The detection and fate of 17beta-estradiol and 17alpha-ethinyl estradiol in engineered treatment wetlands.

摘要

The steroid hormones 17beta-estradiol (E2) and 17alpha-ethinyl estradiol (EE2) have been implicated in the feminization of male fish collected from waters near municipal wastewater treatment plants.; To assess the fate of wastewater-derived steroid hormones in engineered treatment wetlands, an extremely sensitive analytical technique was developed. The technique, which is capable of detecting hormone concentrations as low as 0.05 ng/L, uses solid-phase extraction (SPE) to pre-concentrate samples prior to analysis by enzyme-linked immunosorbent assays (ELISAs). To remove interfering substances present in the SPE extracts, gel-permeation chromatography and high-performance liquid chromatography are employed. Confirmatory analysis by gas chromatography with tandem mass spectrometry is used to validate the results.; The fate of hormones was studied in a wetland consisting of a series of open-water ponds with vegetation limited to the edges of the ponds. Although hormone concentrations varied considerably, data suggested slow removal of the compounds. The estimated half-life for E2 and EE2 removal in this wetland were 16 d and 30 d, respectively.; Hormone fate was studied in a second wetland containing dense stands of cattails and bulrush. Under these conditions, biotransformation of hormones on biofilm-coated plant surfaces resulted in better hormone removal.; Finally, laboratory experiments were conducted to assess the importance of indirect photolysis to hormone attenuation. Photolysis experiments were conducted in hormone-amended water collected from an engineered treatment wetland. The results of these experiments suggest that hydroxyl radical, singlet oxygen and triplet dissolved organic carbon play a role in the photochemical transformation of E2 and EE2.; The results of this research indicate that engineered treatment wetlands are incapable of completely removing estrogenic hormones from wastewater effluent. However, the occurrence of indirect photolysis and biotransformation provide a basis for designing engineered treatment wetlands that are better suited to hormone removal. Furthermore, relative to rivers and other surface waters, constructed wetlands have long HRTs and high concentrations of biofilms and precursors to photoreactive species. If complete hormone attenuation is slow in engineered treatment wetlands, it is unlikely to occur quickly in other freshwater systems. (Abstract shortened by UMI.)