State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China.
Chemosphere. 2013 Sep;92(11):1423-9. doi: 10.1016/j.chemosphere.2013.03.049. Epub 2013 Apr 22.
To elucidate the environmental fate of tetracycline (TC), we reported the light-source-dependent dual effects of humic acid (HA) and NO3(-) on TC photolysis. TC photolysis rate was highly pH- and concentration-dependent, and was especially enhanced at higher pH and lower initial TC concentrations. Under UV-254 and UV-365 irradiation, HA inhibited TC photolysis through competitive photoabsorption or reactive oxygen species (ROS) quenching with TC; under solar and xenon lamp irradiation, TC photolysis was enhanced at low HA concentration due to its photosensitization, whereas was suppressed at high HA concentration due to competitive photoabsorption or ROS quenching with TC. Similarly, the effect of NO3(-) on TC photolysis varied with light irradiation conditions. Even under the same light irradiation conditions, the effects of HA or NO3(-) on TC photolysis varied with their concentrations. The electron spin resonance spectrometer and ROS scavenger experiments demonstrated that TC photolysis was involved in O2(-)-mediated self-sensitized photolysis. The photolysis pathways were involved in hydroxylation and loss of some groups. More toxic intermediates than TC were generated under different light irradiation conditions. These results can provide insight into the potential fate and transformation of TC in surficial waters.
为了阐明四环素（TC）的环境归宿，我们报道了腐殖酸（HA）和 NO3(-) 对 TC 光解的光源依赖性双重作用。TC 的光解速率高度依赖于 pH 值和浓度，并且在较高的 pH 值和较低的初始 TC 浓度下尤其增强。在 UV-254 和 UV-365 辐照下，HA 通过与 TC 的竞争光吸收或活性氧（ROS）淬灭来抑制 TC 光解；在太阳和氙灯辐照下，由于其光敏化作用，在低 HA 浓度下 TC 光解增强，而在高 HA 浓度下由于与 TC 的竞争光吸收或 ROS 淬灭而受到抑制。同样，NO3(-) 对 TC 光解的影响随光照条件而变化。即使在相同的光照条件下，HA 或 NO3(-) 对 TC 光解的影响也随其浓度而变化。电子自旋共振光谱仪和 ROS 清除剂实验表明，TC 光解涉及 O2(-)介导的自敏化光解。光解途径涉及羟化和一些基团的损失。在不同的光照条件下会产生比 TC 更具毒性的中间产物。这些结果可以深入了解 TC 在地表水环境中的潜在归宿和转化。
