Northward Extent of Atmospheric Mercury Transboundary Transport to the Himalayas and Tibetan Plateau Region

Indian monsoon circulation is the primary driver of the long‐range transboundary mercury (Hg) pollution from South Asia to the Himalayas and Tibet Plateau region, yet the northward extent of this transport remains unknown. In this study, a strong δ 202 Hg signature overlapping was found between Lake Gokyo and Indian anthropogenic sources, which is an indicative of the Hg source regions from South Asia. Most of the sediment samples were characterized with relatively large positive Δ 199 Hg values (mean = 0.07‰–0.44‰) and small positive Δ 200 Hg values (mean = 0.03‰–0.08‰). Notably, the Δ 199 Hg values in the lake sediments progressively increased from southwest to northeast. Moreover, the Δ 199 Hg values peaked at Lake Tanglha (mean = 0.44‰ ± 0.04‰) before decreased at Lake Qinghai that is under the influence of the westerlies. Our results suggest that transboundary atmospheric transport could transport Hg from South Asia northwards to at least the Tanglha Mountains in the northern Himalaya‐Tibet.