Universidade Federal do Rio Grande do Sul (UFRGS), Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Av. Bento Gonçalves, 9500, Porto Alegre, RS, Brazil.
Universidade Feevale, Campus II ERS-239, 2755, Novo Hamburgo, RS, Brazil.
Environ Pollut. 2019 Jun;249:354-361. doi: 10.1016/j.envpol.2019.03.057. Epub 2019 Mar 16.
The environmental detriment due to the presence of emerging contaminants has encouraged the development of advanced oxidation processes. Such methods deal with non-selective chemical reactions. Therefore, toxic byproducts can be generated and distinct post treatment toxicity levels can be expected. The present study investigates the phytotoxicity of 2,4,6-tribromophenol (TBP) to L. sativa seeds and A. cepa bulbs, as well as the TBP phytotoxicity and genotoxicity to A. cepa root. L. sativa seeds and A. cepa bulbs were germinated by being exposed to solutions containing TBP before and after treatment by UV-based processes: direct photolysis (DP), heterogeneous photocatalysis (HP) and photoelectrolysis (PEC). Subsequent analysis of the root length, to determine phytotoxicity, as well as evaluation of chromosomal abnormalities, revealed that the samples treated by DP presented higher phytotoxicity than the untreated ones. On the other hand, samples treated by HP and PEC did not present phytotoxicity. In fact, for the A. cepa assays, phytotoxicity was not observed, including the initial sample. However, genotoxicity assays showed a high frequency of chromosomal aberrations in the initial sample, before the UV-based process treatment. After 140 min of treatment by HP, there was a reduction in genotoxicity, while PEC treatment resulted in a sample with no genotoxicity. In contrast, DP presented high levels of phytotoxicity and genotoxicity. Additionally, DP shows similar degradation and debromination values, when compared to the HP and PEC processes, but less mineralization. Therefore, considering that the DP process did not deals with the HO radical, the oxidation pathway can generate byproducts with higher toxicity, which lead to higher levels of phytotoxicity and genotoxicity. These results show that different UV-based oxidation processes are associated to distinct byproducts and toxicity levels. In addition, a toxicity assessment with different organisms should be performed to ensure a safe outcome.
由于新兴污染物的存在对环境造成的损害，促使人们开发了先进的氧化工艺。这些方法涉及非选择性化学反应。因此，可能会产生有毒副产物，并且预计会有不同的毒性水平。本研究调查了 2,4,6-三溴苯酚（TBP）对生菜种子和洋葱鳞茎的植物毒性，以及 TBP 对洋葱根的植物毒性和遗传毒性。在进行基于紫外线的处理（直接光解（DP）、多相光催化（HP）和光电解（PEC））之前和之后，用含有 TBP 的溶液处理生菜种子和洋葱鳞茎，以进行发芽。随后分析根长以确定植物毒性，并评估染色体异常，结果表明 DP 处理的样品比未处理的样品表现出更高的植物毒性。另一方面，经 HP 和 PEC 处理的样品没有表现出植物毒性。实际上，对于洋葱的实验，包括初始样本，都没有观察到植物毒性。然而，遗传毒性实验显示，在基于紫外线的处理之前，初始样本中的染色体异常频率很高。经过 140 分钟的 HP 处理后，遗传毒性降低，而 PEC 处理后则没有遗传毒性。相比之下，DP 表现出较高的植物毒性和遗传毒性。此外，DP 显示出与 HP 和 PEC 过程相似的降解和脱溴值，但矿化程度较低。因此，考虑到 DP 过程不涉及 HO 自由基，氧化途径可能会产生毒性更高的副产物，从而导致更高水平的植物毒性和遗传毒性。这些结果表明，不同的基于紫外线的氧化工艺与不同的副产物和毒性水平有关。此外，应使用不同的生物体进行毒性评估，以确保安全的结果。
