Records of hydrological change and environmental disasters in sediments from deep Lake Issyk-Kul |
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| Authors: | Jingzhong Wang Jinglu Wu Shuie Zhan Jianchao Zhou |
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| Institution: | 1. Hebei Province Key Laboratory of Sustained Utilization and Development of Water Resources, Institute of Paleontology, Hebei GEO University, Shijiazhuang, China;2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (CAS), Nanjing, China;3. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (CAS), Nanjing, China
University of Chinese Academy of Sciences, Beijing, China |
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| Abstract: | In the context of global warming, the mountainous areas of Central Asia are sensitive to climate and environmental changes and are highly vulnerable to natural disasters. Here, we use high-resolution lacustrine grain-size and geochemical records from Lake Issyk-Kul to infer hydrological changes, environmental events, and their driving factors in the western Tianshan Mountains of Central Asia over the last 350 years. The regional hydrological and environmental changes can be divided into three phases. In stage I (1674–1860 AD), the values of total organic carbon (TOC), total nitrogen (TN) and magnetic susceptibility (MS) were high, and the element contents changed indistinctively, suggesting that lake water levels were relatively stable. In Stage II (1860–2000 AD), the TOC and TN contents increased, the MS values decreased, and the grain size changed markedly, suggesting that water levels fluctuated dramatically. In Stage III (2000–2013 AD), the coarse particle and migratory element contents increased dramatically, indicating that regional rainfall and runoff increased and that the water level rose. Studies have also shown that the synchronous increases in sedimentary coarse particles, TOC and migratory elements indicate multiple flood events. Extreme floods have been frequent and intense in recent years, which indicates that the climate is generally warming, which is in good agreement with tree ring data, ice core records and other sediment records in alpine regions. Additionally, the lake sediments recorded a seismic event in approximately 1910 AD, which was consistent with historical documentation. Comparative analysis of records suggests that the Atlantic Multidecadal Oscillation is one of the dominant factors driving climate and hydrological changes in the study area. Climate change, combined with natural disasters (e.g., earthquakes) and anthropogenic activities, is generating extreme floods and variations in hydrological patterns in the mountain basin. These findings can provide crucial information about sedimentary physicochemical clues for tracking past hydrological and environmental conditions and contribute to a better understanding of hydrological processes and driving factors in the mountainous areas of Central Asia. |
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| Keywords: | driving factor hydrologic event Lake Issyk-Kul sediment record western Tianshan Mountains |
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