Estimate of hydrochlorofluorocarbon emissions during 2011-2018 in the Yangtze River Delta, China

Hydrochlorofluorocarbons (HCFCs) are used as temporary substitutes for chlorofluorocarbons and other ozone-depleting substances because they have reduced ozone depletion and global warming potentials. The consumption and production of HCFCs are regulated via the Montreal Protocol and its amendments till 2013, with a complete phase-out being scheduled by 2030 for Article 5 parties (developing countries). To better understand the characteristics and emissions of HCFCs in the Yangtze River Delta (YRD), which is the largest metropolitan area in China, weekly flask samples were collected at the Lin'an regional background station located in the YRD from 2011 to 2018 and measured for four HCFCs (HCFC-22, HCFC-141b, HCFC-142b, and HCFC-124). The HCFC-132b and HCFC-133a measurements began in 2018. The ambient mixing ratios of the HCFCs exhibited higher concentrations and larger variabilities than those at the Shangri-la regional background station at similar latitudes in southwest China. The HCFC emissions in the YRD were estimated based on the tracer ratio method using CO and HFC-134a as tracers, and were comparable within the uncertainties. Our results are generally consistent with previous estimates obtained using top-down approaches. HCFC-22 and HCFC-141b contributed 52% ± 23% and 41% ± 24% of the total ODP-weighted (CFC-11-equivalent) HCFC emissions from the YRD, respectively, whereas HCFC-22 contributed the most (83% ± 36%) to the total CO₂-equivalent HCFC emissions from the YRD. The cumulative ODP-weighted and CO₂-equivalent emissions of HCFCs from the YRD accounted for 25% ± 15% and 20% ± 11% of the national corresponding totals, respectively, for 2011-2017. The HCFC-141b emissions from the YRD contributed approximately half of the total Chinese emissions. HCFC-133a emissions in the YRD accounted for approximately one-fifth of the global total in 2018. Thus, the YRD is an important contributor of HCFC emissions on national and global scales.