Chemistry and the Environment, Chemical Ecology, Short Talk
EV-017

Investigating Urban Halocarbon Emissions: A Seoul Tracer Release Experiment

M. J. Müller1,2, M. K. Vollmer1*, S. Henne1*, J. Yun3*, H. Choi3*, S. Park3,4*, L. Emmenegger1*, S. Reimann1*
1Empa, Laboratory for Air Pollution/Environmental Technology, CH-8600 Dübendorf, Switzerland, 2ETH, Department of Chemistry and Applied Biosciences, CH-8093 Zürich, Switzerland, 3KNU, Kyungpook Institute of Oceanography, 41566 Daegu, Republic of Korea, 4KNU, Department of Oceanography, 41566 Daegu, Republic of Korea

Hydrofluorocarbons (HFCs), the replacement substances of (hydro)chlorofluorocarbons ((H)CFCs), are regulated under the Kyoto Protocol (1997) and, more recently, also under the Kigali amendment (2016) to the Montreal Protocol, which targets a reduction of HFC production and consumption over the following decades.1, 2 To achieve this, HFCs are being replaced by hydrofluoroolefins (HFOs) and other low-global-warming-potential substitutes.3 Monitoring compliance with these treaties by observing halogenated substances in the atmosphere is crucial. This can be achieved by atmospheric measurements using gas chromatography-mass spectrometry (GC-MS), combined with modeling, to yield regional and global emission estimates.4, 5

In this project, we have conducted a deliberate-release tracer experiment to estimate halocarbon emissions of the Seoul metropolitan area. Ethyl fluoride (HFC-161)6 and hexafluorobutane (HFO-1336mzzE), which are practically absent in the atmosphere, were released in the City of Seoul. Release times were carefully selected when favorable meteorological conditions allowed air masses to reach the in-situ measurement site at Gosan (Jeju Island), 485 km away, and further remote sites, Anmyeondo (138 km) and Mokpo (320 km), for flask sampling in between. FLEXPART7 was used to forecast the trajectory and dispersion of the plume, and the release and sampling timing were adjusted accordingly. During the first release in November 2025, both tracers were detected at the flask sampling sites Anmyeondo and Mokpo, as well as at Gosan station. First results show a stable correlation with various urban-used HFCs. First emission estimations from Seoul will be shown, using the November 2024 release. A second release is planned for Spring 2025, and the data will be included for more detailed estimates.

[1] Kyoto Protocol to the United Nations Framework Convention on Climate Change. adopted on December 11th, 1997; Kyoto, 1998, 1-22.

[2] Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer. adopted on October 15th, 2016; United Nations, Kigali.

[3] Mark O. McLinden, J. Steven Brown, Riccardo Brignoli, Andrei F. Kazakov, Piotr A. Domanski, Nature Communications, 2017, 8, 14476.

[4] Matt Rigby, Sunyoung Park, Takuya Saito, Luke M. Western, Alison L. Redington, et al., Nature, 2019, 569 (7757), 546-550.

[5] Peter G. Simmonds, Matthew Rigby, Alistair J. Manning, Sunyoung Park, Kieran M. Stanley, et al., Atmospheric Chemistry and Physics 2020, 20 (12), 7271-7290.

[6] Dominique Rust, Martin K. Vollmer, Stephan Henne, Arnoud Frumau, Pim van den Bulk, et al., Nature, 2024, 633, 96-100.

[7] Ignacio Pisso, Espen Sollum, Henrik Grythe, Nina I. Kristiansen, Massimo Cassiani, et al., Geoscientific Model Development, 2019, 12 (12), 4955-4997.