Abstract：
The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for non-target organisms. Phototransformation is one of the most significant transformation processes, which is directly related to NNIs exposure and environmental risks. In this study, the photodegradation of dinotefuran (DIN, 1-Methyl-2-nitro-3-(tetrahydro-3-furanylmethyl)-guanidine), one of the most promising NNIs, was conducted under irritated light in the presence of Cl-, DOM along with the effect of pH and initial concentration. The findings demonstrated that in ultra-pure (UP) water, the photolysis rate constants (k) of DIN rose with increasing initial concentration. Whereas, in tap water, at varied pH levels, and in the presence of Cl-, the outcomes were reversed. At the same time, lower concentration of DOM promoted DIN photolysis processes due to the production of reactive oxygen species, while higher concentrations of DOM inhibited the photolysis by the predominance of light shielding effects. The singlet oxygen (1O2) was produced in the photolysis processes of DIN with Cl- and DOM, which was confirmed by electron spin resonance (EPR) analysis. Four main photolysis products and three intermediates were identified by UPLC-Q-Exactive Orbitrap MS analysis. The possible photodegradation pathways of DIN were proposed including the oxidation by 1O2, reduction and hydrolysis after the removal of nitro group from parent compounds. This study expanding our understanding of transformation behavior and fate of NNIs in the aquatic environment, which is essential for estimating their environmental risks.
摘要：
新烟碱类杀虫剂（NNIs）的环境行为由于其在水生环境中的频繁检测以及对非目标生物的生物毒性而受到重大关注。光转化是最重要的转化过程之一，这与NNIs暴露和环境风险直接相关。在这项研究中,dinotfuran的光降解(DIN，1-甲基-2-硝基-3-(四氢-3-呋喃基甲基)-胍)，最有前途的NNIs之一,在Cl-存在的情况下在刺激的光线下进行，DOM跟着pH和初始浓度的影响。研究结果表明，在超纯(UP)水中，DIN的光解速率常数（k）随初始浓度的增加而增加。然而,在自来水中，在不同的pH水平下，在Cl-的存在下，结果相反。同时,由于活性氧的产生，较低浓度的DOM促进了DIN光解过程，而较高浓度的DOM通过遮光效应的优势抑制了光解。在DIN的Cl-和DOM的光解过程中产生了单线态氧（1O2），电子自旋共振(EPR)分析证实了这一点。通过UPLC-Q-ExactiveOrbitrapMS分析鉴定了四种主要的光解产物和三种中间体。提出了DIN可能的光降解途径，包括通过1O2氧化，从母体化合物中去除硝基后的还原和水解。这项研究扩大了我们对水生环境中NNIs转化行为和命运的理解，这对于估计他们的环境风险至关重要。
