| 造成香港空气污染的环流聚类特征及对细颗粒物的影响 |
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| 引用本文： | 马媛媛,周杨,盛立芳,王文彩,郁建珍.造成香港空气污染的环流聚类特征及对细颗粒物的影响[J].地球化学,2021,50(1):22-35. |
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| 作者姓名： | 马媛媛 周杨 盛立芳 王文彩 郁建珍 |
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| 作者单位： | 中国海洋大学 海洋与大气学院, 山东 青岛 266100;中国海洋大学 海洋与大气学院, 山东 青岛 266100;香港科技大学 环境学部, 香港 999077;中国海洋大学 海洋与大气学院, 山东 青岛 266100;中国海洋大学 海洋与大气学院, 山东 青岛 266100;香港科技大学 环境学部, 香港 999077;香港科技大学 化学系, 香港 999077 |
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| 基金项目： | 环境与自然保护基金/惠洛克绿色基金;国家自然科学基金 |
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| 摘 要： | 对2012年5月至2013年5月香港空气污染期间89个污染日的天气环流形势通过模糊聚类的方法进行统计分类,得到大陆冷高压型、入海高压型、东北部热带气旋型和南部热带气旋型4种天气类型。结合细颗粒物(PM2.5)及其主要组分、气态污染物的日变化特征以及气象参数的相关性分析不同天气型影响下的污染事件在不同季节的污染特征。入海高压型污染事件发生时PM2.5主成分中二次水溶性无机离子(SIA)的占比明显比其他类型高,尤其是硝酸铵,可能与该天气型造成的高相对湿度、低温度的大气环境有关,进一步研究发现,春季污染事件中二次水溶性无机离子的增长与其前体物的非均相氧化反应有关;秋季硫酸盐的增长与均相氧化反应相关;冬季受季风影响,污染物的跨界输送贡献较大。大陆冷高压天气型造成大范围的下沉运动,静稳大气易导致污染物的积累,在PM2.5主成分中二次水溶性无机离子和有机物(OM)占比均有增高,秋、冬季二次水溶性无机离子前体物的非均相氧化反应与有机物的光化学氧化反应是造成该污染特征的主要原因之一。在东北部热带气旋型污染事件中有机碳与元素碳质量浓度的比值(OC/EC)较高且同O3的相关性较好,说明光氧化反应生成二次有机物是造成PM2.5中有机物占比大幅增高的主要原因。由于受到降水和大风的冲刷、稀释,南部热带气旋污染事件持续时间短,有机碳与元素碳同源,光氧化反应贡献小,二次有机物含量少且二次水溶性无机离子的占比更高。对香港地区在不同天气型影响下大气污染特征进行的系统性统计和分析,加深了该地区气象条件对污染过程影响的认识。
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| 关 键 词： | 空气污染事件 环流形势 聚类分析 细颗粒物 污染特征 香港 |
Cluster analysis of air pollution circulation episodes in Hong Kong and characteristics of fine particulate matter |
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| MA Yuan-yuan,ZHOU Yang,SHENG Li-fang,WANG Wen-cai,YU Jian-zhen.Cluster analysis of air pollution circulation episodes in Hong Kong and characteristics of fine particulate matter[J].Geochimica,2021,50(1):22-35. |
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| Authors: | MA Yuan-yuan ZHOU Yang SHENG Li-fang WANG Wen-cai YU Jian-zhen |
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| Institution: | (College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China;Institute of Environment,Hong Kong University of Science and Technology,Hong Kong 999077,China;Department of Chemistry,Hong Kong University of Science and Technology,Hong Kong 999077,China) |
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| Abstract: | The synoptic circulation patterns during 89 days of pollution episodes were classified by Fuzzy c-means(FCM)algorithm from May 2012 to May 2013 in Hong Kong.Four clusters were obtained:anticyclone,anticyclone easterly,cyclone northeasterly,and cyclone southerly.By combining the diurnal variations of fine particulate matter(PM2.5),its main components,and gaseous pollutants and their correlations with meteorological parameters,different seasonal characteristics and formation mechanisms of aerosols were revealed,even under the same weather patterns.The pollution events controlled by the anticyclone easterly were characterized by a higher proportion of secondary inorganic aerosol(SIA)in PM2.5 in general,especially nitrate,which might be related to higher relative humidity and lower temperature.In spring,the increase in SIA was related to heterogeneous oxidation reactions of the precursor,while in autumn sulfate was associated with homogeneous oxidation reactions.Because of the monsoon in winter,the transboundary transport of pollutants had a certain contribution to PM2.5.The pollution events controlled by the anticyclone cluster were characterized by widely sink movement and stable atmospheric conditions,resulting in air pollution accumulation.Influenced by the anticyclone,both SIA and organic matter(OM)contained higher proportions of PM2.5,which may be attributed to the heterogeneous oxidation reactions of the precursors and the photochemical oxidation of organics,respectively.The dominant component of the PM2.5 was carbonaceous aerosol,when controlled by a cyclone northeasterly,and this may be related to photochemical oxidation formation of secondary organic aerosols,as the organic carbon/elemental carbon(OC/EC)ratio was the highest and correlated well with O3.The pollution events controlled by the cyclone southerly had a short duration and were scavenged by rainfall.Most OC and EC had the same source,with a small contribution from the photochemical aging process,decreased secondary organic content and higher proportion of secondary inorganic aerosol.By systematically analyzing the characteristics of air pollution controlled by different weather patterns in Hong Kong,the understanding of the impact of meteorological processes on pollution was advanced through this study. |
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| Keywords: | air pollution episodes circulation cluster analysis fine particulate matter pollution characteristics Hong Kong |
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