title: Modeling coupled sorption and transformation of 17β-estradiol-17-sulfate in soil-water systems.
abstract: Animal manure is the primary source of exogenous free estrogens in the environment, which are known endocrine-disrupting chemicals to disorder the reproduction system of organisms. Conjugated estrogens can act as precursors to free estrogens, which may increase the total estrogenicity in the environment. In this study, a comprehensive model was used to simultaneously simulate the coupled sorption and transformation of a sulfate estrogen conjugate, 17β-estradiol-17-sulfate (E2-17S), in various soil-water systems (non-sterile/sterile; topsoil/subsoil). The simulated processes included multiple transformation pathways (i.e. hydroxylation, hydrolysis, and oxidation) and mass transfer between the aqueous, reversibly sorbed, and irreversibly sorbed phases of all soils for E2-17S and its metabolites. The conceptual model was conceived based on a series of linear sorption and first-order transformation expressions. The model was inversely solved using finite difference to estimate process parameters. A global optimization method was applied for the inverse analysis along with variable model restrictions to estimate 36 parameters. The model provided a satisfactory simultaneous fit (R(2)adj=0.93 and d=0.87) of all the experimental data and reliable parameter estimates. This modeling study improved the understanding on fate and transport of estrogen conjugates under various soil-water conditions.
authors.affiliation: Department of Soil Science, North Dakota State University, Fargo, ND 58108-6050, USA.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Bai
authors.affiliation: Bayer CropScience, Research Triangle Park, NC 27709, USA.
authors.forename: Suman L
authors.initials: SL
authors.lastname: Shrestha
authors.affiliation: Department of Soil Science, North Dakota State University, Fargo, ND 58108-6050, USA. Electronic address: Francis.Casey@ndsu.edu.
authors.forename: Francis X M
authors.initials: FX
authors.lastname: Casey
authors.affiliation: Biosciences Research Laboratory, USDA-ARS, Fargo, ND 58102-2765, USA.
authors.forename: Heldur
authors.initials: H
authors.lastname: Hakk
authors.affiliation: Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Zhaosheng
authors.initials: Z
authors.lastname: Fan
mesh_terms: D000327:Adsorption; D004784:Environmental Monitoring / Q000379:methods*; D004958:Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism; D008372:Manure / Q000032:analysis; D008962:Models, Theoretical; D012989:Soil Pollutants / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D008372:Manure; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C048615:estradiol 17-sulfate; D004958:Estradiol
keywords: 17β-Estradiol–17-sulfate; Estrogen; Estrogen conjugates; Hormone transport