Changes of hygroscopicity and morphology during ageing of diesel soot

Tritscher, T.; Jurányi, Z.; Martin, M.; Chirico, R.; Gysel, M.; Heringa, M. F.; DeCarlo, P. F.; Sierau, B.; Prévôt, Andrê S. H.; Weingärtner, E.; Baltensperger, Urs

doi:10.1088/1748-9326/6/3/034026

Cited by 163 publications

(202 citation statements)

References 44 publications

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“…10. As discussed in detail by Tritscher et al (2011b), the measured growth factor depended on the particle size selected for the measurement. We show here only the case of 200 nm particles to represent the size range investigated here.…”

Section: Water Uptake In Soot Particlesmentioning

confidence: 95%

“…It was found that the formed SOA mass is significant: after five hours of aging about 80 % of the total organic aerosol was on average secondary. These measurements were complemented by Tritscher et al (2011b) who investigated the water uptake at sub-saturation and cloud condensation nuclei (CCN) activity of the fresh and photochemically aged soot from the same diesel passenger cars. Fresh diesel soot particles were found to be non-hygroscopic, i.e.…”

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confidence: 99%

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Aging induced changes on NEXAFS fingerprints in individual combustion particles

et al. 2011

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Abstract. Soot particles can significantly influence the Earth's climate by absorbing and scattering solar radiation as well as by acting as cloud condensation nuclei. However, despite their environmental (as well as economic and political) importance, the way these properties are affected by atmospheric processing of the combustion exhaust gases is still a subject of discussion. In this work, individual soot particles emitted from two different vehicles, a EURO 2 transporter, a EURO 3 passenger car, and a wood stove were investigated on a single-particle basis. The emitted exhaust, including the particulate and the gas phase, was processed in a smog chamber with artificial solar radiation. Single particle specimens of both unprocessed and aged soot were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and scanning electron microscopy. Comparison of NEXAFS spectra from the unprocessed particles and those resulting from exhaust photooxidation in the chamber revealed changes in the carbon functional group content. For the wood stove emissions, these changes were minor, related to the relatively mild oxidation conditions. For the EURO 2 transporter emissions, the most apparent change was that of carboxylic carbon from oxidized organic compounds condensing on the primary soot particles. For the EURO 3 car emissions oxidation of primary soot particles upon photochemical aging has likely contributed as well. Overall, Correspondence to: M. Ammann (markus.ammann@psi.ch) the changes in the NEXAFS fingerprints were in qualitative agreement with data from an aerosol mass spectrometer. Furthermore, by taking full advantage of our in situ microreactor concept, we show that the soot particles from all three combustion sources changed their ability to take up water under humid conditions upon photochemical aging of the exhaust. Due to the selectivity and sensitivity of the NEXAFS technique for the water mass, also small amounts of water taken up into the internal voids of agglomerated particles could be detected. Because such small amounts of water uptake do not lead to measurable changes in particle diameter, it may remain beyond the limits of volume growth measurements, especially for larger agglomerated particles.

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Section: Water Uptake In Soot Particlesmentioning

confidence: 95%

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confidence: 99%

Aging induced changes on NEXAFS fingerprints in individual combustion particles

et al. 2011

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“…The particles after the structural change (collapse) become less fractal or more compact, which results in decreased electrical mobility diameter, and thus leads to shrinkage (hygroscopic GF<1) or underestimated hygroscopicity obtained by diameter-based methods. The restructuring has been observed for different soot types (Weingartner et al, 1995;Tritscher et al, 2011) and for particles with a Dd >100 nm (Martin et al, 2012). The hygroscopic GF for the LH 15 mode increased monotonically and in a modest way (from 1.31 to 1.38) with particle size, while the fraction of particles in the LH mode increased with diameter from 29% to 59%.…”

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confidence: 81%

“…Particles with median dry diameters of 20,50,75,110 and 145 nm were preselected in a narrow quasi-monodisperse size range by a 10.9-cm long Vienna-type differential mobility analyser (DMA1). The dry diameters were selected considering the shape 20 of the particle number size distribution in Budapest to cover the Aitken and accumulation modes.…”

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confidence: 99%

Winter time hygroscopicity and volatility of ambient urban aerosol particles

Enroth¹,

Mikkilä²,

Németh³

et al. 2017

Preprint

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Abstract. Hygroscopic and volatile properties of atmospheric aerosol particles with dry diameters of (20), 50, 75, 110 and 145 nm were determined in situ by using a VH-TDMA system with a relative humidity of 90% and denuding temperature of 270 C in central Budapest during two months in winter 2014-2015. The probability density function of the hygroscopic growth factor (GF) showed a distinct bimodal distribution. One of the modes was characterised by an overall mean GF of 10 approximately 1.07 (the corresponding hygroscopicity parameter  of 0.033) independently of the particle size, and was assigned to nearly hydrophobic (NH) particles. Its mean particle number fraction was large, and it was decreasing monotonically from 71% to 41% with particle diameter. The other mode showed a mean GF increasing slightly from 1.31 to 1.38 ( values from 0.186 to 0.196) with particle diameter, and it was attributed to less hygroscopic (LH) particles. These hygroscopicity values are low in general. The mode with more hygroscopic particles was not identified. The probability density 15 function of the volatility GF also exhibited a distinct bimodal distribution with an overall mean volatility GF of approximately 0.96 independently of the particle size, and with another mean GF increasing from 0.49 to 0.55 with particle diameter. The two modes were associated with less volatile (LV) and volatile (V) particles. The mean particle number fraction for the LV mode was decreasing from 34% to 21% with particle diameter. The bimodal distributions in the GF spectrum indicated that the urban atmospheric aerosol contained an external mixture of particles with a diverse chemical composition. The mean 20 diurnal variability of the particle number fractions for the NH and LV modes, and of the volatility GF for the LV mode followed the diurnal pattern of the vehicular road traffic, while the mean diurnal variability of the hygroscopicity parameter for the NH, and of the particle number fractions for the V mode on workdays were inversely linked to the road traffic. The particles corresponding to the NH and LV modes were assigned mainly to freshly emitted combustion particles, more specifically to vehicle emissions consisting of large mass fractions of soot likely coated with or containing some water-insoluble organic 25 compounds such as non-hygroscopic hydrocarbon-like organics. The particles related to the LH and V modes could be composed of moderately transformed aged combustion particles consisting of partly oxygenated organics, inorganic salts and soot. Both regional background sources and urban (local) emissions contribute to these particles. Dependency of the volatility GF and the volume fraction remaining after the thermal treatment on the mean hygroscopic GF suggested that the hygroscopic compounds were ordinarily volatile, and that the larger particles contained internally mixed non-volatile chemical species as 30 refractory residuals in 20-25% of the aerosol material (by volume), which could be core-like soot or organic polymers.

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“…At sites like CES, which are classified as background sites but located relatively close to 25 urban agglomerations (20 and 30 km from Rotterdam and Utrecht, respectively), the observed organic matter might have been processed sufficiently to become more hygroscopic than what is normally observed in the urban environment (e.g., Ervens et al, 2010). For black carbon (BC) we use κ = 0 (e.g., Hitzenberger et al, 2003;Rose et al, 2011;Tritscher et al, 2011).…”

Section: Hygroscopicity Parameter Kappa (κ) and Ccn Closurementioning

confidence: 99%

What do we learn from long-term cloud condensation nuclei number concentration, particle number size distribution, and chemical composition measurements at regionally representative observatories?

Schmale

Henning

Decesari

et al. 2017

Preprint

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Abstract.Aerosol-cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN). Numerous observations of CCN number concentration exist, and many closure studies have been performed to predict CCN number concentrations based on particle number size 5 distributions, chemical composition, and the κ-Köhler theory. Most of these studies provide details for short time periods or focus on special environmental conditions. These observations, however, cannot address questions of large-scale temporal and spatial CCN variability. Here we analyze long-term observations of CCN number concentrations, particle number size distributions and chemical composition from twelve sites on three continents. Eight of these stations are part of the European Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS). 10We group the observatories into categories according to their official classification: coastal background (Barrow, Alaska; Mace Head, Ireland; Finokalia, Crete; Noto Peninsula, Japan), rural background (Melpitz, Germany; Cabauw, the Netherlands; Vavihill, Sweden), alpine sites (Puy de Dôme, France; Jungfraujoch, Switzerland), remote forest sites (ATTO, Brazil; SMEAR, Finland) and the urban environment (Seoul, South Korea). Expectedly, CCN characteristics are highly variable across regions. However, they also vary within categories, most strongly in the coastal background group, where 15 CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behavior, most continental stations exhibit very similar relative activation ratios across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the activation ratios spread more widely across the SS spectrum.Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g., atBarrow (Arctic Haze in spring), at the alpine stations (stronger influence of polluted boundary layer air masses in summer), 20 the rain forest (wet and dry season), or Finokalia (forest fire influence in fall). The rural background and urban sites exhibit relatively little variability throughout the year while short-term variability can be high especially at the urban site.The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles, was highest at the coastal site of Mace Head (0.6) and the lowest at the rain forest station ATTO (0.2 -0.3). We performed closure studies to predict CCN number concentrations from the particle number size distribution and chemical composition measurements. 25The prediction accuracy for the average concentrations is high. The ratio between predicted and measured CCN concentrations is between 0.87 and 1.4. The temporal variability is also well represented, as reflected by Pearson c...

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Changes of hygroscopicity and morphology during ageing of diesel soot

Cited by 163 publications

References 44 publications

Aging induced changes on NEXAFS fingerprints in individual combustion particles

Aging induced changes on NEXAFS fingerprints in individual combustion particles

Winter time hygroscopicity and volatility of ambient urban aerosol particles

What do we learn from long-term cloud condensation nuclei number concentration, particle number size distribution, and chemical composition measurements at regionally representative observatories?

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