Toward resolving the budget discrepancy of ozone-depleting carbon tetrachloride (CCl4): An analysis of top-down emissions from China

Sunyoung Park*, Shanlan Li, Jens Mühle, Simon O'Doherty, Ray F. Weiss, Xuekun Fang, Stefan Reimann, Ronald G. Rinn

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
142 Downloads (Pure)

Abstract

Carbon tetrachloride (CCl4) is a first-generation ozone-depleting substance, and its emissive use and production were globally banned by the Montreal Protocol with a 2010 phase-out; however, production and consumption for non-dispersive use as a chemical feedstock and as a process agent are still allowed. This study uses the high frequency and magnitude of CCl4 pollution events from an 8-year real-time atmospheric measurement record obtained at Gosan station (a regional background monitoring site in East Asia) to present evidence of significant unreported emissions of CCl4. Top-down emissions of CCl4 amounting to 23.6±7.1 Gg yrĝ'1 from 2011 to 2015 are estimated for China, in contrast to the most recently reported, post-2010, Chinese bottom-up emissions of 4.3-5.2 Gg yrĝ'1. The missing emissions ( ĝ1/4 19 Gg yrĝ'1) for China contribute to approximately 54 % of global CCl4 emissions. It is also shown that 89ĝ€†% ± 6 % of CCl4 enhancements observed at Gosan are related to CCl4 emissions from the production of CH3Cl, CH2Cl2, CHCl3 and C2Cl4 and its usage as a feedstock and process agent in chemical manufacturing industries. Specific sources and processes are identified using statistical methods, and it is considered highly unlikely that CCl4 is emitted by dispersive uses such as old landfills, contaminated soils and solvent usage. It is thus crucial to implement technical improvements and better regulation strategies to reduce evaporative losses of CCl4 occurring at the factory and/or process levels.

Original languageEnglish
Pages (from-to)11729-11738
Number of pages10
JournalAtmospheric Chemistry and Physics
Volume18
Issue number16
DOIs
Publication statusPublished - 17 Aug 2018

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