Auflistung nach Autor:in "Heringa, Maarten F."
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- PublikationA new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra(Copernicus, 2012) Heringa, Maarten F.; DeCarlo, Peter F.; Chirico, Roberto; Tritscher, Torsten; Clairotte, Michael; Mohr, Christine; Crippa, Monica; Slowik, Jay Gates; Pfaffenberger, Lisa; Dommen, Josef; Weingartner, Ernest; Prévôt, André; Baltensperger, Urs [in: Atmospheric Chemistry and Physics]Abstract. Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25–0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate experiments on the first two principal components (PCs), which explained 79% of the total variance. Projection of ambient SV-OOA spectra resolved by positive matrix factorization (PMF) showed that this approach could be useful to identify large contributions of the tested SOA sources to SV-OOA. The first results from this study indicate that the SV-OOA in Barcelona is strongly influenced by diesel emissions in winter while in summer at SIRTA at the southwestern edge of Paris SV-OOA is more similar to alpha-pinene SOA. However, contributions to the ambient SV-OOA from SOA sources that are not covered by the model can cause major interference and therefore future expansions of the PCA model with additional SOA sources is recommended.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAerosol and trace gas vehicle emission factors measured in a tunnel using an Aerosol Mass Spectrometer and other on-line instrumentation(Elsevier, 04/2011) Chirico, Roberto; Prevot, Andre S.H.; DeCarlo, Peter F.; Heringa, Maarten F.; Richter, Rene; Weingartner, Ernest; Baltensperger, Urs [in: Atmospheric Environment]In this study we present measurements of gas and aerosol phase composition for a mixed vehicle fleet in the Gubrist tunnel (Switzerland) in June 2008. PM1 composition measurements were made with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS) and a Multi Angle Absorption Photometer (MAAP). Gas-phase measurements of CO, CO2, NOx and total hydrocarbons (THC) were performed with standard instrumentation. Weekdays had a characteristic diurnal pattern with 2 peaks in concentrations for all traffic related species corresponding to high vehicle density (∼300 ± 30 vehicles per 5 min) in the morning rush hour between 06:00 and 09:00 and in the afternoon rush hours from approximately 15:30 to 18:30. The emission factors (EF) of OA were heavily influenced by the OA mass loading. To exclude this partitioning effect, only organic aerosol mass concentrations from 60 μg m−3 to 90 μg m−3 were considered and for these conditions the EF(OA) value for HDV was 33.7 ± 2.3 mg km−1 for a temperature inside the tunnel of 20–25 °C. This value is not directly applicable to ambient conditions because it is derived from OA mass concentrations that are roughly a factor of 10 higher than typical ambient concentrations. An even higher EF(OA)HDV value of 47.4 ± 1.6 mg km−1 was obtained when the linear fit was applied to all data points including OA concentrations up to 120 μg m−3. Similar to the increasing EF, the OA/BC ratio in the tunnel was also affected by the organic loading and it increased by a factor of ∼3 over the OA range 10–120 μg m−3. This means that also the OA emission factors at ambient concentrations of around 5–10 μg m−3 would be 2–3 times lower than the emission factor given above. For OA concentrations lower than 40 μg m−3 the OA/BC mass ratio was below 1, while at an OA concentration of 100–120 μg m−3 the OA/BC ratio was ∼1.5. The AMS mass spectra (MS) acquired in the tunnel were highly correlated with the primary organic aerosol (POA) MS from a EURO 3 diesel vehicle with a speed similar to the average tunnel speed.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAging induced changes on NEXAFS fingerprints in individual combustion particles(Copernicus, 24.11.2011) Zelenay, V.; Mooser, R.; Tritscher, Torsten; Křepelová, A.; Heringa, Maarten F.; Chirico, Roberto; Prévôt, André S. H.; Weingartner, Ernest; Baltensperger, Urs; Dommen, Josef; Watts, B.; Raabe, J.; Huthwelker, T.; Ammann, M. [in: Atmospheric Chemistry and Physics]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, 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.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationChanges of hygroscopicity and morphology during ageing of diesel soot(Institute of Physics Publishing, 2011) Tritscher, Torsten; Jurányi, Zsófia; Martin, Maria; Chirico, Roberto; Gysel, Martin; Heringa, Maarten F.; DeCarlo, Peter F.; Sierau, Berko; Prévôt, André S. H.; Weingartner, Ernest; Baltensperger, Urs [in: Environmental Research Letters]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationEffect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles(Copernicus, 2013) Chou, Cédric; Kanji, Zamin A.; Stetzer, Olaf; Tritscher, Torsten; Chirico, Roberto; Heringa, Maarten F.; Weingartner, Ernest; Prévôt, André; Baltensperger, Urs; Lohmann, Ulrike [in: Atmospheric Chemistry and Physics]A measurement campaign (IMBALANCE) conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, −30 °C, −35 °C and −40 °C. Freshly emitted diesel particles showed ice formation only at −40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at −35 °C. Wood burning particles also act as ice nuclei (IN) at −40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at −35 °C whereas no ice nucleation was observed at −30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below −40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationHygroscopic properties of fresh and aged wood burning particles(Elsevier, 2013) Martin, Maria; Tritscher, Torsten; Jurányi, Zsófia; Heringa, Maarten F.; Sierau, Berko; Weingartner, Ernest; Chirico, Roberto; Gysel, Martin; Prévôt, André S.H.; Baltensperger, Urs; Lohmann, Ulrike [in: Journal of Aerosol Science]01A - Beitrag in wissenschaftlicher Zeitschrift