Browsing by Author "Wenjun Tang"

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Anthropogenic and natural drivers of seesaw-like spatial patterns in precipitation mercury over western China
(Elsevier Ltd, 2022) Jie Huang; Shichang Kang; Long Wang; Kaiyun Liu; Kirpa Ram; Mika Sillanpää; Wenjun Tang; Junming Guo; Qianggong Zhang; Ming Ma; Lekhendra Tripathee; Feiyue Wang
Investigation of mercury (Hg) from atmospheric precipitation is important for evaluating its ecological impacts and developing mitigation strategies. Western China, which includes the Tibetan Plateau and the Xinjiang Uyghur Autonomous Region, is one of the most remote region in the world and is understudied in regards to Hg precipitation. Here we report seesaw-like patterns in spatial variations of precipitation Hg in Western China, based on Hg speciation measurements at nine stations over this remote region. The Hg fraction analyzed included total Hg (HgT), particulate-bound Hg (HgP) and methylmercury (MeHg). Spatially, HgT concentrations and percentage of HgP in precipitation were markedly greater in the westerlies domain than those in the monsoon domain, but the higher wet HgT flux, MeHg concentration and percentage of MeHg in precipitation mainly occurred in the monsoon domain. Similar spatial patterns of wet Hg deposition were also obtained from GEOS-Chem modeling. We show that the disparity of anthropogenic and natural drivers between the two domains are mainly responsible for this seesaw-like spatial patterns of precipitation Hg in Western China. Our study may provide a baseline for assessment of environmental Hg pollution in Western China, and subsequently assist in protecting this remote alpine ecosystem. © 2022 Elsevier Ltd
Northward Extent of Atmospheric Mercury Transboundary Transport to the Himalayas and Tibetan Plateau Region
(John Wiley and Sons Inc, 2023) Jie Huang; Shichang Kang; Xinbin Feng; Wenjun Tang; Kirpa Ram; Junming Guo; Qianggong Zhang; Chhatra Mani Sharma; Chaoliu Li; Lekhendra Tripathee; Feiyue Wang
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 δ202Hg 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 Δ199Hg values (mean = 0.07‰–0.44‰) and small positive Δ200Hg values (mean = 0.03‰–0.08‰). Notably, the Δ199Hg values in the lake sediments progressively increased from southwest to northeast. Moreover, the Δ199Hg 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. © 2023. The Authors.