Recently,Prof. Shi Jianbo's lab from the School of Environment, Hangzhou Institute for Advanced Study (HIAS), UCAS has worked with Zhang Qianggong, a research fellow at the Institute of Tibetan Plateau Research, Chinese Academy of Sciences to carry out research on mercury export via glacier runoff in the Himalayan region. They summarized their results in a paper titled "Melting Himalayas and Mercury Export: Results of Continuous Observations from the Rongbuk Glacier on Mt. Everest and Future Insights" and published it inWater Research.
The Himalayas are home to the highest and largest mountain glacier area in the world and an important part of the "Water Tower of Asia". The retreat of Himalayan glaciers has imposed a profound impact on water resources and environment of many rivers in Asia. Against the backdrop of climate change, defining the changes in mercury export via the Himalayan glacier runoff is crucial for understanding the ecological environmental impact and mercury circulation changes in the areas where mountain glaciers are melting.
Photo: Glaciers and Snow Mountains in the Himalayas
Through continuous observations and systematic investigation in the Rongbuk Glacier-fed basin on the northern slope of Mt. Everest, the research group explored the impact of glacier retreat on mercury export via runoff in the region. They found that the mercury content in the Rongbuk Glacier-fed runoff shows great seasonal and daily changes. There is a significantly positive correlation between mercury content and runoff volume, suspended particulate matter content and water turbidity. It shows that glacier melting affects the runoff volume and further the suspended particulate matter content and water turbidity, and it is the main factor affecting changes in the mercury content in the meltwater runoff.
Photo: Rongbuk Glacier on the North Slope of Mt. Everest
The research revealed the impact of glacial lakes near the tail of Rongbuk Glacier on the mercury export via meltwater runoff: The mercury content in the inflow runoff is higher than that in the outflow runoff (down 16%) indicates that some migrating mercury settles in the proglacial lakes. It is believed that with climate change and continuous expansion of glacial lakes in the future, glacial lake outburst will cause the instantaneous release of mercury deposited in glacial lakes.
According to the measured data of the Rongbuk River on Mt. Everest and the meltwater runoff of Himalayan glaciers, the mercury export from the Himalayan glacial meltwater is estimated to be 337 kg/year. As glacier runoff is expected to continue to increase over the next two to three decades, the resulting mercury export is also likely to increase. However, the impact of growing and expanding glacial lakes in the Himalayas on mercury export from glaciers remains to be determined. For one thing, the deposition of mercury in glacial lakes reduces the content and export of mercury in glacial runoff; For another, glacial lakes are prone to burst and lead to sudden release of the mercury stored in the lakes and sediments. The authors suggest a collaborative monitoring study of mercury in glacier runoff and glacial lakes to better assess the changes in mercury export from the glaciers and its impact on the downstream ecosystem.
Research areas of Prof. Shi Jianbo's lab involve mercury morphology analysis, regional pollution and environmental chemical process research. Sun Xuejun, a postdoctoral fellow in the School of Environment, is the first author of the paper. His research has been supported by the National Natural Science Foundation of China, the Second Tibetan Plateau Scientific Expedition and Research (STEP) and the China Postdoctoral Science Foundation.
Link to the paper:
https://doi.org/10.1016/j.watres.2022.118474
Source | School of Environment
Typesetter | Tong Sihui
Published in Zhejiang
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