检索结果-南通市图书馆

Evolution of carbon isotope composition in Potential Global Stratotype Section and Point at Luoyixi, South China, for the Base of the Unnamed Global Seventh Stage of Cambrian System

引用

Journal of China University of Geosciences 2008年第1期19卷 9-22页

作者：左景勋彭善池朱学剑祁玉平林焕令杨显峰 Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China Henan Institute of Geological Survey Zhengzhou 450001 China State Key Laboratory of Palaeontology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences

This work deals with the evolution of carbon isotope composition in the Luoyixi （罗依溪） Section, a candidate of the Global Standard Stratotype-section and Point （GSSP）, defining the base of the as-yet-undefined seventh stage of Cambrian System at the first appearance of the cosmopolitan agnostoid Lejopyge iaevigata. This level is favored in a vote of International Subcommission on Cambrian Stratigraphy （ISCS） as the biohorizon for defining the base of a global stage. Two hundred and sixty-four samples for carbon and oxygen isotope analysis have been collected from the carbonate successions at an interval of 0.25 to 0.5 m in this section. Results of the carbon isotope data exhibit a remarkable disciplinarian trend. The pattern of the carbon isotope evolution is gently undulant with a relatively long period during the underlying Drumian Stage, and then the values of δ13C fluctuate sharply with a short period in provisional seventh stage. The onset of sharp fluctuation in the δ13C values begins at the proposed GSSP level, defining the base of the global seventh stage, where δ13C values change from a gentle trend to a sharp trend. Distinct covariant-relationships among δ13C,δ18O, and sea level fluctuations suggest that a warming change in paleoclimate took place during the early global seventh stage, which led to a positive shift in δ13C values.

关键词： carbon isotope composition global seventh stage of Cambrian System Luoyixi Section northwestern Hunan (湖南).

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Correlations Between Foliar Stable carbon isotope composition and Environmental Factors in Desert Plant Reaumuria soongorica （Pall.） Maxim.

引用

Journal of Integrative Plant Biology 2005年第9期47卷 1065-1073页

作者： Jian-Ying MA Tuo CHEN Wei-Ya QIANG Gang WANG School of Life Sciences Lanzhou University Lanzhou 730000 China Cold and Arid Environmental and Engineering Research Institute the Chinese Academy of Sciences Lanzhou 730000 China

Leaves of 407 individuals of Reaumuria soongorica （Pall.） Maxim. collected from the major distribution areas were measured to investigate the distribution characteristics of the stable carbon isotope in this desert plant, as well as correlations between δ^13C values and environmental factors. Results showed that δ^13C values in R. soongorica ranged from -22.77‰ to -29.85‰ and that the mean δ^13C value （-26.52‰） was higher than a previously reported δ^13C value for a different desert ecosystem. This indicates that R. soongorica belongs to the C3 photosynthetic pathway and has higher water use efficiency than other species. The correlations between δ^13C values and environmental factors demonstrated that the foliar δ^13C values in R. soongorica increased significantly with decreasing mean annual precipitation and mean relative humidity, and decreased with decreasing duration of sunshine and evaporation. The spatial distribution trend of δ^13C values in R. soongorica was not obvious and there was no significant correlation between the δ^13C values and mean annual temperature. We conclude that different distribution trends in δ^13C values for R. soongorica were likely caused by stomatal limitation rather than by nutrient-related changes in photosynthetic efficiency and that precipitation played an important role in the wide distribution range of R. soongorica. This pattern of δ^13C values for R. soongorica reinforced that it is a super-xerophil in terms of its adaptive strategies to a desert environment.

关键词： carbon isotope composition desert plant meteorological factor Reaumuria soongorica.

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Relationships between altitudinal gradient and plant carbon isotope composition of grassland communities on the Qinghai-Tibet Plateau,China

引用

Science China Earth Sciences 2013年第1期56卷 311-320页

作者： ZHOU YongChun FAN JiangWen ZHONG HuaPing ZHANG WenYan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct *** investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C *** δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate *** alpine meadow,root δ13C was significantly higher than of foliar δ*** δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland *** rate was lower than that at species ***,there were no significant relationships between root δ13C and *** pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.

关键词： community level carbon isotope composition altitude atmospheric pressure temperature precipitation QinghaiTibet Plateau

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Distribution and carbon isotope composition of lipid biomarkers in Lake Erhai and Lake Gahai sediments on the Tibetan Plateau

Distribution and carbon isotope composition of lipid biomark...

引用

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Jincai Tuo~(a,*),Chenjun Wu~(a,b),Mingfeng Zhang~a,Ru Chen~(a,b) ~aKey Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,No.382 Donggang West Road,Lanzhou,730000,Gansu,China ~bGraduate University of the Chinese Academy of Sciences,Beijing,100039,China

Lipid biomarkers and carbon isotopes of n-alkanes,n-fatty acids,and n-alkan-2-ones were used to determine organic carbon sources to surface sediments in lakes Erhai and Gahai on the Tibetan *** sediment samples contained n-fatty acids with lower concentrations of n-alkanes and *** chain nalkanes in lake sediments were characteristic of a source mixture of epicuticular waxes of higher plants and submerged littoral zone plants while n-fatty acids sources were bacteria and floating and/or submergent macrophytes;the n-alkan-2-ones had a possible source in epicuticular waxes of higher plants and/or grass from catchment which entered the lake and were reworked by the *** samples examined from Lake Erhai had heavierδC values of bulk organic carbon and specific carbon compounds than samples from Lake Cahai and meadow *** heavier isotopic composition can be best interpreted by the enhanced productivity occurring in Lake Erhai due to its lower salinity and possibly to limited CO concentrations;for the latter,this may have enriched C in the dissolved inorganic carbon pool of the lake water.

关键词： Lipid biomarkers carbon isotope composition Lake sediments Lake Qinghai Lake Erhai and Lake Gahai Tibetan Plateau

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Mechanisms of carbon isotopic fractionation in the process of natural gas generation: Geochemical evidence from thermal simulation experiment

引用

Petroleum Exploration and Development 2020年第5期47卷 1042-1054页

作者： PENG Weilong LIU Quanyou HU Guoyi LYU Yue ZHU Dongya MENG Qingqiang GUO Fengtao WANG Ruoli State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development SinopecBeijing 100083China Petroleum Exploration and Production Research Institute SinopecBeijing 100083China PetroChina Research Institute of Petroleum Exploration&Development Beijing 100083China The Eleventh Oil Extraction Plant PetroChina Changqing Oilfield CompanyQingyang 745000China

Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mechanism of carbon isotopes and the causes of abnormal carbon isotopic compositions of natural *** the heating rates of 2℃/h(slow)and 20℃/h(rapid),the low maturity coal samples of the Ordos Basin had the maximum yields of alkane gas of 302.74 mL/g and 230.16 mL/g,theδ13C1 ranges of-34.8‰to-23.6‰and-35.5‰to-24.0‰;δ13C2 ranges of-28.0‰to-9.0‰and-28.9‰to-8.3‰;andδ13C3 ranges of-25.8‰to-14.7‰and-26.4‰to-13.2‰,*** gas in the thermal simulation products of rapid temperature rise process showed obvious partial reversal of carbon isotope series at 550℃,and at other temperatures showed positive carbon isotope *** the two heating processes,theδ13C1 turned lighter first and then heavier,and the non-monotonic variation of theδ13C1 values is because the early CH4 is from different parent materials resulted from heterogeneity of organic matter or the carbon isotope fractionation formed by activation energy difference of early enriched 12CH4 and late enriched *** reversal of carbon isotope values of heavy hydrocarbon gas can occur not only in high to over mature shale gas(oil-type gas),but also in coal-derived *** thermal simulation experiment of toluene,it is confirmed that the carbon isotope value of heavy hydrocarbon gas can be reversed and inversed at high to over mature *** isotope fractionation effect caused by demethylation and methyl linkage of aromatic hydrocarbons may be an important reason for carbon isotope inversion and reversal of alkane gas at the high to over mature stage.

关键词： thermal simulation experiment natural gas carbon isotope composition fractionation mechanism low maturity coal aromatic hydrocarbon pyrolysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Seasonal variation of foliar δ^(13)C values and its indictor significance in Sabina przewalskii and Sabina chinensis

引用

Research in Cold and Arid Regions 2011年第2期3卷 143-148页

作者： Tuo Chen HuiJuan Pei YouFu Zhang LongYing Wen HongGuan Tang YuanQing He State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Lanzhou Gansu 730000 China Henan University of Science and Technology Luoyang Henan 471003 China

Seasonal variation of foliar δ13C values as well as proline, silicon, MDA and relative water content in Sabina przewalskii Kom. and S. chinensis （Lin.） Ant. were measured. The results show that foliar δ13C values were significantly different at different seasons： lower in winter but higher in summer. δ13C values were positively correlated with air temperature and soil temperature. This demonstrates that foliar δ13C of Sabina is a successful empirical indictor of temperature. Furthermore, foliar δ13C values were positively related to proline and silicon content, and negatively related to relative water content and MDA content. Compared with S. chinensis, S. przewalskii has higher δ13C values, proline and silicon content as well as lower MDA and relative water content. All these results provided strong evidence that it is feasible for δ13C to be regarded as another index to evaluate freezing tolerance of Sabina.

关键词： Sabina carbon isotope composition seasonal changes freezing tolerance

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：