Exploring the long-term variations and high concentration episodes of peroxyacetyl nitrate in Megacity Seoul

IF 4.2 2区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Atmospheric Environment Pub Date : 2024-09-13 DOI:10.1016/j.atmosenv.2024.120821

Anja Savic , Junsu Gil , Junil Cha , Meehye Lee , Yuri Choi , Moon-Soo Park

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引用次数: 0

Abstract

Over the past few years, peroxyacetyl nitrate (PAN) has drawn significant attention as a key indicator of photochemical pollution owing to its intimate relationship with ozone and associated health effects. This study presents measurements conducted at the Korea University campus in Seoul during the high-ozone seasons from 2018 to 2021. PAN concentration was measured using fast gas chromatography with luminol chemiluminescence detection (GC-LCD), alongside measurements of O₃, volatile organic compounds (VOCs), NO, NO₂, and meteorological variables, including boundary layer height (BLH).

The mean concentrations of PAN and O₃ over the years were 0.56 ppbv and 35 ppbv in 2018, 1.29 ppbv and 58 ppbv in 2019, 0.21 ppbv and 50 ppbv 2020, and 0.53 ppbv and 46 ppbv in 2021, respectively. The annual variation observed in Seoul is consistent with trends seen in major cities worldwide during the COVID19 pandemic, reflecting a substantial reduction in urban emissions. Notably, the mean concentration of NOx and VOCs decreased significantly by more than 50 % and 25%, respectively, from 2019 to 2021.

At temperatures above 30 °C, PAN decomposition was accelerated, decoupling a consistent positive relationship between PAN and O₃ in 2020 and 2021. The results of a 0-D photochemical model (F0AM) calculation demonstrated that PAN formation primarily stems from anthropogenic VOCs, particularly > C2 alkenes. Elevated PAN concentrations during nighttime were attributed to boundary layer expansion and upper-air entrainment. Instances where PAN concentrations surged to at least 3 ppbv or higher in 2019 were attributed to biomass burning impacted air, as evidenced by concurrent elevations in K⁺ and OC in PM_2.5, and O₃.

This study underscores the complex interplay of factors influencing PAN and ozone enhancements under decreased precursor levels, with an emphasis on dynamic change in the boundary layer, and long-distance transport of non-fossil sources during agricultural burning seasons.

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探索首尔市过氧乙酰硝酸盐的长期变化和高浓度事件

在过去几年中，由于过氧乙酰硝酸酯（PAN）与臭氧和相关健康影响之间的密切关系，它作为光化学污染的关键指标引起了人们的极大关注。本研究介绍了 2018 年至 2021 年臭氧高发季节在首尔高丽大学校园进行的测量。采用快速气相色谱-鲁米诺化学发光检测法（GC-LCD）测量了 PAN 浓度，同时还测量了 O3、挥发性有机化合物（VOC）、NO、NO2 和气象变量，包括边界层高度（BLH）。2018 年 PAN 和 O3 的平均浓度分别为 0.56 ppbv 和 35 ppbv，2019 年分别为 1.29 ppbv 和 58 ppbv，2020 年分别为 0.21 ppbv 和 50 ppbv，2021 年分别为 0.53 ppbv 和 46 ppbv。在首尔观察到的年度变化与 COVID19 大流行期间全球主要城市的趋势一致，反映出城市排放量的大幅减少。值得注意的是，从2019年到2021年，氮氧化物和挥发性有机化合物的平均浓度分别大幅下降了50%和25%以上。在温度高于30 °C时，PAN分解加速，2020年和2021年，PAN与O3之间的正相关关系脱钩。0-D光化学模型（F0AM）的计算结果表明，PAN的形成主要源于人为挥发性有机化合物，尤其是C2烯烃。夜间 PAN 浓度升高的原因是边界层膨胀和上层空气夹带。这项研究强调了在前体水平降低的情况下，影响 PAN 和臭氧增强的各种因素之间复杂的相互作用，重点是边界层的动态变化，以及农业焚烧季节非化石源的长距离输送。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Atmospheric Environment 环境科学-环境科学

CiteScore

9.40

自引率

8.00%

发文量

458

审稿时长

53 days

期刊介绍： Atmospheric Environment has an open access mirror journal Atmospheric Environment: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. Atmospheric Environment is the international journal for scientists in different disciplines related to atmospheric composition and its impacts. The journal publishes scientific articles with atmospheric relevance of emissions and depositions of gaseous and particulate compounds, chemical processes and physical effects in the atmosphere, as well as impacts of the changing atmospheric composition on human health, air quality, climate change, and ecosystems.