The fuel of atmospheric chemistry: Toward a complete description of reactive organic carbon

Heald, Colette L.; Kroll, J. H.

doi:10.1126/sciadv.aay8967

Cited by 98 publications

(97 citation statements)

References 89 publications

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“…Particulate matter (PM), or aerosol, impacts human health, ecosystem health, visibility, climate, cloud formation and lifetime, and atmospheric chemistry (Meskhidze et al, 2003;Abbatt et al, 2006;Seinfeld. and Pandis, 2006;Jimenez et al, 2009;Myhre et al, 2013;Cohen et al, 2017;Hodzic and Duvel, 2018;Heald and Kroll, 2020;Pye et al, 2020) . Quantitative measurements of the chemical composition and aerosol mass concentration are necessary to understand these impacts and to constrain and improve chemical transport models (CTMs).…”

Section: Introductionmentioning

confidence: 99%

Interferences on Aerosol Acidity Quantification due to Gas-phase Ammonia Uptake onto Acidic Sulfate Filter Samples

Nault¹,

Campuzano‐Jost²,

Day³

et al. 2020

Preprint

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Abstract. Measurements of the mass concentration and chemical speciation of aerosols are important to investigate their chemical and physical processing from near emission sources to the most remote regions of the atmosphere. A common method to analyze aerosols is to collect them onto filters and to analyze filters off-line; however, biases in some chemical components are possible due to changes in the accumulated particles during the handling of the samples. Any biases would impact the measured chemical composition, which in turn affects our understanding of numerous physico-chemical processes and aerosol radiative properties. We show, using filters collected onboard the NASA DC-8 and NSF C-130 during six different aircraft campaigns, a consistent, substantial difference in ammonium mass concentration and ammonium-to-anion ratios, when comparing the aerosols collected on filters versus the Aerodyne Aerosol Mass Spectrometer (AMS). Another on-line measurement is consistent with the AMS in showing that the aerosol has lower ammonium-to-anion ratios than obtained by the filters. Using a gas uptake model with literature values for accommodation coefficients, we show that for ambient ammonia mixing ratios greater than 10 ppbv, the time scale for ammonia reacting with acidic aerosol on filter substrates is less than 30 s (typical filter handling time in the aircraft) for typical aerosol volume distributions. Measurements of gas-phase ammonia inside the cabin of the DC-8 show ammonia mixing ratios of 45 ± 20 ppbv, consistent with mixing ratios observed in other indoor environments. This analysis enables guidelines for filter handling to reduce ammonia uptake. Finally, a more meaningful limit-of-detection for filters that either do not have an ammonia scrubber and/or are handled in the presence of human emissions is ∼0.2 μg m−3 ammonium, which is substantially higher than the limit-of-detection of the ion chromatography.

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Section: Introductionmentioning

confidence: 99%

Interferences on Aerosol Acidity Quantification due to Gas-phase Ammonia Uptake onto Acidic Sulfate Filter Samples

Nault¹,

Campuzano‐Jost²,

Day³

et al. 2020

Preprint

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“…SOA can make up over 50% of submicron aerosol mass (Jimenez et al., 2009), but we still have significant uncertainty in the exact chemical makeup, and models still fail to accurately simulate it (Hodzic et al., 2020; Tsigaridis et al., 2014). Unfortunately, many thousands of different NMVOC species have been identified in the atmosphere, and many more are yet to be discovered, making a complete representation of all NMVOC species and their chemistry in a model an impossible task (Goldstein & Galbally, 2007; Heald & Kroll, 2020).…”

Section: Introductionmentioning

confidence: 99%

The Common Representative Intermediates Mechanism Version 2 in the United Kingdom Chemistry and Aerosols Model

Archer‐Nicholls

Abraham

Shin

et al. 2021

J Adv Model Earth Syst

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We document the implementation of the Common Representative Intermediates Mechanism version 2, reduction 5 into the United Kingdom Chemistry and Aerosol model (UKCA) version 10.9. The mechanism is merged with the stratospheric chemistry already used by the StratTrop mechanism, as used in UKCA and the UK Earth System Model, to create a new CRI-Strat mechanism. CRI-Strat simulates a more comprehensive treatment of non-methane volatile organic compounds (NMVOCs) and provides traceability with the Master Chemical Mechanism. In total, CRI-Strat simulates the chemistry of 233 species competing in 613 reactions (compared to 87 species and 305 reactions in the existing StratTrop mechanism). However, while more than twice as complex than StratTrop, the new mechanism is only 75% more computationally expensive. CRI-Strat is evaluated against an array of in situ and remote sensing observations and simulations using the StratTrop mechanism in the UKCA model. It is found to increase production of ozone near the surface, leading to higher ozone concentrations compared to surface observations. However, ozone loss is also greater in CRI-Strat, leading to less ozone away from emission sources and a similar tropospheric ozone burden compared to StratTrop. CRI-Strat also produces more carbon monoxide than StratTrop, particularly downwind of biogenic VOC emission sources, but has lower burdens of nitrogen oxides as more is converted into reservoir species. The changes to tropospheric ozone and nitrogen budgets are sensitive to the treatment of NMVOC emissions, highlighting the need to reduce uncertainty in these emissions to improve representation of tropospheric chemical composition. Plain Language SummaryTo understand the climate and predict how it will change in the future, we need to understand its chemical composition-the trace gases and small particles that exist in tiny quantities in the atmosphere. A key tool we use to do this are computer models which simulate the atmosphere and processes within it. Key processes include the formation of ozone, a harmful pollutant and greenhouse gas in the lower atmosphere. However, the chemistry involved in forming ozone is very complicated, so computer simulations of the atmosphere must greatly simplify the chemistry. These simple schemes may introduce errors in the model. We also have much more complex chemical mechanisms which simulate our best understanding of all chemical reactions, but these complex schemes require too much computational power to be used when simulating the whole atmosphere. In this paper, we describe the implementation of a chemical mechanism that sits between these levels of complexity, realistically simulating the formation and destruction of ozone without being too slow to run. We compare this new mechanism against measurements taken of the atmosphere and the preexisting, simpler chemical mechanism and show that the new mechanism greatly enhances the amount of ozone that is produced.

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“…The oxidation of VOCs produces lower vapor pressure compounds that form secondary organic aerosol (SOA) through condensation onto preexisting particles, through new particle formation and growth (Seinfeld and Pankow, 2003) and through aqueous oxidation processes in aerosol or cloud water (Ervens et al, 2011). The fate of approximately half the VOC emissions entering the atmosphere cannot be observationally accounted for, and this discrepancy is likely at least partially due to a lack of comprehensive measurements of speciated organic constituents in a variety of atmospherically distinct environments (Goldstein and Galbally, 2007;Hallquist et al, 2009;Heald and Kroll, 2020).…”

Section: Introductionmentioning

confidence: 99%

Development of an In Situ Dual-Channel Thermal Desorption Gas Chromatography Instrument for Consistent Quantification of Volatile, Intermediate Volatility and Semivolatile Organic Compounds

Wernis¹,

Kreisberg²,

Weber³

et al. 2021

Preprint

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Abstract. Aerosols are a source of great uncertainty in radiative forcing predictions and have poorly understood health impacts. Most aerosol mass is formed in the atmosphere from reactive gas phase organic precursors, forming secondary organic aerosol (SOA). Semivolatile organic compounds (SVOCs) (effective saturation concentration, C*, of 10−1–103 μg m−3) comprise a large fraction of organic aerosol, while intermediate volatility organic compounds (IVOCs) (C* of 103–106 μg m−3) and volatile organic compounds (VOCs) (C* ≥ 106 μg m−3) are gas phase precursors to SOA and ozone. The Comprehensive Thermal Desorption Aerosol Gas Chromatograph (cTAG) is the first single instrument simultaneously quantitative for a broad range of compound-specific VOCs, IVOCs and SVOCs. cTAG is a two-channel instrument which measures concentrations of C5–C16 alkane equivalent volatility VOCs and IVOCs on one channel and C14–C32 SVOCs on the other coupled to a single High Resolution Time of Flight Mass Spectrometer, achieving consistent quantification across 15 orders of magnitude of vapor pressure. cTAG obtains concentrations hourly and gas–particle partitioning for SVOCs bihourly, enabling observation of the evolution of these species through oxidation and partitioning into the particle phase. Online derivatization for the SVOC channel enables detection of more polar and oxidized species. In this work we present design details and data evaluating key parameters of instrument performance such as I/VOC collector design optimization, linearity and reproducibility of calibration curves obtained using a custom liquid evaporation system for I/VOCs and the effect of an ozone removal filter on instrument performance. Example timelines of precursors with secondary products are shown and analysis of a subset of compounds detectable by cTAG demonstrates some of the analytical possibilities with this instrument.

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The fuel of atmospheric chemistry: Toward a complete description of reactive organic carbon

Cited by 98 publications

References 89 publications

Interferences on Aerosol Acidity Quantification due to Gas-phase Ammonia Uptake onto Acidic Sulfate Filter Samples

Interferences on Aerosol Acidity Quantification due to Gas-phase Ammonia Uptake onto Acidic Sulfate Filter Samples

The Common Representative Intermediates Mechanism Version 2 in the United Kingdom Chemistry and Aerosols Model

Development of an In Situ Dual-Channel Thermal Desorption Gas Chromatography Instrument for Consistent Quantification of Volatile, Intermediate Volatility and Semivolatile Organic Compounds

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