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 KDOC) of 17β-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 KDOC of E2 for a DOM size fraction less than 0.2 μm was observed by 4.87±1.87 L kg−1DOC, 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-EEQ L−1, 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.