| 秦皇岛市大气PM2.5中一元羧酸的污染特征及来源分析 |
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| 引用本文： | 李丹,伦小秀,邸林栓,王璇.秦皇岛市大气PM2.5中一元羧酸的污染特征及来源分析[J].环境科学研究,2021,34(11):2579-2587. |
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| 作者姓名： | 李丹 伦小秀 邸林栓 王璇 |
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| 作者单位： | 北京林业大学环境科学与工程学院, 北京 100083 |
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| 基金项目： | 国家自然科学基金项目42077454 |
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| 摘 要： | 大气细颗粒物中有机物含量占20%~80%，部分有机物除具有较强的毒性外，还具有较强吸湿性，影响大气环境质量.因此，为充分研究细颗粒物中一元羧酸的来源及其对大气环境的影响，于2020年在秦皇岛市区（海港区站点）和工业园区（昌黎站点）采集细颗粒物，经预处理的样品用三氟化硼-甲醇（BF3-CH3OH）衍生化试剂衍生后，采用气相色谱质谱联用（GC-MS）的方法对PM2.5中的一元羧酸进行测定，一共检测到17种一元羧酸（碳数分布在10~24之间）.结果表明:①PM2.5浓度的季节性变化呈冬季>秋季>春季>夏季的特征，且工业园区（昌黎站点）PM2.5浓度为21.40~112.41 μg/m3，高于市区（海港区站点为9.01~104.88 μg/m3）.②两个采样点一元羧酸浓度的季节性变化特征并不明显，海港区站点、昌黎站点一元羧酸的年均浓度分别为873.91、895.22 ng/m3.③两个站点碳数小于22的一元羧酸浓度均表现出明显的偶数碳优势，海港区站点、昌黎站点浓度最高的一元羧酸均为棕榈酸（C16），年均浓度分别为512.86、514.34 ng/m3；其次是硬脂酸（C18），年均浓度分别为270.06、268.17 ng/m3.两站点各季节C16和C18分别占一元羧酸总浓度的48.83%~66.40%和22.81%~36.96%.一元羧酸的碳优势指数（CPI）与植物贡献的一元羧酸（碳数≥ 22）总浓度呈负相关.④根据碳数分布规律、∑C ≥ 22/∑C < 22（碳数大于等于22的一元羧酸与碳数小于22的一元羧酸浓度的比值）、C18/C16（硬脂酸和棕榈酸浓度的比值）、CPI值以及C18:1/C18（油酸与硬脂酸浓度的比值）来初步判断一元羧酸的来源及其对大气环境的影响，发现秦皇岛市两个站点夏季大气氧化性最强（市区大气氧化性较工业园区强），春、秋两季大气氧化性较弱，尤其是工业园区春季大气氧化性最弱，其一元羧酸主要来自本地源；燃煤、机动车尾气排放、道路扬尘以及肉类烹饪是大气PM2.5中一元羧酸的主要来源；植物源对一元羧酸浓度的贡献较小.研究显示，秦皇岛市两个站点一元羧酸浓度的季节性变化并不显著，燃煤、机动车排放、道路扬尘及肉类烹饪对一元羧酸贡献较大.
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| 关 键 词： | PM2.5 一元羧酸 气相色谱质谱 来源分析 |
| 收稿时间： | 2021-07-01 |
Characteristics and Source Analysis of Monocarboxylic Acids in Atmospheric PM2.5 in Qinhuangdao City |
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| Affiliation: | College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China |
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| Abstract: | The content of organic matter in atmospheric fine particles is about 20%-80%. In addition to strong toxicity, some organic matter also has strong hygroscopicity, which affects the quality of the atmospheric environment. In order to fully understand the source of monocarboxylic acids in fine particles and their impact on the atmospheric environment, fine particles were collected in Qinhuangdao urban area (seaport site) and industrial park (Changli site) in 2020. After the pretreated samples were derivatized with boron trifluoride-methanol (BF3-CH3OH) derivatization reagent, the monocarboxylic acid in PM2.5 was determined by gas chromatography-mass spectrometry (GC-MS). A total of 17 monocarboxylic acids (C10-C24) were detected. The results showed that: (1) The seasonal change of PM2.5 concentration showed the characteristics of winter > autumn > spring > summer, and the PM2.5 concentration of in the industrial park (Changli site) was 21.40-112.41 μg/m3, which was higher than the concentration in the urban area (seaport site) (9.01-104.88 μg/m3). (2) The seasonal variation of the concentration of monocarboxylic acids at the two sampling points was not obvious. The average annual concentration of monocarboxylic acids at the seaport site and Changli site was 873.91 and 895.22 ng/m3, respectively. (3) The concentrations of monocarboxylic acids with carbon numbers less than 22 at the two sites showed obvious even-numbered carbon advantages. The monocarboxylic acid with the highest concentration at the seaport site and the Changli site was palmitic acid (C16), with annual average concentrations of 512.86 and 514.34 ng/m3; followed by stearic acid (C18), with annual average concentrations of 270.06 and 268.17 ng/m3, respectively. C16 and C18 accounted for about 60% and 30% of the annual average concentration of monocarboxylic acids, respectively. The carbon dominance index (CPI) of acid was negatively correlated with the total amount of monocarboxylic acids (carbon number ≥ 22) contributed by plants. (4) The source of monocarboxylic acids and its influence on the atmospheric environment was preliminarily determined based on the carbon number distribution, the ratio of the concentration of monocarboxylic acids with carbon number greater than or equal to 22 to the concentration of monocarboxylic acids with carbon number less than 22 (∑C ≥ 22/∑C < 22), the ratio of the concentration of stearic acid and palmitic acid (C18/C16), the CPI value and the ratio of the concentration of oleic acid to stearic acid (C18:1/C18). The results showed that the two sites in Qinhuangdao City had the most oxidizing atmosphere in summer (the atmospheric oxidation in urban areas was stronger than in industrial park), and the atmospheric oxidizing power was weak in spring and autumn. It was the weakest in spring in the industrial site. The monocarboxylic acids in PM2.5 in Qinhuangdao City mainly came from local sources, such as coal burning, motor vehicle exhaust emissions, road dust and meat cooking, while plant sources contributed less. The study showed that seasonal changes in the concentration of monocarboxylic acids were not significant at two sampling sites. Coal burning, motor vehicle emissions, road dust and meat cooking contributed more to monocarboxylic acids. |
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