Influence of 17β-estradiol binding by dissolved organic matter isolated from wastewater effluent on estrogenic activity

The aims of this study were to determine the sorption coefficient (Log K(DOC)) of 17 beta-estradiol (E2), according to the size and composition of dissolved organic matter (DOM) isolated from wastewater effluent using a fluorescence quenching (FQ) method, and to measure the estrogenic changes due to the extent of E2 sorption onto effluent DOM (EfOM) by using an E-screen bioassay. The highest log K(DOC) of E2 for a DOM size fraction less than 0.2 mu m was observed by 4.87 +/- 1.87 L kg(DOC)(-1), and its estrogenicity was the lowest among all the size fractions at 1.2 ng-EEQ L(-1). However, E2 estrogenicity for a DOM size fraction less than 5 kDa was as high as that for the positive control due to the absence of fulvic acid- and protein-like DOM to bind with E2. The estrogenic activity for the hydrophobic fraction bound with E2 was significantly reduced to 1.6 ng-EEQL1, while that for the hydrophilic fraction having no binding with E2 was 2.6 ng-EEQ L(-1), which was similar to that of the positive control (i.e., 2.8 ng-EEQ L(-1)). The results support a conclusion that the change in estrogenicity was due to the strong sorption affinity of E2 onto DOM. (C) 2011 Elsevier Inc. All rights reserved.