Ice‐nucleating particle emissions from photochemically aged diesel and biodiesel exhaust

Schill, G. P.; Jathar, Shantanu H.; Kodros, John K.; Levin, Ezra J. T.; Galang, A.; Friedman, Beth; Link, Michael F.; Farmer, Delphine K.; Pierce, Jeffrey R.; Kreidenweis, Sonia M.; DeMott, Paul J.

doi:10.1002/2016gl069529

Cited by 52 publications

(92 citation statements)

References 44 publications

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“…Some held the view that BC is not an efficient ice nucleation active species (Kamphus et al, 2010;Schill et al, 2016), whereas some described BC particles as possible INP (Cozic et al, 2008(Cozic et al, , 2007). …”

Section: Particle Number Concentrationsmentioning

confidence: 99%

“…Chou et al (2013) observed that soot particles from diesel engines and wood burning form ice at −40 • C, and unrealistically high relative humidity (RH) was needed for freezing initiation above this temperature. Schill et al (2016) showed that neither fresh nor aged emissions from diesel engines contributed appreciably to atmospheric INP concentrations. However, some studies considered BC-containing particles as possible INP (Cozic et al, 2008;Levin et al, 2016;Cozic et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

Chen

Augustin-Bauditz

et al. 2018

Atmos. Chem. Phys.

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Abstract. Exceedingly high levels of PM 2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM 2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number concentration of INP (N INP ) in the range from −6 to −25 • C in Beijing. No correlations between N INP and either PM 2.5 or black carbon mass concentrations were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between N INP and either total particle number concentration or number concentrations for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing air pollution did not increase or decrease INP concentrations in the examined temperature range above values observed in nonurban areas; hence, the background INP concentrations might not be anthropogenically influenced as far as urban air pollution is concerned, at least in the examined temperature range.

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Section: Particle Number Concentrationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

Chen

Augustin-Bauditz

et al. 2018

Atmos. Chem. Phys.

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“…We follow Schill et al (2016) for correcting sample concentrations for background and for defining confidence intervals for CFDC data, which are represented by error bars in presented plots. Specifically, corrected INP concentrations are the sample concentrations with the interpolated background concentrations subtracted.…”

Section: Colorado State University Cfdcsmentioning

confidence: 99%

Comparative measurements of ambient atmospheric concentrations of ice nucleating particles using multiple immersion freezing methods and a continuous flow diffusion chamber

et al. 2017

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Abstract. A number of new measurement methods for ice nucleating particles (INPs) have been introduced in recent years, and it is important to address how these methods compare. Laboratory comparisons of instruments sampling major INP types are common, but few comparisons have occurred for ambient aerosol measurements exploring the utility, consistency and complementarity of different methods to cover the large dynamic range of INP concentrations that exists in the atmosphere. In this study, we assess the comparability of four offline immersion freezing measurement methods (Colorado State University ice spectrometer, IS; North Carolina State University cold stage, CS; National Institute for Polar Research Cryogenic Refrigerator Applied to Freezing Test, CRAFT; University of British Columbia microorifice uniform deposit impactor-droplet freezing technique, MOUDI-DFT) and an online method (continuous flow diffusion chamber, CFDC) used in a manner deemed to promote/maximize immersion freezing, for the detection of INPs in ambient aerosols at different locations and in different sampling scenarios. We also investigated the comparability of different aerosol collection methods used with offline immersion freezing instruments. Excellent agreement between all methods could be obtained for several cases of co-sampling with perfect temporal overlap. Even for sampling periods that were not fully equivalent, the deviations between atmospheric INP number concentrations measured with different methods were mostly less than 1 order of magnitude. In some cases, however, the deviations were larger and not explicable without sampling and measurement artifacts. Overall, the immersion freezing methods seem toPublished by Copernicus Publications on behalf of the European Geosciences Union. , although more comparisons are needed in this temperature regime that is difficult to access with online methods. Relative to the CFDC method, three immersion freezing methods that disperse particles into a bulk liquid (IS, CS, CRAFT) exhibit a positive bias in measured INP number concentrations below −20 • C, increasing with decreasing temperature. This bias was present but much less pronounced for a method that condenses separate water droplets onto limited numbers of particles prior to cooling and freezing (MOUDI-DFT). Potential reasons for the observed differences are discussed, and further investigations proposed to elucidate the role of all factors involved.

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“…The former study reported evidence for the incorporation of nitrogen into SOA. OFRs have also been increasingly employed to process emissions of vehicles, biomass burning, and other combustion sources (Table 1) in which NO can often be hundreds of ppm Martinsson et al, 2015;Karjalainen et al, 2016;Link et al, 2016;Schill et al, 2016;Alanen et al, 2017;Simonen et al, 2017). It can be expected that such a high NO input together with very high VOC concentrations would cause a substantial deviation from the good OFR operation conditions identified in Peng et al (2016).…”

Section: Introductionmentioning

confidence: 99%

Modeling of the chemistry in oxidation flow reactors with high initial NO

Peng

Jimenez

2017

Atmos. Chem. Phys.

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Abstract. Oxidation flow reactors (OFRs) are increasingly employed in atmospheric chemistry research because of their high efficiency of OH radical production from low-pressure Hg lamp emissions at both 185 and 254 nm (OFR185) or 254 nm only (OFR254). OFRs have been thought to be limited to studying low-NO chemistry (in which peroxy radicals (RO 2 ) react preferentially with HO 2 ) because NO is very rapidly oxidized by the high concentrations of O 3 , HO 2 , and OH in OFRs. However, many groups are performing experiments by aging combustion exhaust with high NO levels or adding NO in the hopes of simulating high-NO chemistry (in which RO 2 + NO dominates). This work systematically explores the chemistry in OFRs with high initial NO. Using box modeling, we investigate the interconversion of Ncontaining species and the uncertainties due to kinetic parameters. Simple initial injection of NO in OFR185 can result in more RO 2 reacted with NO than with HO 2 and minor non-tropospheric photolysis, but only under a very narrow set of conditions (high water mixing ratio, low UV intensity, low external OH reactivity (OHR ext ), and initial NO concentration (NO in ) of tens to hundreds of ppb) that account for a very small fraction of the input parameter space. These conditions are generally far away from experimental conditions of published OFR studies with high initial NO. In particular, studies of aerosol formation from vehicle emissions in OFRs often used OHR ext and NO in several orders of magnitude higher. Due to extremely high OHR ext and NO in , some studies may have resulted in substantial non-tropospheric photolysis, strong delay to RO 2 chemistry due to peroxynitrate formation, VOC reactions with NO 3 dominating over those with OH, and faster reactions of OH-aromatic adducts with NO 2 than those with O 2 , all of which are irrelevant to ambient VOC photooxidation chemistry. Some of the negative effects are the worst for alkene and aromatic precursors. To avoid undesired chemistry, vehicle emissions generally need to be diluted by a factor of > 100 before being injected into an OFR. However, sufficiently diluted vehicle emissions generally do not lead to high-NO chemistry in OFRs but are rather dominated by the low-NO RO 2 + HO 2 pathway. To ensure high-NO conditions without substantial atmospherically irrelevant chemistry in a more controlled fashion, new techniques are needed.

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Ice‐nucleating particle emissions from photochemically aged diesel and biodiesel exhaust

Cited by 52 publications

References 44 publications

Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

Comparative measurements of ambient atmospheric concentrations of ice nucleating particles using multiple immersion freezing methods and a continuous flow diffusion chamber

Modeling of the chemistry in oxidation flow reactors with high initial NO

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