| 2019年国庆节前后北京气态氨和气溶胶铵盐浓度的同步观测 |
| 摘要点击 3872 全文点击 1154 投稿时间：2020-05-19 修订日期：2020-06-28 |
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| 中文关键词 氨气 气溶胶铵盐 日变化 相态分布 国庆节阅兵 |
| 英文关键词 ammonia ammonium diurnal variations gas to particle conversion National Celebration Day Parade |
| 作者 | 单位 | E-mail | | 顾梦娜 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029
中国科学院大学, 北京 100049 | gumengna17@mails.ucas.ac.cn | | 潘月鹏 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029
中国科学院大学, 北京 100049 | panyuepeng@mail.iap.ac.cn | | 宋琳琳 | 中国科学院大学, 北京 100049
中国科学院沈阳应用生态研究所, 辽宁省稳定同位素技术重点实验室, 沈阳 110016 | | | 李萍 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029
中国科学院大学, 北京 100049 | | | 田世丽 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029 | tianshili@mail.iap.ac.cn | | 武岳洋 | 北京农学院生物与资源环境学院, 北京 102206 | | | 杨婷婷 | 北京农学院生物与资源环境学院, 北京 102206 | | | 李浩洋 | 北京农学院生物与资源环境学院, 北京 102206 | | | 石生伟 | 北京农学院生物与资源环境学院, 北京 102206 | | | 吐莉尼沙 | 新疆维吾尔自治区气象台, 乌鲁木齐 830002 | | | 吕雪梅 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029 | | | 孙倩 | 中国科学院大气物理研究所, 大气边界层物理和大气化学国家重点实验室, 北京 100029 | | | 方运霆 | 中国科学院沈阳应用生态研究所, 辽宁省稳定同位素技术重点实验室, 沈阳 110016 | |
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| 中文摘要 |
| 我国自2013年实施《大气污染防治行动计划》以来，大气细颗粒物（PM2.5）特别是硫酸盐浓度迅速下降，但硝酸盐浓度降幅较小，大气中过量的氨气（NH3）是维持硝酸盐居高不下的主要因素.迄今，我国生态环境部门尚未将NH3纳入常规观测，以往有关NH3和气溶胶铵盐（NH4+）的研究多是分别进行的，缺少同步观测.由于NH3和NH4+在大气中可互相转化，只测量其中一种相态很难全面了解它们的动态变化.本研究基于酸涂覆的蜂窝型扩散管和膜采样串联系统，同步测量了2019年国庆节前后北京城区大气NH3和NH4+浓度，时间分辨率为2 h（PM2.5>35 μg·m-3）~5 h（PM2.5<35 μg·m-3）.结果表明，采样期间NH3和NH4+平均浓度分别为（4.1±2.9）μg·m-3和（1.7±1.4）μg·m-3，且二者均与PM2.5、CO和NO2呈现相似的时间变化规律.NH3浓度在早晨（05：30~08：30）和夜间（21：30~05：30）较高，这种双峰日变化特征在污染天（PM2.5>75 μg·m-3）最为明显.NH3浓度在污染天17：30~21：30存在明显的低谷，这主要与有利的扩散条件有关（平均风速6 m·s-1）.NH4+浓度的日变化特征与NH3差异较大，NH4+浓度在非污染天（PM2.5<75 μg·m-3）17：30~21：30出现明显峰值，期间NH3浓度较低，而NO2浓度较高.在非污染天，NH3浓度是NH4+的2.8倍；而在污染天，由于气粒转化加速，大气NH3浓度低于NH4+（NH3/NH4+=0.8）.国庆节前大气NH3、CO、NO2、SO2和PM2.5浓度超过国庆后的幅度分别为54.2%、40.4%、33.3%、0.0%和49.4%.国庆节前虽然实施了减排行动，但极端不利的静稳天气导致大气环境容量下降，掩盖了污染物减排的效果，导致大部分污染物浓度不降反升. |
| 英文摘要 |
| Since 2013, the Chinese government implemented the Air Pollution Prevention and Control Action Plan. As a result, the atmospheric concentrations of sulfate reduced significantly, whereas the nitrate concentrations remain relatively high due to the excess of ammonia (NH3). To date, there is no official observation network monitoring NH3 concentrations in China. Previous studies have focused on NH3 or ammonium (NH4+) separately. These limitations hinder a complete understanding of their dynamic changes due to the rapid gas-to-particle conversion. In this study, the concentrations of NH3 and NH4+ were measured concurrently in urban Beijing during autumn 2019 utilizing an acid-coated denuder-filter combination with a time resolution from 2 h (PM2.5>35 μg·m-3) to 5 h (PM2.5<35 μg·m-3). The mean concentrations of NH3 and NH4+ during the study were (4.1±2.9)μg·m-3 and (1.7±1.4) μg·m-3, respectively. The temporal patterns of NH3 or NH4+ coincided with that of PM2.5, CO, and NO2 throughout the sampling period. The diurnal distributions of NH3 were bimodal, both on polluted (PM2.5>75 μg·m-3) and non-polluted (PM2.5<75 μg·m-3) days, peaking at 21:30-05:30 and 05:30-08:30, respectively. The NH3 concentrations on polluted days were relatively lower during 17:30-21:30, which may be related to higher wind speeds. In contrast to NH3, NH4+ had an obvious peak during 17:30-21:30 due to the formation of ammonium nitrate. The meteorological conditions favor the gas-to-particle conversion on polluted days, resulting in a lower NH3/NH4+ ratio of 0.8. However, this value may reach 2.8 on non-polluted days. The concentrations of NH3, CO, NO2, SO2, and PM2.5 in the emission control period showed a significant increase greater than or comparable to those in the non-control period by 54.2%, 40.4%, 33.3%, 0%, and 49.4%, respectively. This result shows that the stagnant conditions offset the benefit of emission control actions implemented during and before the National Celebration Day. |
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