EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Observation of HClO3 and HClO4 in the Arctic atmosphere

Yee Jun Tham1, Nina Sarnela1, Carlos A. Cuevas2, Iyer Siddharth3, Lisa Beck1, Alfonso Saiz-Lopez2, and Mikko Sipilä1
Yee Jun Tham et al.
  • 1Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, 00014, Helsinki, Finland.
  • 2Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.
  • 3Laboratory of Aerosol Physics, Tampere University, Tampere, Finland.

Atmospheric halogens chemistry like the catalytic reaction of bromine and chlorine radicals with ozone (O3) has been known to cause the springtime surface-ozone destruction in the polar region. Although the initial atmospheric reactions of chlorine with ozone are well understood, the final oxidation steps leading to the formation of chlorate (ClO3-) and perchlorate (ClO4-) remain unclear due to the lack of direct evidence of their presence and fate in the atmosphere. In this study, we present the first high-resolution ambient data set of gas-phase HClO3 (chloric acid) and HClO4 (perchlorate acid) obtained from the field measurement at the Villum Research Station, Station Nord, in high arctic North Greenland (81°36’ N, 16°40’ W) during the spring of 2015. A state-of-the-art chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF) was used in negative ion mode with nitrate ion as the reagent ion to detect the gas-phase HClO3 and HClO4. We measured significant level of HClO3 and HClO4 only during the springtime ozone depletion events in the Greenland, with concentration up to 9x105 molecule cm-3. Air mass trajectory analysis shows that the air during the ozone depletion event was confined to near-surface, indicating that the O3 and surface of sea-ice/snowpack may play important roles in the formation of HClO3 and HClO4. We used high-level quantum-chemical methods to calculate the ultraviolet-visible absorption spectra and cross-section of HClO3 and HClO4 in the gas-phase to assess their fates in the atmosphere. Overall, our results reveal the presence of HClO3 and HClO4 during ozone depletion events, which could affect the chlorine chemistry in the Arctic atmosphere.

How to cite: Tham, Y. J., Sarnela, N., Cuevas, C. A., Siddharth, I., Beck, L., Saiz-Lopez, A., and Sipilä, M.: Observation of HClO3 and HClO4 in the Arctic atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16908,, 2020


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