Preprints
https://doi.org/10.5194/acp-2021-699
https://doi.org/10.5194/acp-2021-699

  23 Sep 2021

23 Sep 2021

Review status: this preprint is currently under review for the journal ACP.

Top-down and bottom-up estimates of anthropogenic methyl bromide emissions from eastern China

Haklim Choi1, Mi-Kyung Park1, Paul J. Fraser2, Hyeri Park3, Sohyeon Geum3, Jens Mühle4, Jooil Kim4, Ian Porter5, Peter K. Salameh4, Christina M. Harth4, Bronwyn L. Dunse2, Paul B. Krummel2, Ray F. Weiss4, Simon O'Doherty6, Dickon Young6, and Sunyoung Park1,3 Haklim Choi et al.
  • 1Kyungpook Institute of Oceanography, Kyungpook National University, Daegu 41566, Republic of Korea
  • 2Climate Science Centre, Commonwealth Scientific and Industrial Research Organisation (CSIRO) Oceans and Atmosphere, Aspendale, Victoria 3195, Australia
  • 3Department of Oceanography, Kyungpook National University, Daegu 41566, Republic of Korea
  • 4Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA
  • 5School of Life Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
  • 6Atmospheric Chemistry Research Group, University of Bristol, Bristol BS8 1TS, UK

Abstract. Methyl bromide (CH3Br) is a potent ozone-depleting substance (ODS) that has both natural and anthropogenic sources. CH3Br has been used mainly for preplant soil fumigation, post-harvest grain and timber fumigation, and structural fumigation. Most non-quarantine/pre-shipment (non-QPS) uses have been phased-out in 2005 for non-Article 5 (developed) countries and in 2015 for Article 5 (developing) countries under the Montreal Protocol on Substances that Deplete the Ozone Layer; some uses have continued under critical use exemptions (CUEs). Under the Protocol, individual nations are required to report annual data on CH3Br production and consumption for quarantine/pre-shipment (QPS) uses, non-QPS uses and CUEs to the United Nations Environment Programme (UNEP). In this study, we analyzed high precision, in situ measurements of atmospheric concentrations of CH3Br obtained at the Gosan station on Jeju island, Korea, from 2008 to 2019. The background concentrations of CH3Br in the atmosphere at Gosan declined from 8.5 ± 0.8 ppt in 2008 to 7.4 ± 0.6 ppt in 2019 at a rate of −0.13 ± 0.02 ppt yr−1. At Gosan, we also observed periods of persistent concentrations (pollution events) elevated above the decreasing background in continental air masses from China. Statistical back trajectory analyses showed that these pollution events predominantly trace back to CH3Br emissions from eastern China. Using an inter-species correlation (ISC) method with the reference trace species CFC-11 (CCl3F), we estimate anthropogenic CH3Br emissions from eastern China at 4.1 ± 1.3 Gg yr−1 in 2008–2019, approximately 2.9 ± 1.3 Gg yr−1 higher than the bottom-up emission estimates reported to UNEP. Possible non-fumigation CH3Br sources – rapeseed production and biomass burning – were assessed and it was found that the discrepancy is more likely due to unreported or incorrectly reported QPS and non-QPS fumigation uses. These largely-unreported anthropogenic emissions of CH3Br are confined to eastern China and account for 30–40 % of anthropogenic global CH3Br emissions. They are likely due to delays in the introduction of CH3Br alternatives, such as sulfuryl fluoride (SO2F2), heat, irradiation and a possible lack of industry awareness of the need for regulation of CH3Br production and use.

Haklim Choi et al.

Status: open (until 13 Nov 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Haklim Choi et al.

Haklim Choi et al.

Viewed

Total article views: 336 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
268 60 8 336 18 1 4
  • HTML: 268
  • PDF: 60
  • XML: 8
  • Total: 336
  • Supplement: 18
  • BibTeX: 1
  • EndNote: 4
Views and downloads (calculated since 23 Sep 2021)
Cumulative views and downloads (calculated since 23 Sep 2021)

Viewed (geographical distribution)

Total article views: 321 (including HTML, PDF, and XML) Thereof 321 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 22 Oct 2021
Download
Short summary
We observed 12-years continuous CH3Br pollution signals at Gosan and estimated anthropogenic CH3Br emissions in eastern China. The analysis revealed a significant discrepancy between top-down estimates and the bottom-up emissions from the fumigation usage reported to the United Nations Environment Programme, and likely from unreported or inaccurately reported fumigation usage. This result provides information to monitor international compliance with the Montreal Protocol.
Altmetrics