| Due to the high global warming potential(GWP,124～22800)of fluorinated greenhouse gases(F-gases)and the rapid rise in their global concentrations,researches on F-gas emissions were of great significance for assessing climate change.Moreover,China is the largest producer,consumer,and emitter of HFCs worldwide,so it is necessary to study the emissions of F-gases in China.At present,there are certain differences in the emission results of F-gases estimated based on the bottom-up method and the top-down method,and there are also many shortcomings in the default emission factor method and mass balance method.Therefore,it is necessary to study the emissions of the production process by using direct measurement method.However,existing studies have mainly carried out the research based on peripheral sampling aroud plants combined with Gaussian model for VOCs,SO2,benzo[a]pyrene,and CTC,but few research have been conducted on F-gas emissions in fluorochemical plants.In this study,for the first time,one chemical plant of typical fluorochemical plant was selected in Shandong Province,Zhejiang Province,and Jiangsu Province,respectively(Plant A.Plant B.and Plant C),where fluorochemical plants were mainly distributed.In Guangdong Province,one typical chemical plant was selected(Plant D),where non-fluorochemical plant and only F-gases were used.A total of 200 effective atmospheric samples were collected from the surrounding areas of four plants in winter and summer,the concentration characteristics were analyzed and the virtual point source postposition method in the modified Gaussian model was used to estimate emissions.The main conclusions are as follows:1.The observation results showed that the difference between the average total concentration of F-gases in the upwind and downwind sites during the daytime is significantly higher than that at nighttime.This may be due to the higher atmospheric stability degree at night,and the emissions of F-gases were not easy to diffuse to the downwind sites.The species of F-gases emitted by Plant A,Plant B,and Plant C were significantly more than Plant D.This may be because there were fluorochemical plants in Plant A.Plant B,and Plant C,while Plant D did not.The fugitive emissions and by-product emissions were generated during the production of F-gases in the plants,with complex emission sources and multiple types of emissions.This study found that the up-down enhanced ratios and up-down differences of HFC-152a and HFC-32 in Plant A,HFC-227ea,HFC-125,and HFC-143a in Plant B,HFC-32 and HFC-125 in Plant C,and HFC-143a in Plant D were the highest.It is speculated that the emission strengths of these substances may be higher in each plant.The average total concentrations of F-gases at sensitive sites in each plant(1381～2878 pptv)were not significantly different at upwind sites(3～854 pptv),speculating that the concentration contribution of the plants to sensitive sites was not significant.2.The emission results showed that the total emissions of F-gases during the production process in Plant A,Plant B,and Plant C had reached 16994(10244-24900)tons/year.In this study,the total emissions of HFCs in these three plants were basically within the uncertainty range of emissions calculated based on the IPCC 2019 emission factor,accounting for approximately 59%of their best estimated emissions,but both were higher than the uncertainty range of emissions calculated based on the IPCC 2006 emission factor,which were approximately four times their best estimated emissions.Therefore,the emission factors recommended by the IPCC 2006 may be underestimated.3.The F-gases emitted by each plant at sensitive sites will not cause toxicity to humans,but due to their high GWP values and radiation efficiencies,the certain climate impacts will be caused.It is necessary to continuously monitor the concentrations of F-gases in the workplaces of fluorochemical plants and try to adopt the best emission reduction technologies to reduce the impact of F-gases on health and the environment. |
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