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Early Holocene environment at a key location of the northwest boundary of the Asian summer monsoon: a synthesis on chronologies of Zhuye Lake, Northwest China

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Journal of arid Land 2014年第5期6卷 511-528页

作者： Yu LI NaiAng WANG ChengQi ZHANG Yue WANG Center for Hydrologic cycle and water Resources in arid region College of Earth and Environmental Sciences Lanzhou University

The intensified monsoon increases summer rainfall and creates wet conditions in the Asian summer monsoon region during the early Holocene. Along with millennial-scale changes of the monsoon intensity, it is still unclear whether the boundary of the monsoon region changes according to monsoon variability. Investigations into the early Holocene environment in monsoon marginal zones are crucial for understanding the monsoon boundary changes. Zhuye Lake is located at the northwest edge of the Asian summer monsoon, the northern Qilian Mountains, which are less affected by modern summer monsoon water vapor. Previous studies have reached different conclusions regarding the early Holocene climatic and environmental changes based on different dating methods（^14C and OSL（optically stimulated luminescence）） and materials（shells, carbonate, pollen concentrates and bulk organic carbon）. In this study, we synthesized 102 ^14C dates and 35 OSL dates from ten Holocene sedimentary sections and ten paleo-shorelines in the lake basin. A comparison between ages from different dating methods and materials generally shows that carbon reservoir effects are relatively slight in Zhuye Lake while the disordered chronologies are mainly related to the erosion processes and reworking effects. In addition, proxy data, including lithology, pollen, total organic carbon and carbonate, were collected from different sites of Zhuye Lake. According to the new synthesis, the early Holocene environment was relatively humid, associated with high runoff and lake water levels. The result indicates that the monsoon boundary moves to the north during the period of the intensified monsoon. A typical arid-area lake was formed during the mid-Holocene when carbonate accumulation and high organic matter contents were the main features of this period. The lake retreated strongly during the late Holocene, showing a drought trend. Overall, the lake evolution is generally consistent with the Holocene Asian summer mons

关键词： the early Holocene ^14C dating OSL dating lacustrine sediments Asian summer monsoon monsoon marginal zones

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Ecological Responses to Holocene Millennial-Scale Climate Change at High Altitudes of East and Central Asia: A Case Study of Picea/Abies Pollen Changes in Lacustrine Sediments

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Journal of Mountain Science 2014年第3期11卷 674-687页

作者： LI Yu ZHANG Cheng-qi ZHOU Xue-hua College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid Region Lanzhou University

Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not dear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.

关键词： Lake sediments Palynological records High-altitude regions Picea/Abies Asian summermonsoon Millennial-scale Climate change

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Holocene Climate cycles in Northwest Margin of Asian Monsoon

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Chinese Geographical Science 2012年第4期22卷 450-461页

作者： LI Yu WANG Nai'ang LI Zhuolun ZHOU Xuehua ZHANG Chengqi College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

In the mid-latitude regions of the Asian continent, Zhuye Lake is located in the northwest margin of the Asian monsoon, where the modem climate is affected by the Asian monsoon and Westerlies. In this study, we investi- gated the absolutely dated Holocene records in Zhuye Lake for detecting the Holocene climate cycles. Totally, 14 14C dates and 6 optically simulated luminescence （OSL） dates are obtained from the QTH01 and QTH02 sections. The proxies of grain-size, total organic carbon content （TOC）, C/N and 813C are used for wavelet analysis, and the results show obvious -256, -512 and -1024-year climate cycles, which are consistent with the Holocene millennial and cen- tennial scale climate cycles in the typical Asian summer monsoon domain. In different parts of the Zhuye Lake, the Holocene sediments show variable climate cycles that are affected by the lake basin topography. In the Zhuye Lake, the Holocene climate cycles are mainly correlated with the solar-related Asian summer monsoon variability and the North Atlantic ice-rafting events.

关键词： Holocene climate cycle Asian monsoon wavelet analysis Zhuye Lake

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Carbonate formation and water level changes in a paleo-lake and its implication for carbon cycle and climate change, arid China

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Frontiers of Earth Science 2013年第4期7卷 487-500页

作者： Yu LI Nai'ang WANG Zhuolun LI Xuehua ZHOU Chengqi ZHANG Yue WANG College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid Region Lanzhou University Lanzhou 730000 China

Carbonate deposition is a main inorganic carbon sink in lakes, which varies depending on climate change and internal lake dynamics. Research on the relationship between lake carbonate and climate will help to understand mechanisms of carbon cycle in lacustrine systems. The approach of this study is to explicitly link carbonate formation with Holocene long-term climate change and lake evolution in a paleo-lake （Zhuye Lake）, which is a terminal lake of a typical inland drainage basin in arid China. This paper presents analysis on grain-size, carbonate content and mineralogical composition of sediment samples from different locations of Zhuye Lake. The results show that calcite and aragonite are two main components for the lake carbonate, and the carbonate enrichment is associated with lake expansion during the Late Glacial and early to middle Holocene. Holocene lake expansion in arid regions of China is usually connected with high basin-wide precipitation that can strengthen the basin-wide surface carbonate accumulation in the terminal lake. For this reason, Zhuye Lake plays a role of carbon sinks during the wet periods of the Holocene.

关键词： carbonate carbon cycle lake sediments,mineralogical composition climate change

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A continuous simulation of Holocene effective moisture change represented by variability of virtual lake level in East and Central Asia

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Science China Earth Sciences 2020年第8期63卷 1161-1175页

作者： Yu LI Yuxin ZHANG Xinzhong ZHANG Wangting YE Lingmei XU Qin HAN Yichan LI Hebin LIU Simin PENG Key laboratory of Western China s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesCenter for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

The fluctuation of a single lake level is a comprehensive reflection of water balance within the basin, while the regional consistent fluctuations of lake level can indicate the change of regional effective moisture. Previous researches were mainly focused on reconstructing effective moisture by multiproxy analyses of lake sediments. We carried out a series of experiments, including a transient climate evolution model, a lake energy balance model and a lake water balance model to simulate continuous Holocene effective moisture change represented by variability of virtual lake level in East and Central *** virtual lake level, area, water depth and salinity are not equivalent to actual values, but we estimated relative changes of the regional effective moisture. We also explored the driving mechanisms of effective moisture change in different geographical regions. Our results indicated that gradually falling effective moisture during the Holocene in northern China was due to the combined effects of high lake evaporation caused by longwave and shortwave radiation, and low precipitation caused by reductions of summer solar insolation. A decline in effective moisture through the Holocene in the Tibetan Plateau and southern Central Asia resulted from decreased precipitation because of the weakening of the Asian summer monsoon. Increased precipitation induced by the strengthening of the westerly circulation contributed to the effective moisture rise during the Holocene in northern Central Asia.

关键词： Effective moisture Virtual lake level Continuous simulation Holocene Solar radiation

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High lake levels on Alxa Plateau during the Late Quaternary

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Chinese Science Bulletin 2011年第17期56卷 1799-1808页

作者： WANG NaiAng LI ZhuoLun CHENG HongYi LI Yu HUANG YinZhou College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid Region Lanzhou University Lanzhou730000 China

Field investigations including lake shoreline measurement and 14 C chronology have been carried out on the Alxa Plateau to better understand the formation and evolution of the high lake levels in northwest China during the late *** field investigations show that there are at least ten shorelines at different elevations at Juyan Lake,at least four on the northwest side of the Jilantai Salt Lake,and nine shorelines and one terrace on the northeast margin of Zhuye *** correlations and chronological evidence indicate that the paleo-lakes have the highest lake levels in Marine Isotope Stage (MIS) *** the optically stimulated luminescence (OSL) results which have been reported by some scholars do not support this view,the fact that the paleo-lakes have the highest lake levels in MIS 3 can not be *** between OSL and 14 C results from this work might indicate that high lake levels existed on the Alxa Plateau during two different *** also suggests that the high lake levels may exist in both MIS 5 and early MIS *** paper also provides the basic hydrological information for further water resources research in this arid region.

关键词：阿拉善高原高湖面晚第四纪 MIS系统中国西北地区湖泊水位更新世晚期吉兰泰盐湖

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Holocene palynological records and their responses to the controversies of climate system in the Shiyang River drainage basin

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Chinese Science Bulletin 2011年第6期56卷 535-546页

作者： LI Yu WANG NaiAng LI ZhuoLun ZHANG HuaAn College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid Region Lanzhou University Lanzhou730000 China

The Shiyang River drainage basin is located in the northwest margin of the Asian monsoon region. Previous studies reached different conclusions about Holocene climatic changes in the basin. Some studies suggested the Holocene climatic changes were mainly controlled by the Asian monsoon and that the climate was relatively humid during the early Holocene (11.6-7.1 cal ka BP). Other studies found the mid-Holocene Climatic Optimum (7.0-5.0 cal ka BP), and this climate condition was similar to the Holocene westerly wind pattern in arid Central Asia. The modern climate is affected by the Asian monsoon and westerly wind in the drainage basin, and the Holocene climatic records showed two different Holocene climatic patterns-a westerly wind pattern and monsoonal pattern. However, it remains unclear what caused the two different Holocene climatic patterns to co-exist in the region. The palynological records are the main evidence for the Holocene climatic changes in the basin. This paper focuses on palynological records for different parts of the drainage basin. Among them, QTH02, QTL-03 and Sanjiaocheng records are located in the terminal lake, and the Hongshuihe record is located in the middle reaches of the basin. In the terminal lake, the palynological records of QTH02 and QTL-03 are similar, but the Sanjiaocheng record differs. The difference is mainly affected by the variable pollen assemblages in the different locations of the lake basin. From comparison and synthesis of the four palynological records, we concluded that the millennial-scale Holocene climatic changes were affected by the combined effects of the Asian monsoon and westerly wind in the drainage basin, which show the complicated Holocene climatic pattern in the northwest margin of the Asian monsoon.

关键词：中全新世流域盆地孢粉记录气候系统石羊河流域亚洲季风区气候变化反应

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Paleoclimatic proxies from global closed basins and the possible beginning of Anthropocene

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Journal of Geographical Sciences 2021年第6期31卷 765-784页

作者： LI Yu HAN Qin HAO Lu ZHANG Xinzhong CHEN Dawei ZHANG Yuxin XU Lingmei YE Wangting PENG Simin LI Yichan FENG Zhuowen LIU Hebin Key laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesCenter for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

Global closed basins,occupying almost one fifth of the world's land area,spatially coincide with arid and semiarid *** proxies can indicate basin-wide environmental change and human ***,previous studies have not approached the use of proxies in the same way to reconstruct natural and anthropogenic processes at regional and global *** we present a regional study to investigate the basic processes of paleoclimatic proxies,from a typical closed-basin system in arid *** use multiple paleoclimatic proxies of surface samples and sediments,as well as groundwater and sediment ages to study environmental change and human *** then establish a dataset for paleoclimatic proxies from global closed basins and do a numerical analysis on *** studies verify that human activity greatly impacts paleoclimatic proxies,especially with regard to surface samples,as well as groundwater age,but Holocene sediments are less *** from global studies indicate that the major changing trend of the wet/dry status of closed basins is associated with the movement of the westerly jet streams controlled by long-term changes in winter *** is an abrupt change between 1800 AD and 1900 AD,according to a numerical synthesis of paleoclimatic proxies from global closed basins,which can be linked to human *** suggest this time period can be considered as a start point for the Anthropocene based on the sedimentary evidence of closed basins,globally.

关键词： Anthropocene closed basins paleoclimatic proxies westerly jet streams Asian summer monsoon climate change

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Global precipitation change during the Holocene:a combination of records and simulations

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Frontiers of Earth Science 2024年第1期18卷 112-126页

作者： Wangting YE Yu LI Key laboratory of Western China᾽s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesCenter for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

Precipitation can shape our climate both in the present and the *** though we have made significant advances in studying the mechanisms of millennial-scale climate changes through high-resolution records,we still cannot quantitatively characterize the global spatiotemporal precipitation variations within the ***,we developed a new approach to integrating data from 349 globally distributed records and climate models to reconstruct regional and global precipitation patterns over the last 12000 *** results reveal that precipitation reconstructions can be divided into monsoon-driven and westerly driven *** results suggest that an arid climate was experienced in the late glacial and early Holocene epoch(~12−7.4 cal ka BP),attaining a middle Holocene optimum(~7.4−3.5 cal ka BP),and drier after the middle *** to our reconstructions,the global precipitation reconstruction increased from the early Holocene until 3.8 cal ka BP and then subsequently *** addition,our reconstructions better reproduce the low-frequency events and extreme precipitation at the millennial scale in the hemispheres,but the performance of the reconstructions in the equatorial Pacific and the Southern Hemisphere of Africa and the Americas is *** resolution of the record and the simulation capability of the climate model remain important means to improve our understanding of past climate change.

关键词： Holocene equatorial glacial

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Ecological and hydrologic evolution history in the sensitive zone of both East Asian summer monsoon and Westerly since the Last Glacial Maximum

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Journal of Mountain Science 2023年第5期20卷 1266-1281页

作者： LI Yu PENG Si-min Key laboratory of Western China’s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesCenter for Hydrologic Cycle and Water Resources in Arid RegionLanzhou UniversityLanzhou 730000China

The Qilian Mountains,located in the northeastern Qinghai-Tibet Plateau,is a sensitive zone of both East Asian summer monsoon(EASM)and westerly winds(WW).The evolution history and driving mechanism of the ecosystem and hydrologic cycle in this region on long-term timescales have not yet been *** this study,we comprehensively study the hydrologic and ecological evolution history in the sensitive zone since the Last Glacial Maximum(LGM)by integrating surface sediments,paleoclimate records,TraCE-21ka transient simulations,and PMIP3-CMIP5 multi-model *** show that hydrologic and ecological proxies from surface sediments are significantly different from west to east and mainly divided into three sections:the monsoonaffected region in the eastern Qilian Mountains,the intersection region in the central Qilian Mountains,and the westerly-affected region in the western Qilian ***,paleo-ecological and paleohydrologic reconstructions from the surroundings uncover a synchronous climate evolution that the EASM mainly controls the eastern Qilian Mountains and penetrates the central Qilian Mountains in monsoon intensity maximum,while the WW dominates the central and western Qilian Mountains on both glacial-interglacial and millennial *** simulation results further bear out the glacial humid climate in the central and western Qilian Mountains caused by the enhanced WW,and the humidity maximum in the eastern Qilian Mountains controlled by the strong mid-Holocene *** general,east-west differences in climate pattern and response for the EASM and the WW are integrally stable on both short-term and long-term timescales.

关键词： EastAsian summer monsoon Westerly winds Last Glacial Maximum Ecological and hydrologic evolution history Qilian Mountains

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