Search Results (4)

Perfluorotetradecanoic acid (PFTeDA), a long-chain per- and polyfluoroalkyl substance (PFAS), is highly persistent and bioaccumulative, yet its effects on soil bacterial communities remain poorly understood. This study evaluated the impact of PFTeDA on the taxonomic composition, diversity, and functional potential of soil bacteria, and assessed whether biostimulants (Shigeki and Aminoprim) could mitigate these effects and improve the growth of Amaranthus cruentus. A pot experiment was conducted using Eutric Cambisols soil (pH 4.62), and bacterial communities were analyzed by 16S rRNA gene sequencing. PFTeDA significantly altered bacterial community composition, reducing the abundance of Actinomycetota, Chloroflexota, and Gemmatimonadota, while also changing alpha and beta diversity and predicted functional profiles. Biostimulant application partially alleviated these effects by promoting recovery of the soil bacterial communities and bacteria associated with nitrogen cycling and organic matter degradation, indicating partial restoration of soil ecosystem functions. PFTeDA reduced aboveground biomass but increased root biomass of A. cruentus, without affecting leaf greenness (SPAD). Both biostimulants enhanced plant growth and SPAD values, with Aminoprim exerting a stronger effect on shoot biomass and Shigeki stimulating root development. This study demonstrates that PFTeDA affects not only the taxonomic composition of the soil bacterial communities but, above all, its stability and predicted functional potential, representing a key mechanism underlying its impact on the soil–plant system. It also highlights that biostimulation may serve as an effective tool supporting the potential improvement in soils contaminated with persistent organic compounds. Full article

Perfluorinated tetradecanoic acid was added as an additive to a base oil and tested under full film elastohydrodynamic (EHD) contact conditions between a steel ball and a steel disc. By varying key performance parameters, we aimed to assess the feasibility and limitations of perfluorinated carboxylic acids in reducing friction in lubricated contacts. The results demonstrate that the tested perfluorinated additive is effective in reducing friction when blended with a non-polar synthetic poly-alpha-olefin oil. However, no significant friction reduction was observed when the same additive was used in a slightly polar synthetic ester. The carboxylic acid functional group plays a crucial role in the observed friction-reducing effect. Adjusting the additive concentration further plays an important role in reducing friction. A concentration of at least 0.35 wt.% is required to achieve a notable friction reduction of approximately 10%. Increasing the concentration beyond this threshold continues to improve the friction-reducing effect. Conversely, increasing the contact pressure has a detrimental impact on friction reduction. The greatest reduction in friction—over 20% compared to the base oil—was achieved at the lowest contact pressure tested (0.69 GPa). Full article

Eighteen per-and polyfluoroalkyl substances (PFASs) were investigated in surface waters of four river basins in Portugal (Ave, Leça, Antuã, and Cértima) during the dry and wet seasons. All sampling sites showed contamination in at least one of the seasons. In the dry season, perfluorooctanoate acid (PFOA) and perfluoro-octane sulfonate (PFOS), were the most frequent PFASs, while during the wet season these were PFOA and perfluobutane-sulfonic acid (PFBS). Compounds detected at higher concentrations were PFOS (22.6 ng L⁻¹) and perfluoro-butanoic acid (PFBA) (22.6 ng L⁻¹) in the dry and wet seasons, respectively. Moreover, the prospective environmental risks of PFASs, detected at higher concentrations, were evaluated based on the Risk Quotient (RQ) classification, which comprises acute and chronic toxicity. The results show that the RQ values of eight out of the nine PFASs were below 0.01, indicating low risk to organisms at different trophic levels in the four rivers in both seasons, wet and dry. Nevertheless, in the specific case of perfluoro-tetradecanoic acid (PFTeA), the RQ values calculated exceeded 1 for fish (96 h) and daphnids (48 h), indicating a high risk for these organisms. Furthermore, the RQ values were higher than 0.1, indicating a medium risk for fish, daphnids and green algae (96 h). Full article

Industrial and consumer products, such as pesticides, lubricants, and cosmetics, can contain perfluorinated compounds (PFCs). Although many short-chain PFCs have been linked to physiological and behavioral changes in fish, there are limited data on longer-chain PFCs. The objective of this study was to determine the potential impact of perfluorotetradecanoic acid (PFTeDA) exposure on zebrafish (Danio rerio) during early developmental stages. We measured several endpoints including gene expression, mitochondrial bioenergetics, and locomotor activity in zebrafish. Survival, timing of hatching, and deformity frequency were unaffected by PFTeDA at the concentrations tested (0.01, 0.1, 1, and 10 µM) over a 7-day exposure period. The expression levels of mitochondrial-related genes (cox1 and mt-nd3) and oxidative stress-related genes (cat, hsp70, and hsp90a) were increased in larval fish with exposure to 10 µM PFTeDA; however, there was no change in oxidative respiration of embryos (i.e., basal respiration and oligomycin-induced ATP-linked respiration). Reactive oxygen species were reduced in larvae treated with 10 µM PFTeDA, coinciding with the increased transcription of antioxidant defense genes. Both the visual motor response test and light–dark preference test were conducted on 7 dpf larvae and yielded no significant findings. This study improves current knowledge regarding toxicity mechanisms for longer-chain PFCs such as PFTeDA. Full article