The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and secondary organic carbon contributions (POC, SOC, respectively) and on source apportionment by positive matrix factorization (PMF). An average TSP concentration of 69.6 ± 51.8 µg m⁻³ was found, exhibiting a pre-monsoon (March–May) maximum (92.9 ± 48.5 µg m⁻³) due to dust transport and forest fires and a monsoon (June–August) minimum due to atmospheric washout, while carbonaceous aerosols and inorganic species expressed a similar seasonality. The mean OC/EC ratio (8.0 ± 3.3) and the good correlations between OC, EC, and nss-K⁺ suggested that biomass burning (BB) was one of the major contributing factors to aerosols in Nainital. Using the EC tracer method, along with several approaches for the determination of the (OC/EC)pri ratio, the estimated SOC component accounted for ~25% (19.3–29.7%). Furthermore, TSP source apportionment via PMF allowed for a better understanding of the aerosol sources in the Central Himalayan region. The key aerosol sources over Nainital were BB (27%), secondary sulfate (20%), secondary nitrate (9%), mineral dust (34%), and long-range transported mixed marine aerosol (10%). The potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses were also used to identify the probable regional source areas of resolved aerosol sources. The main source regions for aerosols in Nainital were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area. The outcomes of the present study are expected to elucidate the atmospheric chemistry, emission source origins, and transport pathways of aerosols over the central Himalayan region.

中文翻译：

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喜马拉雅中部地区总悬浮颗粒的化学成分及来源解析

本研究分析了 3 年（2005-2008 年）在印度喜马拉雅山脉中部奈尼塔尔收集的总悬浮颗粒物 (TSP) 样本数据，并分析了含碳气溶胶（有机碳 (OC) 和元素碳 (EC)）和无机物种，侧重于评估初级和次级有机碳贡献（分别为 POC、SOC）和通过正矩阵分解 (PMF) 进行的源分配。发现平均 TSP 浓度为 69.6 ± 51.8 µg m ^-3，表现出季风前（3 月至 5 月）最大值 (92.9 ± 48.5 µg m ^-3) 是由于灰尘运输和森林火灾以及由于大气冲刷导致的季风（6 月至 8 月）最小，而碳质气溶胶和无机物种表现出类似的季节性。平均 OC/EC 比率 (8.0 ± 3.3) 以及 OC、EC 和 nss-K ⁺之间的良好相关性表明生物质燃烧（BB）是奈尼塔尔气溶胶的主要影响因素之一。使用 EC 示踪剂方法以及确定 (OC/EC)pri 比率的几种方法，估计的 SOC 分量占 ~25% (19.3–29.7%)。此外，通过 PMF 的 TSP 源分配可以更好地了解喜马拉雅中部地区的气溶胶源。Nainital 上空的主要气溶胶来源是 BB (27%)、二次硫酸盐 (20%)、二次硝酸盐 (9%)、矿物粉尘 (34%) 和远距离传输的混合海洋气溶胶 (10%)。潜在源贡献函数 (PSCF) 和浓度加权轨迹 (CWT) 分析也用于识别解析气溶胶源的可能区域源区域。奈尼塔尔气溶胶的主要来源地区是印度西北部和巴基斯坦的平原，德里、塔尔沙漠和阿拉伯海地区等污染城市。本研究的结果有望阐明喜马拉雅中部地区气溶胶的大气化学、排放源来源和传输途径。