Secondary PM2.5 dominates aerosol pollution in the Yangtze River Delta region: Environmental and health effects of the Clean air Plan
Secondary PM2.5 dominates aerosol pollution in the Yangtze River Delta region: Environmental and health effects of the Clean air Plan
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DOI：
10.1016/j.envint.2022.107725
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发表时间：
2023-01-02
影响因子：
11.8
通讯作者：
Li, Jiandong
中科院分区：
文献类型：
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作者：
Li, Nan;Zhang, Haoran;Li, Jiandong
自2013年以来，中国一直在积极实施清洁空气计划，以缓解严重的PM2.5污染。在本研究中，我们应用空气质量模型WRF-Chem模拟了2017年中国长三角地区的PM2.5，旨在评估清洁空气计划最后一年的空气质量改善情况及其相关的健康负担。为了更好地描述各种 PM2.5 成分的命运，我们事先更新了模型中的化学机制，包括非均相硫酸盐反应、水性二次有机气溶胶 (SOA) 吸收和基于挥发性基组 (VBS) 的 SOA 产生。观测和模拟结果都一致认为，严格的净化空气行动有效地将PM2.5污染水平降低了约30%。一次PM2.5（-6类似-16%yr-1）比二次PM2.5（-2类似-8%yr-1）下降趋势更显着，这主要是由于近年来晴空气行动的方向性和臭氧污染恶化造成的。 PM2.5成分下降趋势不一致，随后导致二次PM2.5比例不断增加。除夏季硝酸铵蒸发较强外，长三角中西部地区硝酸盐颗粒物含量较高，已取代硫酸盐成为全年次生无机气溶胶的最大成分。此外，SOA仍然是一个重要的组成部分（21%~22%），尤其是在夏季，其中大部分是由半/中级挥发性有机化合物（S/IVOC）的氧化和老化产生的。此外，我们量化了相关的健康影响，发现清洁空气计划在很大程度上将长三角地区因 PM2.5 暴露造成的过早死亡从 39.91 万人减少到 29.57 万人。我们的研究强调了清洁空气计划的好处，并建议后续 PM2.5 的改善应更多地着眼于控制二次污染物。
The Clean Air Plan has been active in China since 2013 to mitigate severe PM2.5 pollution. In this study, we applied the air quality model WRF-Chem to simulate PM2.5 in the Yangtze River Delta (YRD) region of China in 2017, with the aim of assessing the air quality improvement and its associated health burden in the final year of the Clean Air Plan. To better describe the fate of various PM2.5 compositions, we updated the chemical mech-anisms in the model beforehand, including heterogeneous sulfate reactions, aqueous secondary organic aerosol (SOA) uptake, and volatility basis set (VBS) based SOA production. Both the observation and simulation results agreed that the stringent clear air action effectively reduced the PM2.5 pollution levels by similar to 30 %. The primary PM2.5 (-6 similar to -16 % yr- 1) showed a more significant decreasing trend than the secondary PM2.5 (-2 similar to -8 % yr-1), which was mainly caused by the directivity of the clear air actions and the worsening ozone pollution in the recent years. The inconsistent decreasing trends of PM2.5 components subsequently led to an increasing proportion of secondary PM2.5. Nitrate particles, higher in the central and western YRD region, have replaced sulfate and have become the largest component of secondary inorganic aerosols year-round, except in summer, when strong ammonium nitrate evaporation occurs. In addition, SOA remains an important component (21 similar to 22 %) especially in summer, most of which is produced from the oxidation and ageing of semi/intermediate volatile organic compounds (S/IVOC). Furthermore, we quantified the associated health impacts and found that the Clean Air Plan has largely reduced premature mortality due to PM2.5 exposure in the YRD region from 399.1 thousand to 295.7 thousand. Our study highlights the benefits of the Clean Air Plan and suggests that subsequent PM2.5 improvement should be geared more towards controlling secondary pollutants.