共查询到19条相似文献，搜索用时 250 毫秒
1.
树轮稳定碳同位素组成序列与降水变化 总被引：3，自引：0，他引：3
以长白山红松年轮为气候环境变化的生物记录体，通过分析树轮纤维素的稳定碳同位素组成，从树轮稳定碳同位素组成序列中提取生长环境的降水变化信息。研究结果揭示：树轮稳定碳同位素组成序列与东北地区平均年降水量具有基本平行的变化趋势；在长白山乃至东北地区，降水量沿着自身变化趋势是明显的准22年周期性波动。 相似文献
2.
沉积有机质中稳定碳同位素逆转现象初探 总被引：7，自引：3，他引：7
本文研究了沉积有机质的可溶部分（抽提物）和不溶部分（干酪根）及抽提物的族组分（饱和烃、芳烃、非烃、沥青质）的碳同位素组成特征。通过其δ13C的分布为:干酪根>抽提物;沥青质 >非烃 >芳烃 >饱和烃。研究表明由于生源物质的不同,沉积环境的差异可构沉积有机质碳同位素组成异常。如非烃 >沥青质 >芳烃 >非烃、本文称为沉积有机质碳同位素局部逆转。当沉积有机质可溶部分>干酪根时,称之为总体逆转。湖沼相或河间湖相高等植物来源常为正常组或型;经细菌强烈改造生源以高等植物为主有低等生物为类脂组分加入常形成局部逆转的碳同位素组成。总体逆转则常现于有机质演化程度很高的海相沉积岩中。 相似文献
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4.
树轮作为自然档案内的一种,其同位素研究是较为新颖的领域。文章比较系统地从树轮纤维素的提取,氧的来源,植物体内氧的分馏、与温度变化的关系等４个方面评述了树轮纤维素氧同位素组成的气候学意义。已有的研究结果表明,树轮纤维素氧同位素组成的变化是温度变化的良好载体,但在定量恢复古温度变化时遇到了不少限制。有待于进一步完善分馏模型。 相似文献
5.
树轮稳定碳同位素与全球变化研究 总被引：2，自引：0，他引：2
本文介绍了与全球变化有关的树轮稳定碳同位素的研究现状,分析了树轮δ~(13)与大气CO_2浓度之间的关系,阐明了开展此项研究的目的和意义。通过10~3年尺度的树轮δ~(13)时间序列的研究,可据此分析过去小尺度气候变化的周期性规律,评估人为作用对它的干扰强度,预测未来几十至几百年的气候和环境变迁。 相似文献
6.
贺兰山地区树轮碳氧同位素与夏季风降水的相关性讨论 总被引：1，自引：0，他引：1
分析了贺兰山地区油松树轮的稳定碳氧同位素组成对环境因素的响应关系 , 发现树轮碳氧同位素组成均与当年 5～ 9月总降水量具有较好的响应关系 , 碳同位素组成与 5～ 9月总降水量呈负相关关系 ,而氧同位素组成与 5～ 9月总降水量呈正相关关系 ,二者都可较好地反映该地区夏季风降水量的变化.同时 ,碳氧同位素的相关性分析表明二者具有一定程度的负相关性.树轮碳氧同位素的分馏机理十分复杂,其同位素组成不仅与降水量有关,同时还受其他环境因素的影响,单纯利用一种同位素指标来提取相应的气候信息,存在很大的不确定性.在本研究中 ,同时采用两种同位素指标来研究其气候意义 ,使得出的结论更加可靠.因此 ,夏季风降水量是控制该地区树轮稳定碳氧同位素组成的主要因素. 相似文献
7.
广东现代樟树树轮纤维素的碳同位素与厄尔尼诺事件的关系 总被引：7，自引：0，他引：7
本文对广东阳春河的樟树树轮纤维素△δ13C序列研究发现,厄尔尼诺对树轮C同位素的高频变化的影响有一定的滞后性,一般是厄尔尼诺强度高峰期所对应年的下一年树轮△δ13C值较低.通过谱分析发现,树轮记录的△δ13C序列变化中2～3 a周期与热带气候的"准两年振荡"(QBO)十分一致,这从另一个侧面说明了广东樟树树轮记录了大范围的ENSO信息.其中准4.57 a周期可能与影响全球气候异常的厄尔尼诺事件的周期有关,很可能就是厄尔尼诺事件引起的气候变化对树木生长影响的反映.研究表明,广东厄尔尼诺所引起的气候变化,在树轮同位素中有较好的记录.说明在热湿地区,冬季树木仍有同位素分馏,树轮δ13C依然能记录冬季气温和东亚冬季风强弱的变化. 相似文献
8.
树木年轮稳定碳氧氢同位素(δ13C、δ18O和δD)作为树轮气候学、树轮生态学研究的一种重要信息,随同位素分析技术的发展得到广泛应用.在利用树轮同位素指标进行古气候、古环境研究中,对原木样品进行纯化得到α-纤维素及硝化纤维是一项耗时、耗力且又必须进行的前处理步骤.总结了目前国内外多种纤维素和硝化纤维提取的实验流程,综述了树轮同位素样品分析制备的提取流程,并提出了本研究组的纤维提取试验流程,讨论了该方法的可行性及存在的问题.建议实验室在利用树轮同位素指标进行古气候和全球变化生态学研究时,应关注树木年轮同位素样品制备流程差异对最终获取的同位素比率的影响,以消除不同实验流程造成的实验结果上的差异,为树轮同位素指标大范围空间指标比较提供基础. 相似文献
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10.
《吉林大学学报(地球科学版)》2015,(Z1)
工业革命以来由人类活动带来的大量化石燃料燃烧导致严重的环境污染,并引起气候变化。我国自1970年代开始大量排放人类活动产生的CO2和SO2,而且现在我国已经成为世界最大的CO2和SO2排放国。树轮碳-硫同位素及硫含量能很好地记录长时间尺度的气候变化,水利用效率,及化石燃料燃烧。本摘要报道了来自南方森林115年全树树轮碳-硫同位素及硫含量,目的在于记录人类活动产生的CO2和SO2历排放历史,及试图探讨人类活动产生的CO2和SO2对树碳同位素及水利用效率的影响。结果显示树轮碳同位素自1940年代后期至2000年代后期持续下降,是由持续增加的化石燃料产生的CO2导致的;大气CO2校正后的树轮碳同位素反映了全年降雨量。此外,树轮细胞内CO2浓度及水利用效率自1940年代后期持续升高,其原因是大气CO2浓度增加。另一方面,树轮硫含量没有明显的变化,表明硫是树的基本元素,而硫同位素自1890年代后期以来持续下降,记录了化石燃料(北方煤)使用历史。与之前发表的数据,显示最近几年或几十年来树轮碳同位素的增加(1.2‰~2.5‰),但不能证明是由大气污染(SO2增加)引起的,因其被气候变化所掩盖。 相似文献
11.
Donald W. Northfelt Michael J. DeNiro Samuel Epstein 《Geochimica et cosmochimica acta》1981,45(10):1895-1898
The and C ratios of the cellulose nitrate and saponifiable lipid fractions prepared from eleven annual growth rings of a California redwood were determined. The ratios of the two fractions are related to one another for the annual rings in the sapwood portion of the tree, but not for those in the heartwood or in the wood undergoing the transition from sapwood to heartwood. No relationship was observed between the ratios of the two fractions. These results suggest that analysis of the hydrogen isotopic composition of the saponifiable lipid fractions in plants will provide information useful for climatic reconstruction provided the initial isotopic record has not been changed by subsequent physiological or diagenetic processes. 相似文献
12.
Steffen Holzkämper Päivi Kaislahti Tillman Peter Kuhry Jan Esper 《Quaternary Research》2012,78(2):295-302
Stable isotope ratios from tree rings and peatland mosses have become important proxies of past climate variations. We here compare recent stable carbon and oxygen isotope ratios in cellulose of tree rings from white spruce (Picea glauca), growing near the arctic tree line; and cellulose of Sphagnum fuscum stems, growing in a hummock of a subarctic peatland, in west-central Canada. Results show that carbon isotopes in S. fuscum correlate significantly with July temperatures over the past ~20 yr. The oxygen isotopes correlate with both summer temperature and precipitation. Analyses of the tree-ring isotopes revealed summer temperatures to be the main controlling factor for carbon isotope variations, whereas tree-ring oxygen isotope ratios are controlled by a combination of spring temperatures and precipitation totals. We also explore the potential of combining high-frequency (annual) climate signals derived from long tree-ring series with low-frequency (decadal to centennial) climate signals derived from the moss remains in peat deposits. This cross-archive comparison revealed no association between the oxygen isotopes, which likely results from the varying sensitivity of the archives to different seasons. For the carbon isotopes, common variance could be achieved through adjustments of the Sphagnum age model within dating error. 相似文献
13.
采用质谱和色谱-同位素质谱技术,测定了500余个干酪根及饱和烃、芳烃组份、正构烷烃的δ13C值,以此揭示了四川盆地海、陆相烃源岩有机碳同位素组成随地质时代的变化特点及其在高成熟阶段的演化特征,并结合其他相关分析资料,应用碳同位素剖析了不同类型海、陆相烃源岩的有机质生源及沉积环境。研究结果表明,该盆地从震旦系灯影组到中三叠统雷口坡组的海相地层中,干酪根的碳同位素组成随层位变新呈逐渐变重的趋势,可能的原因之一是浮游植物的进化作用;而上三叠统须家河组至中侏罗统千佛崖组的陆相有机质碳同位素组成则有反向的年代变化,主要与生源构成和沉积环境性质有关。这些海、陆相烃源岩的有机源难以用干酪根δ13C值进行区分,而可用饱和烃与芳烃组份的δ13C及其CV值来区别。海洋和湖泊不同沉积相带烃源岩的干酪根具有明显不同的δ13C值,结合其他相关资料可识别其有机质来源。煤系地层中煤与泥岩在干酪根碳同位素组成上没有可区分性,而两者有不同的正构烷烃碳同位素分布曲线。从成熟晚期到高-过成熟阶段,海、陆相干酪根的碳同位素均变重1~2‰,煤系泥岩的正构烷烃碳同位素分布曲线由负向线型分布向平直型演变。这些碳同位素的变化特征为油气源对比和烃源识别提供了依据。 相似文献
14.
Leonel da S.L. Sternberg Maria C. Pinzon William T. Anderson Kristina Beuning 《Geochimica et cosmochimica acta》2007,71(10):2463-2473
Oxygen atoms within fossil wood provide high-resolution records of climate change, particularly for the Quaternary. However, current analysis methods of fossil cellulose do not differentiate between different positions of the oxygen atoms. Here, we propose a refinement to tree-cellulose paleoclimatology modeling, using the cellulose-derived compound phenylglucosazone as the isotopic substrate. Stem samples from trees were collected at northern latitudes as low as 24°37′N and as high as 69°00′N. We extracted stem water and cellulose from each stem sample and analyzed them for their 18O content. In addition, we derived the cellulose to phenylglucosazone, a compound which lacks the oxygen attached to the second carbon of the cellulose-glucose moieties. Oxygen isotope analysis of phenylglucosazone allowed us to calculate the 18O content of the oxygen attached to the second carbon of the cellulose-glucose moieties. By way of these analyses, we tested two hypotheses: first, that the 18O content of the oxygen attached to second carbon will more closely reflect the 18O content of the stem water, and will not resemble the 18O content of either cellulose or its derivative phenylglucosazone. Second, tree-ring models that incorporate the variable oxygen isotope fractionation shown here and elsewhere are more accurate than those that do not. Our first hypothesis was rejected on the basis that the oxygen isotope ratios of the oxygen attached to the second carbon of the glucose moieties had a noisy isotopic signal with a large standard deviation and gave the poorest correlation with the oxygen isotope ratios of stem water. Related to this isotopic noise, we observed that the correlation between oxygen isotope ratios of phenylglucosazone with both stem water and relative humidity were higher than those observed for cellulose. Our hypothesis about tree-ring models which account for changes in the oxygen isotopic fractionation during cellulose synthesis was consistent only for the 18O content of phenylglucosazone. We showed that the tree-ring model based on the 18O content of phenylglucosazone was an improvement over existing models that are based on whole cellulose. Additionally, this approach may be used in other cellulose based archives such as peat deposits and lacustrine sediments. 相似文献
15.
The fractionation of H isotopes between the water in the growth medium and the organically bonded H from microalgae cultured under conditions, where light intensity and wavelength, temperature, nutrient availability, and the H isotope ratio of the water were controlled, is reproducible and light dependant. All studies were based either on the H isotope ratios of the total organic H or on the lipids, where most of the H is firmly bonded to C. H bonded into other macromolecules, proteins, carbohydrates and nucleic acids, does not exchange with water, when algae are incubated in water enriched with deuterium. Only after the destruction of quaternary H bonds are labile hydrogens in macromolecules free to exchange with water. By growing algae (18 strains), including blue-green algae, green algae and diatoms, in continuous light, the isotope fractionations in photosynthesis were reproducibly ?93 to ?178 %. depending on the organism tested. This fractionation was not temperature dependent. Microalgae grown in total darkness with an organic substrate did not show the isotope fractionation seen in cells grown in light. In both light- and dark-grown algae, however, additional depletion of deuterium (?30 to ?60%.) in cellular organic matter occurs during the metabolism of carbohydrates to form lipids. Plants from several natural populations also fractionated isotopes during photosynthesis by an average of ?90 to ?110%. In addition, the organically bonded H in nonsaponifiable lipids was further fractionated by ?80%. from that in saponifiable lipids, isolated from two geographically distinct populations of marsh plants. This difference between H isotope ratios of these two groups of lipids provides an endogenous isotopic marker. 相似文献
16.
Stable oxygen and carbon isotope ratios (δ18O and δ13C, respectively) of a planktonic foraminiferal species (Globigerinoides sacculifer) and marble carbonate were measured with and without a variety of pretreatments like ultrasonication, soaking in H2O2, methanol and roasting under vacuum. Additionally, organic matter - carbonate mixtures were also analysed with and without the above pretreatments. No significant difference was found in the isotope ratios of treated and untreated samples. It appears that most of the pretreatments may not be necessary when dealing with planktonic foraminifera, especially G. sacculifer. Analysis of two different size fractions (> 400 μm and 250–400 μm) of this species reveals that the smaller size fraction is enriched in 18O and depleted in 13C relative to the bigger size fraction. It is therefore necessary to choose a proper size fraction for isotopic analyses. 相似文献
17.
Mitsugu Nishimura 《Geochimica et cosmochimica acta》1977,41(12):1817-1823
Significant quantities of solvent-inextractable geolipids, obtained by saponification of solvent extracted sediments, were found in various sedimentary samples including soils, river inlet sediment and lake sediments from Lake Suwa.The carbon isotopic composition () of extractable and inextractable geolipids from the same sediment sample were similar. Moreover, the carbon number distributions of sterols in the two geolipid fractions from the same sediment were also similar.Whereas the ratios of both lipids and sterols to total organic carbon for the extractable geolipids in the lake sediments decreased with depth, the former ratio for inextractable giolipids tends to increase with depth and the latter remains fairly constant. On the other hand, the stanol to stenol ratio of the extractable fraction increased with depth but that of the inextractable fraction was lower than that of the extractable fraction and was fairly constant irrespective of sediment depth.The transformation of extractable sterols into inextractable ones was not observed during incubation for 1200 days of sterols with Suwa sediments.Thus, the following conclusions were made: (1) the extractable and inextractable geolipids have similar origins, (2) some constituents of the latter may be protected from chemical or microbiological degradation and transformation in the sediments, and (3) the transformation of some constituents of the former into the inextractable ones virtually does not occur after incorporation into Suwa sediments.These results suggest that some constituents of the inextractable geolipid fraction may provide fundamental information on early diagenetic alteration of geolipids in lake sediments and on the relatively recent paleoenvironment. 相似文献
18.
L. A. Kodina 《Geochemistry International》2010,48(12):1157-1165
Partitioning of carbon isotopes between main polymers of biomass of higher plants was investigated by the example of the structural
polymers of wheat plant: lignin, hemicellulose, and cellulose representing the ligno-carbohydrate complex, starch and proteins
representing storage compounds, and the lipid fraction. Biopolymers account from 80% (grasses) to 95% (trees) of the biomass
of higher plants and are of geochemical interest as biological precursors for the terrigenous organic matter (OM) of sediments
and sedimentary rocks. The biomass of algae is also dominated (∼80%) by polymers: proteins, carbohydrates, and lipids. The
isotopic heterogeneity of the organs and parts of plants is controlled by carbon isotope composition (from −33.3 to −25.9‰)
in biopolymers and their distribution: among various parts of plants. The carbohydrates: starch and hemicellulose are isotopically
heaviest (−25.9 and −26.2‰), proteins are slightly poorer in 13C (up to −27.3‰), and lipids (−33.3‰) and lignin (−32.6‰) are isotopically light components of the biomass. The regularity
of carbon isotopes partitioning among the large complexes of the biomass of higher plants is reflected in the existence of
a common linear trend of δ13C values of biopolymers versus the ranges of thermodynamic β-factor values calculated by the method of isotopic bond numbers
for the whole set of monomers in the composition of each polymer studied. The carbohydrates of grain and straw (starch, xylan,
and cellulose) form a common C6–C5 pool of the isotopically heaviest polymers of the higher plant biomass (wheat). No significant
isotopic effects were observed at the transformation between C6–C5 monomers and their transport between plant organs during
grain ripening. 相似文献
19.
Anne Kress Giles H.F. Young Matthias Saurer Neil J. Loader Rolf T.W. Siegwolf Danny McCarroll 《Chemical Geology》2009,268(1-2):52-57
Annually resolved and replicated tree-ring stable isotope series have the potential to reconstruct growing season environmental parameters over multi-millennial timescales. As this archive may require only minimal statistical detrending, it has the potential to preserve a large portion of low frequency climate signals. To date, many studies have utilised only the latewood portion of the tree ring, in an attempt to minimize carry-over effects from previous year reserves and maximise the annual nature of the climate signal preserved. However, the old trees from tree-line locations, necessary to build long chronologies, often display narrow ring-widths (< 0.5 mm), making accurate earlywood–latewood separation difficult and particular time consuming. The resulting samples may also be too small for efficient cellulose purification or multiple isotopic determinations. As photosynthates from the current year are predominantly used in conifer ring formation at marginal sites with short growing seasons, latewood separation may not be especially advantageous in determining a useful climate signal and therefore unnecessary where resources are limited. To test this hypothesis, Scots pine from Northern Norway and European larch from the Swiss Alps are used. Both sites are tree-line locations where growth is predominantly temperature limited. Tree rings were cut and extracted to cellulose for both the earlywood and latewood of each annual growth ring and stable carbon isotope ratios were measured. Our results demonstrate a very high common carbon isotope signal between earlywood and latewood in both species (rlarch = 0.68 and rpine = 0.79), which also show high correlations with summer temperature over the investigated period (AD 1980–2004 for larch and AD 1929–1978 for pine). High turnover rates and small reserve pools at these tree-line locations may account for these high common signals. These results suggest that for European tree-line conifers, the separation of earlywood from latewood is unnecessary to resolve an annual isotopic signal and make a reliable climate calibration. Using the whole ring may provide additional analytical advantages and consequently even improve climate calibrations. 相似文献