Sorption and Degradation of 17β-Estradiol-17Sulfate in Agricultural Soils.

In the environment, the natural estrogenic hormone, 17ß-estradiol (E2) can potentially induce endocrine disruptions at low concentrations. Laboratory based studies have found low potentials for the persistence and mobility of E2 in the environment due to its high degradation and soil retention. However, field studies have measured estrogens at concentrations and frequency that indicate they are sufficiently persistent and mobile to impact water quality. To facilitate urine excretion, humans and animals release E2 as sulfate or glucuronide conjugates, which have higher aqueous solubilities compared to their deconjugated forms. It is hypothesized that the discrepancy between laboratory and field studies is caused by the deconjugation of estrogens conjugates to form free estrogens. The conjugate, E2-17sulfate (E2-17S) has been detected at a relatively high concentration in swine manure slurry; however, little is understood about its fate and transport in the environment. The objective of this study was to determine the persistence, sorption, and degradation of E2-17S in agricultural soils. In order to achieve this objective, radiolabel E2-17S (¹⁴C E2-17S) was chemically synthesized in a three–step process. Batch studies were then conducted to identify the processes controlling aqueous dissipation of ¹⁴C E2-17S in natural and sterile soils. Four concentrations of ¹⁴C E2-17S in 0.01 M CaCl₂ solutions were added to two soils that had similar mineral composition, but different organic carbon contents (1.5 and 0.5%). Aqueous phase radioactivities in the batch experiments were measured at seven time points using liquid scintillation counting. High performance liquid chromatography was used to determine deconjugation and/or metabolism of the E2-17S. For the natural soils with high and low organic carbon content, there was 12% and 30% of total radioactivity remaining in the aqueous phase after 14 days, respectively. Aqueous radioactivities after 14 d in the sterile soil were 23% and 46% for the high and low organic carbon contents, respectively. The parent compound, E2-17S, was relatively stable in the aqueous phase for both natural and sterile soils. Lesser amounts of two polar metabolites were also detected, indicating the degradation of E2-17S in both sterile and natural soils.