Late Pleistocene／Holocene wetland events recorded in southeast Tengger Desert lake sediments, NW China

The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selected for studying the environmental conditions surrounding the transition between Paleolithic foragers and Neolithic farmer/pastoral-ists. Short cores were obtained from four lake basins in the southwestern Tengger using a hand-driven piston coringdevice. Proxies from these cores were supplemented by ra-diocarbon ages obtained from lake sediment cores, shoreline features and spring mound deposits. Together these records provide evidence of millennial-scale climate change eventsfrom the Pleistocene-Holocene transition to the present.Lake/wetland events, representing periods of more intensive summer monsoon, occur in the records at-12.7-11.6,-10.1, -9.3, -8.0, -5.4, -1.5, and -0.8 ka BP. They do suggest that century- to miliennial-seale climatic cycles are characteristic of the Holocene in the southeastern Tengger Desert although the chronology must be considered extremely tentative.     

Holocene lake deposits of Bosten Lake, southern Xinjiang, China

A 9.25-m-long sediment core from Bosten Lake,Xinjiang, provides detailed information about changes in the water budget and biological acticity over the last 8400 cal-endar years. The chronology is constructed from six AMS radiocarbon dates on the terrestrial plant remains. Based onanalyses of TOC, CO3, detrital compounds and biogenic SiO2,lake level fluctuations and periods of remarkably-negative water budget appeared at 8.4-8.2 cal ka, 7.38-7.25 cal ka,5.7-5.5 cal ka, 3.7-3.4 cal ka and 3.3-2.9 cal ka, respec-tively. As they are in-phase with low lake levels at Sumxl Co and Bangong Co in western Tibet Plateau and with paleo-lakes in Inner Mongolia, a climate-induced change to some-what drier and warmer conditions is inferred. A further drop in lake level after 1320 AD of about 200 yr duration may heattributed to a negative water balance prior to the main phase of the Little Ice Age. Deep and stable lake phases of 1500 yr and 1800 yr duration at 7.2-5.7 cal ka and 5.5-3.7cal ka coincide with maximum moisture during the Holocene Megathermai in China. The long term trend towards aridity since about 4.3 cal ka can dearly be recognised. The reduced water budget of Bosten Lake from 640-1200 AD may be attributed to local effects.     

Environmental changes during early-middle Holocene from the sediment record of the Chaohu Lake,Anhui Province

A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River,Anhui Province,China.The timing scale is constrained by AMS 14 C dating method.Climate proxies such as pollen and grain size in the core are analyzed to reconstruct the environment changes at this site approximately between 9870 and 2170 cal.a BP.The results indicate that at the research area, the climate in the early-middle Holocene had evolved through 3 stages.From 9870 to 6040 cal.a BP, proxy records show a warm and dry climate with low water levels after the late-glacial period.During this stage,cool and dry events occurred at about 8910 and 6060-6030 cal.a BP.Then,between 6040 and 4860 cal.a BP,the climate was humid and vegetation was more flourishing in the Chaohu Lake Valley.The Holocene Optimum occurred at 5840-5500 cal.a BP in the Chaohu Lake,showing the best condition of water and heat.Elm Decline occurred at the period of 5380-4930 cal.a BP.Since 4860 cal.a BP,the climate was warm and dry through 2170 cal.a BP as shown in both pollen spectrum and grain-size histories.Two obvious dry events occurred in 3760 and 2170 cal.a BP,respectively.At 2170 cal.a BP,the water level of the Chaohu Lake reached the lowest as the lakebed possibly exposed. Such lake sediment observations are consistent with the historical records in this area.     

Holocene abrupt climate shifts recorded in Gun Nuur lake core, northern Mongolia

A continuous 7.44 m lake core was successfully drilled at Gun Nuur Lake, northern Mongolia, and analyses on environment magnetic parameters, organic matter content and organic δ^13C were conducted in an attempt to retrieve the Holocene chronosequence of climatic changes based on 6 AMS ^14C dates. We found that the Holocene climate in northern Mongolia has been alternating between cold (or cool)/wet conditions and warm/arid conditions, and also punctuated with a series of abrupt climate shifts. The abrupt climate shifts occurred around 1750, 2800, 4000, 5200, 7200, and 9200 aBP (^14C age), being chronologically correlative to those abrupt climatic events recorded in the high-latitude North Atlantic Ocean. The correlation indicates that the climatic changes in northern Mongolia were linked with those in the North Atlantic Ocean probably via the North Atlantic Oscillation-affected westerly winds. The strength and position of westerly winds might have modulated the Siberian-Mongolian high pressure system (winter monsoon), directly influencing the climate in China.     

大布苏湖全新世沉积岩芯的粒度特征与湖面波动

大布苏湖为构造断陷的封闭湖盆,现代沉积环境的研究表明,自湖岸到湖心,其平均粒径２依次递减,钻孔岩 的粒度分析和年代测定揭示,全新世以来,大布苏湖有两次高湖面和两次低湖面时期晚全新世以来,湖面波动式下降,湖水浓缩而演变为我国东部地区罕见的盐湖。     

Holocene climatic and environmental changes recorded in Baahar Nuur Lake core in the Ordos Plateau, Inner Mongolia of China

A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of meangrain size, organic δ 13C (δ 13Corg), organic carbon content (TOC), C/N, carbonate content, carbonate δ 13C(δ 13Ccar) and δ 18O (δ 18Ocar) were conducted for retrieving the Holocene chronosequence of climaticchanges based on 15 AMS 14C dates. The record documented four major stages of climate change inthe Ordos Plateau: (IV) a cold and dry condition before ～7.65 14C ka BP; (III) a warm and humid stagebetween ～7.65 and ～5.40 ka BP; (II) a generally drier and cooler climate since ～5.40 ka BP with twohumid events occurring from ～4.70 to ～4.60 ka BP and from ～4.20 to ～3.70 ka BP, and (I) a dry climatecharacterized by complete desiccation of the lake after 3.70 ka BP. Stage III can be further divided intothree sub-stages: (IIIa) a warm and humid episode from ～7.65 to ～6.70 ka BP, (IIIb) a warm and relativelydry episode from ～6.70 to ～6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holo-cene from ～6.20 to ～5.40 ka BP.     

New progress of lake sediments and environmental changes research in China

Environmental change recorded by lake sediments is one of the important branches of the past global changes study. The new progress of lake sediments and environmental changes in China since the late 1980s has been comprehensively discussed. The highlights emphasized are Asian paleomonsoon migration reflected by lake level fluctuation, uplift of the Qinghai-Xizang Plateau recorded by lacustrine sediments, saltlake sediments and environmental evolution, lake response to the natural-human interaction and modern lake biogeochemical process. Meanwhile important suggestions for the lake sediments and environmental research in the future are proposed, which include studies on the quantitative relationship between lake environment proxies and climate factors, high-resolution evolutionary sequence and spatial differentiation of environments, modern lake dynamic process and environment, Quaternary Chinese lake database and global changes.     

萨拉乌苏河流域全新世气候变化的元素地球化学记录

通过对萨拉乌苏河流域滴哨沟湾左岸沉积剖面常量元素Si、Al、Fe、Ca、Mg、K、Na含量及其比值变化的分析,结合~(14)C测年结果及粒度、有机质指标,并综合已有研究,探讨了该地区全新世以来的气候变化.研究表明,9.6ka BP前气候干冷,沉积相为风成沉积;9.6~8.4ka BP气候由干冷向暖湿转变,期间存在干冷波动;8.4~4.0ka BP进入全新世大暖期,其中,8.4~6.5ka BP为全新世大暖期的鼎盛时期,降水增加,积水成湖,湖泊水位高且稳定;6.5ka BP气候发生明显转变;6.5~4.0ka BP湖泊水位逐步下降形成富含螺壳的浅水环境,但气候整体仍较为湿润;4.0~1.2ka BP气候变干冷,发育沼泽;1.2~0.7ka BP气候转暖湿,沉积相由沼泽相转变为湖泊相;0.7~0.5ka BP为河流相沉积,气候较为干冷.剖面记录的气候变化可与东亚季风变化、温度变化、太阳辐射进行对比,反映了该区域气候变化与全球气候变化的一致性.     

Palaeoclimatic evolution recorded by multidicipline in sediments in gahai lake, qaidam basin since late last deglacial

Based on the analyses of Loss-on-Ignition (LOI), carbonate content and sediment characteristics, this paper reconstructs the climatic and environmental evolution of the Gahai Lake area since the late Last Deglacial Period.The results cover the late Last Deglacial Period and the Holocene.The climate was very unstable and rather arid during the late Last Deglacial Period.The Holocene can be divided into three pe-riods:the early Holocene (11360-8240 cal aB.P.), which was dry but unstable and featured rising tem-peratttres, the mid-Holocene (8240-3200 cal aB.P.), which was warm and wet and the late Holocene (since 3200 cal aBP), which was cold and dry.Results also show a warm-wet event around 1500 cal aB.P.     

渭河阶地全新世成壤过程及人类因素研究

通过对陕西眉县清湫村全新世黄土剖面的野外考察研究、粒度分析和磁化率测定，揭示了在渭河阶地自然地带性土壤褐土的形成过程中，由于气候恶化和风尘堆积，以及仰韶文化期人类农业耕垦和聚落建设活动的影响，造成了某些区域全新世古土壤分裂为两层的现象．根据清湫村全新世黄土剖面层序模式，论证了全新世时期风尘堆积仍在继续，古土壤覆盖层亦具有风尘堆积的性质，但是它们受到历史时期人类耕作活动的改造     

Late holocene man-induced environmental change in central russian plain: paleopedological evidences from early-medieval archaeological site.

Local natural and man-induced environmental changes in the early medieval archaeological site in the central Russian plain were reconstructed by study of surface and buried soil profiles. Natural soils and ecosystems on watersheds were similar to present ones in agreement with palynological data. In the floodplain there are remains of forest soils and anthropogenic horizons. These formed in ancient urban environments and are buried under recent alluvium indicating that alluvial sedimentation and flood intensities were much less than at present. Ancient man-induced environmental change related to crop growing activity is well documented by palynological data but corresponding cultivated horizons are found only in few buried profiles, being unstable if left on the surface. Paleopedological signs of the ancient urban environment are very stable and preserved in surface soils even 1000 years after the settlement stopped functioning.     

Fluctuation of Picea timberline and paleo-environment on the northern slope of Tianshan Mountains during the late Holocene

The fluctuation of alpine timberline, which can serve as a good indicator for Holocene climate, is the syn-thetically effective results of many environmental fac-tors during geological and historical periods and mod-ern times. In recent years, researches …     

洪湖的环境变迁及其生态对策

总结了洪湖的湖泊环境和生物资源在近几十年开发过程中所发生的改变,分析了目前洪湖所存在的水生物资源衰退、富营养化过程加速、养殖调蓄矛盾、过滤圈养和潜在污染威胁等主要生态问题,提出了合理规划、应用生态工程措施保护湖泊生物资源、综合治理洪湖的生态对策措施。     

Abrupt Holocene changes of the Asian monsoon at millennial- and centennial-scales: Evidence from lake sediment document in Minqin Basin, NW China

Considerable research is now focusing on abrupt Holocene changes at millennial- and centennial-scales all over the world. This study shows that the changes in the Holocene summer monsoon can be divided into two main periods, based on climatic proxy records of lake sediments from the Sanjiaocheng section located at the NW boundary of the summer monsoon, Gansu Province. The early and middle Holocene was humid with stronger summer monsoon, while the late Holocene is dry with weak summer monsoon. Detailed results also show a series of millennial- and centennial-scale changes in the intensity of the summer monsoon, with a periodicity of {dy1600} years during the whole Holocene, and with a periodicity of 800 years during the early Holocene. Ten dry events during the Holocene are associated with the weakening of the summer monsoon. These rapid climatic changes may be representative of a global climatic change pattern during the Holocene.     

Climate in China during the four special periods in Holocene

Characteristics of temperature over China during the four special periods in the Holocene, i.e. the Megathermal, the Medieval Warm Period, the Little Ice Age and the Modem Warm Period, are analyzed. The Megath-ermal period was 8.5—3.0 kaBP.the maximum temperature appeared at about 5.5—6.0 ka and 7.0 kaBP, while the temperatures were about 2X1 above the average of the latest one hundred years. During the Medieval Warm Period, from the late 9th century to the 13th century, the temperatures were warmer over eastern China. Some maximum temperatures were close to the mean value in 1880s—1970s. However, the climate in the 12th century was cold. Over the west part of China, temperatures did not show the same features as that over the east except the moderate warmth appeared during the second half of the 9th century. There were five cold spells in China during the last millennium; in the early 12th, 14th and 16th centuries, the late of 15th century, the 17th and 19th centuries. In these cold periods, the last three spells can be considered as the Little Ice Age of China, the minimum of temperature anomaly was below - 1.01 and - 0.51 for the 10 years' and 30—50 years' mean respectively. The 20th century was the warmest in the last 12 centuries, and was 0.5t wanner than the last 1200 year's mean. During the last one hundred years, the warmest period appeared in 1920s—1940s, but the highest annual temperature occurred in 1998 in which the temperature anomaly was + 1.38t with respect to the mean temperaure of 1961s—1990s.     

北京平原东北部晚更新世晚期金鸡河一级阶地孢粉记录

通过对北京平原东北部金鸡河左岸一级阶地的孢粉资料开展研究,并结合光释光测年数据,恢复北京平原东北部地区的古植被类型,分析晚更新世晚期北京平原东北部古气候变化。结果表明,北京平原东北部气候演化可分为三个阶段:第一阶段气候温凉干旱;第二阶段气候寒冷湿润;第三阶段气候较寒冷湿润。结果与前人研究结果有一定可比性。     

临汾盆地陶寺遗址附近全新世黄土剖面的环境指标分析

在对临汾盆地陶寺遗址北城墙外全新世黄土剖面粒度、磁化率、Rb/Sr值和CaCO₃含量等气候指标进行分析的基础上, 结合光释光测年结果和考古学资料, 探讨该剖面记录的环境信息及其与文化发展的相互关系。研究发现: 全新世早期(10.5~9.6 kaBP), 东亚冬季风较弱, 风化成壤作用增强, 气候由凉干转向暖湿; 全新世早中期(9.6~4.9 kaBP), 风化成壤作用最强, 气候最为暖湿; 全新世中后期(4.9~2.5 kaBP), 风化成壤作用较之前有所下降, 气候较之前温干, 但较现今暖湿; 全新世晚期(2.5 kaBP)以来, 东亚冬季风增强, 风化成壤作用较弱, 气候较为凉干。暖湿气候期与文化的繁荣发展时期有较好的对应关系, 凉干气候期植被的退化可能受气候和人类活动共同作用的影响。     

Sea surface temperature variations recorded on coralline Sr／Ca ratios during Mid-Late Holocene in Leizhou Peninsula

High-resolution Sr/Ca ratios of two Porites corals from Leizhou Peninsula were measured using inductively coupled plasma atomic spectrometry (ICP-AES). TIMS U-Th dating reveals that the life-spans of the two corals are 489-500 AD and 539-530 BC, respectively. Monthly sea surface temperatures (SSTs) during these two periods can be reconstructed from their skeletal Sr/Ca ratios. The results reveal that SSTs during 539-530 BC were roughly the same as those during 1990-2000 AD in this area, indicating a relative warm climate period. However, the period of 489-500 AD was significantly cooler, with annual mean SST, the 10-a average of minimum monthly winter SSTs and the 10-a average of maximum monthly summer SSTs being about 2, 2.9 and 1℃ lower than that in the 1990s, respectively. Such climate patterns agree well with the phenological results recorded in the historic documents in other areas of China.