Quantitative Characterization of the Volatility Distribution of Organic Aerosols in a Polluted Urban Area: Intercomparison Between Thermodenuder and Molecular Measurements
Quantitative Characterization of the Volatility Distribution of Organic Aerosols in a Polluted Urban Area: Intercomparison Between Thermodenuder and Molecular Measurements
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DOI：
10.1029/2023jd040284
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发表时间：
2024-02-28
影响因子：
4.4
通讯作者：
Wang，Xinming
中科院分区：
文献类型：
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作者：
Chen，Wei;Hu，Weiwei;Wang，Xinming
为了量化有机气溶胶(OA)的挥发性，在中国的特大城市开展了一项全面的运动。基于五种方法估算了有机硝酸盐和颗粒相有机硝酸盐(PON)的挥发性分布：(A)经验法和(B)基于热质谱计(TD)测量的动力学模型；(C)基于公式的SIMPOL模型驱动方法；(D)使用分子式测量OA的基于元素的估算；以及(E)气体/颗粒分配。结果表明，采用SIMPOL模型，假设环境油酸主要由有机硝酸盐(PON)、有机硫酸盐和酸性基团组成，两种加热方法与基于公式的方法得到的环境油酸挥发分分布具有较好的一致性。然而，与上述三种方法相比，基于元素的方法往往高估了OA的挥发性，这表明在参数设置或分子测量的代表性方面存在很大的不确定性，需要进一步完善。环境骨关节炎的波动性一般低于实验室衍生的继发性骨关节炎，强调了老化的影响。在较高和较低的挥发性范围内(约logC*≤和−9和≥2和μg和−3)发现了很大一部分PON，这意味着极低挥发性和半挥发性物种的重要性。总体而言，本研究评估了不同的波动率估计方法，并对城市地区的OA和PON的波动性提供了新的见解。
To quantify the volatility of organic aerosols (OA), a comprehensive campaign was conducted in the Chinese megacity. Volatility distributions of OA and particle‐phase organic nitrate (pON) were estimated based on five methods: (a) empirical method and (b) kinetic model based on the measurement of a thermodenuder (TD) coupled with an aerosol mass spectrometer; (c) Formula‐based SIMPOL model‐driven method; (d) Element‐based estimations using molecular formula measurements of OA; and (e) gas/particle partitioning. Our results demonstrate that the ambient OA volatility distribution shows good agreement between the two heating methods and the formula‐based method when assuming ambient OA was mainly composed of organic nitrate (pON), organic sulfate and acid groups using the SIMPOL model. However, the element‐based method tends to overestimate the volatility of OA compared to the above three methods, suggesting large uncertainties in the parameterizations or in the representativeness of the molecular measurements that need further refinement. The volatility of ambient OA is generally lower than that of the laboratory‐derived secondary OA, emphasizing the impact of aging. A large fraction at the higher and lower volatility ranges (approximately logC*≤ −9 and ≥2 μg m−3) was found for pON, implying the importance of both extremely low volatile and semi‐volatile species. Overall, this study evaluates different methods for volatility estimation and gives new insight into the volatility of OA and pON in urban areas.