The chemical composition of particulate matter impacts both human health and climate. In this study, the chemical characteristics of particulate matter was measured for four months (November 2016–February 2017) at Varanasi, which is located in the middle of the Indo-Gangetic Basin (IGB). The daily observed mean values of PM 10 and PM 2.5 are 134 ± 48 and 213 ± 80 μg/m 3 , respectively, which exceeds both national and international standards. The average value of PM 2.5 /PM 10 ratio is 0.64 ± 0.16 which indicates a relatively higher fraction of fine particles that are attributed to anthropogenic emission sources (biomass/post-harvest burning) as corroborated by MODIS fire counts and back trajectory analysis. Ion chromatographic measurements showed that SO 4 2− , Cl − , K + , NO 3 − , Na + , Ca 2+ , Mg 2+ are the major ionic species present in the aerosol. Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM–EDX) analysis shows the prevalence of carbon-rich particles at Varanasi which is likely due to biomass burning and other anthropogenic sources.

中文翻译：

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瓦拉纳西冬季颗粒物化学特征及其排放源

颗粒物的化学成分会影响人类健康和气候。在这项研究中，在位于印度恒河盆地 (IGB) 中部的瓦拉纳西 (Varanasi) 对颗粒物质的化学特征进行了四个月 (2016 年 11 月至 2017 年 2 月) 的测量。PM 10 和PM 2.5 的日观测平均值分别为134 ± 48 和213 ± 80 μg/m 3 ，均超过国家和国际标准。PM 2.5 /PM 10 比率的平均值为 0.64 ± 0.16，这表明归因于人为排放源（生物质/收获后燃烧）的细颗粒的比例相对较高，MODIS 火灾计数和反向轨迹分析证实了这一点。离子色谱测量表明，SO 4 2- 、Cl - 、K + 、NO 3 - 、Na + 、Ca 2+ 、Mg 2+ 是气溶胶中存在的主要离子物质。具有能量色散 X 射线的扫描电子显微镜 (SEM-EDX) 分析显示瓦拉纳西富含碳颗粒的普遍存在，这可能是由于生物质燃烧和其他人为来源。