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Dissipation and transformation of 17β-estradiol-17-sulfate in soil-water systems

Bai, Xuelian, Casey, Francis X. M., Hakk, Heldur, DeSutter, Thomas M., Oduor, Peter G., Khan, Eakalak
Journal of hazardous materials 2013 v.260 pp. 733
agricultural soils, animal manures, biodegradation, carbon, conjugated estrogens, environmental fate, estrone, half life, hydroxylation, oxidation, runoff, soil organic carbon, soil water, subsurface soil layers, topsoil
In the environment, estrogen conjugates can be precursors to the endocrine-disrupting free estrogens, 17-estradiol (E2) and estrone (E1). Compared to other estrogen conjugates, 17-estradiol-17-sulfate (E2-17S) is detected at relatively high concentrations and frequencies in animal manure and surface runoff from fields receiving manure. To elucidate the lifecycle of manure-borne estrogens and their conjugates in the environment, the fate of radiolabelled E2-17S in agricultural soils was investigated using laboratory batch studies with soils of different organic carbon (OC) content (1.29% for topsoil versus 0.26% for subsoil). E2-17S was found relatively persistent in the aqueous phase throughout the duration of the 14 d experiment. The aqueous E2-17S persisted longer in the subsoil (half-lives (DT50) = 64–173 h) than the topsoil (DT50 = 4.9–26 h), and the aqueous persistence of E2-17S depended on its initial concentration. The major transformation pathway was hydroxylation, yielding mono- and di-hydroxy-E2-17S (OH-E2-17S and diOH-E2-17S). Free estrogens, E2 and E1, were only observed in the sorbed phase of the soil at low concentrations (∼1% of applied dose), which demonstrated that deconjugation and subsequent oxidation had occurred. Although deconjugation was not a major pathway, E2-17S could be a precursor of free estrogens in the environment.