Stable Carbon Isotope Analysis of Anthropogenic Volatile Halogenated C1 and C2 Organic Compounds

Nicole R. Auer; Detlef E. Schulz-Bull

doi:10.1071/EN06027

RESEARCH ARTICLE

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Stable Carbon Isotope Analysis of Anthropogenic Volatile Halogenated C₁ and C₂ Organic Compounds

Nicole R. Auer ^A and Detlef E. Schulz-Bull ^A ^B

+ Author Affiliations

- Author Affiliations

^A Department of Marine Chemistry, Baltic Sea Research Institute (IOW), Rostock 18119, Germany.

^B Corresponding author. Email: detlef.schulz-bull@io-warnemuende.de

Environmental Chemistry 3(4) 268-275 https://doi.org/10.1071/EN06027
Submitted: 21 April 2006 Accepted: 1 August 2006 Published: 5 September 2006

Environmental Context. Volatile halogenated organic compounds (VHOCs), ubiquitous trace gases of natural or man-made origin, have gained increasing attention due to their adverse health effects on humans and wildlife, and their potential for catalytic ozone destruction. However, it is difficult to confront VHOC emission budgets as the processes responsible for the formation and degradation of these compounds are complex, and their emission and persistence are affected by variations in the environment and climate. In order to understand VHOCs and reduce their environmental impact, it is necessary to study the isotopic composition of VHOCs produced by different sources, in addition to their concentrations and fluxes in the environment. In this paper, the determination of the carbon isotope range of VHOCs produced by human activities adds useful basic information for future studies of their environmental fate.

Abstract. This paper presents the C¹³/C¹² determination of 27 industrial volatile halogenated organic compounds (VHOCs) from different suppliers via gas chromatography combustion isotope-ratio mass spectrometry (GC-C-IRMS). A total of 60 samples, containing one or two carbon atoms, plus chlorine, bromine and iodine substituents, were analyzed to provide a basis for their further comparison with naturally produced VHOC δ¹³C values. The results indicate a wide range in the carbon isotope signature (–62‰ and –5‰). For chloroiodomethane alone, positive carbon isotope values of 33‰ (Fluka) and 59‰ (VWR International) were found. Each C₁ and C₂ compound has a distinctive carbon isotope composition, depending on the individual manufacturing reactions, the use of different carbon sources, differences in the composition of the same type of raw material and/or conditions during the manufacturing process. The last two factors are probably responsible for the δ¹³C discrepancies of ~5‰ found between manufacturers of the same compound. Larger deviations are mainly associated with different carbon isotope signatures of the reactant. Therefore, it is suggested that the reporting of a stable carbon isotope ratio for an anthropogenic VHOC include details of the manufacturing process or alternatively the supplier.

Keywords. : anthropogenic emissions — atmospheric chemistry — carbon isotope signature — gas chromatography combustion isotope-ratio mass spectrometry — halogen compounds

Acknowledgements

We would like to thank Dirk Wodarg for his measuring efforts and technical assistance. Dr Kilian Smith and Dr Bert Manzke are acknowledged for helpful comments and corrections to the draft manuscript. Finally, we thank the two anonymous referees for the constructive criticism and their help to clarify and improve the manuscript.

References

Stable Carbon Isotope Analysis of Anthropogenic Volatile Halogenated C1 and C2 Organic Compounds

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Stable Carbon Isotope Analysis of Anthropogenic Volatile Halogenated C₁ and C₂ Organic Compounds