scholarly journals Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere

2013 ◽  
Vol 13 (4) ◽  
pp. 11357-11394
Author(s):  
J. Wintel ◽  
E. Hösen ◽  
R. Koppmann ◽  
M. Krebsbach
Keyword(s):  
Boundary Layer ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Stable Carbon Isotope ◽  
Isotope Ratios ◽  
Free Troposphere ◽  
Stable Carbon ◽  
Stable Carbon Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Mixing Ratios

Abstract. Measurements of stable carbon isotope ratios in VOC are a powerful tool to identify sources or to track both dynamical and chemical processes. During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer and the lower free troposphere over south-west Germany. These samples were analysed with respect to VOC mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer. In this study we present the results for toluene, one of the major anthropogenic pollutants. In the boundary layer we observed rather fresh emissions mixing into the background and derived a toluene source isotope ratio of δ13C = −28.2 ± 0.5 ‰. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We estimated the photochemical age of toluene in the atmosphere in two different ways (using isotope ratios and mixing ratios, respectively). The results differ strongly in the planetary boundary layer, probably due to mixing processes, but are compatible with each other in the free troposphere.

scholarly journals Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere

2013 ◽  
Vol 13 (21) ◽  
pp. 11059-11071 ◽  
Author(s):  
J. Wintel ◽  
E. Hösen ◽  
R. Koppmann ◽  
M. Krebsbach ◽  
A. Hofzumahaus ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Isotope Ratio ◽  
Stable Carbon Isotope ◽  
Isotope Ratios ◽  
Free Troposphere ◽  
Stable Carbon ◽  
Air Samples ◽  
Stable Carbon Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Mixing Ratios

Abstract. During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer (PBL) and the lower free troposphere (LFT) over south-west Germany using the ZEppelin Based Isotope Sampler (ZEBIS). These samples were analysed with respect to volatile organic compound (VOC) mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer (GC-C-IRMS). In this study we present results for toluene, one of the major anthropogenic pollutants, which emphasise the viability of isotope ratio measurements in VOC for atmospheric research, especially to study VOC sources or to track both dynamical and chemical processes. In situ measurements of CO mixing ratios on board the Zeppelin NT were used to allocate the air samples either to the PBL or the LFT. In the PBL we observed rather fresh emissions mixing into the background air. We estimated a toluene source isotope ratio of δ13C = −28.2 ± 0.5‰. Samples from the PBL and the LFT were clearly distinguishable by means of their mixing ratio and isotope ratio signatures. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We calculated the photochemical age of toluene in the atmosphere in two different ways using isotope ratios and mixing ratios. The results differ strongly in the PBL, probably due to mixing processes, but are compatible with each other in the LFT. Here, they correlate with a slope of 0.90±0.31.

scholarly journals A method for stable carbon isotope ratio and concentration measurements of ambient aromatic hydrocarbons

2015 ◽  
Vol 8 (6) ◽  
pp. 2301-2313 ◽  
Author(s):  
A. Kornilova ◽  
S. Moukhtar ◽  
M. Saccon ◽  
L. Huang ◽  
W. Zhang ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Isotope Ratio ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Isotope Ratios ◽  
Stable Carbon ◽  
Stable Carbon Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Concentration Measurements ◽  
Better Than

Abstract. A technique for compound-specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOCs) is presented. It is based on selective VOC sampling onto adsorbent-filled cartridges by passing large volumes of air (up to 80 L) through the cartridge. The hydrocarbons are recovered by thermal desorption followed by two-step cryogenic trapping and then are separated by gas chromatography in the laboratory. Once separated, individual VOCs are subjected to online oxidation in a combustion interface and isotope ratio analysis by isotope ratio mass spectrometry. The method allows measurements of stable carbon isotope ratios of ambient aromatic VOCs present in low pptV to ppbV levels with an accuracy of typically better than 0.5 ‰. The precision of concentration measurements is better than 10%. Examples of measurements conducted as part of a joint Environment Canada–York University (EC-YU) measurement campaign at a semi-rural location demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an overrepresentation of samples that are strongly impacted by recent emissions.

scholarly journals A method for stable carbon isotope ratio and concentration measurements of ambient aromatic hydrocarbons

2015 ◽  
Vol 8 (1) ◽  
pp. 1365-1400
Author(s):  
A. Kornilova ◽  
S. Moukhtar ◽  
M. Saccon ◽  
L. Huang ◽  
W. Zhang ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Isotope Ratio ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Isotope Ratios ◽  
Stable Carbon ◽  
Stable Carbon Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Concentration Measurements ◽  
Better Than

Abstract. A technique for compound specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOC) is presented. It is based on selective VOC sampling onto adsorbent filled cartridges by passing large volumes of air (up to 80 L) through the cartridge. The hydrocarbons are recovered by thermal desorption followed by two step cryogenic trapping and then are separated by gas chromatography in the laboratory. Once separated, individual VOC are subjected to online oxidation in a combustion interface and isotope ratio analysis by isotope ratio mass spectrometry. The method allows measurements of stable carbon isotope ratios of ambient aromatic VOC present in low pptV to ppbV levels with an accuracy of typically better than 0.5‰. The precision of concentration measurements is better than 10%. Examples of measurements conducted as part of a joint Environment Canada-York University (EC-YU) measurement campaign at a semi-rural location demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an over-representation of samples that are strongly impacted by recent emissions.

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