Trifluoroacetic Acid (TFA) Deposition and Accumulation Potential from Future Emissions of HFO-1234yf in China

The substitution of potent greenhouse gases, hydrofluorocarbons (HFCs), with hydrofluoroolefin HFO-1234yf, carries an environmental risk: its rapid atmospheric degradation yields trifluoroacetic acid (TFA), a persistent, mobile, and ubiquitous perfluoroalkyl substance. As the world's largest consumer of HFCs, China's future adoption of HFO-1234yf may substantially elevate regional TFA levels. This study provides projections of TFA deposition patterns and the potential for TFA accumulation in Chinese surface lakes driven by anticipated HFO-1234yf emissions (1.5-79.0 kt yr^-1) from 2025 to 2060. The results indicate that by 2060, mean TFA deposition fluxes over China are projected to reach 0.91-1.27 kg km^-2 yr^-1, leading to mean TFA concentrations in lakes of 0.90-1.54 μg/L. TFA accumulation exhibits strong spatial heterogeneity, with the highest TFA concentrations of lakes predicted for northern China, particularly the Beijing-Tianjin-Hebei region and its surroundings. The mean TFA concentrations in lakes over these regions are anticipated to be 1.83-3.58 μg/L, with hotspots ranging from 10 to 49 μg/L. This could be due to a combination of high atmospheric TFA inputs, shallow lake depths, and long residence times. This work provides a modeling framework for assessing the secondary environmental impacts of HFCs/HFOs under evolving refrigerant policies.