| 长三角背景点夏季大气PM2.5中正构烷烃和多环芳烃的污染特征和来源解析 |
| 摘要点击 2254 全文点击 978 投稿时间：2019-08-02 修订日期：2019-09-16 |
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| 中文关键词 崇明岛 PM2.5 正构烷烃 多环芳烃(PAHs) 机动车 燃煤 船舶排放 |
| 英文关键词 Chongming Island PM2.5 n-alkanes polycyclic aromatic hydrocarbons (PAHs) vehicle exhaust coal burning ship emission |
| 作者 | 单位 | E-mail | | 薛国艳 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | 51173901063@stu.ecnu.edu.cn | | 王格慧 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241
崇明生态研究院, 上海 200062 | ghwang@geo.ecnu.edu.cn | | 吴灿 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 谢郁宁 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 陈玉宝 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 李杏茹 | 首都师范大学化学系分析测试中心, 北京 100048 | | | 王心培 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 李大鹏 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 张思 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 葛双双 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | | | 丁志健 | 华东师范大学地理科学学院, 地理信息科学教育部重点实验室, 上海 200241 | |
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| 中文摘要 |
| 为探讨长三角背景点有机气溶胶的污染特征和来源，于2018年夏季在崇明岛进行了为期3个月的PM2.5样品昼夜采集，使用气相色谱-质谱技术分析其中正构烷烃（normal alkanes，n-alkanes）和多环芳烃（polycyclic aromatic hydrocarbons，PAHs）的质量浓度和分子组成，并结合后向轨迹和正交矩阵（positive matrix factorization，PMF）解析其来源.结果表明，观测期间崇明岛PM2.5的质量浓度为（33±21）μg·m-3，低于国家空气质量一级标准（GB3095-2012，35 μg·m-3），但仍有部分时段污染较重，超标率为35%.其中n-alkanes和PAHs的浓度均值分别为（26±44）ng·m-3和（0.76±1.0）ng·m-3，污染期（PM2.5≥35 μg·m-3）比清洁期（PM2.5<15 μg·m-3）高出一个数量级，二者在污染期均呈昼低夜高趋势，而清洁期PAHs昼夜无显著差异，n-alkanes呈现白天大于晚上的特征.分子组成、特征比值及相关性分析显示：PM2.5中67%的n-alkanes来源于化石燃料燃烧，其余为植物排放，PAHs则主要来自化石燃料和生物质燃烧.后向轨迹及PMF的分析结果进一步显示：污染期PAHs主要来自内陆、沿海及长三角地区的机动车与工业排放，贡献了51%，而清洁期受海洋气团控制，PAHs主要来源于船舶排放，贡献了45%，高于燃煤和机动车排放的贡献之和（38%）. |
| 英文摘要 |
| To investigate the pollution characteristics and sources of organic aerosols at a background site of the Yangtze River Delta, day- and night- PM2.5 samples were collected from May 30th to August 15th, 2018 in Chongming Island, China and measured for their normal alkanes (n-alkanes) and polycyclic aromatic hydrocarbons (PAHs) content employing a GC-MS technique. Concentrations of PM2.5, n-alkanes, and PAHs during the entire sampling period were (33±21) μg·m-3, (26±44) ng·m-3, and (0.76±1.0) ng·m-3, respectively. During the entire campaign, 35% of the collected PM2.5 samples were of a particle loading larger than the first grade of the China National Air Quality Standard (35 μg·m-3), suggesting that further mitigation with respect to air pollution in Chongming Island remains imperative. In the period with a PM2.5 concentration higher than 35 μg·m-3, which was classified as the pollution period, concentrations of n-alkanes and PAHs were one order of magnitude higher than those in the period with PM2.5 less than 15 μg·m-3, which was classified as the clean period. During the entire campaign, OC was higher in the daytime than in the nighttime, mainly due to the daytime photooxidation that enhanced the formation of secondary organic aerosols. During the pollution period, concentrations of EC and other pollutants were higher in the nighttime than in daytime, mainly due to the transport of the inland pollutants by the nighttime land breeze. Such a diurnal difference was not observed for the pollutants in clean periods, mainly due to the relatively clean breeze from East China Sea that diluted the air pollution. Diagnostic ratios showed that 67% of n-alkanes in PM2.5 was derived from fossil fuel combustion. PMF analysis further showed that during the pollution period, vehicle exhausts and industrial emissions were the largest sources of PAHs, both accounting for 51% of the total in PM2.5. In contrast, during the clean periods ship emissions were the largest source, contributing about 45% of the total PAHs, exceeding the sum (38%) of vehicle and industrial emissions. |
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