Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China, University of Science and Technology, Shanghai 200237, China.
Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029, China.
Sci Total Environ. 2016 Feb 1;543(Pt A):116-122. doi: 10.1016/j.scitotenv.2015.11.018. Epub 2015 Nov 12.
Cycloxaprid (CYC) is a novel broad-spectrum neonicotinoid insecticide that has been developed for agricultural pest control. The fate of the (14)C-labeled racemic and enantio-pure CYC isomers in flooded and anaerobic soil was investigated using radioisotope tracing techniques. After 100 d of incubation, only a minor portion (<1%) of the applied CYC isomers is mineralized by each of the four tested soil types. The fraction of initially applied radioactive CYC dissipated into the bound or non-extractable residues (BR) increases with increase in the length of the incubation period, reaching up to 53.0-81.6%. The dissipation of the CYC through mineralization or formation of BR is strongly influenced by soil properties, such as humic content, pH value, and retained microbial activity. Amongst the soils studied, the fluvio-marine yellow loamy soil displayed the highest tendency to mineralize CYC while the coastal saline soil exhibited the strongest tendency to form BR. The observation that the water phase retained the large portion(>60%) of the radioactivity attributed to the total extractable residue suggested that under the experimental condition, the initially applied (14)C-labeled CYC residues were readily available for leaching or offsite transport. Additionally, no enantiomer-specific behaviors are observed. The results from this study provide a framework for assessing the environmental impact resulting from the use of this pesticide.
噻虫嗪（CYC）是一种新型的广谱烟碱类杀虫剂，已被开发用于农业害虫防治。采用放射性同位素示踪技术研究了（14）C 标记的外消旋和对映纯噻虫嗪异构体在淹水和厌氧土壤中的命运。在 100 d 的培养期后，四种测试土壤类型中只有一小部分（<1%）的施用噻虫嗪异构体被矿化。最初施用的放射性噻虫嗪消散到结合或不可提取残留物（BR）的分数随培养期的延长而增加，最高可达 53.0-81.6%。噻虫嗪通过矿化或 BR 的形成而消散强烈受土壤特性的影响，如腐殖质含量、pH 值和保留的微生物活性。在所研究的土壤中，河流-海洋黄壤显示出最高的矿化噻虫嗪的趋势，而沿海盐土则表现出最强的形成 BR 的趋势。观察到水相保留了归因于总可提取残留物的大部分（>60%）放射性，这表明在实验条件下，最初施用的（14）C 标记的噻虫嗪残留物易于淋溶或场外迁移。此外，没有观察到对映体特异性行为。这项研究的结果为评估该农药使用对环境的影响提供了框架。
