There is limited information available regarding the bioaccumulation potential of polyfluoroalkyl substances (PFAS) in urban vegetation. Using a controlled greenhouse exposure setting, we investigated the bioaccumulation and translocation of select PFAS in four common urban spontaneous plants. Target compounds included legacy PFAS (perfluoroalkyl carboxylic and sulfonic acids, PFCA/PFSA), a fluorotelomer sulfonate (6:2 FTS), and an emerging fluorinated ether (i.e., hexafluoropropylene oxide dimer acid (HFPO-DA), or GenX). Results from this study showed that bioaccumulation factors in root and shoot (BCFroot and BCFshoot) ranged from 0.7 to 83.6 and 0.95 to 26.9, respectively. Phyllanthus urinaria harbored the highest PFAS bioaccumulation capacity among the four urban weed species. The log BCFroot of PFCA homologues showed a concave shape as a function of chain length, while log BCFroot of PFSA increased with chain length. The BCFroot of GenX was lower than that of PFOA; likewise, 6:2 FTS bioaccumulated to a less extent than PFOS. Root uptake seemed to be the dominant accumulation mechanism for the shorter-chain compounds, whereas adsorption was the dominant mechanism for longer-chain compounds such as PFOA. BCFroot and BCFshoot showed consistent trends in response to foliar and root characteristics. Leaf area and average root diameter were the most correlated traits with PFAS bioaccumulation factors, with higher BCF values for plants with smaller leaves and finer roots. This study also provides an important basis for the role and selection of urban weeds in future PFAS bioaccumulation and translocation studies within urban settings.

The present study assessed the bioaccumulation potential of per-and polyfluoroalkyl substances (PFAS) in ferns and linked root uptake behaviors to root characteristics and PFAS molecular structure. Tissue and subcellular-level behavioral differences between alternative and legacy PFAS were compared via an electron probe microanalyzer with energy dispersive spectroscopy (EPMA-EDS) and differential centrifugation. Our results show that ferns can accumulate PFAS from water, immobilize them in roots, and store them in harvestable tissue. The PFAS loading in roots was dominated by PFOS; however, a substantial amount of associated PFOS could be rinsed off by methanol. Correlation analyses indicated that root length, surface and project area, surface area per unit length of the root system, and molecular size and hydrophobicity of PFAS were the most significant factors affecting the magnitude of root uptake and upward translocation. EPMA-EDS images together with exposure experiments suggested that long-chain hydrophobic compounds tend to be adsorbed and retained on the root epidermis, while short-chain compounds are absorbed and quickly translocated upward. Our findings demonstrated the feasibility of using ferns in phytostabilization and phytoextraction initiatives of PFAS in the future.