Delhi is one of the most polluted cities globally, with frequent severe air pollution episodes and haze events occurring in recent years, thereby compelling us to understand the sources to develop effective mitigation plans. Complete chemical characterization of fine particulate matter (PM_2.5) components (non-refractory, refractory and elements) with high time resolution has been done during the summer season (June–July 2019). The total PM equivalent (PM_2.5(eq)) was 28.7 ± 13.2 μg m⁻³ of which elements dominated the PM_2.5(eq) with 34% contribution followed by organics (28%), black carbon (BC) (17%), SO₄²⁻ (10%), Cl⁻ (5%) NH₄⁺ (3.5%) and NO₃⁻ (2.5%). The contributions from organic aerosols (OA) and SO₄²⁻ were observed to be more than Cl⁻ and NO₃⁻. The total elemental mass concentration (PM_El) was mostly contributed (~96%) by Si, S, Cl, Ca, K, Fe and Al with Si and S alone contributing around 50% of PM_El. Crustal elements (Al, Fe, Ca and Si) were highly enhanced in summer than elements emitted from anthropogenic emissions (Cl, S, K, Pb and Zn). Source apportionment (SA) of PM was performed using positive matrix factorization (PMF) together with ME-2 (multilinear engine) for OA and elements, separately. PMF on both datasets helped resolve sources such as combustion, industrial, dust-related, incineration and traffic. OA PMF identified three factors related to primary emissions: hydrocarbon-like OA (HOA, 12.3%), solid fuel combustion (SFC, 16.2%) and cooking OA (COA, 7.3%) and two oxygenated OA (OOA): semi-volatile OOA (SVOOA, 15.2%) and low-volatile OOA (LVOOA, 49.1%). The elemental PMF resolved 8 factors: dust (52.5%), S-rich (16.2%), Cl-rich (10.7%), 2 SFC factors (10.5%), non-exhaust (7.2%), Cu-rich (1.5%) and industrial (1.4%). The contribution of BC to total PM mass is shown to increase in the summer compared to previous studies reported for the winter season. The secondary oxidized sources dominated both the OA and elements SA during the summer with 64.3% and 27% (dust not considered) contribution, respectively. The domination of secondary sources implies that it is crucial to control the secondary aerosols' precursors in Delhi for developing pollution control strategies. The ME-2 resolved factors, coupled with concentration weighted trajectory (CWT) showed the probable major elemental source regions of local origin (Delhi- National Capital Region (Delhi-NCR)) as well as regional (from Punjab, Haryana, Uttar Pradesh and Pakistan). The local sources included Cu-rich (Haryana) and SFC-II (Delhi and Uttar Pradesh), while the regional sources were dust (south-west (SW)), industrial, Cl-rich (north-west (NW)), SFC-I (east and south-east (SE)) and S-rich (SE).

德里是全球污染最严重的城市之一，近年来频繁发生严重的空气污染事件和雾霾事件，因此迫使我们了解来源以制定有效的缓解计划。已在夏季（2019 年 6 月至 7 月）完成了具有高时间分辨率的细颗粒物 (PM _2.5 ) 成分（非耐火材料、耐火材料和元素）的完整化学表征。总 PM 当量 (PM _2.5(eq) ) 为 28.7 ± 13.2 μg m ^-3其中元素在 PM _{2.5(eq) 中}占主导地位，贡献率为 34%，其次是有机物 (28%)、黑碳 (BC) (17%) , SO ₄ ²⁻ (10%), Cl ^- (5%) NH ₄ ⁺(3.5%) 和 NO ₃ ^- (2.5%)。观察到来自有机气溶胶 (OA) 和 SO ₄ ^2-的贡献大于 Cl ^-和 NO ₃ ^-。总元素质量浓度 (PM _El ) 主要由 Si、S、Cl、Ca、K、Fe 和 Al 贡献 (~96%)，仅 Si 和 S 贡献了 PM _{El 的}50% 左右. 地壳元素（Al、Fe、Ca 和 Si）在夏季比人为排放的元素（Cl、S、K、Pb 和 Zn）高度增强。PM 的源分配 (SA) 使用正矩阵分解 (PMF) 和 ME-2（多线性引擎）分别用于 OA 和元素。两个数据集上的 PMF 都有助于解决燃烧、工业、粉尘相关、焚烧和交通等来源。OA PMF 确定了与初级排放相关的三个因素：类碳氢化合物 OA（HOA，12.3%）、固体燃料燃烧（SFC，16.2%）和烹饪 OA（COA，7.3%）和两种含氧 OA (OOA)：半挥发性OOA (SVOOA, 15.2%) 和低挥发性 OOA (LVOOA, 49.1%)。元素 PMF 解决了 8 个因素：灰尘 (52.5%)、富 S (16.2%)、富 Cl (10.7%)、2 个 SFC 因素 (10.5%)、非排放 (7.2%)、富 Cu (1.5 %) 和工业 (1.4%)。与先前报告的冬季研究相比，BC 对 PM 总质量的贡献在夏季有所增加。夏季，二次氧化源在 OA 和元素 SA 中占主导地位，分别占 64.3% 和 27%（不考虑灰尘）。二次源的统治意味着在德里控制二次气溶胶的前体对于制定污染控制策略至关重要。ME-2 解决的因素，加上浓度加权轨迹 (CWT) 显示了可能的主要元素来源区域是当地（德里-国家首都地区 (Delhi-NCR)）和区域（来自旁遮普邦、哈里亚纳邦、北方邦和巴基斯坦）。当地来源包括富铜（哈里亚纳邦）和 SFC-II（德里和北方邦），