Impacts of Environmental Colloids on the Transport of 17 β-estradiol in Intact Soil Cores

ABSTRACT

Estrogens such as 17-β estradiol (E2) are endocrine-disrupting compounds and can affect the reproductive systems of aquatic organisms. Therefore, it is important to understand the mechanisms of their transport in the environment. E2 and its daughter product estrone (E1) are both strongly adsorbed by soil organic matter and have relatively short half-lives. Reduced contact time with soil makes transport of E2 and E1 in soil more likely. In this study, intact soil cores from three soils representing a range of particle size distribution, structure, and organic matter content were used to compare the transport of E2 with and without the presence of colloidal material fractionated from soil or swine manure. In chemical transport experiments conducted with undisturbed soil columns, E2 and E1 were measured both in solution and attached to suspended solids in column effluent. During the transport experiments, colloids carrying E2 passed through all soils, with the exception of the sandy soil. The presence of colloids decreased the first detection time of E2 in the aqueous phase, was correlated with greater peak E2 concentrations in the effluent of both loamy and clayey soils, but not through the sandy soil, and increased mass fractions of the E2 that was transported.

KEYWORDS:

• Estrone
• macropore
• estrogens
• water-dispersible colloids

Acknowledgements

This work was supported by the National Institute for Food and Agriculture, U.S. Department of Agriculture, Award no. 2007-35107-18410; by the Binational Agricultural Research and Development Fund, Project US-4656-13; and by the Agronomy Department of Iowa State University. We also gratefully acknowledge the laboratory assistance of Colton Meyer, Colby Moorberg, Anna Johnson, and Teresita Chua.