中国西北C-3植物的碳同位素组成与年降雨量关系初探   总被引：2，自引：0，他引：2  

王国安  韩家懋 《地质科学》2001,(4):494

 本文对不同年降雨量环境下生长的藜、独行菜、魁蓟和平车前这4种常见C-3植物的δ¹³C进行了分析,发现这4种C-3植物的δ¹³C组成都表现出随年降雨量减少而变重的趋势,其中藜和独行菜的碳同位素组成对降水变化的响应相对要较其它2种植物强烈得多。藜、独行菜和魁蓟的δ¹³C组成与年降雨量有显著的线性关系,平车前碳同位素组成与年降雨量没有显著的相关性,表明藜、独行菜和魁蓟的δ¹³C组成可作为年降雨量的替代性指标,平车前的δ¹³C组成不能作为年降水的替代性指标。  相似文献   

环境中Al13的研究进展     

刘璟  赵峰华  刘建权 《地球科学进展》2007,22(3):305-312

铝的水解反应及其水解聚合铝形态的研究，特别是具有Keggin结构的Al13聚合形态一直是地球化学、环境科学、形态分析以及生物毒理学等众多领域的研究热点之一。综述了近20年来Al13的分析方法、形成和转化机制、影响因素以及动力学方面研究的进展。  相似文献   

天目山柳杉树轮δ¹³C对华东地区降水序列的重建          下载免费PDF全文

吕军  屠其璞  钱君龙 《大气科学学报》2001,24(3):350-355

对采自天目山的柳杉树轮进行交叉定年后,得到树轮的δ¹³C年序列。将δ¹³C年序列去除大气CO₂的影响,保留其高频振荡部分。利用华东地区部分气象站的降水资料,通过主成份分析,分析了降水与树轮δ¹³C之间的关系。考虑滞后效应,利用回归方法重建了过去一百多年来的华东地区不同时段的降水序列,并分析其变化特征。  相似文献   

岩石变形所反映的地震作用过程--第13届国际变形机理、流变学和构造学学术会议概述   总被引：2，自引：0，他引：2  

姚大全 《国际地震动态》2001,(7):9-12

简要介绍了第13届国际变形机理、流变学和构造学学术会议的概况和特点，综述了地震变形作用的研究现状。  相似文献   

Elucidation of the Alum Shale kerogen structure using a multi-disciplinary approach     

Sunil Bharati  Richard L. Patience  Steve R. Larter  Guy Standen  Iain J. F. Poplett 《Organic Geochemistry》1995,23(11-12)

The significance and validity of integrating data obtained from a variety of analytical techniques to understand, elucidate and model kerogen's complex chemical structure is reported here using degradative (open and closed system pyrolysis, chemical oxidation), non-degradative (¹³C CP/MAS NMR) and optical (incident white light and blue light) methods. Seven Cambrian Alum Shale samples, ranging in maturity from immature to post-mature with respect to petroleum generation, were studied and were chosen for their simple geological history, uniform organic matter type and high organic carbon content. The Alum Shale kerogens, which primarily consist of algal organic matter, liberate low molecular weight gaseous and aromatic compounds on pyrolysis and give mostly branched dicarboxylic acids on chemical oxidation. ¹³C NMR spectroscopy shows that the Alum Shale kerogens are anomalously rich in oxygen-bearing functional groups (such as C = O, ArCO, CHO, CH_xO), most of which apparently remain intact within the kerogen macro-molecule (KMM) through the diagenetic and catagenetic stages. Fragments released by different degradative techniques are quantified and the aromaticity (f_a), O/C and relative proportions of various carbon types estimated by ¹³C NMR. A synthesis of these data has allowed us to better understand the chemistry of the Alum Shale kerogen.  相似文献   

Global synchroneity of a positive carbon isotope excursion at the Cenomanian/Turonian boundary: Validation by calcareous microfossil biostratigraphy of the Yezo Group, Hokkaido, Japan     

Takashi  Hasegawa Tsunemasa  Saito 《Island Arc》1993,2(3):181-191

Abstract Isotopic analyses of organic carbon from the mid-Cretaceous sequence in Hokkaido, Japan, revealed a 2‰ positive excursion of δ¹³C values at the biostratigraphically defined Cenomanian/Turonian (C/T) boundary recognized in the Yezo Group. The planktonic foraminiferal Whiteinella archaeocretacea Zone, which is known to bracket the Cenomanian/Turonian boundary elsewhere in the world, was recognized in the Oyubari area of central Hokkaido based on the distribution of commonly occurring planktonic foraminifera. In the Tappu area of northwestern Hokkaido, where diagnostic planktonic foraminifera are rare but calcareous nannoplankton occur commonly, the interval coeval with the W. archaeocretacea Zone can also be established by recognizing the conjoined last appearance levels of Corollithion kennedyi and Axopodorhabdus albianus, both calcareous nannoplankton species. Carbon isotope profiles exhibit a similar pattern with comparable peaks and troughs occurring in the same stratigraphic position in the sequences. A prominent, positive 2‰ shift of δ¹³C values, here called ‘δ¹³C spike’ occurs in the middle of the W. archaeocretacea Zone in the Oyubari area and just above the conjoined last appearances of the two above-mentioned nannoplankton taxa in the Tappu area. The Cenomanian/Turonian boundary can be drawn just above the peak position of the spike in both sections. The Rock Eval analyses and biomarker analyses of organic carbon indicate that organic carbon subjected to our isotope analyses is of terrestrial origin. Therefore, the observed 2%o shift should reflect changes in the isotopic composition of the atmospheric CO₂. A unique layer composed predominantly of sand-grain sized spumellarian Radiolaria is present immediately above the δ¹³C spike both in the Oyubari and Tappu areas, suggesting an increasing availability of both nutrients and silica in surface waters.  相似文献   

西藏改则西北部喀湖错把拉湖区13kaBP以来的湖泊沉积与环境演化   总被引：1，自引：0，他引：1  

牟世勇贺永忠  朱勋易成兴  徐安全赵伟立 《地质通报》2007,26(1):94-99

通过对藏北喀湖错把拉湖区湖积剖面的研究,建立了该区13kaBP以来的沉积序列,并将13kaBP以来的气候划分为2个干冷期和2个湿润期。其中2个湿润期和第二旋回的干冷期可分别与北半球第一、二新高温期和第二新冰期大致对比,基本反映了末次冰消期以来全球气候变化的一般规律,青藏高原腹地对于全球气候变化的响应是比较敏锐的。  相似文献   

Assessment of δ13C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments,northwest Scotland     

Elizabeth A. V. Mackie  Jeremy M. Lloyd  Melanie J. Leng  Michael J. Bentley  Carol Arrowsmith 《第四纪科学杂志》2007,22(6):579-591

Carbon isotopes (δ¹³C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea‐level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between δ¹³C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of δ¹³C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between δ¹³C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO₂ concentration, poor vegetation development and temperature influence δ¹³C values during this period. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Nature and role of CO2 in some hot and cold HCO3/Na/CO2-rich Portuguese mineral waters: a review and reinterpretation     

José M. Marques  Paula M. M. Carreira  Luís Aires-Barros  Rui C. Graça 《Environmental Geology》2000,40(1-2):53-63

 At the northern part of the Portuguese mainland, the upflow zone of several hot and cold HCO₃/Na/CO₂-rich mineral waters is mainly associated with important NNE–SSW faults. Several geochemical studies have been carried out on thermal and non-thermal hydromineral manifestations that occur along or near these long tectonic alignments. The slight chemical differences that exist between these meteoric hot and cold HCO₃/Na/CO₂-rich mineral waters seem to be mainly caused by CO₂. δ¹³C_(TIDC) values observed in these groundwaters range between –6.00 and –1.00‰ versus V-PDB (V denotes Vienna, the site of the International Atomic Energy Agency; PDB originates from the CaCO₃ of the rostrum of a Cretaceous belemnite, Belemnitella americana, collected in the Peedee formation of South Carolina, USA) indicating a deep-seated (mantle) origin for most of the CO₂. Nevertheless, in the case of the heavier δ¹³C_(TIDC) values, the contribution of metamorphic CO₂ or the dissolution of carbonate rock levels at depth cannot be excluded. Concerning the hot waters, the lack of a positive ¹⁸O-shift should be attributed to water-rock interaction in a low temperature environment, rather than to the isotopic influence of CO₂ on the δ¹⁸O-value of the waters. Received: 9 August 1999 · Accepted: 8 March 2000  相似文献   

Comparison of ecophysiological characteristics between introduced and indigenous mangrove species in China   总被引：2，自引：1，他引：1  

Luzhen Chen  Nora F.Y. Tam  Jianhui Huang  Xueqin Zeng  Xiangli Meng  Cairong Zhong  Yuk-shan Wong  Guanghui Lin   《Estuarine, Coastal and Shelf Science》2008,79(4):644-652

Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and A–C_i curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.  相似文献