Behaviors of N-ethyl perfluorooctane sulfonamide ethanol (N-EtFOSE) in a soil-earthworm system: Transformation and bioaccumulation

Abstract

N-ethyl perfluorooctane sulfonamido ethanol (N-EtFOSE) is a typical precursor of perfluorooctane sulfonate (PFOS). In this study, the behaviors of N-EtFOSE in a soil-earthworm system, including biodegradation in soil and bioaccumulation and biotransformation in earthworms (Eisenia fetida) were investigated. N-EtFOSE could be biodegraded in soil and biotransformed in earthworms to several metabolites, including n-ethylperfluorooctane sulfonamide acetate (N-EtFOSAA), perfluorooctane sulfonamide acetate (FOSAA), perfluorooctane sulfonamide (FOSA) and PFOS, with N-EtFOSAA as the predominant intermediate and PFOS as the terminal product in both soil and earthworm. The uptake rate coefficients (ku, 0.746 goc gdw(-1)d(-1)), degradation rate constant in soil (k0, 0.138 d(-1)) and the biota-to-soil accumulation factor (BSAF, 0.523 goc gdw(-1)) of N-EtFOSE were estimated. For N-EtFOSE, N-EtFOSAA, FOSAA, FOSA and PFOS, their loss rate constants in earthworms were in the range of 0.467-30.2 (α) and 0.006-0.415 (β) d(-1), respectively. The results provided important information about the behaviors of N-EtFOSE in the soil-earthworm system.

Keywords: Bioaccumulation; Biotransformation; Earthworm; N-EtFOSE; Soil.