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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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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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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 high lake-levels and pan-lake period on Badain Jaran Desert

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Science China Earth Sciences 2016年第8期59卷 1633-1641页

作者： WANG NaiAng NING Kai li zhuolun WANG YiXin JIA Peng MA ling College of Earth and Environmental Sciences Lanzhou University Lanzhou 730000 China History & Culture School of Lanzhou University Lanzhou 730000 China

Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred(11–10 cal kyr BP). Many lakes reached their maximal water-level during 8.6–6.3 cal kyr BP and retreated or dried up in the late Holocene(about 3.5–0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr^(-1) for 7.7–5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture.

关键词： Badain Jaran Desert Holocene High lake-level Pan-lake period Peat period Water balance Prehistoric culture

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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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Drought fluctuations based on dendrochronology since 1786 for the Lenglongling Mountains at the northwestern fringe of the East Asian summer monsoon region

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Journal of Arid Land 2016年第4期8卷 492-505页

作者： HOU Ying NIU Zhenmin ZHENG Fang WANG Nai'ang WANG Jianyu li zhuolun CHEN Hongxiang ZHANG Xuemin College of Earth and Environmental Sciences Ningxia University Center for Climate Change and Hydrologic Cycle in Arid Region College of Earth and Environmental ScienceLanzhou University

The Lenglongling Mountains （LLM） located in northeastern part of the Tibet Plateau, belong to a marginal area of the East Asian summer monsoon （EASM） and are sensitive to monsoon dynamics. Two tree-ring width chronologies developed from six sites of Picea crassifolia in the LLM were employed to study the regional drought variability. Correlation and temporal correlation analyses showed that relationships between the two chronologies and self-calibrated Palmer Drought Severity Index （sc_PDSI） were significant and stable across time, demonstrating the strength of sc_PDSI in modeling drought conditions in this region. Based on the relationships, the mean sc_PDSI was reconstructed for the period from 1786 to 2013. Dry conditions prevailed during 1817-1819, 1829-1831, 1928-1931 and 1999-2001. Relatively wet periods were identified for 1792-1795 and 1954-1956. Spatial correlations with other fourteen precipitation/drought reconstructed series in previous studies revealed that in arid regions of Northwest China, long-term variability of moisture conditions was synchronous before the 1950s at a decadal scale （1791-1954）. In northwestern margin of the EASM, most of all selected reconstructions had better consistency in low-frequency variation, especially during dry periods, indicating similar regional moisture variations and analogous modes of climate forcing on tree growth in the region.

关键词： dendrochronology East Asian summer monsoon region self-calibrated Palmer Drought Severity Index Lenglongling Mountains

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Relationship between pollen assemblages and organic geochemical proxies and the response to climate change in the Zhuye Lake sediments

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Research in Cold and Arid Regions 2014年第1期6卷 37-43页

作者： Yu li XueHua Zhou ChengQi Zhang zhuolun li Yue Wang NaiAng Wang College of Earth and Environmental Sciences/Center for Hydrologic Cycle and Water Resources in Arid Region Lanzhou University

This paper examines the relationship among organic geochemical proxies （TOC, C/N ratio and ~13C） and pollen assemblages in Zhuye Lake sediments since the Late Glacial. Results show that the reaction extent of organic geochemical proxies and pollen as- semblages to environment changes are different. Organic geochemical proxies are sensitive to overall environmental change, while pollen assemblages indicate detailed information of environmental change. For the entire sedimentary section （except the sand layer fi＇om the bottom of the section）, when values of TOC, C/N ratio and total pollen concentrations are high, 813C values are low, and vice versa. The different responses of organic geochemical proxies and pollen records in Zhuye Lake are mainly due to their different sensitivity and diverse influencing factors in different environmental conditions.

关键词： Zhuye Lake lacustrine sediments pollen assemblages geochemical proxies

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Applicability of different indices for delineating the boundary of arid region: A case study in northwestern China

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Journal of Earth Science 2024年

作者： Xue Peng Xiang li Yingyibing Shen Xuehua Che Shipei Dong zhuolun li Key Laboratory of Western China's Environmental Systems (Ministry of Education)， College of Earth and Environmental Sciences， Center for Glacier and Desert Research， Lanzhou University

Arid regions are vital components of Earth's land surface. Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms. However， the accuracy and applicability of arid region boundary delineated by different indices remain unclear. In this study， the annual precipitation （AP）， humidity index （H）， and aridity index （K） were calculated for delineating arid region of China using 106 meteorological stations during 1990–2019. The results suggest that AP and H can accurately delineate arid region， because they are consistent with the distribution of typical soil and vegetation in arid region， whereas K is not. Moreover， AP is the best index for delineating arid region in regions with limited meteorological data， especially in studying long-term patterns and mechanisms of area changes. The accuracy of delineating arid region using H is enhanced in regions with abundant meteorological data. Over the past 30 years， influenced by the increase of atmospheric moisture influx and precipitation， the area in arid region of northwestern China decreased by 70×103–90×103km2， resulting in the present area of approximately 1.55×106km2. This study provides appropriate indices for delineating arid region， contributing to improving our knowledge of regional responses difference to climate change.

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Climatic and environmental change in Yanchi Lake, Northwest China since the Late Glacial： A comprehensive analysis of lake sediments

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Journal of Geographical Sciences 2013年第5期23卷 932-946页

Modern climate research has shown that the Asian summer monsoon water vapor transport is limited to the eastern part of the Qilian Mountains. On the Holocene millennial-scale, whether the northwest boundary of the summer monsoon varies according to climate change is a key scientific issue. Yanchi Lake is located in the northern Qilian Mountains and the middle of the Hexi Corridor, where the modern climate is less affected by the Asian summer monsoon. It is a key research area for examining the long-term variations of the Asian summer monsoon. Paleoclimatic data, including AMS ^14C dates of pollen concentrates and bulk organic carbon, lithology, grain-size, mineral composition and geochemical proxies were acquired from sediments of Yanchi Lake. The chronological results show that the lower part of the lacustrine section is formed mainly in the Late Glacial and early Holocene period, while the proxies＇ data indicate the lake expansion is associated with high content of mineral salts. The middle part of this section is formed during the transitional period of the early and middle Holocene. Affected by the reworking effect, the pollen concentrates AMS^14C dates from the middle part of the section are generally older than those from the lower part. Since the mid-Holocene, Yanchi Lake retreated significantly and the deposition rate dropped obvi- ously. The Yanchi Lake record is consistent with the Late Glacial and Holocene lake records in the Qinghai-Tibet Plateau and the climatic records in typical monsoon domain, which indicate the lake expansion and the strong Asian summer monsoon during the Late Glacial and early Holocene. The long-term monsoonal pattern is different from the lake evolution in Central Asia on the Holocene millennial-scale. This study proves the monsoon impacts on the northwestern margin of the summer monsoon, and also proves the fact that the northern boundary of the summer monsoon moves according to millennial-scale climate change.

关键词： Yanchi Lake Asian summer monsoon Holocene the Late Glacial lake sediments monsoon marginal zones

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Lake evaporation： A possible factor affecting lake level changes tested by mod- ern observational data in arid and semi-arid China

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Journal of Geographical Sciences 2013年第1期23卷 123-135页

作者： li Yu WANG Nai'ang li zhuolun MA Ning ZHOU Xuehua ZHANG Chengqi College of Earth and Environmental Sciences Center for Hydrologic Cycle and Water Resources in Arid Re-gion Lanzhou University Lanzhou 730000 China

Qinghai Lake and Zhuye Lake, -400 km apart, are located in the northwest margin of the Asian summer monsoon. Water of these two lakes mostly comes from the middle and eastern parts of the Qilian Mountains. Previous studies show that the Holocene climate changes of the two lakes implied from lake records are different. Whether lake evaporation plays a role in asynchronous Holocene climate changes is important to understand the lake records. In this paper, we used modern observations beside Qinghai Lake and Zhuye Lake to test the impact factors for lake evaporation. Pan evaporation near the two lakes is mainly related to relative humidity, temperature, vapor pressure and sunshine duration. But tem- perature has different impacts to lake evaporation of the two lakes, which can affect Holocene millennial-scale lake level changes. In addition, differences in relative humidity on the millen- nial-scale would be more significant, which also can contribute to asynchronous lake records.

关键词： Holocene lake level lake evaporation Qinghai Lake Zhuye Lake temperature relative humidity

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