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

Abstract

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%).

Constraining Trifluoromethane (HFC‐23) Emission in Eastern China Based on Two‐Year Online Measurements

“…Meanwhile, the mixing ratios of HFC-23 were 42.7 ± 3.6 ppt during January May 2023 compared to 41.2 ± 3.2 ppt during January-May 2022, with an increase rate of 3.6%. When our data are pooled together along with those previously reported in China (Pu et al, 2020;Xie et al, 2019;Yao et al, 2012;Yi et al, 2023;Zhang et al, 2017), HFC-23 mixing ratios exhibited an increasing trend since 2011 with an annual increase rate of 1.0 ppt yr 1 (Figure S3 in Supporting Information S1), aligning with the increasing trend of the global background values of HFC-23 and comparable to the 1 ppt yr 1 reported by Park et al (2023).…”

“…Therefore PFC-318 and HFC-23 emissions from eastern China are quite near As shown in Figure 5, prior to 2012, the bottom-up inventories and top-down results for HFC-23 were found to be fairly consistent (Arnold et al, 2018;Fang et al, 2014Fang et al, , 2015Kim et al, 2010;Li et al, 2011;Simmonds et al, 2018;Stohl et al, 2010;Yao et al, 2012). However, starting from 2012, increasingly apparent differences between bottom-up inventories and top-down results were revealed among the HFC-23 emission estimates in China, with near-zero bottom-up emission estimates against much greater top-down emission estimates (Liang et al, 2022;Pu et al, 2020;Stanley et al, 2020;Xie et al, 2019;Yi et al, 2023;Zhao et al, 2023). The most recent data revealed HFC-23 emissions for China in 2021 were documented to be 1.09 Gg yr 1 , according to reports from the Montreal Protocol's Multilateral Fund (MLF) (TEAP, 2022(TEAP, , 2023.…”

“…A Stirling cryocooler (TC4189, Shenzhen LiHan Technology Co., Ltd, China) with smaller volume but higher refrigeration capacity is used for cooling traps to 228.2°C in ODS5-PRO system, instead of the "cryotiger" refrigeration unit of Medusa-GC/MS. The detailed description about the ODS5-PRO system can be found in Yi et al (2023). Briefly, ambient air is pumped by a KNF diaphragm pump (N86 KTE, KNF, Germany) into the system for subsequent processing.…”

“…The tracer used should have a good correlation with HFC-23 and available emission estimates (Huang et al, 2021;Zhang et al, 2014). The mixing ratios of HFC-23 and tracers are subtracted with their annual means observed at the regional background station SDZ as reported by Yi et al (2023) to calculate the enhanced ratio of ΔHFC-23/Δtracer. The emission of HFC-23, E HFC-23 (Gg yr 1 ), can be calculated as:…”

“…The emission of HFC-23 in eastern China was estimated to increase from 5.73 Gg yr 1 in 2015 to 9.45 Gg yr 1 in 2019 based on measurements at the Gosan background station in South Korea (Park et al, 2023). Meanwhile, studies based on measurements at Shangdianzi (SDZ) regional background station reported HFC-23 emissions of 6.4 Gg yr 1 for China in 2018 (Xie et al, 2019) and of 3.2 ± 0.9 Gg yr 1 for northern China in 2021 (Yi et al, 2023). Despite the inconsistency in the estimated HFC-23 emissions in China, no ambient monitoring data after 2015, other than those at SDZ, are available to assess HFC-23 emissions in China.…”