检索结果-南通市图书馆

Different climatic controls of soil δ^(13)C_(org) in three mid-latitude regions of the Northern Hemisphere since the Last Glacial period

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第2期52卷 259-266页

作者： rao zhiguo ZHU ZhaoYu ZHANG JiaWu Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese 510640 China Center for Arid Environment and Paleoclimate Research (CAEP) Key Laboratory of Westem China's Environmental System ofo Ministry of Education Lanzhou University Lanzhou 730000 China Graduate University of Chinese Academy of Sciences Beijing 100039 China

Paleoecological records of soil δ13Corg from three regions in the middle latitudes of the Northern Hemisphere, including the Chinese Loess Plateau (CLP), the Great Plains and adjacent areas of North America and northwestern Europe, showed different variations since the Last Glacial period. An at-tempt was made to evaluate the causes for the difference in δ13Corg on the basis of the modern climatic data collected in these regions and of the modern C3 and C4 plant distributions. The analysis indicates that temperature, especially the growing season temperature, has a dominant control on the growth of C4 plants. When the mean annual or growing season temperatures are below the "threshold value" , the growth of C4 plants is limited. When the temperature is above the "threshold value" , C4 plants can grow under a wide range of precipitation. However, when the precipitation is high enough to favor the growth of trees, the proportions of C4 plants in local biomass will decline. The implicit control factor recovered by sedimentary records is consistent with the control factor on modern C3/C4 distribution. Pure C3 plants have been dominating the local biomass since the Last Glacial period in European loess region, mainly owing to the low local temperature. The increases in C4 plants from the late Pleistocene to the Holocene in the Chinese Loess Plateau, the Great Plains and adjacent areas, mainly reflect the influ-ence of increasing temperature.

关键词：冰河时代大气污染二氧化碳温度气候变化

Compound-specific hydrogen isotopes of long-chain n-alkanes extracted from topsoil under a grassland ecosystem in northern China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2011年第12期54卷 1902-1911页

作者： rao zhiguo ZHU ZhaoYu JIA GuoDong ZHANG Xiao WANG SuPing Key Laboratory of Western China＇s Environment Systems （Ministry of Education） Lanzhou University Lanzhou 730000 China Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

To investigate characteristics of H isotope variation in long-chain n-alkanes （δDn-alkanes） from higher plants in surface soils under a single ecosystem, 12 samples from a basalt regolith were randomly collected from Damaping in Wanquan County of Zhangjiakou in North China. Molecular distribution and C （δ^13Cn-alkanes） and H isotopes of long-chain n-alkanes, as well as C isotopes of TOC （δ^13CTOC）, were analyzed. Both δ^13CTOC and δ^13Cn-alkanes values from four representative dominant long-chain n-alkanes （n-C27, n-C29, n-C31, n-C33） derived from terrestrial higher plants show minor variations among the 12 samples, indicating the major contributor is from local grasses with a uniform C3 photosynthetic pathway. In contrast, variations in δ^13Cn-alkanes values of the four long-chain n-alkanes are relatively large, with the more abundant homologs generally showing more negative δDn-alkanes values and less variation. However, variation of 〈30‰ among weighted averaged δDn-alkanes values of the four long-chain n-alkanes is not only less than that among δDn-alkanes values for different modern terrestrial C3 grasses from the specific locations, but also less than the literature values of δDn-alkanes of long-chain n-alkanes for single species over different seasons. Thus, because the sources of long-chain n-alkanes in surface soils and sediments are similarly from multiple individual plants, our results are significant in confirming that paleoclimatic, paleoenvironmental and paleohydrological information can be interpreted more accurately from δDn-alkanes values of long-chain n-alkanes from sediments, particularly terrestrial sediments with organic matter derived from in-situ plants.

关键词： C3 grassland surface soil long-chain n-alkanes compound-specific hydrogen isotope

湖南城步十万古田泥炭地现生莎草δ^(13)C_(cell)观测

在线全文

学校读者我要写书评

暂无评论

科学通报 2024年第17期69卷 2429-2440页

作者：秦倩倩田怡苹李云霞石福习李嘉燕赵明华林添妍曾瑶瑶饶志国湖南师范大学地理科学学院洞庭湖流域生态环境变化与固碳增汇湖南省重点实验室长沙410081 江西农业大学林学院鄱阳湖流域森林生态系统保护与修复国家林业与草原局重点实验室南昌330045

莎草是泥炭地中的常见植物,对其开展现代观测研究,可为利用泥炭岩芯开展古气候变化研究提供重要参照.2021年3月~2022年7月,对湖南城步十万古田(Shiwangutian,SWGT)泥炭地开放环境和林下环境的新生莎草嫩叶(SCNY)进行了大致的逐月采集,... 详细信息

莎草是泥炭地中的常见植物,对其开展现代观测研究,可为利用泥炭岩芯开展古气候变化研究提供重要参照.2021年3月~2022年7月,对湖南城步十万古田(Shiwangutian,SWGT)泥炭地开放环境和林下环境的新生莎草嫩叶(SCNY)进行了大致的逐月采集,并对其开展了α-纤维素稳定碳同位素(δ^(13)C_(cell))测试.将获得的δ^(13)C_(cell)数据与原地观测的采样前1个月的气温、水温、降水量和相对湿度数据进行了相关分析.结果表明:(1)开放环境中,SCNY的δ^(13)C_(cell)与温度(包括气温和水温)均呈显著正相关关系,但是其与降水量和相对湿度并无显著相关性,表明温度是SWGT开放环境中莎草δ^(13)C_(cell)的主要环境控制因素;(2)林下环境中,SCNY的δ^(13)C_(cell)与气温、水温、降水量和相对湿度均无显著相关性,表明了局地环境对莎草δ^(13)C_(cell)的影响;(3)位于亚热带季风湿润地区的SWGT开放环境中的莎草δ^(13)C_(cell)研究结果,与中亚干旱区阿尔泰山哈拉沙子泥炭地(Sahara sand peatland,SSP)的研究结果具有一致性,暗示泥炭地莎草δ^(13)C_(cell)的确可能具有开展古温度变化研究的潜力.鉴于古温度,尤其是全新世古温度历史研究的重要性,对于泥炭地莎草δ^(13)C_(cell),尤其是高纬度和高海拔地区开放型泥炭地当中的莎草δ^(13)C_(cell),值得在将来开展更多更深入的研究工作.

关键词：十万古田泥炭莎草δ^(13)C_(cell) 温度降水量相对湿度

溶洞深处人工灯光下新发现的蕨类植物具有目前已知最为偏负的碳同位素值

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2024年第7期69卷 881-884页

作者：李云霞秦倩倩田怡苹李嘉燕杨晨曦彭诗茵石福习饶志国 Hunan Provincial Key Laboratory for Eco-environmental Changes and Carbon Sequestration of the Dongting Lake Basin School of Geographical SciencesHunan Normal UniversityChangsha 410081China Institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410081China Key Laboratory of State Forestry Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of ForestryJiangxi Agricultural UniversityNanchang 330045China

The carbon isotope ratios(δ^(13)C) of modern land plants have been widely studied,and they provide valuable information about modern and past atmospheric,ecological and climatic changes [1].According to their different photosynthetic pathways,land plants are mostly C_(3) and C_(4) *** δ^(13)C values of C_(3) plants are mainly within the range of-20‰ to-34‰.

关键词：碳同位素值蕨类植物 (4)

Comparison of the carbon isotope composition of total organic carbon and long-chain n-alkanes from surface soils in eastern China and their significance

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第24期53卷 3921-3927页

作者： rao zhiguo JIA GuoDong ZHU ZhaoYu WU Yi ZHANG JiaWu State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Key Laboratory of Western China's Environment Systems Ministry of Education Lanzhou University Lanzhou 730000 China

Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition(δ 13C) of total organic carbon(TOC) and higher plant-derived long-chain n-alkanes,with the latter reported as weighted mean *** two sets of δ 13C values are significantly correlated and show similar trends in spatial *** spatial distribution of δ 13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower *** is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing conditions for C4 ***,δ 13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ 13C of a soil samples remains relatively *** data demonstrate that in eastern China,soil δ 13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing *** work suggests that -22‰ and -32‰ are good estimated end members for the weighted mean δ 13C values of long-chain n-alkanes(C27,C29 and C31 n-alkanes) from soils under dominant C4 or C3 vegetation,allowing us to reconstruct paleovegetation trends.

关键词：植物总有机碳碳同位素表面土壤

Is the maximum carbon number of long-chain n-alkanes an indicator of grassland or forest? Evidence from surface soils and modern plants

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第16期56卷 1714-1720页

作者： rao zhiguo WU Yi ZHU ZhaoYu JIA GuoDong HENDERSON Andrew Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Key Laboratory of Western China's Environmental Systems (Ministry of Education) Lanzhou University Lanzhou 730000 China Graduate University of Chinese Academy of Sciences Beijing 100049 China School of Geographical & Earth Sciences University of Glasgow Glasgow G12 8QQ UK

The molecular distribution of long-chain n-alkanes in 62 soil samples collected from diverse locations across eastern China was *** long-chain n-alkanes were mostly dominated by n-C29 or n-C31,regardless of the overlying vegetation type at each *** results were compared with those summarized from the literature,covering more than 100 soil samples within China and more than 300 genera of modern plants distributed *** were similar n-alkane distribution patterns for most genera, with no clear differences among grasses,shrubs,and *** evidence from analyses of surface soils and modern plants indicates that the relationship between the molecular distribution of long-chain n-alkanes of surface soils and source vegetation is highly complex,and is influenced by many ***,it is suggested that source vegetation types should not be simply inferred from distribution patterns of long-chain n-alkanes in sediments.

关键词：长链正构烷烃土壤样品植物分析碳原子数证据表面中国东部地区森林

Mid-Late Quaternary loess-paleosol sequence in Lantian's Yushan,China:An environmental magnetism approach and its paleoclimatic significance

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第26期55卷 2989-3000页

作者： WU Yi ZHU ZhaoYu rao zhiguo QIU ShiFan YANG Tian Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Key Laboratory of Western China's Environment Systems (Ministry of Education) Lanzhou University Lanzhou 730000 China School of Geography and Planning Sun Yat-sen University Guangzhou 510275 China Graduate University of Chinese Academy ofScienees Beijing 100049 China

The application of rock magnetism methods to investigating the variations of magnetic minerals in the sediments is an important approach to the reestablishment of paleoclimate evolution. Thus we performed fine magnetic measurements on the loess-paleosol sequence (from L15 upwards to S5, in which L is short for Loess, S is short for Paleosol, the same hereinafter) of Yushan strati-graphic section, which is on the southeastern margin of Chinese Loess Plateau, in Lantian County of China's Shaanxi Province, and the thickness of which is ca. 40 m. Our study shows that the primary magnetic carriers of loess and paleosol in this section are magnetite, maghemite, hematite and goethite. Thermomagnetic analyses on the samples of representative horizons show that the higher pedogenesis degree of the sediments, the smaller variations of magnetization there will be before and after heating, probably related to the pedogenic alteration of loess sediments. Analyses of several magnetic parameters show a significant discrepancy between the paleoclimatic conditions recorded in the strata from the loess unit L15 upward to the paleosol unit S5 in the study area and those recorded in the relative strata of other sections on the Chinese Loess Plateau, and those recorded in marine sediments, indicating the great impact of regional geological background. Similarly, the rapid and intensive change recorded in the segment from L15 to S9-1, and the significant difference between the paleoclimate evolutions of the two periods before and after the change (from L15 to S9-1, and from L9 to the base of S6) indicate the strong alteration of magnetic carriers in the study area as a result of the alternations of summer and winter monsoons in East Asia.

关键词：古土壤序列黄土高原古气候意义环境磁学晚第四纪中国玉山黄土沉积物

Variations of organic carbon isotopic composition and its environmental significance during the last glacial on western Chinese Loess Plateau

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2006年第13期51卷 1593-1602页

作者： CHEN Fahu rao zhiguo ZHANG Jiawu JIN Ming MA Jianying Center for Arid Environment and Paleoclimate Research (CAEP) Key Laboratory of Western China's Environmental System of Ministry of Education Lanzhou University Lanzhou 730000 China Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Graduate School of Chinese Academy of Sciences Beijing 100039 China

A high-resolution loess section in the western Chinese Loess Plateau, Yuanbao Section, was sampled for organic carbon isotopic analyses. The soil organic carbon isotope (δ13Corg) varied be- tween ?22.6‰ and ?27.5‰ during the last glacial at the section. During the last interstadial, the δ 13Corg values were more negative than those in both early and late periods of the last glacial by 4‰. The iso- topic composition indicates a coupled response of the pure C3 plants to the temperature, precipitation and the concentration of atmospheric CO2. Decrease in temperature and the atmospheric CO2 concentration from the last interstadial to Last Glaicial Maximum (LGM) caused the organic carbon isotopes to be- come positive by 1.5‰―2.0‰. The amplitude of 4‰ in the δ 13Corg variation during the last glacial should be mainly caused by the precipitation change. Therefore, the δ 13Corg variations of the Yuanbao Section during the last glacial period documented the large-amplitude fluctuation of the monsoon precipita- tion, which is estimated to be 250―310 mm more during the last interstadial than that in the LGM, and 100 mm more than that during early last glacial. The rapid changes of the monsoon precipitation on mil-lennial scale during the last glacial have also been recorded in the isotopic variations in Yuanbao loess section. As the isotopic composition varies compli- catedly as shown in the loess-paleosol sequence, it cannot be simply attributed to the abundances of C3 and C4 plants or be used as an indicator of the summer monsoon variations.

关键词：有机碳同位素成品冰黄土高原华西地区

Spatial and temporal variations of C_3/C_4 relative abundance in global terrestrial ecosystem since the Last Glacial and its possible driving mechanisms

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2012年第31期57卷 4024-4035页

作者： rao zhiguo CHEN FaHu ZHANG Xiao XU YuanBin XUE Qian ZHANG PingYu Key Laboratory of Western China's Environmental Systems(Ministry of Education) Lanzhou UniversityLanzhou 730000China

The primary factor controlling C 3 /C 4 relative abundance in terrestrial ecosystem since the Last Glacial has been widely debated. Now more and more researchers recognize that climate, rather than atmospheric CO 2 concentration, is the dominant factor. However, for a specific area, conflicting viewpoints regarding the more influential one between temperature and precipitation still exist. As temperature and precipitation in a specific area usually not only vary within limited ranges, but also covary with each other, it is difficult to get a clear understanding of the mechanism driving C 3 /C4 relative abundance. Therefore, systematic analysis on greater spatial scales may promote our understanding of the driving force. In this paper, records of C3/C4 relative abundance since the Last Glacial on a global scale have been reviewed, and we conclude that: except the Mediterranean climate zone, C3 plants predominated the high latitudes during both the Last Glacial and the Holocene; from the Last Glacial to the Holocene, C4 relative abundances increased in the middle latitudes, but decreased in the low latitudes. Combining with studies of modern process, we propose a simplified model to explain the variations of C3 /C4 relative abundance in global ecosystem since the Last Glacial. On the background of atmospheric CO2 concentration since the Last Glacial, temperature is the primary factor controlling C3/C4 relative abundance; when temperature is high enough, precipitation then exerts more influence. In detail, in low latitudes, temperature was high enough for the growth of C4 plants during both the Last Glacial and the Holocene; but increased precipitation in the Holocene inhibited the growth of C4 plants. In middle latitudes, rising temperature in the Holocene promoted the C4 expansion. In high latitudes, temperature was too low to favor the growth of C4 plants and the biomass was predominated by C3 plants since the Last Glacial. Our review would benefit interpretation of

关键词：陆地生态系统末次冰期相对丰度驱动机制时空变化大气CO2浓度温度升高高纬度地区