Removal of Per-, Poly-fluoroalkyl substances (PFASs) and multi-biosphere community dynamics in a bacteria-algae symbiotic aquatic ecosystem

The presence of Per-, Poly-fluoroalkyl substances (PFASs) in aquatic ecosystems has drawn broad concerns in the scientific community due to their biological toxicity. However, little has been explored regarding PFASs' removal in phytoplankton-dominated environments. This study aimed to create a simulated bacteria-algae symbiotic ecosystem to observe the potential transportation of PFASs. Mass distributions showed that sand (63-2000 mu m), silt & clay (0-63 mu m), the phycosphere (> 3 mu m plankton), and the free-living biosphere (0.22-3 mu m plankton) contained 19.00, 7.78, 5.73 and 2.75% PFASs in their total mass, respectively. Significant correlations were observed between carbon chain lengths and removal rates (R-2 = 0.822, p < 10(-4)). Structural equation models revealed potential PFAS transportation pathways, such as water-phycosphere-free-living biosphere-sand-silt & -clay, and water-sand-silt & clay (p < 0.05). The presence of PFASs decreased the bacterial density but increased algal density (p < 0.01) in the planktonic environment, and PFASs with longer carbon chain lengths showed a stronger enhancement in microbial community successions (p < 0.05). In algal metabolisms, chlorophyll-a and carotenoids were the key pigments that resisted reactive oxygen species caused by PFASs. PFBA (perfluorobutyric acid) (10.38-14.68%) and PFTeDA (perfluorotetradecanoic acid) (10.33-15.96%) affected bacterial metabolisms in phycosphere the most, while in the free-living biosphere was most effected by PFPeA (perfluorovaleric acid) (13.21-13.99%) and PFDoA (perfluorododecanoic acid) (10.04-10.50%). The results of this study provide new guidance measures for PFAS removal and management in aquatic environments.

Automated summary

This study investigated the removal of PFASs in phytoplankton-dominated environments and found distribution and effects of PFASs in different microbial spheres. The results provide new guidance for PFAS removal and management in aquatic environments.