Levels and Temporal Trends of Trifluoroacetate (TFA) in Archived Plants: Evidence for Increasing Emissions of Gaseous TFA Precursors over the Last Decades

Trifluoroacetate (TFA) is a highly mobile and persistent compound that occurs ubiquitously in the environment. Results from previous studies suggested an increase in the atmospheric deposition of TFA in the Northern Hemisphere starting in the 1990s. Due to its physicochemical properties, TFA can be efficiently taken up and accumulated by vascular plants. Consequently, plants could serve as a biomonitoring tool to evaluate the presence of TFA in the terrestrial environment. This is the first study which describes the concentrations and temporal trends of TFA in biota by analyzing archived leaf samples of various tree species from the German Environmental Specimen Bank (observation period: 1989–2020). Samples from different locations of the same species were each in a similar concentration range. The highest concentrations (up to ∼1000 μg/kg dry weight) were found in Lombardy poplar (Populus nigra 'Italica') leaves. A statistically significant positive trend in the TFA concentration within the study period was found for most species/sites, which is likely the result of both bioaccumulation as well as increasing emissions of gaseous TFA precursors over the last three decades. These results contribute to the current discussion on the regulation of per- and polyfluoroalkyl substances (PFAS) to protect human and environmental health.