In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 16 ( 2018-08-17), p. 11729-11738
Abstract:
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 yr−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 yr−1. The missing emissions
(∼19 Gg yr−1) for China contribute to approximately 54 % of global
CCl4 emissions. It is also shown that 89 %±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.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-11729-2018
DOI:
10.5194/acp-18-11729-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1