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A high-time resolution study of PM2.5, organic carbon, and elemental carbon at an urban traffic site in Istanbul
Atmospheric Environment ( IF 5 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.atmosenv.2019.117241
Rosa M. Flores , Elif Mertoğlu , Hüseyin Özdemir , Bülent O. Akkoyunlu , Göksel Demir , Alper Ünal , Mete Tayanç

Abstract Organic Carbon (OC) and Elemental Carbon (EC) were investigated on selected days between January 2017 and January 2018 in an urban area heavily impacted by traffic in Istanbul megacity. 300 PM2.5 samples were collected with a time resolution of 2 h during the daytime between 07:00–19:00. Nighttime samples were collected with a time resolution of 12 h between 19:00–07:00. Samples were collected for three weeks during the winter and one week during the spring, summer, and fall. The daily PM2.5 concentrations exceeded the standard of 35 μg m−3 29% of the time. Air quality was classified as fair (PM2.5>26.4 μg m−3) and unhealthy (PM2.5>39.9 μg m−3) 43% and 20% of the days, respectively. The annual average OC and EC were 11.3 ± 4.91 and 4.1 ± 1.16 μg m−3, respectively. Organic carbon showed strong seasonal variation with high concentrations during the heating season and low concentrations during the summer. Elemental carbon did not show strong seasonality due to the continuous influence of heavy traffic. Diurnal variations of OC and EC were characterized by high concentrations during the morning and evening rush hours, and low concentrations in the middle of the day due to the dilution effect of an increased mixing layer. Formation of secondary organic carbon was uncertain during the summer due to dilution and low primary organic carbon emissions. Concentrations heavily depended on surface wind speed. Average OC concentrations were 56–72% higher at wind speeds lower than 2 m s−1 compared to that at wind speeds higher than 3 m s−1 during fall and winter. Higher EC concentrations (15–56%) were observed at wind speeds higher than 3 m s−1, showing that in addition to traffic emissions, EC was transported from nearby areas. Continuous measurements of high time resolved OC and EC are necessary for the development and evaluation of air pollution mitigation strategies, particularly from combustion sources.

中文翻译:

伊斯坦布尔城市交通站点 PM2.5、有机碳和元素碳的高时间分辨率研究

摘要 2017 年 1 月至 2018 年 1 月期间,在伊斯坦布尔特大城市交通严重影响的城市地区,对有机碳 (OC) 和元素碳 (EC) 进行了调查。在白天 07:00-19:00 期间以 2 小时的时间分辨率收集了 300 个 PM2.5 样本。在 19:00–07:00 之间以 12 小时的时间分辨率收集夜间样本。样品在冬季采集 3 周,在春季、夏季和秋季采集 1 周。每日 PM2.5 浓度超过 35 μg m−3 标准的概率为 29%。空气质量被分类为一般(PM2.5>26.4 μg m-3)和不健康(PM2.5>39.9 μg m-3)的天数分别为 43% 和 20%。年平均 OC 和 EC 分别为 11.3 ± 4.91 和 4.1 ± 1.16 μg m-3。有机碳呈现强烈的季节性变化,采暖季高浓度,夏季低浓度。由于交通繁忙的持续影响,元素碳没有表现出强烈的季节性。OC 和 EC 的日变化特征是早晚高峰时段的高浓度,而由于混合层增加的稀释效应,白天的浓度较低。由于稀释和初级有机碳排放量低,夏季二次有机碳的形成是不确定的。浓度在很大程度上取决于表面风速。与秋季和冬季风速高于 3 m s-1 时相比,平均 OC 浓度在风速低于 2 m s-1 时高 56-72%。在高于 3 m s-1 的风速下观察到更高的 EC 浓度(15-56%),表明除了交通排放外,EC 还从附近地区运输。持续测量高时间分辨 OC 和 EC 对于空气污染缓解策略的开发和评估是必要的,尤其是来自燃烧源的空气污染缓解策略。
更新日期:2020-02-01
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