title: Mitigating 17α-ethynylestradiol water contamination through binding and photosensitization by dissolved humic substances.
abstract: Photodegradation is an important abiotic pathway transforming organic pollutants in natural waters. Humic substances (HS), including humic and fulvic acids, are capable of accelerating the photodegradation of steroid estrogens. However, how the photodegradtion of the emerging pollutants influenced by HS is not clear. Thus, we studied the roles and mechanisms of HS in inducing the photodegradation of 17α-ethynylestradiol (EE2). HS generally induces EE2 photodegradation through binding and reactive species generation. Apart from hydroxyl radical (HO), the excited triplets of humic substances (3HS*) are other key reactive species degrading EE2 by abstracting electrons. HO and3HS* were responsible for about 60% of the overall EE2 photodegradation at 250μmol HS L-1. Most of EE2 molecules bound to the HS via H-bonding, π-π and hydrophobic interactions. The binding role of HS in promoting EE2 photodegradation was rationalized by 17β-estradiol competitive binding with EE2 to the humic and fulvic acids. Furthermore, HS-promoted photodegradation can alter EE2 toxicity to wheat, rice and Ormosia plants. This study extends our knowledge on the photochemical behaviors and ecological risks of steroid estrogens in natural waters.
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Ren
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
authors.forename: Benqin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China. Electronic address: xjpan@kmust.edu.cn.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Pan
authors.affiliation: Environmental Engineering and Science Program, Department of Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA. Electronic address: dionysios.d.dionysiou@uc.edu.
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
mesh_terms: D000465:Algorithms; D001578:Benzopyrans / Q000737:chemistry; D052244:Endocrine Disruptors / Q000302:isolation & purification* / Q000633:toxicity*; D004997:Ethinyl Estradiol / Q000302:isolation & purification* / Q000633:toxicity*; D018525:Germination / Q000187:drug effects; D006812:Humic Substances / Q000032:analysis*; D017665:Hydroxyl Radical / Q000737:chemistry; D060106:Lakes; D010777:Photochemistry; D010944:Plants / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D018508:Water Purification / Q000379:methods
chemical_list: D001578:Benzopyrans; D052244:Endocrine Disruptors; D006812:Humic Substances; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical; D004997:Ethinyl Estradiol; C005023:fulvic acid
keywords: Binding role; Humic substances; Photodegradation; Phytotoxicity; Reactive species