Oxidation of solid thin films of neonicotinoid pesticides by gas phase hydroxyl radicals
Oxidation of solid thin films of neonicotinoid pesticides by gas phase hydroxyl radicals
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DOI：
10.1039/d2ea00134a
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发表时间：
2022-11-24
期刊：
影响因子：
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通讯作者：
Shiraiwa, M.
中科院分区：
文献类型：
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作者：
Finlayson-Pitts, B. J.;Anderson, A.;Shiraiwa, M.
新烟碱类杀虫剂 (NN) 普遍存在于整个环境的表面，例如种子、土壤、植被和扬尘颗粒。然而，关于与大气接触时形成的动力学和氧化产物的数据很少，这限制了对其潜在深远影响的理解。在本研究中，使用原位衰减全反射（ATR）FTIR光谱研究了吡虫啉（IMD）、呋虫胺（DNF）和噻虫胺（CLD）三种固体NN薄膜在295 +/- 3 K下的OH氧化。基于NN初始损失率的实验测得的反应概率为(1.6 +/- 0.8) x 10(-2) IMD，DNF 为 (1.5 +/- 0.6) x 10(-2)，CLD 为 (0.9 +/- 0.2) x 10(-2) (+/- 1 sigma)，表明相对于 OH 的初始 NN 寿命为 10-17 天。使用多相动力学模型 KM-SUB 解释了动力学，该模型表明 OH 吸收和反应主要发生在表面层。质谱鉴定的产物包括通过从脂肪族C-H基团中夺氢而形成的含羰基、醇和烯烃的物质。此外，从最初形成的光降解产物的副反应中观察到含羰基的脱硝基和脲衍生物产物。当存在该自由基的非光解来源时，与 OH 的反应将在白天和夜间导致 NN 损失。因此，在评估其环境影响时应考虑与母体新烟碱类杀虫剂及其光降解产物的 OH 反应。
Neonicotinoids (NNs) are commonly found throughout the environment on surfaces such as seeds, soil, vegetation, and blowing dust particles. However, there is a paucity of data on the kinetics and oxidation products formed on contact with the atmosphere which limits understanding of their potentially far-reaching impacts. In this study, in situ attenuated total reflectance (ATR) FTIR spectroscopy was used to investigate the OH oxidation of thin films of three solid NNs, imidacloprid (IMD), dinotefuran (DNF) and clothianidin (CLD) at 295 +/- 3 K. The experimentally measured reaction probabilities based on initial rates of NN loss are (1.6 +/- 0.8) x 10(-2) for IMD, (1.5 +/- 0.6) x 10(-2) for DNF and (0.9 +/- 0.2) x 10(-2) for CLD (+/- 1 sigma), suggesting initial NN lifetimes with respect to OH of 10-17 days. The kinetics were interpreted using a multiphase kinetics model, KM-SUB, which showed that the OH uptake and reaction occurred primarily in the surface layer. Products identified by mass spectrometry included carbonyl-, alcohol- and olefin-containing species formed via hydrogen abstraction from aliphatic C-H groups. Additionally, carbonyl-containing desnitro and urea derivative products were observed from secondary reactions of the initially formed photodegradation products. Reaction with OH will contribute to NN loss both during the day as well as at night when there are non-photolytic sources of this radical. Thus, OH reactions with both the parent neonicotinoid and its photodegradation products should be considered in assessing their environmental impacts.