title: Photodegradation of 17α-ethynylestradiol in dissolved humic substances solution: Kinetics, mechanism and estrogenicity variation.
abstract: 17α-Ethynylestradiol (EE2) in natural waters may cause adverse effects on organisms due to its high estrogenic potency. Laboratory studies were performed to study the effects of a local humic acid (LHA), fulvic acid (LFA) and Aldrich humic acid (AHA) on the photochemical behavior and estrogenic potency of EE2. Here photolytic experiments demonstrated that pure aqueous EE2 could undergo direct and self-sensitized photodegradation at a global rate of 0.0068hr-1. Photodegradation rate of EE2 in 5.0mg/L dissolved humic substances (DHS) was determined to be 0.0274, 0.0296 and 0.0254hr-1for LHA, LFA and AHA, respectively. Reactive oxygen species (ROS) and triplet dissolved humic substances (3DHS*) scavenging experiments indicated that the promotion effect of DHS on EE2 photodegradation was mainly aroused by the reactions of HO (35%-50%),1O2(<10%) and3DHS* (22%-34%). However, the photodegradation of EE2 could also be inhibited when DHS exceeded the threshold of 10mg/L. Three hydroxylation products of EE2 were identified using GC-MS and their formation pathways were also proposed. In vitro estrogenicity tests showed that EE2 was transformed into chemicals without estrogenic potency. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens in sunlit natural waters.
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China. Electronic address: rdong0421@163.com.
authors.forename: Dong
authors.initials: D
authors.lastname: Ren
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China. Electronic address: huangbin@kmust.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Xiong
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
authors.forename: Huan
authors.initials: H
authors.lastname: He
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
authors.forename: Xiangqi
authors.initials: X
authors.lastname: Meng
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Pan
mesh_terms: D004997:Ethinyl Estradiol / Q000737:chemistry*; D006812:Humic Substances; D007700:Kinetics; D055668:Photochemical Processes; D010782:Photolysis; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol
keywords: 17α-Ethynylestradiol; Dissolved humic substances; Estrogenic potency; Photodegradation; Reactive oxygen species