Reevaluation of the contributions of reactive intermediates to the photochemical transformation of 17β-estradiol in sewage effluent.
Reevaluation of the contributions of reactive intermediates to the photochemical transformation of 17β-estradiol in sewage effluent.
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DOI：
10.1016/j.watres.2020.116633
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发表时间：
2020-11
期刊：
影响因子：
12.8
通讯作者：
Lushi Lian;C. Miao;Z. Hao;Qian Liu;Yingjie Liu;Weihua Song;Shuwen Yan
中科院分区：
文献类型：
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作者：
Lushi Lian;C. Miao;Z. Hao;Qian Liu;Yingjie Liu;Weihua Song;Shuwen Yan
研究了在模拟太阳光照射下，不同pH值废水中天然甾体17β-雌二醇（E2）的光降解。污水中E2的降解速率在pH 6.0-7.0时稳定，但从pH 8.0-10.0时突然增加。E2与3EfOM * 和CO 3·−的二级反应速率常数从pH 6.0到10.0分别增加了11.0倍和18.0倍。对这一急剧增长提出了两个主要原因。首先，E2电离状态的变化使其易于被三重态流出物有机物（3EfOM*）和碳酸根（CO 3·−）氧化。其次，CO 3·−的稳态浓度随pH值的升高而升高。间接光解被认为是污水中的主要降解途径，3EfOM * 在pH值8.0-9.0时起主要作用，而CO 3·−在pH值10.0时起重要作用。在这项研究中，EfOM首次被证明可以抑制由3EfOM * 和CO 3·−引发的E2氧化。因此，我们认为EfOM在E2的光降解中起着双重作用：EfOM不仅可以被激活为3EfOM * 来降解E2，而且可以通过将E2氧化中间体还原为E2来抑制E2的降解。并对降解产物的雌激素活性进行了研究。在体外雌激素活性的E2解决方案的下降大约一样快的E2光降解发生在废水中，在不同的pH值，这表明太阳能污水中的光降解降低了内分泌干扰的风险沃茨受E2的影响，并受到持续的投入。本研究的结果对于预测内分泌干扰化学品的环境归宿和开发从水生环境中去除它们的方法具有重要意义。
Photodegradation of the natural steroid 17β-estradiol (E2), an endocrine-disrupting hormone that has been widely detected in aquatic environments, was investigated in wastewater effluents at various pH ranges under simulated solar irradiation. The rate of E2 degradation in the sewage effluents was stable at pH 6.0-7.0 but suddenly increased from pH 8.0-10.0. The second-order reaction rate constants of E2 with3EfOM* and CO3•−were measured to increase 11.0-fold and 18.0-fold from pH 6.0 to 10.0, respectively. Two main reasons are proposed for this sharp increase. First, the change in the ionization state of E2 made it susceptible to oxidation by triplet-state effluent organic matter (3EfOM*) and carbonate radicals (CO3•−). Second, the steady-state concentration of CO3•−increased with increasing pH. Indirect photolysis was suggested to be the main degradation pathway in the sewage effluents, and3EfOM* was proposed to play a major role at pH 8.0-9.0, while CO3•−played a significant role at pH 10.0. In this study, EfOM was shown for the first time to inhibit the oxidation of E2 initiated by3EfOM* and CO3•−. Thus, we suggest that EfOM plays a dual role in the photodegradation of E2: EfOM can not only be activated as3EfOM* to degrade E2 but also can inhibit the degradation of E2 by reducing the E2 oxidation intermediate back to E2. The estrogenic activity of the photodegradation products was also studied. The in vitro estrogenic activity of E2 solutions decreased approximately as fast as the E2 photodegradation occurred in the effluent water at various pH values, suggesting that solar photodegradation in sewage effluents reduces the risk of endocrine disruption in waters impacted by E2 and subject to continuing inputs. The results of this study are important for predicting the environmental fate of endocrine-disrupting chemicals and developing methods for their removal from aquatic environments.