关键词: 企业, 消耗臭氧层物质, 含氟温室气体, 大气观测, 体积分数特征

Abstract: Objective　Ozone-depleting substances (ODS) and fluorinated greenhouse gases (F-GHGs) have significant impacts on ozone layer depletion and greenhouse effect, and are the key halogenated gases controlled by international conventions such as the Montreal Protocol on Substances that Deplete the Ozone Layer. Atmospheric observation is an important foundation for estimating the volume fraction and emissions of ODS and F-GHGs. However, existing observations mainly focus on background stations and urban areas, with few research on typical plants. With the development of the Chinese economy, there is an urgent need for atmospheric observation of typical plants involved in the production and use of ODS and F-GHGs to learn their emissions during their production and use. Therefore, this study selectes four typical plants from different regions in China to conduct ODS and F-GHGs observation, analyze the volume fraction of ODS and F-GHGs at the plant boundary and within the plant area, and explores the emission processes of key pollutants. The results will provide fundamental data and scientific support for estimating the annual emission from typical plants in China, as well as for managing and controlling the emissions of ODS and F-GHGs. Methods　The research on the observation of ODS and F-GHGs emissions from typical plants includes three stages: site selection, sampling, and analysis. First, considering the industry, plants, and regional distribution characteristics of ODS and F-GHGs, this study selectes two fluorine chemical plants in Zhejiang, one fluorine chemical plants in Shandong, and one electrical dismantling plant in Guangxi to conduct the observation of ODS and F-GHGs fugitive emissions. The observation sites include the plant boundary, plant area, and discharge outlet. Then, 6-liter SUMMA canisters are used to collect ambient air samples at the observation sites. Each canister is cleaned before use and pressurized with high-purity nitrogen to maintain a positive pressure. After being transported to the observation sites, the canisters are used with a positive pressure sampling device for sample collection. Finally, samples from each site are analyzed using a cryogenic preconcentration/gas chromatography-mass spectrometry system, and a total of 21 ODS and F-GHGs are detected, including 6 chlorofluorocarbons (CFCs), 4 hydrochlorofluorocarbons (HCFCs), 9 hydrofluorocarbons (HFCs), and 2 perfluorocarbons (PFCs). To ensure the accuracy of the analytical results, the entire system is checked by injecting a blank sample with highpurity nitrogen before analysis to ensure that no target compounds are detected. Additionally, parallel samples are collected simultaneously at each observation site during sampling for measurement, and the relative deviation of target compounds in the parallel samples is ≤ 20%. Results and discussion　Based on observation data from four plants, this study reveals the primary reasons for the difference in ODS and F-GHGs volume fraction between plant boundary and plant area, elucidates the emission processes of the key component CHClF2 (HCFC-22), and explores the constituent characteristics of waste gas around discharge outlets of different plants. The main results are as follows: (1) The ODS and F-GHGs volume fractions within the plant area are significantly higher than those at the plant boundary, especially for HCFCs and HFCs. This phenomenon is primarily attributed to the fugitive emissions during the production of HCFCs and HFCs within the plants, as well as during the dismantling of electrical appliances such as air conditioners; (2) In fluorine chemical plants, the volume fraction of HCFC-22 near the reactor, caustic scrubber, and HCFC-22 distillation tower are significantly higher than that at other observation sites. Similarly, in electrical dismantling plant, the volume fraction of HCFC-22 in the disassembly workshop, sorting area, and storage area also significantly higher than that at other sites; (3) Incinerator can effectively remove ODS and F-GHGs from industrial waste gas. Untreated waste gas has a complex composition and a higher volume fraction of pollutants. Conclusions　The observation results of three fluorine chemical plants and one electrical dismantling plant show that the volume fractions of ODS and F-GHGs at the plant boundaries and within the plant areas are higher than background levels, indicating the need to strengthen control over fugitive emissions. By comparison, the volume fraction of HCFCs and HFCs within the plant areas are significantly higher than at the plant boundaries, confirming that they are the main pollutants of fugitive emission in these plants. Additionally, reactor, caustic scrubber and distillation tower in fluorine chemical plants, as well as disassembly workshop, sorting areas and storage area in electrical dismantling plants, are identified as crucial processes for HCFC-22 emission, respectively. Finally, it is worth noting that incinerators have good destruction effects on ODS and F-GHGs. In the future, more typical plants should be selected to conduct atmospheric observation to further understand the emissions of ODS and F-GHG.

Key words: plants, ozone-depleting substances, fluorinated greenhouse gases, atmospheric observation, volume fraction characteristics