Natural and anthropogenic C2 to C6 hydrocarbons in the central-eastern Venezuelan atmosphere during the rainy season

Donoso, Loreto; Romero, Rodrigo; Rondôn, Alberto; Fernandez, Emmanuel; Oyola, Pedro; Sanhueza, Eugenio

doi:10.1007/bf00053791

Cited by 25 publications

(13 citation statements)

References 33 publications

(41 reference statements)

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“…Surprisingly, the three data sets show quite different details, not only in the levels of isoprene, but also in the shape of the diurnal variations. The isoprene variation recorded at Calabozo during the wet season, is very similar to the one found at the same site during an earlier measurement campaign (13–23 September 1993), when samples were collected in canisters and the analysis was made by gas chromatography [ Donoso et al , 1996]. During the wet season, maximum mixing ratios of about 3.1 nmol/mol were recorded between 1200 and 1500 local time.…”

Section: Resultssupporting

confidence: 80%

“…Recently, Karl et al [2001] measured at the high mountain Sonnblick Observatory, Austria, high concentrations of 1‐penten‐3‐ol coming from freeze damaged leaves, which also is detected at mass 69. We do not believe that other compounds than isoprene contributed to the signal at mass 69 in Venezuela owing to following facts: We did not measure high concentrations of other leave‐wounding compounds; freeze damages do not occur; and even slightly higher levels of isoprene had been measured using the GC‐technique at the same site in an earlier campaign [ Donoso et al , 1996]. During the dry season campaign in Calabozo, however, there was some influence from biomass burning and thereby some contribution to mass 69 from other compounds than isoprene.…”

Section: Measurement Techniquesmentioning

confidence: 99%

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Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere

Holzinger¹,

Sanhueza²,

Kuhlmann³

et al. 2002

Global Biogeochemical Cycles

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[1] Using the proton transfer reaction mass spectrometry (PTR-MS) technique, isoprene and its oxidation products were measured in a productive woodland savanna (Calabozo site, during the wet and dry seasons) and a less productive grassland savanna (La Gran Sabana, Parupa site). The measured protonated masses in the PTR-MS, postulated compounds, and daytime average volume mixing ratios at the Calabozo site during the wet season are: 69 isoprene (1.62 nmol/mol), 71 methyl vinyl ketone + methacrolein (0.98 nmol/mol), 83 3-methyl furan + unsaturated C 5 -hydroxycarbonyls (0.12 nmol/mol), and 101 isoprene hydroperoxides (0.16 nmol/mol). Significant diurnal cycles of the hydrocarbon concentrations were observed, with distinct characteristics between sites and seasons. Two times lower levels of isoprene were observed during the dry season. At the Parupa site measured concentrations of all masses were about three times lower than at the Calabozo site during the wet season, and significant transport of isoprene from upwind forests was observed. Comparison with a photochemical box model revealed that surface deposition is likely a significant sink for isoprene and its oxidation products. An isoprene source of 2.1-3.2 Â 10 6 molec/cm 3 /s and an HO concentration of 4.1-6.0 Â 10 5 molec/cm 3 averaged over 24 hours were needed to match the observed mixing ratios. Assuming a mixed boundary layer of 1500 m and an isoprene source half the strength during the 5 months dry season, a global emission of isoprene to the atmosphere from tropical savannas between 53 and 79 Tg C/yr can be calculated from our results if the Calabozo site is representative. Citation: Holzinger, R., E. Sanhueza, R. von Kuhlmann, B. Kleiss, L. Donoso, and P. J. Crutzen, Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere, Global Biogeochem.

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Section: Resultssupporting

confidence: 80%

Section: Measurement Techniquesmentioning

confidence: 99%

Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere

Holzinger¹,

Sanhueza²,

Kuhlmann³

et al. 2002

Global Biogeochemical Cycles

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“…In the Amazon basin the model predicts ∼1.3 nmol/mol C 2 H 4 and 0.2 nmol/mol C 3 H 6 , in agreement with the observations [ Greenberg and Zimmerman , 1984; Zimmerman et al , 1988]. Comparison with measurements in Venezuela [ Donoso et al , 1996] does not give a clear picture for C 2 H 4 , but propene observations are mostly underestimated.…”

Section: Nonmethane Hydrocarbonssupporting

confidence: 76%

A model for studies of tropospheric ozone and nonmethane hydrocarbons: Model evaluation of ozone‐related species

et al. 2003

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[1] A global three-dimensional model for studies of the tropospheric chemistry of HO x , ozone, and their precursors is thoroughly evaluated with available observations of 15 species from surface stations and/or aircraft campaigns. The effect of grid-resolution was studied by comparing the measurements to model runs at a high ($1.9°Â 1.9°) and a reduced resolution. This study is a follow-up to a previous paper where the model was described and results for ozone were discussed. A statistical analysis of the complete comparison of each species is also presented in order to serve as a quantitative baseline for future evaluations. The seasonality and magnitude of the CO abundance is well simulated except for an overestimate of up to 20 nmol/mol in southern low latitudes. The tropospheric mean methane lifetime is calculated to be 8.7 and 9.1 years for the high-and low-resolution run, respectively, in agreement with recent estimates. Industrial emissions of alkanes from North America appear to be too low in the current data set. Indications for a biogenic source of propane were found by comparing with measurements over the Amazon rain forest. Alkene emissions from oceans are underestimated in the model indicating that they are higher than previous studies suggested. Nitrogen species are mostly reproduced within a factor of 2 or better, but a general bias to underestimate HNO 3 and to overpredict peroxyacetyl nitrate (PAN), especially in remote regions could also be found. NO was well simulated in the lower and mid troposphere, but significantly understimated in the upper troposphere. A sensitivity run shows that studies are needed to better constrain the rate constants for the thermal equilibrium of PAN. Acetone is often underestimated indicating that additional wide-spread sources, likely oceanic, are present. The comparison with other oxygenated species (acetaldehyde, methanol, formic and acetic acid) indicates severe gaps in our understanding of the present budgets of these species. In particular the underestimate of acetaldehyde implies large missing sources (order 100 Tg/yr) of this compound.

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“…Although butane in the atmosphere comes predominantly from anthropogenic sources (Kesselmeier and Staudt, 1999), some studies have reported emission of n-butane from vegetation (Donoso et al, 1996;Greenberg and Zimmerman, 1984;Hellén et al, 2006;König et al, 1995;Zimmerman et al, 1988). The MEK yield from n-butane oxidation is ∼ 80 % (Singh et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric mixing ratios of methyl ethyl ketone (2-butanone) in tropical, boreal, temperate and marine environments

et al. 2016

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Abstract. Methyl ethyl ketone (MEK) enters the atmosphere following direct emission from vegetation and anthropogenic activities, as well as being produced by the gas-phase oxidation of volatile organic compounds (VOCs) such as nbutane. This study presents the first overview of ambient MEK measurements at six different locations, characteristic of forested, urban and marine environments. In order to understand better the occurrence and behaviour of MEK in the atmosphere, we analyse diel cycles of MEK mixing ratios, vertical profiles, ecosystem flux data, and HYSPLIT back trajectories, and compare with co-measured VOCs. MEK measurements were primarily conducted with protontransfer-reaction mass spectrometer (PTR-MS) instruments. Results from the sites under biogenic influence demonstrate that vegetation is an important source of MEK. The diel cycle of MEK follows that of ambient temperature and the forest structure plays an important role in air mixing. At such sites, a high correlation of MEK with acetone was observed (e.g. r 2 = 0.96 for the SMEAR Estonia site in a remote hemiboreal forest in Tartumaa, Estonia, and r 2 = 0.89 at the ATTO pristine tropical rainforest site in central Amazonia). Under polluted conditions, we observed strongly enhanced MEK mixing ratios. Overall, the MEK mixing ratios and flux data presented here indicate that both biogenic and anthropogenic sources contribute to its occurrence in the global atmosphere.

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Natural and anthropogenic C2 to C6 hydrocarbons in the central-eastern Venezuelan atmosphere during the rainy season

Cited by 25 publications

References 33 publications

Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere

Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere

A model for studies of tropospheric ozone and nonmethane hydrocarbons: Model evaluation of ozone‐related species

Atmospheric mixing ratios of methyl ethyl ketone (2-butanone) in tropical, boreal, temperate and marine environments

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