This study reports for the first-time the ambient concentrations of HULIS mass (HULIS-OM, Humic-like substances) and HULIS-C (carbon) in PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) from the Indo-Gangetic Plain (IGP at Kanpur, wintertime). HULIS extraction followed by purification and isolation protocol with methanol: acetonitrile (1:1 v/v) on HLB (Hydrophilic-Lipophilic Balanced) cartridge has been established. Quantification of HULIS-C was achieved on a total organic carbon (TOC) analyser whereas HULIS-OM was determined gravimetrically. Consistently high recovery (> 90%) of HULIS-C based on analysis of Humic standard (sodium salt of Humic acid) suggested suitability of our established analytical protocol involving solvent extraction, purification and accurate quantification of HULIS. HULIS-OM varied from 17.3–38 μg m−3 during daytime and from 19.8–40.6 μg m−3 during night in this study. During daytime the HULIS-OM constituted 20–30% mass fraction of OMTotal and 10–15% of PM10 mass. However, a relatively low contribution of HULIS-OM has been observed during the night. This observation has been attributed to higher concentrations of OM and PM10 in night owing to nighttime chemical reactivity and condensation of organics in conjunction with shallower planetary boundary layer height. Strong correlation of HULIS-C with K+BB (R2 > 0.80) and significant day-night variability of HULIS-C/WSOC ratio in conjunction with air-mass back trajectories (showing transport of pollutants from upwind IGP) suggest biomass burning emission and secondary transformations as important sources of HULIS over IGP. High-loading of atmospheric PM10 (as high as 440 μg m−3) with significant contribution of water-soluble organic aerosols (WSOC/OC: ~ 0.40–0.80) during wintertime highlights their plausible potential role in fog and haze formation and their impact on regional-scale atmospheric radiative forcing over the IGP.

中文翻译：

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印度恒河平原冬季大气中 HULIS 的丰度：生物质燃烧排放的影响

本研究首次报告了印度-恒河平原 PM10（空气动力学直径 ≤ 10 μm 的颗粒物）中 HULIS 质量（HULIS-OM，类腐殖质）和 HULIS-C（碳）的环境浓度（坎普尔的 IGP，冬季）。HULIS 提取，然后是使用甲醇：乙腈 (1:1 v/v) 在 HLB（亲水亲油平衡）柱上进行纯化和分离的协议已经建立。HULIS-C 的定量是在总有机碳 (TOC) 分析仪上实现的，而 HULIS-OM 是通过重量分析确定的。基于对腐殖酸标准品（腐殖酸的钠盐）的分析，HULIS-C 的持续高回收率 (> 90%) 表明我们建立的分析方案的适用性，包括溶剂萃取、纯化和 HULIS 的准确定量。HULIS-OM 从 17 不等。在本研究中，白天为 3-38 μg m-3，夜间为 19.8-40.6 μg m-3。在白天，HULIS-OM 占 OMTotal 的 20-30% 质量分数和 PM10 质量的 10-15%。然而，在夜间观察到 HULIS-OM 的贡献相对较低。这一观察结果归因于夜间化学反应和有机物凝结以及较浅的行星边界层高度导致夜间较高浓度的 OM 和 PM10。HULIS-C 与 K+BB (R2 > 0.80) 的强相关性以及 HULIS-C/WSOC 比率的显着昼夜变异性以及空气质量反向轨迹（显示来自逆风 IGP 的污染物传输）表明生物质燃烧排放和二次转换作为 HULIS over IGP 的重要来源。