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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Animal Metabolism-Agricultural Chemicals Research » Research » Publications at this Location » Publication #298825
Title: Modeling coupled sorption and transformation of 17ß-estradiol-17-sulfate in soil-water systems

Author
item BAI, XUELIAN - North Dakota State University
item SHRESTHA, SUMAN - North Dakota State University
item CASEY, FRANCIS - North Dakota State University
item Hakk, Heldur
item FAN, ZHAOSHENG - Argonne National Laboratory

Submitted to: Journal of Contaminant Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2014
Publication Date: 11/1/2014
Publication URL: https://handle.nal.usda.gov/10113/61183
Citation: Bai, X., Shrestha, S.L., Casey, F.X., Hakk, H., Fan, Z. 2014. Modeling coupled sorption and transformation of 17ß-estradiol-17-sulfate in soil-water systems. Journal of Contaminant Hydrology. 168:17-24.

Interpretive Summary: Animal manure is an important source of estrogens into the environment, and these compounds can produce detrimental effects, particularly in aquatic wildlife when exposed exogenously. Estrogens are commonly eliminated from production animals as water-soluble metabolites, known as conjugates, which we have shown to be reasonably stable in soil-water systems, but can degrade to parent. We have previously hypothesized, and subsequently demonstrated, that conjugate transport is one mechanism for the long-range environmental transport of estrogens. As part of our effort to completely explain the movement of these conjugates, we generated a model for the fate and transport of 17ß-estradiol-17-sulfate (E2-17S) from our data generated in soil-water systems. The modeling was the most ambitious to date for estrogens and involved simultaneously solving 52 equations for 36 parameters and 13 compounds, and took into consideration all the degradation, mass transfer, and sorption processes we observed during the study phase. And yet, the model provided a very satisfactory simulation of the experimental data, demonstrated its ability to simulate complex scenarios, and gave significant insights in understanding the processes governing the environmental fate of manure-borne estrogen conjugates.

Technical Abstract: Animal manure is an important source of estrogens in the environment, which are known to be endocrine-disrupting chemicals. 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 predict the coupled sorption and transformation of a sulfate estrogen conjugate, 17ß-estradiol-17-sulfate (E2-17S), in various soil-water systems. 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 the 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 restrictions to estimate the total 36 parameters. The model provided a satisfactory simulation (R2adj = 0.93 and d = 0.87) to the experimental data and reliable parameter estimates. The modeling study improved the understanding of fate and transport of estrogen sulfate conjugate under various soil-water conditions.