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Bates, Matthew S.; Gonzalez-Flesca, Norbert; Sokhi, Ranjeet S.; Cocheo, Vincenzo

doi:10.1023/a:1006420412523

Cited by 17 publications

(20 citation statements)

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“…Problems from co-collection of ozone have been recognized previously (Goldan et al, 1995) and are documented in several studies (Bates et al, 2000;Plass-Dülmer et al, 2002;Pollmann et al, 2005;Lee et al, 2006;Apel et al, 2008;Arnts, 2008;Hellen et al, 2012). The ozone interference can be either positive via artefact formation from reaction with ozone in the sampling system (e.g.…”

Section: Ozonementioning

confidence: 97%

An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

et al. 2017

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Abstract. Volatile organic compounds (VOCs) are important for global air quality and oxidation processes in the troposphere. In addition to ground-based measurements, the chemical evolution of such species during transport can be studied by performing in situ airborne measurements. Generally, aircraft instrumentation needs to be sensitive, robust and sample at higher frequency than ground-based systems while their construction must comply with rigorous mechanical and electrical safety standards. Here, we present a new System for Organic Fast Identification Analysis (SOFIA), which is a custom-built fast gas chromatography-mass spectrometry (GC-MS) system with a time resolution of 2-3 min and the ability to quantify atmospheric mixing ratios of halocarbons (e.g. chloromethanes), hydrocarbons (e.g isoprene), oxygenated VOCs (acetone, propanal, butanone) and aromatics (e.g. benzene, toluene) from sub-ppt to ppb levels. The relatively high time resolution is the result of a novel cryogenic pre-concentration unit which rapidly cools ( ∼ 6 • C s −1 ) the sample enrichment traps to −140 • C, and a new chromatographic oven designed for rapid cooling rates (∼ 30 • C s −1 ) and subsequent thermal stabilization. SOFIA was installed in the High Altitude and Long Range Research Aircraft (HALO) for the Oxidation Mechanism Observations (OMO) campaign in August 2015, aimed at investigating the Asian monsoon pollution outflow in the tropical upper troposphere. In addition to a comprehensive instrument characterization we present an example monsoon plume crossing flight as a case study to demonstrate the instrument capability. Hydrocarbon, halocarbon and oxygenated VOC data from SOFIA are compared with mixing ratios of carbon monoxide (CO) and methane (CH 4 ), used to define the pollution plume. By using excess (ExMR) and normalized excess mixing ratios (NEMRs) the pollution could be attributed to two air masses of distinctly different origin, identified by back-trajectory analysis. This work endorses the use of SOFIA for aircraft operation and demonstrates the value of relatively high-frequency, multicomponent measurements in atmospheric chemistry research.

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Section: Ozonementioning

confidence: 97%

An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

et al. 2017

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“…When chemisorption or chemical reactions occur between the analyte and the adsorbent or between adsorbed compounds they are seen as an adverse effect leading to a deterioration of the quality of the sample (22,23). Extensive reports explaining these adsorption processes from thermodynamic (24), statistical (25), kinetic (26), and potential theory (27) approaches are widely available in the literature.…”

Section: Theorymentioning

confidence: 99%

An Investigation of the Adsorption of C₅-C₁₂ Hydrocarbons in the ppmv and ppbv Ranges on Carbotrap B

Foley

Gonzalez-Flesca

Zdanevitch

et al. 2001

Environ. Sci. Technol.

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The effects of concentration and temperature on the breakthrough volumes (Vb) of 23 volatile organic compounds on Carbotrap B have been determined using the frontal chromatography method. From the measured Vb, original isotherms have been produced and adsorption parameters based on the Langmuir, Freundlich, and Dubinin-Polyani adsorption models have been calculated. The calculated adsorption parameters describe the behavior of these VOC on Carbotrap B under the experimental conditions and are useful data for VOC sampling applications including adsorption modeling of pumped and diffusive sampling. Each of the adsorption models give similar results and are in good agreement with the experimental data in the ppmv concentration range. It will be shown that contrary to previous assumptions the Langmuir adsorption parameters obtained at ppmv concentrations cannot be used to predict Vb at ppbv concentrations and the calculated parameter mmax does not represent the maximum adsorbent capacity. The Freundlich and Dubinin-Polyani models are shown to be more successful in describing the adsorption behavior of the VOC at ppbv levels where Vb is independent of concentration. The isosteric heats of adsorption (-delta Hst) for some of the compounds have been determined using the Van't Hoff equation which can be used to predict the effect of temperature on Vb.

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“…Atmospheric volatile organic compounds (VOCs) are emitted from both natural and anthropogenic sources (Bates et al, 2000;Brasseur et al, 1999;Hewitt, 1999). Anthropogenic VOC emissions result from petrochemical industries, combustion processes (e.g.…”

Section: Introductionmentioning

confidence: 99%

Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

et al. 2014

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Abstract. Aromatic hydrocarbons are associated with direct adverse human health effects and can have negative impacts on ecosystems due to their toxicity, as well as indirect negative effects through the formation of tropospheric ozone and secondary organic aerosol, which affect human health, crop production and regional climate. Measurements of aromatic hydrocarbons were conducted at the Welgegund measurement station (South Africa), which is considered to be a regionally representative background site. However, the site is occasionally impacted by plumes from major anthropogenic source regions in the interior of South Africa, which include the western Bushveld Igneous Complex (e.g. platinum, base metal and ferrochrome smelters), the eastern Bushveld Igneous Complex (platinum and ferrochrome smelters), the Johannesburg-Pretoria metropolitan conurbation (> 10 million people), the Vaal Triangle (e.g. petrochemical and pyrometallurgical industries), the Mpumalanga Highveld (e.g. coal-fired power plants and petrochemical industry) and also a region of anticyclonic recirculation of air mass over the interior of South Africa. The aromatic hydrocarbon measurements were conducted with an automated sampler on Tenax-TA and Carbopack-B adsorbent tubes with heated inlet for 1 year. Samples were collected twice a week for 2 h during daytime and 2 h during night-time. A thermal desorption unit, connected to a gas chromatograph and a mass selective detector was used for sample preparation and analysis. Results indicated that the monthly median (mean) total aromatic hydrocarbon concentrations ranged between 0.01 (0.011) and 3.1 (3.2) ppb. Benzene levels did not exceed the local air quality standard limit, i.e. annual mean of 1.6 ppb. Toluene was the most abundant compound, with an annual median (mean) concentration of 0.63 (0.89) ppb. No statistically significant differences in the concentrations measured during daytime and night-time were found, and no distinct seasonal patterns were observed. Air mass back trajectory analysis indicated that the lack of seasonal cycles could be attributed to patterns determining the origin of the air masses sampled. Aromatic hydrocarbon concentrations were in general significantly higher in air masses that passed over anthropogenically impacted regions. Inter-compound correlations and ratios gave some indications of the possible sources of the different aromatic hydrocarbons in the source regions defined in the paper. The highest contribution of aromatic hydrocarbon concentrations to ozone formation potential was also observed in plumes passing over anthropogenically impacted regions.

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Cited by 17 publications

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An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

An Investigation of the Adsorption of C₅-C₁₂ Hydrocarbons in the ppmv and ppbv Ranges on Carbotrap B

Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

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Untitled

Cited by 17 publications

References 0 publications

An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

An Investigation of the Adsorption of C5-C12 Hydrocarbons in the ppmv and ppbv Ranges on Carbotrap B

Ambient aromatic hydrocarbon measurements at Welgegund, South Africa

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An Investigation of the Adsorption of C₅-C₁₂ Hydrocarbons in the ppmv and ppbv Ranges on Carbotrap B