Estimation of Secondary PM2.5 in China and the United States using a Multi-Tracer Approach
Estimation of Secondary PM2.5 in China and the United States using a Multi-Tracer Approach
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DOI：
10.5194/acp-2021-683
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发表时间：
2021-10
影响因子：
6.3
通讯作者：
H. Zhang;Nannan Li;Keqin Tang;H. Liao;Chong Shi;Cheng Huang;Hongli Wang;Song Guo;M. Hu
中科院分区：
文献类型：
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作者：
H. Zhang;Nannan Li;Keqin Tang;H. Liao;Chong Shi;Cheng Huang;Hongli Wang;Song Guo;M. Hu
抽象的。通过直接排放和二次形成产生的PM2.5，由于其成分的物理和化学性质不同，可能会产生不同的环境影响。然而，量化不同PM2.5成分的传统方法通常基于在线观测或实验室分析，通常经济成本高且劳动密集。在本研究中，我们开发了一种新方法，称为多示踪剂估计算法（MTEA），用于从PM2.5的常规观测中识别主要和次要成分。通过与中国气溶胶化学成分的长期和短期观测数据以及美国气溶胶成分监测网的对比，证明MTEA能够成功地捕捉到一次PM2. 5（PPM）和二次PM2. 5（SPM）的量级和变化。将MTEA应用于中国国家空气质量监测网，发现1）2014-2018年中国南方城市平均SPM占PM2.5的63.5%，而北方的比例下降到57.1%，同时区域背景区的次比例比人口密集区高约19%; 2）夏季二次PM2.5比例呈小幅但持续上升趋势（从58. 5%到59. 2%）在人口最多的城市，主要是因为最近中国的O 3污染增加; 3）在COVID-19封城期间，北京的二次PM2.5比例显著增加了34%，这可能是在这个特殊时期观察到的意外PM污染的主要原因;至少，4）BTH和YRD地区的SPM和O_3表现出相似的正相关关系，但PM_2.5和O_3的相关性在这两个地区有很大差异。总体而言，MTEA是一种有效估算PPM和SPM的有效工具，对未来PM减排具有巨大潜力。
Abstract. PM2.5, generated via both direct emissions and secondary formations, can have varying environmental impacts due to different physical and chemical properties of its components. However, traditional methods to quantify different PM2.5 components are often based on online observations or lab analyses, which are generally high economic cost and labor-intensive. In this study, we develop a new method, named multi-tracer estimation algorithm (MTEA), to identify the primary and secondary components from routine observation of PM2.5. By comparing with the long-term and short-term measurements of aerosol chemical components in China, as well as aerosol composition network in the United States, MTEA is proved to be able to successfully capture the magnitude and variation of the primary PM2.5 (PPM) and secondary PM2.5 (SPM). Applying MTEA to China national air quality network, we find that 1) SPM accounts for 63.5 % of PM2.5 in southern cities of China averaged for 2014–2018, while in the North the proportion drops to 57.1 %, and at the same time the secondary proportion in regional background regions is ~19 % higher than that in populous regions; 2) the summertime secondary PM2.5 proportion presents a slight but consistent increasing trend (from 58.5 % to 59.2 %) in most populous cities, mainly because of the recent increase in O3 pollution in China; 3) the secondary PM2.5 proportion in Beijing significantly increases by 34 % during the COVID-19 lockdown, which might be the main reason of the observed unexpected PM pollution in this special period; and at least, 4) SPM and O3 show similar positive correlations in the BTH and YRD regions, but the correlations between total PM2.5 and O3 in these two regions are quite different as PPM levels determines. In general, MTEA is a promising tool for efficiently estimating PPM and SPM, and has huge potential for the future PM mitigation.