Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
J Hazard Mater. 2017 Apr 5;327:197-205. doi: 10.1016/j.jhazmat.2016.12.054. Epub 2017 Jan 3.
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 (HS*) are other key reactive species degrading EE2 by abstracting electrons. HO and HS* were responsible for about 60% of the overall EE2 photodegradation at 250μmol HS L. 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.
光降解是一种将天然水体中的有机污染物转化为非生物途径的重要途径。腐殖质（HS），包括腐殖酸和富里酸，能够加速甾体雌激素的光降解。然而，HS 如何影响新兴污染物的光降解还不清楚。因此，我们研究了 HS 在诱导 17α-乙炔基雌二醇（EE2）光降解中的作用和机制。HS 通常通过结合和活性物质的产生来诱导 EE2 的光降解。除了羟基自由基（HO）之外，腐殖质的激发三重态（HS*）也是通过提取电子降解 EE2 的其他关键活性物质。HO 和 HS* 负责约 250μmol HS L 时 EE2 总光降解的 60%左右。大多数 EE2 分子通过氢键、π-π 和疏水相互作用与 HS 结合。HS 通过与 EE2 竞争与腐殖质和富里酸结合来促进 EE2 光降解的结合作用。此外，HS 促进的光降解可以改变 EE2 对小麦、水稻和 Ormosia 植物的毒性。本研究扩展了我们对天然水中甾体雌激素光化学行为和生态风险的认识。
