In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) at the Shangdianzi regional background station, China

Abstract

Abstract. Atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) were measured in-situ at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for five HFCs and three PFCs showed occasionally high-concentration events while background conditions occurred for 36 % (HFC-32) to 83 % (PFC-218) of all measurements. The mean mixing ratios during background conditions were 24.5 ppt (parts per trillion, 10 −12 , molar) for HFC-23, 5.86 ppt for HFC-32, 9.97 ppt for HFC-125, 66.0 ppt for HFC-134a, 9.77 ppt for HFC-152a, 79.1 ppt for CF 4 , 4.22 ppt for PFC-116, and 0.56 ppt for PFC-218. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere. North-easterly winds were associated with negative contributions to atmospheric HFC and PFC loadings (mixing ratio anomalies weighted by time associated with winds in a given sector), whereas southwesterly advection (urban sector) showed positive loadings. Chinese emissions estimated by a tracer ratio method using carbon monoxide as tracer were 3.6 ± 3.2 kt yr −1 for HFC-23, 4.3 ± 3.6 kt yr −1 for HFC-32, 2.7 ± 2.3 kt yr −1 for HFC-125, 6.0 ± 5.6 kt yr −1 for HFC-134a, 2.0 ± 1.8 kt yr −1 for HFC-152a, 2.4 ± 2.1 kt yr −1 for CF 4 , 0.27 ± 0.26 kt yr −1 for PFC-116, and 0.061 ± 0.095 kt yr −1 for PFC-218. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of Clean Development Mechanism (CDM) projects that started in 2005.

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF<sub>3</sub>) and the link to HCFC-22 (CHClF<sub>2</sub>) production

“…Several papers report Asian emissions of HFC-23, including those for China Stohl et al, 2010;Kim et al, 2010;Li et al, 2011;Yao et al, 2012). Recent papers by Fang et al (2014Fang et al ( , 2015 noted inconsistencies between the various bottom-up and top-down emissions estimates and provided an improved bottom-up inventory and a multi-annual top-down estimate of HFC-23 emissions for East Asia.…”

“…Kim et al (2010), reported HFC-23 measurements (November 2007-December 2008 from Gosan, Jeju Island and South Korea and also estimated regional atmospheric emissions. Asian emissions of HFC-23, including those for China have been reported by Yokouchi et al (2006); Stohl et al (2010); Li et al (2011);and Yao et al (2012). Most recently, Fang et al (2014Fang et al ( , 2015 have provided bottom-up and top-down estimates of HFC-23 emissions from China and East Asia and included observed HFC-23 mixing ratios at three stations -Gosan, South Korea, and Hateruma and Cape Ochi-ishi, Japan.…”

Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH<sub>3</sub>CHF<sub>2</sub>) from in situ and air archive observations

“…5.2 and Table 3. Yao et al (2012), using the interspecies correlation method with carbon monoxide as the reference tracer, reported more recent Chinese emissions of 2 ± 1.8 Gg yr −1 in 2010-2011. This would imply some reduction in Chinese emissions compared with earlier years.…”

Atmospheric sulfur hexafluoride in-situ measurements at the Shangdianzi regional background station in China

“…The Medusa-GC/MS system used a similar sampling mechanism, sharing the same inlet and sampling tubing with GC-ECD system. The HFC and PFC measurements made by this system were reported by Yao et al (2012b).…”

“…The details of the procedure were described by Yao et al (2012b). Approximately 63% of the valid results had been selected as non-background data.…”