Association of Estradiol With Manure and Soil Colloidal and Dissolve Fractions and Potential Bioactivity.

Dissolved (DF) and colloidal fractions (CF) of soil and manure play an important role in the environmental fate and transport of steroidal estrogens. This study quantified the association of the natural occurring 17beta-estradiol (E2), with the DF and CF isolated from liquid swine manure (LSM), Soil, and LSM and Soil mixtures (Soil+LSM). The appropriate CF and DF size fractions of the Soil, Soil+LSM, and LSM materials were obtained by first filtering through a 0.45 µm filter, which provided the combined DF and CF (DF/CF). The DF/CF from the three media were spiked with radiolabelled (14C) E2, and then ultrafiltrated to isolate the CF (<0.45 mm and > 1 kDa) from the DF (<1 kDa). The average recoveries of the 14C E2 associated with the DF were 67%-72%, 67%-79%, and 76%-78% for the Soil, Soil+LSM and LSM, respectively. For the CF that was retained on the 1 kDa filter, organic carbon (OC) and 14C-E2 were dislodged with subsequent water rinses for all three media. The Soil media was found to continue to elute organic carbon and 14C-E2 for all three water rinses where Soil+LSM and LSM did not after the first water rinse. The second objective was to evaluate whether the E2 associated with the DF/CF, DF and CF of the various media was still estrogenic. Estrogenicity was assessed using an E2 receptor (ER) competitor assay, which provided E2 equivalent concentrations (EEQ). The ER assay indicated that E2 in the DF of the Soil and Soil+LSM solution could still induce estrogenic responses. Results from this study indicated that E2 preferentially associated with the DF of soil and manure, which may enhance its dissolved advective transport surface and subsurface water. Furthermore, this study indicated that E2 associated with DF solutions in the environment could potentially induce endocrine responses through its interactions with ER.