Environment Research Institute, Shandong University, Qingdao 266237, China.
Environment Research Institute, Shandong University, Qingdao 266237, China.
Sci Total Environ. 2020 Apr 20;714:136760. doi: 10.1016/j.scitotenv.2020.136760. Epub 2020 Jan 16.
Nitrated phenols are a major class of brown carbon in the atmosphere and have adverse effects on human and plants health. They are emitted from combustion sources or produced by oxidation of phenolic precursors. In this study, fine particulates, total suspended particulates, and gas-phase samples were collected in urban Jinan in winter, spring, and summer, and UHPLC-MS analysis was used to determine 8 phenolic compounds and 12 nitrated phenols in these samples. The seasonal average concentrations of total phenolic compounds and total nitrated phenols were in the ranges of 2.6-18.7 ng m and 13.5-105.4 ng m, respectively. The concentrations of phenolic compounds and nitrated phenols were highest in winter, followed (in decreasing order) by spring, and summer. Phenol and salicylic acid were the most abundant phenolic species in both gaseous and particulate samples. 4-Nitrophenol was the most abundant nitrated phenols in particulate matters, followed by 4-nitrocatechol and 5-nitrosalicylic acid, while 4-nitrophenol and 2,4-dinitrophenol were the dominant species in the gas phase. The distributions of phenolic compounds and nitrated phenols in fine and coarse particles and in gas and particle phases were largely dependent on the aerosol size distribution, the ambient temperature, and the compound volatility. More of them were distributed in fine particles and gas-phase in summer than in spring. It was found that phenol, catechol, methyl-catechols, 4-nitrophenol, and methyl-nitrophenols mainly derived from coal combustion, while biomass burning was the main source of cresols, 2,6-dimethyl-4-nitrophenol, 4-nitrocatechol, and methyl-nitrocatechols. In addition, secondary formation contributed the largest fraction of nitrosalicylic acids and vehicle exhaust was the major source of cresols, 2,6-dimethyl-4-nitrophenol, and 4-methyl-2,6-dinitrophenol. Further correlation analysis revealed positive correlations between nitrated phenols and corresponding phenolic precursors, indicating the important roles that phenolic precursors played in the secondary formation and abundance of nitrated phenols in the atmosphere.
硝酚是大气中一类重要的棕色碳物质，对人类和植物健康有不利影响。它们主要来源于燃烧源排放或酚类前体物的氧化。本研究在济南冬、春、夏三季采集了细颗粒物、总悬浮颗粒物和气态样品，并用 UHPLC-MS 分析方法测定了这些样品中 8 种酚类化合物和 12 种硝酚。总酚类化合物和总硝酚类化合物的季节平均浓度分别为 2.6-18.7ng/m和 13.5-105.4ng/m。酚类化合物和硝酚类化合物的浓度在冬季最高，其次是春季，然后是夏季。气态和颗粒物样品中最丰富的酚类物质均为苯酚和水杨酸。4-硝基苯酚是颗粒物中最丰富的硝酚类化合物，其次是 4-硝基邻苯二酚和 5-硝基水杨酸，而 4-硝基苯酚和 2,4-二硝基苯酚则是气相中的主要物质。酚类化合物和硝酚类化合物在细颗粒物和粗颗粒物以及气粒两相间的分布在很大程度上取决于气溶胶的粒径分布、环境温度和化合物的挥发性。夏季细颗粒物和气态中的含量比春季更多。研究发现，苯酚、邻苯二酚、甲基邻苯二酚、4-硝基苯酚和甲基-4-硝基苯酚主要来源于煤炭燃烧，而生物质燃烧是甲酚、2,6-二甲基-4-硝基苯酚、4-硝基邻苯二酚和甲基-4-硝基邻苯二酚的主要来源。此外，二次形成对硝水杨酸的贡献最大，而机动车尾气是甲酚、2,6-二甲基-4-硝基苯酚和 4-甲基-2,6-二硝基苯酚的主要来源。进一步的相关性分析表明，硝酚类化合物与相应的酚类前体物之间存在正相关，这表明酚类前体物在大气中硝酚类化合物的二次形成和丰度中起着重要作用。
