Yale-NUIST Center on Atmospheric Environment, Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China; Key Laboratory of Meteorological Disaster Ministry of Education (KLME), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing 210044, China; School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Yale-NUIST Center on Atmospheric Environment, Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China; Key Laboratory of Meteorological Disaster Ministry of Education (KLME), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing 210044, China; School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Sci Total Environ. 2020 Jun 1;719:137416. doi: 10.1016/j.scitotenv.2020.137416. Epub 2020 Feb 19.
Oxalate-iron is an integral part of the photochemical system in the atmosphere. Here, we combined high-resolution online observations and laboratory simulations to discuss the distribution of oxalate and oxalate-iron photochemical system in Nanjing atmosphere at the molecular level. The results show that the oxidation state of iron in the oxalate-iron photochemical system changes significantly and regularly. Among them, Fe (II)/Fe (III) is 3.82 during the day and 0.76 at night. At the same time, Cl may accelerate the generation of hydroxyl radicals in the system and promote the photooxidation rate of oxalate. Oxalate can be converted into formate (C1) and acetate (C2) in the photochemical system, but <4% of degraded oxalate is converted, which means that the photochemical system may not be the main source of formate and acetate in the atmosphere. Besides, the ratio of C1/C2 < 1 in the conversion is opposite to the ratio of C1/C2 > 1 in the general secondary conversion, which means that not all ratio of C1/C2 in the photochemical pathway is >1. These results are beneficial for us to understand the effect of the oxalate-iron photochemical system on the distribution of oxalate in the atmosphere, and also help us to analyze the conversion of organics in the atmospheric aqueous phase.
草酸盐-铁是大气光化学系统的一个组成部分。在这里，我们结合高分辨率在线观测和实验室模拟，从分子水平上讨论了南京大气中草酸盐和草酸盐-铁光化学系统的分布。结果表明，草酸盐-铁光化学系统中铁的氧化态变化显著且有规律。其中，Fe(II)/Fe(III)在白天为 3.82，在夜间为 0.76。同时，Cl 可能会加速系统中羟基自由基的生成，促进草酸盐的光氧化速率。草酸盐可以在光化学系统中转化为甲酸盐（C1）和乙酸盐（C2），但<4%的降解草酸盐发生转化，这意味着光化学系统可能不是大气中甲酸盐和乙酸盐的主要来源。此外，在转化过程中 C1/C2 < 1 的比例与一般二次转化中 C1/C2 > 1 的比例相反，这意味着光化学途径中并非所有 C1/C2 的比例都>1。这些结果有助于我们理解草酸盐-铁光化学系统对大气中草酸盐分布的影响，也有助于我们分析大气水相中的有机物转化。
