Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

High levels of molecular chlorine in the Arctic atmosphere

Abstract

Chlorine radicals can function as a strong atmospheric oxidant1,2,3, particularly in polar regions, where levels of hydroxyl radicals are low. In the atmosphere, chlorine radicals expedite the degradation of methane4,5,6 and tropospheric ozone4,7, and the oxidation of mercury to more toxic forms3. Here we present direct measurements of molecular chlorine levels in the Arctic marine boundary layer in Barrow, Alaska, collected in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. We report high levels of molecular chlorine, of up to 400 pptv. Concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone are required for molecular chlorine formation. Using a time-dependent box model, we estimate that the chlorine radicals produced from the photolysis of molecular chlorine oxidized more methane than hydroxyl radicals, on average, and enhanced the abundance of short-lived peroxy radicals. Elevated hydroperoxyl radical levels, in turn, promoted the formation of hypobromous acid, which catalyses mercury oxidation and the breakdown of tropospheric ozone. We therefore suggest that molecular chlorine exerts a significant effect on the atmospheric chemistry of the Arctic.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Observed Cl2 and O3.
Figure 2: Average diurnal profiles of chlorine species.
Figure 3: An example of the impact of Cl2 on RO2 and HO2.

Similar content being viewed by others

References

  1. Sander, S. P. et al. Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies Evaluation Number 17 JPL Publ. 10–6 (NASA Jet Propulsion Laboratory, California Institute of Technology, 2011).

  2. Jobson, B. T. et al. Measurements of C2−C6 VOCs during the polar sunrise 1992 experiment—evidence for Cl atom and Br atom chemistry. J. Geophys. Res.-Atmos. 99, 25355–25368 (1994).

    Article  Google Scholar 

  3. Donohoue, D. L., Bauer, D. & Hynes, A. J. Temperature and pressure dependent rate coefficients for the reaction of Hg with Cl and the reaction of Cl with Cl: A pulsed laser photolysis-pulsed laser induced fluorescence study. J. Phys. Chem. A 109, 7732–7741 (2005).

    Article  Google Scholar 

  4. Saiz-Lopez, A. & von Glasow, R. Reactive halogen chemistry in the troposphere. Chem. Soc. Rev. 41, 6448–6472 (2012).

    Article  Google Scholar 

  5. Platt, U., Allan, W. & Lowe, D. Hemispheric average Cl atom concentration from C-13/C-12 ratios in atmospheric methane. Atmos. Chem. Phys. 4, 2393–2399 (2004).

    Article  Google Scholar 

  6. Lawler, M. J. et al. HOCl and Cl(2) observations in marine air. Atmos. Chem. Phys. 11, 7617–7628 (2011).

    Article  Google Scholar 

  7. Tuckermann, M. et al. DOAS-observation of halogen radical-catalysed arctic boundary layer ozone destruction during the ARCTOC-campaigns 1995 and 1996 in Ny-Alesund, Spitsbergen. Tellus B 49, 533–555 (1997).

    Article  Google Scholar 

  8. Ravishankara, A. R. & Wine, P. H. Laser flash photolysis-resonance fluorescence kinetics study of the reaction Cl (P-2)+CH4→CH3+HCl. J. Chem. Phys. 72, 25–30 (1980).

    Article  Google Scholar 

  9. Friedl, R. R. & Sander, S. P. Kinetics and product studies of the reaction ClO and BrO using discharge flow mass spectrometry. J. Phys. Chem. 93, 4756–4764 (1989).

    Article  Google Scholar 

  10. Avallone, L. M. & Toohey, D. W. Tests of halogen photochemistry using in situ measurements of ClO and BrO in the lower polar stratosphere. J. Geophys. Res. 106, 10411–10421 (2001).

    Article  Google Scholar 

  11. Osthoff, H. D et al. High levels of nitryl chloride in the polluted subtropical marine boundary layer. Nature Geosci. 1, 324–328 (2008).

    Article  Google Scholar 

  12. Thornton, J. A. et al. A large atomic chlorine source inferred from mid-continental reactive nitrogen chemistry. Nature 464, 271–274 (2010).

    Article  Google Scholar 

  13. Spicer, C. W. et al. Unexpectedly high concentrations of molecular chlorine in coastal air. Nature 394, 353–356 (1998).

    Article  Google Scholar 

  14. Riedel, T. P. et al. Nitryl chloride and molecular chlorine in the coastal marine boundary layer. Environ. Sci. Technol. 46, 10463–10470 (2012).

    Article  Google Scholar 

  15. Ren, X. et al. Airborne intercomparison of HOx measurements using laser-induced fluorescence and chemical ionization mass spectrometry during ARCTAS. Atm. Meas. Technol. 5, 2025–2037 (2012).

    Article  Google Scholar 

  16. Pohler, D., Vogel, L., Friess, U. & Platt, U. Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy. Proc. Natl Acad. Sci. USA 107, 6582–6587 (2010).

    Article  Google Scholar 

  17. Impey, G. A., Shepson, P. B., Hastie, D. R. & Barrie, L. A. Measurements of photolyzable chlorine and bromine during Polar Sunrise Experiment 1995. J. Geophys. Res. 102 (D13), 16005–16010 (1997).

    Article  Google Scholar 

  18. Liao, J. et al. A comparison of Arctic BrO measurements by chemical ionization mass spectrometry and long path-differential optical absorption spectroscopy. J. Geophys. Res. 116, D00R02 (2011).

    Article  Google Scholar 

  19. Liao, J. et al. Observations of inorganic bromine (HOBr, BrO, and Br-2) speciation at Barrow, Alaska, in spring 2009. J. Geophys. Res. 117, D00R16 (2012).

    Google Scholar 

  20. Oum, K. W., Lakin, M. J., DeHaan, D. O., Brauers, T. & Finlayson-Pitts, B. J. Formation of molecular chlorine from the photolysis of ozone and aqueous sea-salt particles. Science 279, 74–77 (1998).

    Article  Google Scholar 

  21. Knipping, E. M. et al. Experiments and simulations of ion-enhanced interfacial chemistry on aqueous NaCl aerosols. Science 288, 301–306 (2000).

    Article  Google Scholar 

  22. Pratt, K. A. et al. Photochemical production of molecular bromine in arctic surface snowpacks. Nature Geosci. 6, 351–356 (2013).

    Article  Google Scholar 

  23. Carpenter, L. J. et al. Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine. Nature Geosci. 6, 108–111 (2013).

    Article  Google Scholar 

  24. Thomas, J. L. et al. Modeling chemistry in and above snow at Summit, Greenland — Part 1: Model description and results. Atmos. Chem. Phys. 11, 4899–4914 (2011).

    Article  Google Scholar 

  25. Abbatt, J. P. D. et al. Halogen activation via interactions with environmental ice and snow in the polar lower troposphere and other regions. Atmos. Chem. Phys. 12, 6237–6271 (2012).

    Article  Google Scholar 

  26. Guimbaud, C. et al. Snowpack processing of acetaldehyde and acetone in the Arctic atmospheric boundary layer. Atmos. Environ. 36, 2743–2752 (2002).

    Article  Google Scholar 

  27. Stohl, A., Forster, C., Frank, A., Seibert, P. & Wotawa, G. Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2. Atmos. Chem. Phys. 5, 2461–2474 (2005).

    Article  Google Scholar 

  28. Hornbrook, R. S. et al. Measurements of tropospheric HO2 and RO2 by oxygen dilution modulation and chemical ionization mass spectrometry. Atmos. Meas. Technol. 4, 735–756 (2011).

    Article  Google Scholar 

  29. Stephens, C. R. et al. The relative importance of chlorine and bromine radicals in the oxidation of atmospheric mercury at Barrow, Alaska. J. Geophys. Res. 117, D00R11 (2012).

    Article  Google Scholar 

  30. Neuman, J. A. et al. Bromine measurements in ozone depleted air over the Arctic Ocean. Atmos. Chem. Phys. 10, 6503–6514 (2010).

    Article  Google Scholar 

Download references

Acknowledgements

This work is part of the international multidisciplinary OASIS program and is financially supported by NSF grants ATM-0807702, ARC-0806437 and ARC-0732556. We thank the OASIS campaign organizers and the National Center for Atmospheric Research shipping department for logistical support. We also thank J. Fast and A. Stohl for making the FLEXPART-WRF code public (http://transport.nilu.no/flexpart). The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research, under the sponsorship of the National Science Foundation.

Author information

Authors and Affiliations

Authors

Contributions

H.J.B., P.B.S., F.M.F. and J.J.O. planned and organized the project. J.L., D.J.T. and L.G.H. conducted measurements of halogen species by CIMS at Barrow. J.L. analysed and modelled the data, performed laboratory tests and wrote the manuscript. L.G.H. revised the manuscript. Z.L. and Y.W. calculated FLEXPART back trajectories. C.A.C. and R.S.H. performed HO2 and RO2 measurements. P.B.S. and C.R.S. performed ClOx measurements. A.J.W. performed O3 and NO measurements. S.R.H. and K.U. performed photolysis rate measurements. H.J.B. measured chloride concentrations in the snow. E.C.A., D.R. and A.F. performed VOC measurements. R.L.M. performed OH measurements. J.N.S. measured aerosol size distribution. R.M.S performed ozonesonde measurements. All authors reviewed and commented on the paper.

Corresponding author

Correspondence to L. Gregory Huey.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1558 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Liao, J., Huey, L., Liu, Z. et al. High levels of molecular chlorine in the Arctic atmosphere. Nature Geosci 7, 91–94 (2014). https://doi.org/10.1038/ngeo2046

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo2046

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing