Stable carbon isotope analysis of selected halocarbons at parts per trillion concentration in an urban location
M. I. Mead A , M. A. H. Khan A C , I. D. Bull B , I. R. White A , G. Nickless A and D. E. Shallcross AA Atmospheric Chemistry Research Group (ACRG), Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock’s Close, BS8 1TS, United Kingdom.
B Organic Geochemistry Unit (OGU), Bristol Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock’s Close, BS8 1TS, United Kingdom.
C Corresponding author. Email: anwar.khan@bristol.ac.uk
Environmental Chemistry 5(5) 340-346 https://doi.org/10.1071/EN08037
Submitted: 1 July 2008 Accepted: 28 August 2008 Published: 31 October 2008
Environmental Context. Halocarbons can have significant effects on the atmosphere and the environment, particularly with regard to ozone depletion and climate change impacts. The determination of isotopic concentrations for selected halocarbon species should provide useful information to identify and constrain halocarbon sources and sinks within the urban environment. In the present study, a new instrumental method is described to determine these isotope ratios for selected halocarbons and the resultant data are interpreted in terms of local sources and sinks.
Abstract. δ13C values of a suite of halocarbons have been determined in an urban background site in Bristol, UK. A novel mobile preconcentration system, based on the use of multi-adsorbent sample tubes, has been developed for trapping relatively large-volume air samples in potentially remote areas. An Adsorption Desorption System–Gas Chromatography–Electron Capture Detector was used to measure the mixing ratios of the selected halocarbon species, while a Gas Chromatography–Combustion–Isotope Ratio Mass Spectrometer was used to determine δ13C values. For the species with strong local sources, the variation of isotope ratios has been observed over the experimental period. Some of the results reported in the present study differ from previously reported values and reasons for this are discussed. The reporting of different δ13C values for selected halocarbons from different areas in the present study suggests that δ13C values may be used to determine the relative magnitudes of anthropogenic and biogenic sources.
Additional keywords: Adsorption Desorption System (ADS), Automated Thermal Desorber (ATD), Electron Capture Detector (ECD), Gas Chromatography (GC), Isotope Ratio Mass Spectrometry (IRMS).
Acknowledgement
M.I.M. would like to thank Natural Environment Research Council (NERC) for his studentship and M.A.H.K. would like to thank the Dorothy Hodgkin Foundation for his Fellowship. The authors would also like to thank EUROCHLOR under whose auspices various aspects of the current work were carried out. Part of this work was undertaken within the Organic Geochemistry Unit (OGU), a subdivision of the Bristol Biogeochemistry Research Centre at The University of Bristol. The authors wish to thank the NERC for funding of the mass spectrometry facilities at Bristol (contract no. R8/H12/15).
[1]
J. G. Anderson ,
D. W. Toohey ,
W. H. Brune ,
Free radicals within the Antarctic vortex: the role of CFC’s in Antarctic Ozone loss.
Science 1991
, 251, 39.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
PubMed |
[Verified May 2008].
[25]
A. C. Rivett ,
D. Martin ,
G. Nickless ,
P. G. Simmonds ,
S. J. O’Doherty ,
D. J. Gray ,
D. E. Shallcross ,
In situ gas chromatographic measurements of halocarbons in an urban environment.
Atmos. Environ. 2003
, 37, 2221.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
[26]
K. R. Redeker ,
S. Davis ,
R. M. Kalin ,
Isotope values of atmospheric halocarbons and hydrocarbons from Irish urban, rural and marine locations.
J. Geophys. Res. 2007
, 112, D16307.
| Crossref | GoogleScholarGoogle Scholar |
[27]
N. R. Auer ,
D. E. Schulz-Bull ,
Stable carbon isotope analysis of anthropogenic volatile halogenated C-1 and C-2 organic compounds.
Environ. Chem. 2006
, 3, 268.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
[28]
L. G. Miller ,
R. M. Kalin ,
S. E. McCauley ,
J. T. G. Hamilton ,
D. B. Harper ,
D. B. Millet ,
R. S. Oremland ,
A. H. Goldstein ,
Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria.
Proc. Natl. Acad. Sci. USA 2001
, 98, 5833.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
