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Found 37 results
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2013
[Karl2013] Karl, T., A. Hansel, L. Cappellin, L. Kaser, I. Herdlinger-Blatt, and W. Jud, "BVOC measurements based on NO+ ionization", CONFERENCE SERIES, pp. 84, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
2012
[Mueller2012] Müller, M., M. Graus, A. Wisthaler, A. Hansel, A. Metzger, J. Dommen, and U. Baltensperger, "Analysis of high mass resolution PTR-TOF mass spectra from 1, 3, 5-trimethylbenzene (TMB) environmental chamber experiments", Atmospheric Chemistry and Physics, vol. 12, no. 2: Copernicus GmbH, pp. 829–843, 2012.
Link: http://www.atmos-chem-phys.net/12/829/
Abstract
A series of 1,3,5-trimethylbenzene (TMB) photo-oxidation experiments was performed in the 27-m3 Paul Scherrer Institute environmental chamber under various NOx conditions. A University of Innsbruck prototype high resolution Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF) was used for measurements of gas and particulate phase organics. The gas phase mass spectrum displayed  200 ion signals during the TMB photo-oxidation experiments. Molecular formulas CmHnNoOp were determined and ion signals were separated and grouped according to their C, O and N numbers. This allowed to determine the time evolution of the O:C ratio and of the average carbon oxidation state OSC of the reaction mixture. Both quantities were compared with master chemical mechanism (MCMv3.1) simulations. The O:C ratio in the particle phase was about twice the O:C ratio in the gas phase. Average carbon oxidation states of secondary organic aerosol (SOA) samples OSCSOA were in the range of −0.34 to −0.31, in agreement with expected average carbon oxidation states of fresh SOA (OSC = −0.5–0).
[Bamberger2012] Bamberger, I., L. Hoertnagl, T. Ruuskanen, R. Schnitzhofer, M. Müller, M. Graus, T. Karl, G. Wohlfahrt, and A. Hansel, "Deposition of terpenes to vegetation-a paradigm shift towards bidirectional VOC exchange?", EGU General Assembly Conference Abstracts, vol. 14, pp. 7949, 2012.
Link: http://adsabs.harvard.edu/abs/2012EGUGA..14.7949B
Abstract
Biogenic volatile organic compounds (BVOCs) are important precursors for secondary organic aerosol (SOA) formation (Hallquist et al., 2009). In addition reactive BVOCs play a crucial role in local tropospheric ozone production (Atkinson, 2000). According to the present scientific understanding vegetation is recognized as a major VOC emission source rather than a deposition sink. Our recent observations however demonstrate that an uptake of terpene compounds to mountain grassland can be significant - at least under certain atmospheric conditions. After a severe hailstorm volume mixing ratios (VMR) of locally emitted terpene compounds originating from conifers located at the mountain slopes were strongly enhanced, even during daytime hours. Weeks after the hailstorm our PTR-MS and PTR-time-of-flight (PTR-TOF) instruments still measured deposition fluxes of monoterpenes (m/z 137.133), sesquiterpenes (m/z 205.195), and oxygenated terpenes (m/z 153.128) to the grassland. The total amount of terpenoids (on a carbon basis) deposited to the grassland during the weeks after the hailstorm is comparable to the total methanol emission of the entire growing season (Bamberger et al., 2011). These findings pose the question whether the terminology should be adjusted from VOC emission to VOC exchange.
[Karl2012] Karl, T., A. Hansel, L. Cappellin, L. Kaser, I. Herdlinger-Blatt, and W. Jud, "Selective measurements of isoprene and 2-methyl-3-buten-2-ol based on NO+ ionization mass spectrometry", Atmospheric Chemistry and Physics, vol. 12, no. 24: Copernicus GmbH, pp. 11877–11884, 2012.
Link: http://www.atmos-chem-phys.net/12/11877/2012/acp-12-11877-2012.html
Abstract
Biogenic VOC emissions are often dominated by 2-methyl-1,3-butadiene (isoprene) and 2-methyl-3-buten-2-ol (232 MBO). Here we explore the possibility to selectively distinguish these species using NO+ as a primary ion in a conventional PTR-MS equipped with an SRI unit. High purity of NO+ (>90%) as a primary ion was utilized in laboratory and field experiments using a conventional PTR-TOF-MS. Isoprene is ionized via charge transfer leading to the major product ion C5H8+ (>99%) (e.g. Spanel and Smith, 1998). 232 MBO undergoes a hydroxide ion transfer reaction resulting in the major product ion channel C5H9+ (>95%) (e.g. Amelynck et al., 2005). We show that both compounds are ionized with little fragmentation (>5%) under standard operating conditions. Typical sensitivities of 11.1 ± 0.1 (isoprene) and 12.9 ± 0.1 (232 MBO) ncps ppbv−1 were achieved, which correspond to limit of detections of 18 and 15 pptv respectively for a 10 s integration time. Sensitivities decreased at higher collisional energies. Calibration experiments showed little humidity dependence. We tested the setup at a field site in Colorado dominated by ponderosa pine, a 232 MBO emitting plant species. Our measurements confirm 232 MBO as the dominant biogenic VOC at this site, exhibiting typical average daytime concentrations between 0.2–1.4 ppbv. The method is able to detect the presence of trace levels of isoprene at this field site (90–250 ppt) without any interference from 232 MBO, which would not be feasible using H3O+ ionization chemistry, and which currently also remains a challenge for other analytical techniques (e.g. gas chromatographic methods).
2011
[Bamberger2011] Bamberger, I., L. Hörtnagl, TM. Ruuskanen, R. Schnitzhofer, M. Müller, M. Graus, T. Karl, G. Wohlfahrt, and A. Hansel, "Deposition fluxes of terpenes over grassland", Journal of Geophysical Research: Atmospheres (1984–2012), vol. 116, no. D14: Wiley Online Library, 2011.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2010JD015457/full
Abstract
Eddy covariance flux measurements were carried out for two subsequent vegetation periods above a temperate mountain grassland in an alpine valley using a proton-transfer-reaction-mass spectrometer (PTR-MS) and a PTR time-of-flight-mass spectrometer (PTR-TOF). In 2008 and during the first half of the vegetation period 2009 the volume mixing ratios (VMRs) for the sum of monoterpenes (MTs) were typically well below 1 ppbv and neither MT emission nor deposition was observed. After a hailstorm in July 2009 an order of magnitude higher amount of terpenes was transported to the site from nearby coniferous forests causing elevated VMRs. As a consequence, deposition fluxes of terpenes to the grassland, which continued over a time period of several weeks without significant reemission, were observed. For days without precipitation the deposition occurred at velocities close to the aerodynamic limit. In addition to monoterpene uptake, deposition fluxes of the sum of sesquiterpenes (SQTs) and the sum of oxygenated terpenes (OTs) were detected. Considering an entire growing season for the grassland (i.e., 1 April to 1 November 2009), the cumulative carbon deposition of monoterpenes reached 276 mg C m−2. This is comparable to the net carbon emission of methanol (329 mg C m−2), which is the dominant nonmethane volatile organic compound (VOC) emitted from this site, during the same time period. It is suggested that deposition of monoterpenes to terrestrial ecosystems could play a more significant role in the reactive carbon budget than previously assumed.
[Ruuskanen2011] Ruuskanen, TM., M. Müller, R. Schnitzhofer, T. Karl, M. Graus, I. Bamberger, L. Hoertnagl, F. Brilli, G. Wohlfahrt, and A. Hansel, "Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF", Atmos. Chem. Phys, vol. 11, pp. 611–625, 2011.
Link: http://www.atmos-chem-phys.net/11/611/2011/acp-11-611-2011.html
Abstract
Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5–20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+ – water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes.
2010
[Bamberger2010] Bamberger, I., L. Hörtnagl, R. Schnitzhofer, M. Graus, TM. Ruuskanen, M. Müller, J. Dunkl, G. Wohlfahrt, and A. Hansel, "BVOC fluxes above mountain grassland", Biogeosciences, vol. 7, no. 5: Copernicus GmbH, pp. 1413–1424, 2010.
Link: http://www.biogeosciences.net/7/1413/2010/bg-7-1413-2010.pdf
[Ruuskanen2010] Ruuskanen, TM., M. Müller, R. Schnitzhofer, T. Karl, M. Graus, I. Bamberger, L. Hoertnagl, F. Brilli, G. Wohlfahrt, and A. Hansel, "VOC Emission and Deposition Eddy Covariance Fluxes above Grassland using PTR-TOF", AGU Fall Meeting Abstracts, vol. 1, pp. 0219, 2010.
Link: http://adsabs.harvard.edu/abs/2010AGUFM.A53C0219R
Abstract
Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5-20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+ - water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes. The smallest reliable fluxes we determined were less than 0.1 nmol m-2 s-1, as in the case of sesquiterpene emissions from freshly cut grass. Terpenoids, including mono- and sesquiterpenes, were also deposited to the grassland before and after the harvesting. During cutting, total VOC emission fluxes up to 200 nmolC m-2 s-1 were measured. Methanol emissions accounted for half of the emissions of oxygenated VOCs and a third of the carbon of all measured VOC emissions during harvesting.
2009
[Graus2009] Graus, M., M. Müller, and A. Hansel, "Field performance and identification capability of the Innsbruck PTR-TOF", EGU General Assembly Conference Abstracts, vol. 11, pp. 10200, 2009.
Link: http://adsabs.harvard.edu/abs/2009EGUGA..1110200G
Abstract
Over the last one and a half decades Proton Transfer Reaction Mass Spectrometry (PTR-MS) [1, 2] has gained recognition as fast on-line sensor for monitoring volatile organic compounds (VOC) in the atmosphere. Sample collection is very straight forward and the fact that no pre-concentration is needed is of particular advantage for compounds that are notoriously difficult to pre-concentrate and/or analyze by gas chromatographic (GC) methods. Its ionization method is very versatile, i.e. all compounds that perform exothermic proton transfer with hydronium ions - and most VOCs do so - are readily ionized, producing quasi-molecular ions VOC.H+. In the quasi-molecular ion the elemental composition of the analyte compound is conserved and allows, in combination with some background knowledge of the sample, conclusions about the identity of that compound. De Gouw and Warneke (2007) [3] summarized the applicability of PTR-MS in atmospheric chemistry but they also pointed out shortcomings in the identification capabilities. Goldstein and Galbally (2007) [4] addressed the multitude of VOCs potentially present in the atmosphere and they emphasized the gasphase-to-aerosol partitioning of organic compounds (volatile and semi-volatile) in dependence of carbon-chain length and oxygen containing functional groups. In collaboration with Ionicon and assisted by TOFWERK we developed a PTR time-of-flight (PTR-TOF) instrument that allows for the identification of the atomic composition of oxygenated hydrocarbons by exact-mass determination. A detection limit in the low pptv range was achieved at a time resolution of one minute, one-second detection limit is in the sub-ppbv range. In 2008 the Innsbruck PTR-TOF was field deployed in the icebreaker- and helicopter based Arctic Summer Cloud Ocean Study (ASCOS) to characterize the organic trace gas composition of the High Arctic atmosphere. During the six-week field campaign the PTR-TOF was run without problems even under harsh conditions in the open water and during ice breaking. Continuous time-series of full mass spectra with a one minute time resolution were recorded throughout the campaign between August 2nd and September 7th 2008 running up to a net VOC data set of 745 hours. Over 370 mass peaks have been separated, about 340 show signal intensities above the 30 minute detection limit of  3pptv. Additionally we analyzed samples from nine helicopter based soundings providing vertical VOC profiles up to 3000 m.a.s.l. The performance of the newly developed instrument will be discussed and ASCOS data will be shown. Acknowledgment: The ASCOS expedition was arranged by the Swedish Polar Research Secretariat (SPRS) and was an effort within the framework of SWEDARCTIC 2008. For more information on ASCOS see http://ascos.se/. We thank the ASCOS organizers - Caroline Leck and Michael Tjernström - all ASCOS participants, the SPRS and the Oden crew for the excellent team work and Armin Wisthaler for his assistance in planning and preparations. The TOF-MS system was funded by the University of Innsbruck (Uni Infrastruktur Programm). The development project was financially supported by the Austrian Research Funding Association (FFG). [1] Hansel, A.; Jordan, A.; Holzinger, R.; Prazeller, P.; Vogel, W.; Lindinger, W. International Journal of Mass Spectrometry and Ion Processes 1995, 149-150, 609-619. [2] Lindinger, W.; Hansel, A.; Jordan, A. Chemical Society Review 1998, 27, 347-375. [3] De Gouw, J. A.; Warneke, C. Mass Spectrometry Reviews 2007, 26, 223-257. [4] Goldstein, A. H.; Galbally, I. E. Environmental Science and Technology 2007, 41, 154-1521.
[Mueller2009] Müller, M., LH. Mielke, M. Breitenlechner, SA. McLuckey, PB. Shepson, A. Wisthaler, and A. Hansel, "MS/MS studies for the selective detection of isomeric biogenic VOCs using a Townsend Discharge Triple Quadrupole Tandem MS and a PTR-Linear Ion Trap MS", Atmospheric Measurement Techniques Discussions, vol. 2, no. 4: Copernicus GmbH, pp. 1837–1861, 2009.
Link: http://www.atmos-meas-tech-discuss.net/2/1837/2009/
Abstract
We performed MS/MS investigations of biogenic volatile organic compounds (BVOC) using a triple quadrupole tandem mass spectrometer (QqQ-MS) equipped with a Townsend Discharge ion source and a Proton Transfer Reaction Linear Ion Trap (PTR-LIT) mass spectrometer. Both instruments use H2O chemical ionization to produce protonated molecular ions. Here we report a study of the application of these instruments to determine methyl vinyl ketone (MVK) and methacrolein (MACR) and a series of monoterpenes (α-pinene, β-pinene, 3-carene, limonene, myrcene, ocimene) and sesquiterpenes (humulene and farnesene). Both instruments achieved sub-ppb detection limits in the single MS mode and in the MS/MS mode for differentiating MVK and MACR. Collision induced dissociation (CID) of protonated monoterpenes and sesquiterpenes was studied under the high-energy, single-to-few collision conditions of the QqQ-MS instrument and under the low-energy, multiple collision conditions of the PTR-LIT. Differences and similarities in the breakdown curves obtained are discussed. In addition, we performed MS4 of protonated limonene to illustrate the analytical power of the PTR-LIT. In spite of the progress we have made, the selective on-line mass-spectrometric detection of individual monoterpenes or sesquiterpenes in complex mixtures currently does not yet seem to be possible.
[Beauchamp2009] Beauchamp, J., J. Frasnelli, A. Buettner, M. Scheibe, A. Hansel, and T. Hummel, "PTR-MS Characterisation of an Olfactometer", CONFERENCE SERIES, pp. 186, 2009.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_4.pdf
2006
[Grabmer2006] Grabmer, W., J. Kreuzwieser, A. Wisthaler, C. Cojocariu, M. Graus, H. Rennenberg, D. Steigner, R. Steinbrecher, and A. Hansel, "VOC emissions from Norway spruce ( Picea abies L.[Karst]) twigs in the field�Results of a dynamic enclosure study", Atmospheric Environment, vol. 40: Elsevier, pp. 128–137, 2006.
Link: http://www.sciencedirect.com/science/article/pii/S135223100600327X
Abstract
During the 2002 summer intensive field campaign of BEWA2000 a proton-transfer-reaction mass spectrometer (PTR-MS) was used for online determination of volatile organic compounds (VOC) emitted by Norway spruce (Picea abies L. [Karst]) twigs in a dynamic sampling enclosure. Emissions of isoprenoids (isoprene and monoterpenes) and oxygenated VOC (OVOC; acetaldehyde, acetone, methanol, and ethanol) were investigated. Emissions showed clear diurnal patterns with high daytime emission rates amounting to 1.8 μg C g−1 dwt h−1 for the sum of monoterpenes and in the range of 0.1 to 0.6 μg C g−1 dwt h−1 for isoprene>acetone>ethanol>methanol. Data were used to validate existing models on isoprene and monoterpene emissions and to discuss environmental and physiological factors affecting VOC emissions. Isoprene and acetaldehyde emission rates were best modelled applying the Guenther 1993 temperature and solar radiation algorithm. Emissions of monoterpenes, acetone and ethanol were best described by a temperature-only exponential algorithm. Using these model approaches a maximum emission variability of 66% was covered (isoprene). Poor r2 values ranging from 0.15 to 0.42 were typical for oxygenated VOC emission modelling indicating the need for model improvement e.g. development of process-based models describing the emission as a result of biochemical de novo synthesis as well as physico-chemical transport properties inside the leaves.
2005
[Graus2005] Graus, M., JP. Schnitzler, J. Kreuzwieser, U. Heizmann, H. Rennenberg, A. Wisthaler, and A. Hansel, "Alternative Carbon Sources for Leaf Isoprene Formation", Mass Spectrometry and Its Applications, pp. 19, 2005.
Link: http://www.uibk.ac.at/iup/infofolder/contributions_ptrms.pdf#page=30
[Spirig2005] Spirig, C., A. Neftel, C. Ammann, J. Dommen, W. Grabmer, A. Thielmann, A. Schaub, J. Beauchamp, A. Wisthaler, A. Hansel, et al., "Eddy covariance flux measurements of biogenic VOCs during ECHO 2003 using proton transfer reaction mass spectrometry", Atmospheric Chemistry and Physics, vol. 5, no. 2, pp. 465–481, 2005.
Link: http://hal.archives-ouvertes.fr/hal-00295614/
Abstract
Within the framework of the AFO 2000 project ECHO, two PTR-MS instruments were operated in combination with sonic anemometers to determine biogenic VOC fluxes from a mixed deciduous forest site in North-Western Germany. The measurement site was characterised by a forest of inhomogeneous composition, complex canopy structure, limited extension in certain wind directions and frequent calm wind conditions during night time. The eddy covariance (EC) technique was applied since it represents the most direct flux measurement approach on the canopy scale and is, therefore, least susceptible to these non-ideal conditions. A specific flux calculation method was used to account for the sequential multi-component PTR-MS measurements and allowing an individual delay time adjustment as well as a rigorous quality control based on cospectral analysis. The validated flux results are consistent with light and temperature dependent emissions of isoprene and monoterpenes from this forest, with average daytime emissions of 0.94 and 0.3µg m-2s-1, respectively. Emissions of methanol reached on average 0.087µg m-2s-1 during daytime, but fluxes were too small to be detected during night time. Upward fluxes of the isoprene oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) were also found, being two orders of magnitude lower than those of isoprene. Calculations with an analytical footprint model indicate that the observed isoprene fluxes correlate with the fraction of oaks within the footprints of the flux measurement.
2004
[Grabmer2004] Grabmer, W., M. Graus, C. Lindinger, A. Wisthaler, B. Rappenglück, R. Steinbrecher, and A. Hansel, "Disjunct eddy covariance measurements of monoterpene fluxes from a Norway spruce forest using PTR-MS", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 111–115, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003914
Abstract
Interest in reliable quantification of organic trace compounds released from terrestrial ecosystems stems from their impact on oxidant levels such as ozone and hydroxyl radicals and on secondary organic aerosol formation. In an attempt to quantify these emissions, a disjunct sampler (DS) was coupled to a PTR-MS instrument. In the disjunct eddy covariance (DEC) technique, an instantaneous grab sample is taken at intervals of tens of seconds and vertical wind speed is recorded at the instant of sample collection. The intermittent periods are used for sample analysis by a moderately fast chemical sensor, in this case a PTR-MS instrument, which allows for fast and sensitive detection of biogenic volatile organic compounds. The vertical turbulent transport of a trace compound is then calculated from the covariance of the fluctuations in vertical wind speed and compound mixing ratio. Fluxes of monoterpenes from a Norway spruce forest were measured during the 2002 summer intensive field campaign of BEWA2000 and results compared well with data obtained using relaxed eddy accumulation (REA) and the enclosure approach. In addition to this field experiment, a laboratory test was carried out to validate the disjunct sampling procedure.
[Beauchamp2004] Beauchamp, J., A. Wisthaler, W. Grabmer, C. Neuner, A. Weber, and A. Hansel, "Short-term measurements of CO, NO, NO< sub> 2, organic compounds and PM< sub> 10 at a motorway location in an Austrian valley", Atmospheric environment, vol. 38, no. 16: Elsevier, pp. 2511–2522, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S135223100400144X
Abstract
In situ measurements of CO, NOx, PM10 and certain organic compounds took place over an 11 day period encompassing a 12 h motorway blockade. Located within the Inn valley (Tirol, Austria), the monitoring site experiences varying meteorological conditions and traffic frequency throughout the day which both strongly influence air pollutant levels. Early morning increases of NOx, PM10 and aromatic hydrocarbons were clearly correlated with rising traffic. Midday minima and afternoon maxima may be explained by changing wind conditions and varying inversion layer dynamics. Night time lows in concentrations can be explained by minimal traffic activity. Classification of compound sources was made through grouping of data, separated into times when heavy duty vehicles (HDV) were permitted to use the motorway and HDV-ban periods. Increased levels of NOx and PM10 were observed from data that included periods of high HDV numbers, with levels decreasing significantly during HDV-ban periods. In contrast, the aromatic hydrocarbons and CO displayed only minor variations between these two periods. Furthermore, on typical workdays NOx levels reached a maximum that corresponded to a peak in HDV numbers, whereas the aromatic compounds peaked later when LDV numbers had reached their maximum. Our findings give strong evidence that increased NOx and PM10 levels can be predominantly attributed to HDV traffic. Principal components analyses for the separated data further support this conclusion.
[Steinbrecher2004] Steinbrecher, R., B. Rappenglück, A. Hansel, M. Graus, O. Klemm, A. Held, A. Wiedensohler, and A. Nowak, "Vegetation-atmospheric interactions: The emissions of biogenic volatile organic compounds (BVOC) and their relevance to atmospheric particle dynamics", Biogeochemistry of Forested Catchments in a Changing Environment: A Case Study in NE-Bavaria, Germany, Ecol. Stud, vol. 172, pp. 215–232, 2004.
2003
[Guazzotti2003] Guazzotti, SA., DT. Suess, KR. Coffee, PK. Quinn, TS. Bates, A. Wisthaler, A. Hansel, WP. Ball, RR. Dickerson, C. Neusüß, et al., "Characterization of carbonaceous aerosols outflow from India and Arabia: Biomass/biofuel burning and fossil fuel combustion", Journal of geophysical research, vol. 108, no. D15: American Geophysical Union, pp. 4485, 2003.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2002JD003277/abstract
Abstract
A major objective of the Indian Ocean Experiment (INDOEX) involves the characterization of the extent and chemical composition of pollution outflow from the Indian Subcontinent during the winter monsoon. During this season, low-level flow from the continent transports pollutants over the Indian Ocean toward the Intertropical Convergence Zone (ITCZ). Traditional standardized aerosol particle chemical analysis, together with real-time single particle and fast-response gas-phase measurements provided characterization of the sampled aerosol chemical properties. The gas- and particle-phase chemical compositions of encountered air parcels changed according to their geographic origin, which was traced by back trajectory analysis. The temporal evolutions of acetonitrile, a long-lived specific tracer for biomass/biofuel burning, number concentration of submicrometer carbon-containing particles with potassium (indicative of combustion sources), and mass concentration of submicrometer non-sea-salt (nss) potassium are compared. High correlation coefficients (0.84 < r2 < 0.92) are determined for these comparisons indicating that most likely the majority of the species evolve from the same, related, or proximate sources. Aerosol and trace gas measurements provide evidence that emissions from fossil fuel and biomass/biofuel burning are subject to long-range transport, thereby contributing to anthropogenic pollution even in areas downwind of South Asia. Specifically, high concentrations of submicrometer nss potassium, carbon-containing particles with potassium, and acetonitrile are observed in air masses advected from the Indian subcontinent, indicating a strong impact of biomass/biofuel burning in India during the sampling periods (74 (±9)% biomass/biofuel contribution to submicrometer carbonaceous aerosol). In contrast, lower values for these same species were measured in air masses from the Arabian Peninsula, where dominance of fossil fuel combustion is suggested by results from single-particle analysis and supported by results from gas-phase measurements (63 (±9))% fossil fuel contribution to submicrometer carbonaceous aerosol). Results presented here demonstrate the importance of simultaneous, detailed gas- and particle-phase measurements of related species when evaluating possible source contributions to aerosols in different regions of the world.
[Kreuzwieser2003] Kreuzwieser, J., M. Graus, JP. Schnitzler, U. Heizmann, H. Rennenberg, and A. Hansel, "Quantification of carbon sources for isoprene emission in poplar leaves", AGU Fall Meeting Abstracts, vol. 1, pp. 0119, 2003.
Link: http://adsabs.harvard.edu/abs/2003AGUFM.A32A0119K
Abstract
Isoprene is the most abundant volatile organic compound emitted by plants and in particular by trees. Current interest in understanding its biosynthesis in chloroplasts is forced by the important role isoprene plays in atmospheric chemistry. Leaf isoprene formation is closely linked to photosynthesis by a dynamic use of recently fixed photosynthetic precursors in the chloroplast. Under steady state conditions in [13C]CO2 atmosphere approximately 75 % of isoprene became labeled within minutes. The source of unlabeled C is suggested to be of extra-chloroplastidic and/or from starch degradation. In order to test whether these alternative carbon sources - leaf internal C-pools and xylem-transported carbohydrates, contribute to leaf isoprene formation in poplar (Populus tremula x P. alba) on-line proton-transfer-reaction-mass spectrometry (PTR-MS) was used to follow 13C-labeling kinetics.
[Karl2003c] Karl, T., A. Guenther, C. Spirig, A. Hansel, and R. Fall, "Seasonal variation of biogenic VOC emissions above a mixed hardwood forest in northern Michigan", Geophysical Research Letters, vol. 30, no. 23: Wiley Online Library, 2003.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2003GL018432/full
Abstract
Fluxes of biogenic volatile organic compounds (VOCs) were measured at a hardwood forest in northern Michigan (UMBS, Prophet research site) over the course of the growing and senescing season. Methanol, acetaldehyde, acetone and isoprene were found to be the most abundant biogenic VOCs with maximum fluxes (mixing ratios in ppbv) of 2.0 mg m−2 h−1 (21.0), 1.0 mg m−2 h−1 (2.7), 1.6 mg m−2 h−1 (5.6) and 7.6 mg m−2 h−1 (6), respectively. The emission patterns show distinct seasonal changes and indicate a spring peak for methanol due to rapid leaf expansion and a fall peak for acetone and acetaldehyde most likely attributed to senescing and decaying biomass; isoprene emissions peaked as expected in the summer. We estimate potential source strengths of 8.9 Tg (C) y−1 methanol, 2.7 Tg (C) y−1 acetaldehyde and 7.0 Tg (C) y−1 acetone for deciduous temperate forests, which is a substantial contribution to the global atmospheric VOC budget.
[Graus2003] Graus, M., J. Kreuzwieser, J. Schnitzler, A. Wisthaler, A. Hansel, and H. Rennenberg, "Xylem-Transported Glucose as an Additional Carbon Source for Leaf Isoprene Formation in Quercus Robur L.", EGS-AGU-EUG Joint Assembly, vol. 1, pp. 10692, 2003.
Link: http://adsabs.harvard.edu/abs/2003EAEJA....10692G
Abstract
Isoprene is emitted from mature, photosynthesizing leaves of many plant species, particularly of trees. Current interest in understanding the biochemical and physiological mechanisms controlling isoprene formation is caused by the important role isoprene plays in atmospheric chemistry. Isoprene reacts with hydroxyl radicals (OH) thereby generating oxidizing agents such as ozone and organic peroxides. Ozone causes significant deterioration in air quality and can pose threats to human health therefore its control is a major goal in Europe and the United States. In recent years, much progress has been made in elucidating the pathways of isoprene biosynthesis. Nevertheless the regulatory mechanisms controlling isoprene emission are not completely understood. Light and temperature appear to be the main factors controlling short-term variations in isoprene emission. Exposure of plants to C-13 labeled carbon dioxide showed instantaneous assimilated carbon is the primary carbon source for isoprene formation. However, variations in diurnal and seasonal isoprene fluxes, which cannot be explained by temperature, light, and leaf development led to the suggestion that alternative carbon sources may exist contributing to isoprene emissions. The aim of the present study was to test whether xylem-transported carbohydrates act as additional sources for isoprene biosynthesis. For this purpose, [U-C-13] alpha-D-glucose was fed to photosynthesizing leaves via the xylem of Quercus robur L. seedlings and the incorporation of glucose derived C-13 into emitted isoprene was monitored in real time using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS). A rapid incorporation of C-13 from xylem-fed glucose into single (mass 70) and double (mass 71) C-13 labeled isoprene molecules was observed after a lag phase of approximately 5 to 10 minutes. This incorporation was temperature dependent and was highest (up to 13% C-13 of total carbon emitted as isoprene) at the temperature optimum of isoprene emission (40 - 42°C) when net assimilation was strongly reduced. Fast dark-to-light transitions led to a strong single or double C-13 labeling of isoprene from xylem-fed [U-C-13] glucose. During a time period of 10 - 15 minutes up to 86% of all isoprene molecules became single or double C-13 labeled, resulting in a C-13 portion of up to 30% of total carbon emitted as isoprene. The results provide potential evidence that xylem-transported glucose or its degradation products can be used as additional precursors for isoprene biosynthesis and this carbon source becomes more important under conditions of limited photosynthesis.
2002
[Stroud2002] Stroud, CA., JM. Roberts, EJ. Williams, D. Hereid, WM. Angevine, FC. Fehsenfeld, A. Wisthaler, A. Hansel, M. Martinez-Harder, H. Harder, et al., "Nighttime isoprene trends at an urban forested site during the 1999 Southern Oxidant Study", Journal of Geophysical Research: Atmospheres (1984–2012), vol. 107, no. D16: Wiley Online Library, pp. ACH–7, 2002.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2001JD000959/full
Abstract
[1] Measurements of isoprene and its oxidation products, methacrolein, methyl vinyl ketone and peroxymethacrylic nitric anhydride, were conducted between 13 June and 14 July 1999, at the Cornelia Fort Airpark during the Nashville intensive of the Southern Oxidant Study. Trends in isoprene and its oxidation products showed marked variability from night-to-night. The reaction between isoprene and the nitrate radical was shown to be important to the chemical budget of isoprene and often caused rapid decay of isoprene mixing ratios in the evening. Trends in methacrolein, methyl vinyl ketone, and peroxymethacrylic nitric anhydride were steady during the evening isoprene decay period, consistent with their slow reaction rate with the nitrate radical. For cases when isoprene sustained and even increased in mixing ratio throughout the night, the observed isoprene oxidation rates via the hydroxyl radical, ozone, and the nitrate radical were all small. Sustained isoprene mixing ratios within the nocturnal boundary layer give a unique opportunity to capture hydroxyl radical photochemistry at sunrise as isoprene was observed to rapidly convert to its first stage oxidation products before vertical mixing significantly redistributed chemical species. The observed nighttime isoprene variability at urban, forested sites is related to a complex coupling between nighttime boundary layer dynamics and chemistry.
2001
[Williams2001] Williams, J., U. Poeschl, PJ. Crutzen, A. Hansel, R. Holzinger, C. Warneke, W. Lindinger, and J. Lelieveld, "An atmospheric chemistry interpretation of mass scans obtained from a proton transfer mass spectrometer flown over the tropical rainforest of Surinam", Journal of atmospheric chemistry, vol. 38, no. 2: Springer, pp. 133–166, 2001.
Link: http://www.springerlink.com/index/v26n6440307112k1.pdf
[Poeschl2001] Pöschl, U., J. Williams, P. Hoor, H. Fischer, PJ. Crutzen, C. Warneke, R. Holzinger, A. Hansel, A. Jordan, W. Lindinger, et al., "High acetone concentrations throughout the 0–12 km altitude range over the tropical rainforest in Surinam", Journal of atmospheric chemistry, vol. 38, no. 2: Springer, pp. 115–132, 2001.
Link: http://link.springer.com/article/10.1023/A:1006370600615
[Warneke2001a] Warneke, C., R. Holzinger, A. Hansel, A. Jordan, W. Lindinger, U. Poeschl, J. Williams, P. Hoor, H. Fischer, PJ. Crutzen, et al., "Isoprene and its oxidation products methyl vinyl ketone, methacrolein, and isoprene related peroxides measured online over the tropical rain forest of Surinam in March 1998", Journal of Atmospheric Chemistry, vol. 38, no. 2: Springer, pp. 167–185, 2001.
Link: http://www.springerlink.com/index/u14w8w3187r33ur2.pdf

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F. Biasioli, C. Yeretzian, F. Gasperi, T. D. Märk: PTR-MS monitoring of VOCs and BVOCs in food science and technology, Trends in Analytical Chemistry 30 (7) (2011).
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J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257.
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W. Lindinger, A. Hansel, A. Jordan: Proton-transfer-reaction mass spectrometry (PTR–MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev. 27 (1998), 347-375.
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Lists with PTR-MS relevant publications of the University of Innsbruck can be found here: Atmospheric and indoor air chemistry, IMR, Environmental Physics and Nano-Bio-Physics

 

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