Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF

Ruuskanen, T. M.; Müller, Markus; Schnitzhofer, R.; Karl, T.; Graus, M.; Bamberger, Ines; Hörtnagl, Lukas; Brilli, Federico; Wohlfahrt, Georg; Hansel, Armin

doi:10.5194/acp-11-611-2011

Cited by 118 publications

(142 citation statements)

References 58 publications

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“…The transmission efficiency of both mass spectrometers were measured from m/z 33 to m/z 219 using a gas standard mixture of methanol, acetonitrile, acetaldehyde, acetone, methylvinyl-ketone, benzene, toluene, xylene, trifluorobenzene, bromobenzene, trichlorobenzene, and iodotoluene at concentrations of ∼ 100 ppb each (Apel & Riemer). During the measurement period, the averaged sensitivities for PTR-TOF-MS ranged between 8 and 36 ncps ppbv −1 , similar to that reported by Ruuskanen et al (2011). For PTR-MS, the sensitivity to each measured compound has been reported by Fares et al (2012a).…”

Section: Instrumentationsupporting

confidence: 72%

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

et al. 2013

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Abstract. During summer 2010, a proton transfer reaction – time of flight – mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/Δm) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m−2 h−1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m−2 h−1) and methanol (m/z 33.032, 18%, 72 μg C m−2 h−1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m−2 h−1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m−2 h−1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m−2 h−1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m−2 h−1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 μg C m−2 h−1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 μg C m−2 h−1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

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Section: Instrumentationsupporting

confidence: 72%

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

et al. 2013

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“…The preponderance of methanol emissions over all other BVOCs has been reported in numerous cropland and grassland studies (Bamberger et al, 2010;Copeland et al, 2012;Crespo et al, 2013;Custer and Schade, 2007;Eller et al, 2011;Ruuskanen et al, 2011;Warneke et al, 2002), including maize studies (Das et al, 2003;Graus et al, 2013). Smaller (compared with methanol exchanges) but significant bi-directional exchanges of other OVOCs and terpenes were also reported in those studies.…”

Section: Bvocs Exchange Composition At Lto and Qualitative Comparisonmentioning

confidence: 69%

Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season

et al. 2016

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Abstract. Although maize is the second most important crop worldwide, and the most important C4 crop, no study on biogenic volatile organic compounds (BVOCs) has yet been conducted on this crop at ecosystem scale and over a whole growing season. This has led to large uncertainties in cropland BVOC emission estimations. This paper seeks to fill this gap by presenting, for the first time, BVOC fluxes measured in a maize field at ecosystem scale (using the disjunct eddy covariance by mass scanning technique) over a whole growing season in Belgium. The maize field emitted mainly methanol, although exchanges were bi-directional. The second most exchanged compound was acetic acid, which was taken up mainly in the growing season. Bi-directional exchanges of acetaldehyde, acetone and other oxygenated VOCs also occurred, whereas the terpenes, benzene and toluene exchanges were small, albeit significant. Surprisingly, BVOC exchanges were of the same order of magnitude on bare soil and on well developed vegetation, suggesting that soil is a major BVOC reservoir in agricultural ecosystems. Quantitatively, the maize BVOC emissions observed were lower than those reported in other maize, crops and grasses studies. The standard emission factors (SEFs) estimated in this study (231 ± 19 µg m −2 h −1 for methanol, 8 ± 5 µg m −2 h −1 for isoprene and 4 ± 6 µg m −2 h −1 for monoterpenes) were also much lower than those currently used by models for C4 crops, particularly for terpenes. These results suggest that maize fields are small BVOC exchangers in north-western Europe, with a lower BVOC emission impact than that modelled for growing C4 crops in this part of the world. They also reveal the high variability in BVOC exchanges across world regions for maize and suggest that SEFs should be estimated for each region separately.

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“…was determined by searching for the maximum/minimum cross correlation in a given time window. For the PTR-TOF data this approach was further used to apply a quality rating following Ruuskanen et al [2011]: Fluxes with a clearly visible covariance maximum or minimum were rated class 1; fluxes with a recognizable but uncertain (in peak position) maximum or minimum were rated class 2 (recognizable peak); all other half-hourly periods were rated class 3 and excluded from the analysis. Examples for these three quality classes are shown in Figure A1.…”

Section: Discussionmentioning

confidence: 99%

Deposition fluxes of terpenes over grassland

et al. 2011

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[1] 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.

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Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF

Cited by 118 publications

References 58 publications

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season

Deposition fluxes of terpenes over grassland

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