Research Group in Advanced Oxidation Processes (AdOx), Chemical Systems Engineering Center, Department of Chemical Engineering, Escola Politécnica, University of São Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil.
Energy Engineering Department, São Paulo State University (UNESP), Av. dos Barrageiros, 1881, Rosana, SP, Brazil.
Environ Sci Pollut Res Int. 2022 Jun;29(28):42290-42304. doi: 10.1007/s11356-021-17991-5. Epub 2022 Jan 15.
In addition to direct photolysis studies, in this work the second-order reaction rate constants of pesticides imidacloprid (IMD) and ametryn (AMT) with hydroxyl radicals (HO), singlet oxygen (O), and triplet excited states of chromophoric dissolved organic matter (CDOM) were determined by kinetic competition under sunlight. IMD and AMT exhibited low photolysis quantum yields: (1.23 ± 0.07) × 10 and (7.99 ± 1.61) × 10 mol Einstein, respectively. In contrast, reactions with HO radicals and CDOM* dominate their degradation, with O exhibiting rates three to five orders of magnitude lower. The values of k and k were (3.51 ± 0.06) × 10 and (4.97 ± 0.37) × 10 L mol s, respectively, while different rate constants were obtained using anthraquinone-2-sulfonate (AQ2S) or 4-carboxybenzophenone (CBBP) as CDOM proxies. For IMD this difference was significant, with k = (1.02 ± 0.08) × 10 L mol s and k = (3.17 ± 0.14) × 10 L mol s; on the contrary, the values found for AMT are close, k = (8.13 ± 0.35) × 10 L mol s and k = (7.75 ± 0.80) × 10 L mol s. Based on these results, mathematical simulations performed with the APEX model for typical levels of water constituents (NO, NO, CO, TOC, pH) indicate that the half-lives of these pesticides should vary between 24.1 and 18.8 days in the waters of the Paranapanema River (São Paulo, Brazil), which can therefore be impacted by intensive agricultural activity in the region.
除了直接光解研究外，在这项工作中，还通过动力学竞争在阳光下测定了杀虫剂噻虫啉（IMD）和莠去津（AMT）与羟基自由基（HO）、单线态氧（O）和发色溶解有机物质（CDOM）的三重激发态的二级反应速率常数。IMD 和 AMT 的光解量子产率较低：（1.23 ± 0.07）×10 和（7.99 ± 1.61）×10 mol Einstein，分别。相比之下，与 HO 自由基和 CDOM*的反应主导了它们的降解，而 O 的反应速率低 3 到 5 个数量级。k 和 k 的值分别为（3.51 ± 0.06）×10 和（4.97 ± 0.37）×10 L mol s，而使用蒽醌-2-磺酸盐（AQ2S）或 4-羧基二苯甲酮（CBBP）作为 CDOM 探针时，得到了不同的速率常数。对于 IMD，这种差异是显著的，k=（1.02 ± 0.08）×10 L mol s和 k=（3.17 ± 0.14）×10 L mol s；相反，对于 AMT，发现的值很接近，k=（8.13 ± 0.35）×10 L mol s和 k=（7.75 ± 0.80）×10 L mol s。基于这些结果，使用 APEX 模型对典型的水成分（NO、NO、CO、TOC、pH）水平进行的数学模拟表明，在帕拉纳帕内马河（巴西圣保罗）的水中，这些农药的半衰期应在 24.1 到 18.8 天之间变化，因此该地区密集的农业活动可能会对其产生影响。
