| 广州市城区站点冬季PM2.5时间变化及碳氮同位素组成特征 |
| Temporal Variation of PM2.5 and Its Carbon and Nitrogen Isotopic Composition at an Urban Site in Guangzhou in Winter |
| 投稿时间：2021-11-01 修订日期：2022-02-14 |
| DOI：10.19316/j.issn.1002-6002.2023.01.10 |
| 中文关键词: PM2.5 碳同位素 氮同位素 水溶性离子 机动车排放 |
| 英文关键词:PM2.5 carbon isotopes nitrogen isotopes water-soluble ions motor vehicle emissions |
| 基金项目:国家自然科学基金(41975156) |
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| 通讯作者:赖森潮* 华南理工大学环境与能源学院工业聚集区污染控制与生态修复教育部重点实验室, 广东 广州 510006 |
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| 中文摘要: |
| 于2018年冬季在广州城区磨碟沙站点开展细颗粒物(PM2.5)样品采集,并获得PM2.5中水溶性离子、含碳组分、稳定碳氮同位素的组成及时间变化特征,重点讨论了PM2.5浓度升高时段的化学组成特征变化,进而利用稳定碳氮同位素变化特征探究了主要污染来源。结果表明:采样期间,研究站点PM2.5平均质量浓度为22.1 μg/m3,共出现两个PM2.5浓度水平升高时段,所对应的平均质量浓度分别达46.0 μg/m3和63.0 μg/m3。风速降低、温度升高等不利气象条件是导致上述时段PM2.5浓度上升的重要原因。在上述时段,伴随着PM2.5浓度的升高,NO-3和NH+4浓度均出现显著升高,NO-3与SO2-4的摩尔质量比(NO-3/SO2-4)同时出现高值,表明当地PM2.5浓度主要受到机动车排放的影响。研究发现,伴随着PM2.5浓度的升高,稳定氮同位素比值(δ15N)显著升高,而稳定碳同位素比值(δ13C)则出现降低。δ13C与NH+4、NO-3、NO-3/SO2-4之间均呈现显著的负相关关系,说明机动车排放对δ13C有重要影响。硝酸盐氮(NO-3-N)和铵盐氮(NH+4-N)表现出与δ15N相似的变化趋势。其中,NH+4对总氮(TN)的贡献为46%,高于NO-3对TN的贡献(36%)。在PM2.5浓度升高时段,NH+4/SO2-4表现出高值,NO-3也出现浓度高值,表明PM2.5中富含铵盐,并进一步证明机动车排放对PM2.5污染贡献较大。 |
| 英文摘要: |
| In this study,fine particulate matter (PM2.5) samples were collected at an urban site (Modiesha) in Guangzhou during the winter of 2018.The composition and variation characteristics of water-soluble ions,carbonaceous components and stable carbon and nitrogen isotopic compositions in PM2.5 were obtained.The characteristics of chemical components in PM2.5 during the period of PM2.5 enhancement were discussed,and then the pollution sources were explored.The results showed that the average mass concentration of PM2.5 during the sampling period was 22.1 μg/m3.Two periods with PM2.5 enhancements were observed with the average PM2.5 mass concentrations of 46.0 μg/m3 and 63.0 μg/m3,respectively.Unfavorable weather conditions such as wind speed decrease and temperature increase were suggested as the main factors affecting the increase of PM2.5 concentration.NO-3 and NH+4 concentrations increased significantly during these two periods with PM2.5 enhancement.The ratio of NO-3/SO2-4 was relatively high,indicating that the increase of PM2.5 was possibly affected by motor vehicle emissions.When the concentration of PM2.5 increased,δ15N increased significantly but δ13C decreased.There were significant negative correlations between δ13C and NH+4,NO-3 and NO-3/SO2-4,indicating the important impact of vehicle emissions.δ15N and NO-3-N and NH+4-N showed quite similar trends during the mentioned periods.The contribution of NH+4(46%) to total nitrogen (TN) was higher than that of NO-3(36%).High ratios of NH+4/SO2-4 during the periods with PM2.5 enhancement was observed,and NO-3 also showed high concentration.It showed that the observed PM2.5 aerosol was rich in sufficient ammonium salt.In summary,it further proved that motor vehicle emission was the major contributor to PM2.5 enhancement. |
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