Observations and Potential Source Regions of Hfc-152a in Southeastern China

Abstract

1,1-Difluoroethane (HFC-152a) is a type of hydrofluorocarbon (HFCs) that has been adopted as a substitute for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) for small ozone depletion potential. However, the production of HFC-152a has increased in recent years, prompting greater regulatory attention. In this study, we conducted a continuous daily in situ observation of HFC-152a at a remote site in southeastern China from May 2023 to May 2024. HFC-152a exhibits seasonal variations in mixing ratios and enhancements, with summer values being lower than in other seasons. During the observation period, the average mixing ratio was 13.6 ± 5.2 ppt, while the average enhancement was 5.8 ± 4.1 ppt. The Yangtze River Delta, eastern and northern Jiangxi, the border between Jiangxi and Fujian, and the coastal areas of Fujian were identified as the primary potential source regions of HCF-152a by employing the Potential Source Contribution Function (PSCF) and the Concentration Weighted Trajectory (CWT) methods. Moreover, using the interspecies correlation (ISC) method with trichloromethane (CHCl3) and difluoromethane (HFC-32) as tracers, the estimated emissions of HFC-152a in southeastern China were found to range from 1.5 to 3.5 Gg/yr and 1.8 to 2.2 Gg/yr, respectively. The estimated emissions of HFC-152a in the Yangtze River Delta were found to range from 1.0 to 2.2 Gg/yr and 1.1 to 1.3 Gg/yr, respectively. This study presents the emission status of HFC-152a in southeastern China and provides a reference for assessing the effectiveness of emission control measures for HFC-152a in the same region.

Keywords: in-situ observation, emission estimation, fluorinated greenhouse gases, Montreal Protocol, potential source regions