In Situ Observations of Halogenated Gases at the Shangdianzi Background Station and Emission Estimates for Northern China

Halogenated gases include ozone-depleting substances
and greenhouse
gases, such as chlorofluorocarbons, halons, hydrochlorofluorocarbons,
hydrofluorocarbons, and perfluorinated gases. In situ atmospheric
observations of major halogenated gases were conducted at the Shangdianzi
(SDZ) background station, China, from October 2020 to September 2021
using ODS5-pro, a newly developed measurement system. The measurement
time series of 36 halogenated gases showed occasional pollution events,
where background conditions represented 25% (CH2Cl2) to 81% (CF3Cl, CFC-13) of the measurements. The
annual mean background mole fractions of most species at SDZ were
consistent with those obtained at the Mace Head station in Ireland.
The background conditions were distinguished from pollution events,
and the enhanced mole fractions were used to estimate the emissions
of four categories of fluorinated gases (F-gases) from northern China
using a tracer ratio method. The CO2-equivalent (CO2-equiv) emission of F-gases from northern China reached 181
± 18 Tg year–1 during 2020–2021. Among
the four categories of F-gases estimated, SF6 accounted
for the highest proportion of CO2-equiv emissions (24%),
followed by HFC-23 (22%), HFC-125 (17%), HFC-134a (13%), NF3 (10%), CF4 (5.9%), HFC-143a (3.9%), HFC-32 (3.4%), and
HFC-152a (0.2%).