Effects of long-chained perfluoroalkyl acids (PFAAs) on the uptake and bioaccumulation of short-chained PFAAs in two free-floating macrophytes: Eichhornia crassipes and Ceratophyllum demersum

Short-chained perfluoroalkyl acids (PFAAs, C n F 2n+1 –R, n ≤ 6) have merged as global concerns due to their extensive application and considerable toxicity. However, long-chained PFAAs (n ≥ 7) featured with high persistence are still ubiquitously observed in aquatic environment . To understand the uptake behavior of short-chained PFAAs in aquatic macrophytes , the uptake kinetics, bioconcentration , and translocation of short-chained PFAAs (3 ≤n ≤ 6) in two typical free-floating macrophytes ( Eichhornia crassipes and Ceratophyllum demersum ) were investigated in the treatments with and without long-chained PFAAs (7 ≤n ≤ 11). Results showed that short-chained PFAAs can be readily accumulated in both E. crassipes and C. demersum , and the uptake of short-chained PFAAs fit the two-compartment kinetic model well ( p  < 0.05). In the treatments with long-chained PFAAs, significant concentration decreases of all concerned short-chained PFAAs in E. crassipes and PFAAs with n ≤ 5 in C. demersum were observed. Long-chained PFAAs could hinder the uptake rates, bioconcentration factors , and translocation factors of most short-chained PFAAs in free-floating macrophytes ( p  < 0.01). Significant correlations between bioconcentration factors and perfluoroalkyl chain length were only observed when long-chained PFAAs were considered ( p  < 0.01). Our results underlined that the effects of long-chained PFAAs should be taken into consideration in understanding the uptake and bioaccumulation behaviors of short-chained PFAAs.