Callback Service

Undefined

The world's leading PTR-MS company

Providing ultra-sensitive solutions for real-time trace gas analysis since 1998

Navigation

You are here

Scientific Articles - PTR-MS Bibliography

Welcome to the new IONICON scientific articles database!

Publications

Found 9 results
Title [ Year(Asc)]
Search results for flux
Filters: Author is Hansel, Armin  [Reset Search]
2013
[Fares2013] Fares, S., R. Schnitzhofer, X. Jiang, A. Guenther, A. Hansel, and F. Loreto, "Observations of diurnal to weekly variations of monoterpene-dominated fluxes of volatile organic compounds from Mediterranean forests: implications for regional modeling.", Environ Sci Technol, Sep, 2013.
Link: http://dx.doi.org/10.1021/es4022156
Abstract
The Estate of Castelporziano (Rome, Italy) hosts many ecosystems representative of Mediterranean vegetation, especially holm oak and pine forests, and dune vegetation. In this work, Basal Emission Factors (BEFs) of biogenic volatile organic compounds (BVOCs) obtained by Eddy Covariance in a field campaign using a Proton Transfer Reaction - Time of Flight - Mass Spectrometer (PTR-TOF-MS) were compared to BEFs reported in previous studies that could not measure fluxes in real-time. Globally, broadleaf forests are dominated by isoprene emissions, but these Mediterranean ecosystems are dominated by strong monoterpene emitters, as shown by the new BEFs. The original and new BEFs were used to parameterize the Model of Emissions of Gases and Aerosols from Nature (MEGAN v2.1), and model outputs were compared with measured fluxes. Results showed good agreement between modelled and measured fluxes when a model was used to predict radiative transfer and energy balance across the canopy. We then evaluated whether changes in BVOC emissions can affect the chemistry of the atmosphere and climate at a regional level. MEGAN was run together with the land surface model (Community Land Model, CLM v4.0) of the Community Earth System Model (CESM v1.0). Results highlighted that tropospheric ozone concentration and air temperature predicted from the model are sensitive to the magnitude of BVOC emissions, thus demonstrating the importance of adopting the proper BEF values for model parameterization.
2012
[Brilli2012] Brilli, F., L. Hörtnagl, I. Bamberger, R. Schnitzhofer, T. M. Ruuskanen, A. Hansel, F. Loreto, and G. Wohlfahrt, "Qualitative and quantitative characterization of volatile organic compound emissions from cut grass.", Environ Sci Technol, vol. 46, no. 7: Ionicon Analytik GmbH, Eduard-Bodem-Gasse 3, 6020 Innsbruck, Austria., pp. 3859–3865, Apr, 2012.
Link: http://dx.doi.org/10.1021/es204025y
Abstract
Mechanical wounding of plants triggers the release of a blend of reactive biogenic volatile organic compounds (BVOCs). During and after mowing and harvesting of managed grasslands, significant BVOC emissions have the potential to alter the physical and chemical properties of the atmosphere and lead to ozone and aerosol formation with consequences for regional air quality. We show that the amount and composition of BVOCs emitted per unit dry weight of plant material is comparable between laboratory enclosure measurements of artificially severed grassland plant species and in situ ecosystem-scale flux measurements above a temperate mountain grassland during and after periodic mowing and harvesting. The investigated grassland ecosystem emitted annually up to 130 mg carbon m(-2) in response to cutting and drying, the largest part being consistently represented by methanol and a blend of green leaf volatiles (GLV). In addition, we report the plant species-specific emission of furfural, terpenoid-like compounds (e.g., camphor), and sesquiterpenes from cut plant material, which may be used as tracers for the presence of given plant species in the ecosystem.
2011
[1587] Hörtnagl, L., I. Bamberger, M. Graus, T. M. Ruuskanen, R. Schnitzhofer, M. Müller, A. Hansel, and G. Wohlfahrt, "Biotic, abiotic and management controls on methanol exchange above a temperate mountain grassland.", J Geophys Res Biogeosci, vol. 116, Sep, 2011.
Link: http://dx.doi.org/10.1029/2011jg001641
Abstract
<p>Methanol (CH3OH) fluxes were quantified above a managed temperate mountain grassland in the Stubai Valley (Tyrol, Austria) during the growing seasons 2008 and 2009. Half-hourly methanol fluxes were calculated by means of the virtual disjunct eddy covariance (vDEC) method using 3-dimensional wind data from a sonic anemometer and methanol volume mixing ratios measured with a proton-transfer-reaction mass spectrometer (PTR-MS). During (undisturbed) mature and growing phases methanol fluxes exhibited a clear diurnal cycle with close-to-zero fluxes during nighttime and emissions, up to 10 nmol m(-2) s(-1), which followed the diurnal course of radiation and air temperature. Management events were found to represent the largest perturbations of methanol exchange at the studied grassland ecosystem: Peak emissions of 144.5 nmol m(-2) s(-1) were found during/after cutting of the meadow reflecting the wounding of the plant material and subsequent depletion of the leaf internal aqueous methanol pools. After the application of organic fertilizer, elevated methanol emissions of up to 26.7 nmol m(-2) s(-1) were observed, likely reflecting enhanced microbial activity associated with the applied manure. Simple and multiple linear regression analyses revealed air temperature and radiation as the dominant abiotic controls, jointly explaining 47 % and 70 % of the variability in half-hourly and daily methanol fluxes. In contrast to published leaf-level laboratory studies, the surface conductance and the daily change in the amount of green plant area, used as ecosystem-scale proxies for stomatal conductance and growth, respectively, were found to exert only minor biotic controls on methanol exchange.</p>
2010
[1584] Hörtnagl, L., R. Clement, M. Graus, A. Hammerle, A. Hansel, and G. Wohlfahrt, "Dealing with disjunct concentration measurements in eddy covariance applications: a comparison of available approaches.", Atmos Environ (1994), vol. 44, May, 2010.
Link: http://www.sciencedirect.com/science/article/pii/S1352231010001810
Abstract
<p>Using proton transfer reaction mass spectrometry equipped with a quadrupol mass analyser to quantify the biosphere-atmosphere exchange of volatile organic compounds (VOC), concentrations of different VOC are measured sequentially. Depending on how many VOC species are targeted and their respective integration times, each VOC is measured at repeat rates on the order of a few seconds. This represents an order of magnitude longer sample interval compared to the standard eddy covariance (EC) method (5-20 Hz sampling rates). Here we simulate the effect of disjunct sampling on EC flux estimates by decreasing the time resolution of CO2 and H2O concentrations measured at 20 Hz above a temperate mountain grassland in the Austrian Alps. Fluxes for one month are calculated with the standard EC method and compared to fluxes calculated based on the disjunct data (1, 3 and 5 s sampling rates) using the following approaches: i) imputation of missing concentrations based on the nearest neighbouring samples (iDECnn), ii) imputation by linear interpolation (iDECli), and iii) virtual disjunct EC (vDEC), i.e. flux calculation based solely on the disjunct concentrations. It is shown that the two imputation methods result in additional low-pass filtering, longer lag times (as determined with the maximum cross-correlation method) and a flux loss of 3-30 % as compared to the standard EC method. A novel procedure, based on a transfer function approach, which specifically corrects for the effect of data treatment, was developed, resulting in improved correspondence (to within 2 %). The vDEC method yields fluxes which approximate the true (20 Hz) fluxes to within 3-7 % and it is this approach we recommend because it involves no additional empirical corrections. The only drawback of the vDEC method is the noisy nature of the cross-correlations, which poses problems with lag determination - practical approaches to overcome this limitation are discussed.</p>
2006
[Graus2006] Graus, M., A. Hansel, A. Wisthaler, C. Lindinger, R. Forkel, K. Hauff, M. Klauer, A. Pfichner, B. Rappenglück, D. Steigner, et al., "A relaxed-eddy-accumulation method for the measurement of isoprenoid canopy-fluxes using an online gas-chromatographic technique and PTR-MS simultaneously", Atmospheric Environment, vol. 40: Elsevier, pp. 43–54, 2006.
Link: http://www.sciencedirect.com/science/article/pii/S1352231006003190
Abstract
A relaxed-eddy-accumulation set-up using an online gas-chromatographic technique and proton-transfer-reaction mass spectrometry was applied to determine isoprenoid fluxes above a Norway spruce forest in July 2001/2002. The system was quality assured and its suitability for determination of canopy fluxes of isoprenoids was demonstrated. Flux measurements of oxygenated hydrocarbons failed the data quality check due to artefacts presumably arising from line and ozone-scrubber effects. Observations of turbulent fluxes of isoprenoids during the two field experiments show good agreements with primary flux data derived from enclosure measurements and modelling results using a canopy-chemistry emission model (CACHE).
[Forkel2006] Forkel, R., O. Klemm, M. Graus, B. Rappenglück, W. R. Stockwell, W. Grabmer, A. Held, A. Hansel, and R. Steinbrecher, "Trace gas exchange and gas phase chemistry in a Norway spruce forest: A study with a coupled 1-dimensional canopy atmospheric chemistry emission model", Atmospheric Environment, vol. 40: Elsevier, pp. 28–42, 2006.
Link: http://www.sciencedirect.com/science/article/pii/S1352231006003189
Abstract
Numerical modelling is an efficient tool to investigate the role of chemical degradation of biogenic volatile organic compounds (BVOC) and the effect of dynamical processes on BVOC and product mixing ratios within and above forest canopies. The present study shows an application of the coupled canopy-chemistry model CACHE to a Norway spruce forest at the Waldstein (Fichtelgebirge, Germany). Simulated courses of temperature, trace gas mixing ratios, and fluxes are compared with measurements taken during the BEWA2000 field campaigns. The model permits the interpretation of the observed diurnal course of ozone and VOC by investigating the role of turbulent exchange, chemical formation and degradation, emission, and deposition during the course of the day. The simulation results show that BVOC fluxes into the atmosphere are 10–15% lower than the emission fluxes on branch basis due to chemical BVOC degradation within the canopy. BVOC degradation by the NO3 radical was found to occur in the lower part of the canopy also during daytime. Furthermore, the simulations strongly indicate that further research is still necessary concerning the emission and deposition of aldehydes and ketones.
2005
[Jacob2005] Jacob, D. J., B. D. Field, Q. Li, D. R. Blake, J. de Gouw, C. Warneke, A. Hansel, A. Wisthaler, H. B. Singh, and A. Guenther, "Global budget of methanol: Constraints from atmospheric observations", Journal of Geophysical Research: Atmospheres (1984–2012), vol. 110, no. D8: Wiley Online Library, 2005.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2004JD005172/full
Abstract
We use a global three-dimensional model simulation of atmospheric methanol to examine the consistency between observed atmospheric concentrations and current understanding of sources and sinks. Global sources in the model include 128 Tg yr−1 from plant growth, 38 Tg yr−1 from atmospheric reactions of CH3O2 with itself and other organic peroxy radicals, 23 Tg yr−1 from plant decay, 13 Tg yr−1 from biomass burning and biofuels, and 4 Tg yr−1 from vehicles and industry. The plant growth source is a factor of 3 higher for young than from mature leaves. The atmospheric lifetime of methanol in the model is 7 days; gas-phase oxidation by OH accounts for 63% of the global sink, dry deposition to land 26%, wet deposition 6%, uptake by the ocean 5%, and aqueous-phase oxidation in clouds less than 1%. The resulting simulation of atmospheric concentrations is generally unbiased in the Northern Hemisphere and reproduces the observed correlations of methanol with acetone, HCN, and CO in Asian outflow. Accounting for decreasing emission from leaves as they age is necessary to reproduce the observed seasonal variation of methanol concentrations at northern midlatitudes. The main model discrepancy is over the South Pacific, where simulated concentrations are a factor of 2 too low. Atmospheric production from the CH3O2 self-reaction is the dominant model source in this region. A factor of 2 increase in this source (to 50–100 Tg yr−1) would largely correct the discrepancy and appears consistent with independent constraints on CH3O2 concentrations. Our resulting best estimate of the global source of methanol is 240 Tg yr−1. More observations of methanol concentrations and fluxes are needed over tropical continents. Better knowledge is needed of CH3O2 concentrations in the remote troposphere and of the underlying organic chemistry.
[Beauchamp2005] Beauchamp, J., A. Wisthaler, A. Hansel, E. Kleist, M. Miebach, ÜLO. NIINEMETS, U. Schurr, and JÜRGEN. WILDT, "Ozone induced emissions of biogenic VOC from tobacco: relationships between ozone uptake and emission of LOX products", Plant, Cell & Environment, vol. 28, no. 10: Wiley Online Library, pp. 1334–1343, 2005.
Link: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2005.01383.x/full
Abstract
Volatile organic compound (VOC) emissions from tobacco (Nicotiana tabacum L. var. Bel W3) plants exposed to ozone (O3) were investigated using proton-transfer-reaction mass-spectrometry (PTR-MS) and gas chromatography mass-spectrometry (GC-MS) to find a quantitative reference for plants’ responses to O3 stress. O3 exposures to illuminated plants induced post-exposure VOC emission bursts. The lag time for the onset of volatile C6 emissions produced within the octadecanoid pathway was found to be inversely proportional to O3 uptake, or more precisely, to the O3 flux density into the plants. In cases of short O3 pulses of identical duration the total amount of these emitted C6 VOC was related to the O3 flux density into the plants, and not to ozone concentrations or dose–response relationships such as AOT 40 values. Approximately one C6 product was emitted per five O3 molecules taken up by the plant. A threshold flux density of O3 inducing emissions of C6 products was found to be (1.6 ± 0.7) × 10−8 mol m−2 s−1.
2004
[Graus2004] Graus, M., JÖRG-PETER. SCHNITZLER, A. Hansel, C. Cojocariu, H. Rennenberg, A. Wisthaler, and J. Kreuzwieser, "Transient release of oxygenated volatile organic compounds during light-dark transitions in grey poplar leaves", Plant Physiology, vol. 135, no. 4: American Society of Plant Biologists, pp. 1967–1975, 2004.
Link: http://www.plantphysiology.org/content/135/4/1967.short
Abstract
In this study, we investigated the prompt release of acetaldehyde and other oxygenated volatile organic compounds (VOCs) from leaves of Grey poplar [Populus x canescens (Aiton) Smith] following light-dark transitions. Mass scans utilizing the extremely fast and sensitive proton transfer reaction-mass spectrometry technique revealed the following temporal pattern after light-dark transitions: hexenal was emitted first, followed by acetaldehyde and other C6-VOCs. Under anoxic conditions, acetaldehyde was the only compound released after switching off the light. This clearly indicated that hexenal and other C6-VOCs were released from the lipoxygenase reaction taking place during light-dark transitions under aerobic conditions. Experiments with enzyme inhibitors that artificially increased cytosolic pyruvate demonstrated that the acetaldehyde burst after light-dark transition could not be explained by the recently suggested pyruvate overflow mechanism. The simulation of light fleck situations in the canopy by exposing leaves to alternating light-dark and dark-light transitions or fast changes from high to low photosynthetic photon flux density showed that this process is of minor importance for acetaldehyde emission into the Earth's atmosphere.

Featured Articles

Download Contributions to the International Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications:

 

Selected PTR-MS related Reviews

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).
Link

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.
Link

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.
Link

 

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

 

Download the latest version of the IONICON publication database as BibTeX.