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Challenges and opportunities in Quaternary palynology

Science China Earth Sciences 2024年第7期67卷 2148-2161页

作者： qinghai xu Houyuan LU Zhuo ZHENG College of Geographical Sciences Hebei Key Laboratory of Environmental Change and Ecological ConstructionHebei Normal UniversityShijiazhuang 050024China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China School of Earth Sciences and Engineering Sun Yat-sen UniversityZhuhai 519082China

Quaternary palynology plays a pivotal role in investigating global climate change and various other research fields,serving as an essential tool for the quantitative analysis of paleoenvironment changes.However,due to the vast diversity of terrestrial ecosystems and intricate interactions between vegetation,climate,and human activities,further advancements are required in the following aspects within this discipline.(1)The accuracy of classification in pollen morphology and fossil pollen identification needs improvement,particularly at the species level.This represents a significant challenge in present Quaternary palynology.Computer-aided intelligent recognition holds promise as a solution for species identification based on more detail pollen morphology.(2)Most pollen-based vegetation and climate reconstructions overlook the significance of bare ground.Neglecting bare ground can lead to substantial inaccuracies when quantitatively reconstructing past vegetation and climate.(3)While pollen records provide reliable information on paleoclimate changes,current quantitative climate reconstruction models heavily rely on modern pollen datasets derived from present-day vegetation disturbed more or less by human activities.This introduces bias and uncertainties into paleoclimate reconstruction.(4)Although pollen can serve as an indicator of human activities,accurately quantifying the intensity of human influence remains challenging.Improving accurate identification of crop pollen,reconstructing reliable land cover/use data,and integrating multidisciplinary data may enhance the identification and quantification of signals related to human activity in pollen records.

关键词： Quaternary palynology Paleoclimate Paleovegetation Human activity

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从艺术家形象到中世纪秩序论乔伊斯对但丁的重写

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上海文化 2024年第5期 109-120页

作者：许清海南京师范大学文学院

乔伊斯和意大利有着不解之缘,的里雅斯特是他流亡生涯的重要一站。他的小说创作也离不开意大利先驱们的影响,托马斯·阿奎那、乔丹尔诺·布鲁诺、乔瓦尼·巴蒂斯塔·维柯等人的形象或思想在他的作品中反复出现。作为意大利历史上最重要... 详细信息

乔伊斯和意大利有着不解之缘,的里雅斯特是他流亡生涯的重要一站。他的小说创作也离不开意大利先驱们的影响,托马斯·阿奎那、乔丹尔诺·布鲁诺、乔瓦尼·巴蒂斯塔·维柯等人的形象或思想在他的作品中反复出现。作为意大利历史上最重要的作家,但丁也成为乔伊斯推崇、学习和书写的对象。根据理查德·艾尔曼的记载,在大学期间,乔伊斯就开始阅读、研究但丁的作品,他的意大利语教师查尔斯·盖齐(Charles Ghezzi)神父教授了他关于但丁的基础知识,在当时,他就在盖齐面前表现出对但丁推崇备至。到了意大利之后,乔伊斯有了更充足的条件去研究但丁。

关键词：意大利语托马斯·阿奎那乔伊斯布鲁诺推崇备至人的形象的里雅斯特但丁

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Surface pollen and its relationship to vegetation on the southern slope of the eastern Qilian Mountains

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Journal of Geographical Sciences 2006年第2期16卷 215-222页

作者： LU Xinmiao CHEN Hui xu qinghai Institute of Tibetan Plateau Research CAS Beijing 100085 China Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China College of Resources and Environment Hebei Normal University Shijiazhuang 050016 China

The objective of this study is to investigate pollen-vegetation relationship in the Qilian Mountains. The eastern Qilian Mountains are located in the transitional zone of the Tibetan Plateau, the Loess Plateau and the arid region of Northwest China; which is one of the key areas of global environmental change. A total of 13 surface pollen samples from main vegetation have been collected. Pollen percentages were calculated in all samples. In order to reveal the relationship between pollen composition and the vegetation types from which the soil samples have been collected, Detrended Correspondence Analysis （DCA） ordination method was employed on the pollen data. The results show that dominating vegetation types can be recognized by their pollen spectra： Picea crassifolia forest, alpine shrub and alpine meadow as well. Altitude and temperature determine the distribution of the surface pollen and the vegetation. The good agreement between modern vegetation and surface samples across this area provides a measure of the reliability of using pollen data to reconstruct paleoenvironment and paleovegetation patterns in this or other similar regions. However the loss of Betula pollen in forest needs further investigation. Pollen oxidation is the most important factor contributing to the damage of modern pollen in the study area. Pollen concentrations decrease with the increase of pH values of soils, and decrease sharply when the pH exceeds 7.6.

关键词： surface pollen vegetation DCA Qilian Mountains Tibetan Plateau

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Pollen flux and vertical dispersion in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains

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Chinese Science Bulletin 2007年第11期52卷 1540-1544页

作者： xu qinghai LI YueCong ZHOU LiPing LI YiYin ZHANG ZhenQing LIN FengYou College of Resources and Environmental Sciences Hebei Normal University Shijiazhuang 050016 China College of Environmental Sciences Peking University Beijing 100871 China Changbaishan Forest Ecosystem Station of Chinese Academy of Sciences Antu 133613 China

The pollen flux in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains is presented in one year's experiments. The results indicate that arboreal pollen percentages are more than 65% and pollen flux is higher than 5000 grain·cm-2·a-1,while less than 2% and lower than 1000 grain·cm-2·a-1 for shrubby pollen,and less than 20% and lower than 3000 grain·cm-1·a-1 for herbaceous pollen for most samples at different heights. The pollen assemblages are similar to those in the samples under 8 m height where Pinus and Ouercus are dominant and followed by the few non-local pollen types,and Fraxinus percentages are high with a few non-local pollen types at 16 m to 32 m height as well as non-local pollen clearly increased at 40 m height. Comparisons between pollen assemblages and vegetation composition suggest that similarities are higher for pollen trap samples than for surface moss samples.

关键词：长白山落叶植物森林花粉

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On the timing of the East Asian summer monsoon maximum during the Holocene—Does the speleothem oxygen isotope record reflect monsoon rainfall variability?

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Science China Earth Sciences 2016年第12期59卷 2328-2338页

作者： CHEN JianHui RAO ZhiGuo LIU JianBao HUANG Wei FENG Song DONG GuangHui HU Yu xu qinghai CHEN FaHu Key Laboratory of West China s Environmental System(Ministry of Education) College of Earth and Environmental SciencesLanzhou University Department of Geosciences University of Arkansas Institute of Nihewan Archaeology Research Hebei Normal University

The evolution of the East Asian summer monsoon(EASM) during the Holocene has long been of significant interest.Knowledge of past EASM variability not only increases our understanding of monsoon dynamics on a long timescale,but it also provides an environmental and climatic background for research into Chinese cultural development.However,the timing of the EASM maximum remains controversial.The popular concept of an "early Holocene maximum" is mainly based on speleothemδ18O(δ18Oc) records from caves in southern China;however,the interpretation of δ18OCas a reliable proxy for EASM intensity is being increasingly challenged.The present paper is a critical review of the climatic significance of the δ18OCrecord from China.Firstly,we suggest that precipitation in northern China is an appropriate index of EASM intensity,the variation of which clearly indicates a mid-Holocene monsoon maximum.Secondly,an interregional comparison demonstrates that the precipitation record in northern China is quite different from that in southern China on a range of timescales,and is inconsistent with the spatial similarity exhibited by speleothem oxygen isotope records.Furthermore,both modeling and observational data show that the δ18OCrecords from southern China indeed reflect changes in precipitation δ18O(δ18OP) rather than precipitation amount,and therefore that their use as an EASM proxy is inappropriate.Finally,we address several significant monsoon-related issues-including the driving mechanism of the EASM on an orbital timescale,the climatic significance of speleothem oxygen isotopes,and the relationship between atmospheric circulation and precipitation in monsoonal regions.

关键词： East Asian summer monsoon Holocene Speleothem oxygen isotopes

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Humid Medieval Warm Period recorded by magnetic characteristics of sediments from Gonghai Lake, Shanxi, North China

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Chinese Science Bulletin 2011年第23期56卷 2464-2474页

作者： LIU JianBao CHEN FaHu CHEN JianHui XIA DunSheng xu qinghai WANG ZongLi LI YueCong Key Laboratory of Western China's Environmental System (Ministry of Education) Lanzhou University Lanzhou 730000 China College of Resources and Environment Hebei Normal University Shijiazhuang 0500161 China

Variations in monsoon strength, moisture or precipitation in eastern China during the MWP reflected by different climatic records have shown apparent discrepancies. Here, detailed environmental magnetic investigations and mineralogical analyses were conducted on lacustrine sediments of Core GH09B1 (2.8 m long) from Gonghai Lake, Shanxi, North China, concerning the monsoon history during the MWP. The results demonstrate that the main magnetic mineral is magnetite. The sediments with relatively high magnetic mineral concentrations were characterized by relatively fine magnetic grain sizes, which were formed in a period of relatively strong pedogenesis and high precipitation. In contrast, the sediments with low magnetic mineral concentrations reflected an opposite process. The variations of magnetic parameters in Gonghai Lake sediments were mainly controlled by the degree of pedogenesis in the lake drainage basin, which further indicated the strength of the Asian summer monsoon. The variations in the and S 300 parameters of the core clearly reveal the Asian summer monsoon history over the last 1200 years in the study area, suggesting generally abundant precipitation and a strong summer monsoon during the Medieval Warm Period (MWP, AD 910–1220), which is supported by pollen evidence. Furthermore, this 3–6-year resolution environmental magnetic record indicates a dry event around AD 980–1050, interrupting the generally humid MWP. The summer monsoon evolution over the last millennium recorded by magnetic parameters in sediments from Gonghai Lake correlates well with historical documentation (North China) and speleothem oxygen isotopes (Wanxiang Cave), as well as precipitation modeling results (extratropical East Asia), which all indicate a generally humid MWP within which centennial-scale moisture variability existed. It is thus demonstrated that environmental magnetic parameters could be used as an effective proxy for monsoon climate variations in high-resolution lacustrine sediments.

关键词：湖泊沉积物中世纪暖期磁性矿物中国北方潮湿特征记录山西季风强度

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Pollen indication to source plants in the eastern desert of China

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Chinese Science Bulletin 2005年第15期50卷 1632-1641页

作者： LI Yuecong xu qinghai ZHAO Yinclkui YANG Xiaolan XIAO Jule CHEN Hui Lü Xinmiao Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029 China College of Resources and Environment Hebei Normal UniversityShijiazhuang 050016 China Department of Environmental Management University of Central Lancashire Preston UN Hebei Geography Institute Hebei Academy of Sciences Shijiazhuang 050011 China Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

In order to investigate the indication of major pollen types to source plants, 39 surface pollen samples are collected from 39 plant communities. The results show that diversity of pollen assemblages presents in different commu-nities. Chenopodiaceae pollen percentages are highest in Kalidium communities and Ceratoides communities (higher than 45%, average is 63.4%), but high Ephedra pollen per-centages (higher than 3.3%, average is 16.5%)in Ceratoides communities make it distinguished from Kalidium communi-ties. Artemisia pollen percentages (more than 50%) are much higher than Chenopodiaceae (less than 35%) in Artemisia Communities. Nitraria pollen percentages (higher than 2%, average is 13.6%) are highest in Nitraria communities com-pared with those in other community patterns. Tamariceae pollen percentages (higher than 2%, average is 8.6%) are highest both in Tetraena and Reaumuria communities com-pared with those in other community patterns. But in Reau-muria communities, Artemisia pollen percentages are higher than Chenopodiaceae with some other pollen types such as Gramineae, Compositae, Leguminosae; on the contrary, in Tetraena communities, Artemisia pollen percentages are less than Chenopodiaceae with few other pollen types. Calli-gonum pollen only appears in Calligonum communities (higher than 2%,average is 5%). The results of cluster analysis (CLA) and detrended correspondence analysis (DCA) show that the pollen indication to source plants can be reflected by association indices (A), over-representation in-dices (O), under-representation indices (U), R-value, the av-erage pollen percentages where parent plants are absent (Xa) and the average pollen percentages where parent plants are present (Xp). Zygophyllum, Calligonum, Tetraena, Tribulus and Tamariceae can indicate source plants very well, owing to high A scores. Artemisia, Chenopodiaceae and Gramineae have high R-values, and Nitraria, Cruciferae and sedum have high O scores, so they are over-represented types, but the higher Xp and the lower Xa valu

关键词：中国沙漠地区花粉传播遗传特性繁殖方法

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Surface pollen assemblages of human-disturbed vegetation and their relationship with vegetation and climate in Northeast China

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Chinese Science Bulletin 2012年第5期57卷 535-547页

作者： LI ManYue LI YueCong xu qinghai PANG RuiMing DING Wei ZHANG ShengRui HE ZhiGuo College of Resources and Environment and Hebei Key Laboratory of Environmental Change and Ecological Construction Hebei Normal UniversityShijiazhuang 050024China

Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentratio

关键词：中国东北地区花粉组合植被组成区域气候人为干扰年平均气温禾本科杂草花粉浓度

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鄂尔多斯盆地志靖—安塞地区延长组7段致密砂岩微观孔隙结构评价

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吉林大学学报（地球科学版） 2024年第1期54卷 83-95页

作者：余光展王健吴楠徐清海刘显凤付清萌长江大学地球科学学院武汉430100 构造与油气资源教育部重点实验室(中国地质大学) 武汉430074

储层微观孔隙结构的研究对油气勘探开发具有重要意义。本文采用氮气吸附、铸体薄片观察、扫描电子显微镜(SEM)观察、X射线衍射(XRD)和核磁共振等实验手段研究志靖—安塞地区延长组7段致密砂岩的微观孔隙结构,计算孔隙结构参数,观察微孔... 详细信息

储层微观孔隙结构的研究对油气勘探开发具有重要意义。本文采用氮气吸附、铸体薄片观察、扫描电子显微镜(SEM)观察、X射线衍射(XRD)和核磁共振等实验手段研究志靖—安塞地区延长组7段致密砂岩的微观孔隙结构,计算孔隙结构参数,观察微孔分布,分析微孔隙类型,探讨并分析影响微孔发育的矿物成分、粒度及分选等相关参数。结果表明:研究区长7段的岩性主要为长石砂岩;致密砂岩微孔隙结构复杂,主要以黏土粒间溶孔、长石溶孔等形式存在;长7段主要发育小孔喉,微孔体积平均值为6.19×10^(-3)mL/g,孔隙发育差;长7油层组砂岩样品中,长7段的BET(Brunauer-Emmett-Teller)比表面积平均值为4.252 m^(2)/g,总孔体积平均值为0.0183 mL/g,最大孔径平均值为185.9 nm;砂岩孔隙以介孔为主,宏孔和微孔次之。

关键词：鄂尔多斯盆地长7段致密砂岩氮气吸附微观孔隙研究

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Surface pollen in the east of Qaidam Basin

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Journal of Geographical Sciences 2006年第4期16卷 439-446页

作者： CHEN Hui ZHAO Dongsheng LU Xinmiao LI Yuecong xu qinghai LI Shuangcheng OUYANG Hua College of Resources and Environment Sciences Hebei Normal University Shijiazhuang 050016 China Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Institute of Tibetan Plateau Research CAS Beijing 100085 China College of Environmental Sciences Peking University Beijing 100871 China

Pollen analysis of 23 surface samples in the east of Qaidam Basin reveals the characteristics of pollen assemblages and their relationships with vegetation and climate. In pollen assemblages, Chenopodiaceae and Artemisia are preponderant types in all the samples, and Ephedra, Gramineae and Compositae are common types. The results of DCA （Detrended Correspondance Analysis） and Correlation Analysis show different pollen assemblages indicate different vegetations, coincided with respective vegetation types. A/C （Artemisia/Chenopodiaceae） in the desert can indicate the aridity. Depending on the aridity, the vegetation communities are divided into four groups： severe drought group, moderate drought group, slight drought group and tropophilous group. A/C value is less 0.2 in the severe drought group, 0.2-0.5 in the moderate drought group, 1.63 in the slight drought group and 5.72 slight-wetness group.

关键词： surface pollen Detrended Correlation Analysis A/C （Artemisia/Chenopodiaceae） values Qaidam Basin

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