The Indo-Gangetic Plain (IGP) is one of the most highly polluted regions of the world, yet the temporal pattern of transport of anthropogenic aerosols from this region to the Himalayas is poorly constrained. On the basis of the seasonal variation of planetary boundary layer heights, air mass back trajectory analysis, and year-long time-series data for ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁶Pb/²⁰⁴Pb, and ¹⁴³Nd/¹⁴⁴Nd from aerosols collected over a high-altitude station, we demonstrate that anthropogenic Pb transport to the glacierized catchment has a seasonal pattern. The Pb isotope data reveal that during winter, the thinned boundary layer traps up to 10 ± 7% more coal-derived Pb in the IGP. In contrast, in nonwinter months, a thicker boundary layer and enhanced subtropical westerly winds result in efficient Pb transport to the Himalayas. As Pb isotope ratios are robust conservative chemical tracers and Pb is predominantly derived from anthropogenic sources, these observations suggest that enhanced transport of anthropogenic aerosols to the glacierized catchment of the Himalayas coincides with higher near-surface temperatures in the summer, creating positive feedback that enhances melting. Our results further suggest that >50% of Pb in the Himalayan aerosols originates from the resuspension of historic Pb derived from phased out leaded gasoline, highlighting the importance of legacy Pb stored in the Indo-Gangetic Plains.

中文翻译：

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夏季数月期间人为粒子向喜马拉雅山的传输增强的铅同位素证据

印度恒河平原 (IGP) 是世界上污染最严重的地区之一，但从该地区到喜马拉雅山脉的人为气溶胶运输的时间模式几乎没有受到限制。基于行星边界层高度的季节性变化、气团反向轨迹分析，以及²⁰⁸ Pb/ ²⁰⁴ Pb、²⁰⁷ Pb/ ²⁰⁴ Pb、²⁰⁶ Pb/ ²⁰⁴ Pb 和¹⁴³ Nd/ ¹⁴⁴从高海拔站收集的气溶胶中的 Nd，我们证明了人为 Pb 向冰川集水区的迁移具有季节性模式。Pb 同位素数据显示，在冬季，变薄的边界层在 IGP 中捕获了高达 10±7% 的煤衍生的 Pb。相比之下，在非冬季月份，较厚的边界层和增强的亚热带西风会导致铅有效传输到喜马拉雅山。由于 Pb 同位素比率是稳健的保守化学示踪剂，而且 Pb 主要来自人为来源，这些观察结果表明，人为气溶胶向喜马拉雅山脉冰川集水区的传输增强与夏季较高的近地表温度相吻合，产生正反馈，增强融化。我们的结果进一步表明 >