Behavior of N-ethyl perfluorooctanesulfonamido acetic acid (N-EtFOSAA) in biosolids amended soil-plant microcosms: Uptake, translocation and degradation

Perfluorooctane sulfonate (PFOS) has been added to the persistent organic pollutants list of the Stockholm Convention. With the effective reduction in release from direct sources in recent years, exploring the indirect sources... [ view full abstract ]

Perfluorooctane sulfonate (PFOS) has been added to the persistent organic pollutants list of the Stockholm Convention. With the effective reduction in release from direct sources in recent years, exploring the indirect sources of PFOS has become increasingly important. N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) has been found extensively in sewage sludge and biosolids-amended soils. The degradation of N-EtFOSAA serves as a significant source of PFOS in the environment. In this study, the uptake, translocation of N-EtFOSAA in seven species of plants, namely maize, soy bean, mung bean, radish, ryegrass, alfalfa and lettuce, and the degradation of N-EtFOSAA in soil-plant microcosms were evaluated over 60 days. N-EtFOSAA was found in roots of all plant species studied, while was not found in the above part of plants. The root concentration factors ranged 0.65-2.54 (pmol/groot)/(pmol/gsoil). Four degradation products, including N-Ethyl perfluorooctane sulfonamide (N-EtFOSA), perfluorooctane sulfonamide (FOSA), perfluorooctane sulfonamide acetate (FOSAA) and PFOS were found in the soils and plant roots, straws and leaves, indicating the degradation of N-EtFOSAA in soil-plant system. Evidence of a relatively higher proportion of degradation products in plant tissues than in the soil indicates that there is further degradation of N-EtFOSAA within plants or degradation products are more readily taken up by plants. Degradation kinetics fitted first-order kinetic model well. In the presence of plants, degradation rates of N-EtFOSAA were 2.03-3.59 times higher than those in the absence of plants. Degradation rate of N-EtFOSAA in plant-soil system of maize was relatively higher than those of other plant species.