state of ambient BC and the chemical characteristics of its associated coatings is particularly important to evaluate BC fate and environmental impacts. In this study, we investigate the formation of organic coatings on BC particles in an urban environment (Fontana, California) under hot and dry conditions using a soot-particle aerosol mass spectrometer (SP-AMS). The SP-AMS was operated in a configuration that can exclusively detect refractory BC (rBC) particles and their coatings. Using the −log(NO x / NO y ) ratio as a proxy for photochemical age of air masses, substantial formation of secondary organic aerosol (SOA) coatings on rBC particles was observed due to active photochemistry in the afternoon, whereas primary organic aerosol (POA) components were strongly associated with rBC from fresh vehicular emissions in the morning rush hours. There is also evidence that cooking-related organic aerosols were externally mixed from rBC. Positive matrix factorization and elemental analysis illustrate that most of the observed SOA coatings were freshly formed, providing an opportunity to examine SOA coating formation on rBCs near vehicular emissions. Approximately 7-20 wt % of secondary organic and inorganic species were estimated to be internally mixed with rBC on average, implying that rBC is unlikely the major condensation sink of SOA in this study. Comparison of our results to a co-located standard high-resolution time-offlight aerosol mass spectrometer (HR-ToF-AMS) measurement suggests that at least a portion of SOA materials condensed on rBC surfaces were chemically different from oxygenated organic aerosol (OOA) particles that were externally mixed with rBC, although they could both be generated from local photochemistry.

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Section: Chemical Characteristics Of Rbc Coating Materialsmentioning

confidence: 86%

Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

Lee

Chen

et al. 2017

Atmos. Chem. Phys.

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“…The O : C range can be extended up to 2 (for CO 2 ). However, there are only a few atmospheric organic compounds with O : C higher than unity and the observed O : C of ambient OA rarely exceeds 1.1 (Ng et al, 2010;Kroll et al, 2011). The ability of ORACLE 2-D to simulate the degree of oxidation of OA allows for the simulation of its hygroscopicity by using proposed parameterizations that link the hygroscopicity parameter kappa with the O : C of OA Lambe et al, 2011;Kuwata and Lee, 2017).…”

Section: Module Overviewmentioning

confidence: 99%

ORACLE 2-D (v2.0): an efficient module to compute the volatility and oxygen content of organic aerosol with a global chemistry–climate model

et al. 2018

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Abstract. A new module, ORACLE 2-D, simulating organic aerosol formation and evolution in the atmosphere has been developed and evaluated. The module calculates the concentrations of surrogate organic species in two-dimensional space defined by volatility and oxygen-to-carbon ratio. It is implemented into the EMAC global chemistry-climate model, and a comprehensive evaluation of its performance is conducted using an aerosol mass spectrometer (AMS) factor analysis dataset derived from almost all major field campaigns that took place globally during the period 2001-2010. ORACLE 2-D uses a simple photochemical aging scheme that efficiently simulates the net effects of fragmentation and functionalization of the organic compounds. The module predicts not only the mass concentration of organic aerosol (OA) components, but also their oxidation state (in terms of O : C), which allows for their classification into primary OA (POA, chemically unprocessed), fresh secondary OA (SOA, low oxygen content), and aged SOA (highly oxygenated). The explicit simulation of chemical OA conversion from freshly emitted compounds to a highly oxygenated state during photochemical aging enables the tracking of hygroscopicity changes in OA that result from these reactions. OR-ACLE 2-D can thus compute the ability of OA particles to act as cloud condensation nuclei and serves as a tool to quantify the climatic impact of OA.

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“…1B is built on the 2D volatility basis set (2D-VBS) framework. The 2D-VBS classifies organics based on volatility (C Ã ) and oxidation extent (1,(28)(29)(30). To construct a lumped mechanism, described in detail in the SI Text, we discretize this 2D space into bins and consider the changes to C Ã and O∶C caused by OH oxidation.…”

Section: Modelmentioning

confidence: 99%

Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions

Donahue

Henry

Mentel

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The Multiple Chamber Aerosol Chemical Aging Study (MUCHA-CHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described by a mechanism suitable for implementation in those models.atmospheric chemistry | biosphere-atmosphere interactions O rganic aerosol (OA) comprises a large fraction of fine-particle mass (PM 2.5 ) (1). In the developed world, 1-2% of deaths are blamed on inhalation of PM 2.5 (2), and the leading uncertainty in climate forcing is the interplay between the number of fine particles large enough to nucleate cloud droplets and the amount of sunlight reflected by those clouds (3). Oxidation and condensation of organics play a major but uncertain role in both phenomena.Traditional models treat most OA as nonvolatile primary OA (POA), augmented by secondary OA (SOA) (4), and they underpredict OA concentrations by a factor of 3-10 (5). α-Pinene is a major biogenic SOA source, sometimes used to represent all SOA in global models (4, 6). However, less than 20% of the carbon from fresh α-pinene oxidation condenses in chambers at room temperature; (7) the remainder is gaseous (Fig. 1A). This "chamber" SOA is modestly oxidized, with an oxygen to carbon ratio ðO∶CÞ < 0.4 (7). It is unambiguously semivolatile: Yields rise with increasing SOA mass loading (8, 9) and decreasing temperature (10), and the SOA evaporates upon heating (11-13) and after isothermal dilution (14).In contrast, ambient OA is highly oxidized (0.5 ≤ O∶C ≤ 1.0) (1, 15) and not very volatile (16). Ambient SOA is much less volatile than ambient POA (16). Consequently, "chamber" SOA does not represent the atmosphere. Our hypothesis is that homogeneous gas-phase aging by OH is a major missing process connecting chamber studies to the atmosphere. Considerable attention has been paid to heterogeneous uptake of oxidants to particles (17, 18), and recently gas-phase oxidation of semivolatile primary emissions (19), but the degree to which gas-phase oxidation can age chamber SOA is uncertain (1,4,18,20).OA resides in the atmosphere for about one week (21), while the gas-phase lifetimes of major semivolatile SOA constituents are far shorter. Typical α-pinene products pinonaldehyde, cispinonic acid, and pinic acid all have lifetimes of only a few hours for summertime conditions (22). Without question, oxidation of semivolatile SOA vapors will perturb the equilibrium phase partitioning of these constituents. Because almost all of the first-generation products are less volatile than α...

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Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

Abstract: and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state 39 and carbon number (n C ).

Cited by 970 publications

References 45 publications

Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

ORACLE 2-D (v2.0): an efficient module to compute the volatility and oxygen content of organic aerosol with a global chemistry–climate model

Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions

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