Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, India.
Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 PSI Villigen, Switzerland.
Sci Total Environ. 2021 May 20;770:145324. doi: 10.1016/j.scitotenv.2021.145324. Epub 2021 Jan 23.
National Capital Region (NCR) encompassing New Delhi is one of the most polluted urban metropolitan areas in the world. Real-time chemical characterization of fine particulate matter (PM and PM) was carried out using three aerosol mass spectrometers, two aethalometers, and one single particle soot photometer (SP2) at two sites in Delhi (urban) and one site located ~40 km downwind of Delhi, during January-March 2018. The campaign mean PM (NR-PM + BC) concentrations at the two urban sites were 153.8 ± 109.4 μg.m and 127.8 ± 83.2 μg.m, respectively, whereas PM (NR-PM + BC) was 72.3 ± 44.0 μg.m at the downwind site. PM particles were composed mostly of organics (43-44)% followed by chloride (14-17)%, ammonium (9-11)%, nitrate (9%), sulfate (8-10)%, and black carbon (11-16)%, whereas PM particles were composed of 47% organics, 13% sulfate as well as ammonium, 11% nitrate as well as chloride, and 5% black carbon. Organic aerosol (OA) source apportionment was done using positive matrix factorization (PMF), solved using an advanced multi-linear engine (ME-2) model. Highly mass-resolved OA mass spectra at one urban and downwind site were factorized into three primary organic aerosol (POA) factors including one traffic-related and two solid-fuel combustion (SFC), and three oxidized OA (OOA) factors. Whereas unit mass resolution OA at the other urban site was factorized into two POA factors related to traffic and SFC, and one OOA factor. OOA constituted a majority of the total OA mass (45-55)% with maximum contribution during afternoon hours ~(70-80)%. Significant differences in the absolute OOA concentration between the two urban sites indicated the influence of local emissions on the oxidized OA formation. Similar PM chemical composition, diurnal and temporal variations at the three sites suggest similar type of sources affecting the particulate pollution in Delhi and adjoining cities, but variability in mass concentration suggest more local influence than regional.
涵盖新德里的国家首都地区（NCR）是世界上污染最严重的城市大都市区之一。在 2018 年 1 月至 3 月期间，在德里（城市）的两个地点和德里下风处约 40 公里的一个地点使用三台气溶胶质谱仪、两台黑碳仪和一台单颗粒 soot 光度计（SP2）对细颗粒物（PM 和 PM）进行了实时化学特征描述。两个城市站点的日平均 PM（NR-PM+BC）浓度分别为 153.8±109.4μg.m和 127.8±83.2μg.m，而下风站点的 PM（NR-PM+BC）浓度为 72.3±44.0μg.m。PM 颗粒主要由有机物（43-44）%组成，其次是氯（14-17）%、铵（9-11）%、硝酸盐（9%）、硫酸盐（8-10%）和黑碳（11-16%），而 PM 颗粒由 47%有机物、13%硫酸盐和铵、11%硝酸盐和氯以及 5%黑碳组成。使用正矩阵因子化（PMF）对有机气溶胶（OA）源进行了分配，并使用高级多线性引擎（ME-2）模型进行了解决。在一个城市和下风站点对高度质量分辨的 OA 质谱进行了因子分解，得到了三个主要的有机气溶胶（POA）因子，包括一个与交通有关的和两个与固体燃料燃烧（SFC）有关的因子，以及三个与氧化有关的 OA（OOA）因子。而在另一个城市站点，单位质量分辨率的 OA 被分解为两个与交通和 SFC 有关的 POA 因子和一个 OOA 因子。OOA 占总 OA 质量的大部分（45-55%），下午时间的贡献最大（70-80%）。两个城市站点之间绝对 OOA 浓度的显著差异表明，本地排放对氧化 OA 形成的影响。三个站点的 PM 化学组成、日变化和时间变化相似，表明影响德里和邻近城市颗粒物污染的是类似类型的源，但质量浓度的可变性表明，本地影响大于区域影响。
