Fate and transformation of a conjugated natural hormone 17beta-Estradiol-3-Glucuronide in soil-water systems

The objectives of the study were to investigate the sorption and degradation of a glucuronide conjugated natural hormone, 17beta-estradio1-3-glucuronide (E2-3G), and its estrogenic metabolites in soil-water systems. Radiolabeled E2-3G was first synthesized in the laboratory. Soil-water batch experiments were then conducted using natural and sterilized topsoil (0-6 cm) and subsoil (18-24 cm) with the radiolabeled E2-3G to investigate the effects of soil organic matter content and microbial activity.;The aqueous dissipation of 14C in the batch experiments followed a biphasic pattern with an initial rapid dissipation phase followed by a second slower phase. Significant differences in total aqueous 14C dissipation were observed for the different initial concentrations for both soils, with greater persistence of intact E2-3G at higher initial concentrations.;Analysis indicated that E2-3G metabolized into estrone glucuronide (E1-3G), E2, and estrone (E1). The sorbed phase fraction that was bound to the soil contained E1 and E2. Concentration of E1 was at least 1.8 times greater than E2 in the sorbed phase of the natural topsoil, while E2 concentration was greater in the sorbed phase of the subsoil.;Compared to the subsoil, more rapid E2-3G deconjugation in the topsoil was observed, which resulted in rapid aqueous phase dissipation that was primarily caused by aglycone (E2 and E1) hydrophobic sorption dynamics. In case of the subsoil, transformation of E2-3G to free estrogens was slower. For the topsoil and subsoils, the first 24 h and up to 14 d, respectively, were critical periods for the potential estrogenic contribution to the environment from intact glucuronide conjugates.;A comprehensive kinetic biogeochemical model was developed to describe various non-equilibrium degradation and sorption processes of E2-3G and its metabolites. The E2-3G hydrolysis in the natural topsoil was two orders of magnitude greater than the subsoil. The sorption capacity for E2-3G was one and three orders of magnitude lower than the E2 in the topsoil and subsoils, respectively.;This study shows that estrogen conjugates may be significant contributors in the environmental detection of potent free estrogens.