Photo-degradation behavior of seven benzoylurea pesticides with C3N4 nanofilm and its aquatic impacts on Scendesmus obliquus
Photo-degradation behavior of seven benzoylurea pesticides with C3N4 nanofilm and its aquatic impacts on Scendesmus obliquus
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C3N4纳米膜对7种苯甲酰脲类农药的光降解行为及其对斜生栅藻的水生影响
DOI：
10.1016/j.scitotenv.2021.149470
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发表时间：
2021
影响因子：
9.8
通讯作者：
Li Guangke
中科院分区：
文献类型：
--
作者：
Zhu Na;Li Ruiying;Zhang Jie;Yan Qian;Jiao Junheng;Liang Dong;Yue Huifeng;Sang Nan;Li Guangke
针对苯甲酰脲类农药残留问题，选取了7种典型的苯甲酰脲类农药，研究了其光降解行为和生态影响。在载玻片上构建厚度为50-80 nm的氮化碳（C3 N4）纳米膜，并用于评价农药在可见光下的光稳定性。结果表明，纳米C3 N4对BUP的降解有促进作用，其降解符合一级动力学机理。根据取代基的不同，它们可分为三类，降解程度按氯氟取代、氯氟烷氧基取代和氯氟苯氧基取代的顺序进行了区分。通过超高效液相色谱-质谱联用技术对中间产物进行分析，推测BUP的生成途径与脲桥断裂、羟基化和脱卤等类似。有吸引力的是，它们都传递到同一分子2-氟苯甲酰胺（m/z，301.14）中。此外，还应用栅藻（Scendesmus）研究了原生植物及其光产物的生态效应。农药处理对叶绿素a的抑制作用大于叶绿素B。其中虱螨脲和定虫隆对藻细胞的毒性最高，光降解产物的毒性最低。抗氧化酶的活性是光降解后的重要补救措施。可见光照射下残留的BUPs可能通过类似的途径降解，C3 N4纳米膜的存在降低了BUPs对水生生物的毒性。
Present concerns on the residual benzoylurea pesticides (BUPs) are rapidly climbing as their market shares increase and now seven typical compounds were picked to study their photo-degradation behavior and ecological impacts. Carbon nitride (C3N4) nanofilm at a thickness of 50–80 nm was built on the glass slides and utilized to evaluate the photostability of pesticides under visible light. The results showed that the nano-C3N4can promote the degradation efficiency of BUPs and it follows the first-order dynamic mechanism. They could be divided into three categories with the substituents and their degradations were discriminated in order of chlorofluoro-, chlorofluoroalkoxy- and chlorofluorophenoxy- substituted ones. Analyzing the intermediates by UHPLC-MS, it can be speculated that the similar pathways came to BUPs such as cleavage of urea-bridge, hydroxylation and dehalogenation. It is attractive that they all passed into a same molecule, 2-fluorobenzamide (m/z, 301.14). MoreoverScendesmus obliquuswas applied to indicate the ecological impacts of originals and their photoproducts. Exposed to pesticides, the levels ofchlorophyll ademonstrated much more inhibition thanchlorophyll b. Lufenuron and chlorfuazuron among seven showed the higher toxicity for algal cells and finally the photodegradation products showed the lowest toxicity. The activities of antioxidant enzymes happened to a significant remedy after photodegradation. It can be concluded that the residual BUPs under visible-light irradiation may degrade through similar pathways and reduce the aquatic toxicity with the presence of C3N4nanofilm.