首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
对青藏高原海北站区的自然土壤和扰动土壤进行高分辨率采样,测定土壤根系、有机碳及其14C含量;用14C示踪技术探讨土地利用变化对高寒草甸土壤有机质更新的影响.研究表明,土地利用变化对高寒草甸土壤碳循环影响显著.耕作活动导致扰动土壤有机碳储量比自然土壤增加29.35%;扰动土壤剖面10~50 cm深土壤有机质的14C含量相对富集;自然土壤大多数有机碳储存在土壤表层,更新时间<50 a,同一深度扰动土壤有机碳储量显著少,更新时间长(171~294 a);自然土壤10 cm以下有机碳主要为更新时间>1 000 a的稳定碳所控制,扰动土壤的相应值出现在40 cm以下;自然土壤有机质更新产生的CO2通量为114 gC·m-2·a-1,扰动土壤为48.7 gC·m-2·a-1.  相似文献   

2.
2030年前实现碳达峰,2060年前实现碳中和是2020年我国提出的国家重大战略目标.以当前我国的二氧化碳排放及能源结构现状,要实现这一伟大目标形势十分严峻.介绍了全球碳循环过程,阐述了碳源与碳汇对于大气CO2浓度的贡献,从减源与增汇2个方面,初步分析了地质调查在推动碳达峰与碳中和目标实现中的作用与可能的贡献,并提出了...  相似文献   

3.
新疆阿勒泰地区小冰期特征的树轮δ13C记录   总被引:9,自引:6,他引:3  
建立了新疆阿勒泰地区一个长约450a的落叶松树轮碳同位素年表.该年表一个最为明显的特点是1850年后年轮δ13C显著降低,这是化石燃料燃烧和土地利用方式改变的缘故.在1550—1850年期间,该年表经历了明显的距平“正负”(即暖冷)变化:17世纪年轮δ13C值相对偏负,气温较低,18世纪年轮δ13C值相对偏正,温度较高.根据已有的树轮δ13C温度系数,17世纪的温度相对偏低约0.67~2.46℃.广泛的区域性对比表明,该年表所揭示的小冰期温度变化具有较高的可信度。  相似文献   

4.
Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous, Permian and Triassic, as the transition from Paleozoic to Mesozoic-Cenozoic have very high 13C value. Taking this as the main point, and combined with the oxygen, strontium isotopic composition in carbonates, distribution of carbonate basin area through geologic time, the correlation of carbon isotopic composition of marine carbonates to sea level change, organic carbon burial flux, exchange of CO2 content in atmosphere and ocean, and long cycle evolution of the earth ecosystems were approached. The results are shown as follows: ①The interval of 13C >3‰ during Phanerozoic was concentrated in Carboniferous, Permian and the beginning of Triassic, but the beginning of Triassic was characterized by higher frequency and larger fluctuations in 13C value during a short time, whereas the Carboniferous-Permian presented a continuously stable high 13C value, indicating a larger amount of organic carbon accumulation in this time interval. Relatively high 18O values during this time was also observed, showing a long time of glaciations and cold climate, which suggest a connection among rapid organic carbon burial, cold climate, as well as pCO2 and pO2 states of atmosphere. ②The over consumption of atmosphere CO2 by green plants during the time with high 13C of seawater forced CO2 being transferred from ocean to atmosphere for the balance, but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO2 in seawater and carbon storage of marine carbonates, and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform, which resulted in the decrease of marine invertebrates, suggesting the Permian chert event should be global. ③The Phanerozoic 87Sr/86Sr trend of seawater showed a sharp fall in Permian and drop to a minimum at the end of the Permian, indicting input of strontium from the submarine hydrothermal systems (mantle flux). Such process should accompany with a supplement of CO2 from deep earth to atmosphere and ocean system, but the process associated with widespread volcanism and rises of earth’s surface temperature pricked up the mass extinction during the time of end Permian. ④Cold climate and increase of continental icecap volume, the amalgamation of northern Africa and Laurentia continentals were the main reasons responsible for the sea level drop, but the water consumption result from the significantly increased accumulation of organic carbon should also be one of the reasons for the sea level drop on the order of tens of meters. ⑤The mass extinction at the end Permian was an inevitable event in the process of earth system adjustment. It was difficult for marine invertebrates to survive because of the continuously rapid burial of organic carbon, and of the decrease of sea water amount and its dissolution ability to CO2. At last, at the end of Paleozoic, the supplement of CO2 to atmosphere and ocean by widely magma activities resulted in a high temperature of earth surface and intensified mass extinction.  相似文献   

5.
土壤碳动力学同位素示踪研究进展   总被引:1,自引:1,他引:0  
土壤是陆地生态系统中最大的碳库。土壤碳动力学旨在研究土壤有机碳库的大小及更新速率。土壤有机碳库可分为 3个亚碳库:"活动"、"缓慢"和"稳定"碳库。碳同位素特别是 14 C可作为研究土壤碳动力学的理想示踪剂;δ 13 C值是定量研究C3和C4植被更替历史的有效手段; 14 C示踪及年代测定与 13 C信号联合使用,可以估算土壤碳库的大小和驻留时间。碳同位素示踪应用于土壤碳动力学研究取得了较大进展,但是由于缺乏可靠的全球数据库和标准方法来量化土壤有机碳库,导致对土壤各亚碳库的大小和更新速率以及土壤CO2的估算仍存在较大的不确定性,从而难以估计土壤碳库大小的变化对大气CO 2浓度和全球气候变化的潜在贡献。  相似文献   

6.
受到植物化石材料局限性与时代久远性的限制,目前用古生代植物化石δ13C值来反演古环境的研究程度较低。文中通过对云南省曲靖市下泥盆统徐家冲组和文山州下泥盆统坡松冲组的部分植物化石进行稳定碳同位素测试,分析了早泥盆世植物的光合作用途径以及古环境。结果表明: 徐家冲组镰蕨属(Drepanophycus)δ13C值为-29.0‰~-22.8‰,平均值为-24.5‰,其中镰蕨属茎轴的δ13C值高于叶片0.1‰~0.3‰;坡松冲组工蕨属(Zosterophyllum)和始叶蕨属(Eophyllophyton)δ13C值分别为-24.8‰~-22.1‰和-23.0‰~-22.6‰,平均值分别为-23.2‰和-22.7‰;三者的δ13C值分布范围都与现代C3植物一致。自徐家冲组第57至第79沉积旋回,δ13C值总体呈上升趋势,达到2‰左右,推测可能与早泥盆世大气CO2浓度下降和气候变冷相关。镰蕨属和工蕨属的Ci/Ca值较为稳定,说明这2种植物可能对大气CO2浓度变化较为敏感,曲靖市古气候可能为当今的热带疏林草原气候或热带季风气候。  相似文献   

7.
Yao Ying  Sun Qiang 《地球科学进展》2016,31(10):1032-1040
Carbon dioxide is a common and important component in fluid inclusions. Because carbon isotopic ratio of CO2 in fluid inclusion can provide geochemical characteristics of source rocks, many works have been conducted to measure the carbon isotopic ratio (13C/12C) of CO2. In general, carbon isotopic composition (13C/12C) of CO2 fluid inclusions are measured by mass spectroscopy. However, mass spectroscopy is a destructive analytical technique, and can not be applied to measure single inclusion. Raman spectroscopy is an efficient non-contact and non-destructive method, and has been widely employed in many research fields. In fact, due to the difference of carbon atom mass, the Femi resonance of 13CO2 is lower than that of 12CO2, so they can be identified in Raman spectrum. In principle, the carbon isotopic composition (13CO2/12CO2) in CO2 is closely related to the Raman intensity ratio between 13CO2 and 12CO2 (I+13/I+12). Therefore, Raman spectroscopy can theoretically be utilized to measure the carbon isotopic composition (13CO2/12CO2) of CO2. However, this method is seriously hampered by the poor measurement accuracy and precision. In this study, based on the theoretical analysis, and in combination with previous Raman studies on carbon isotopic composition in CO2, a preliminary research on Raman quantitative measurement for carbon isotopic composition in CO2 was carried out.  相似文献   

8.
Oxidized reactive nitrogen in the atmosphere mainly consists of nitrogen oxides (NO X =NO+NO2, NO3) and nitric acid. The atmospheric cycling of NO X influences the formation of ozone and hydroxyl radicals that are important for atmospheric oxidation capacity. Nitric acid, the final product of NO X oxidation, not only is an important component of particulate pollutants, but also has a direct impact on the ecosystem through dry and wet deposition. The stable nitrogen isotope (δ15N) shows the potential to study reactive nitrogen cycle, and to trace the emission, transport and deposition of reactive nitrogen from local to global scales. Here, we reviewed previous studies using δ15N to investigate NO X emission and atmospheric reactive nitrogen cycle, and discuss the uncertainties of δ15N signatures of different NO X sources from two aspects: NO X generation mechanism and NO X collection methods. We also discussed the nitrogen isotope fractionation and the consequences during the conversions of NO y molecules. We ended up with discussions on the possibility of using δ15N to trace NO X emissions. Although there are still large uncertainties in quantifying and tracing NO X emissions using nitrogen stable isotopes, such isotope tool is efficient enough to trace reactive nitrogen cycles in the atmosphere. On the basis of this, we proposed that we can combine atmospheric chemistry transmission models with isotope tracers to improve our understanding of regional and global atmospheric reactive nitrogen cycle regarding the fluxes of different emission sources, their atmospheric transformation, etc.  相似文献   

9.
为掌握不同蓄水阶段温室气体通量强度,揭示水生生态系统在水库蓄水后的重建过程,选择2004年(蓄水后第1年)、2008年(蓄水后第5年)为典型年,结合同期主要环境参量,比较研究了三峡典型支流澎溪河回水区水柱表层CO2分压p(CO2)及其扩散通量FCO2特征。研究发现,2004年澎溪河双江大桥处水柱表层p(CO2)、FCO2年均值分别为(101.9±7.5)Pa、(13.99±1.58)mmol/(m2·d),2008年相应为(129.1±16.4)Pa、(19.92±3.55)mmol/(m2·d)。水位上升淹没土地带来更多有机质降解,可能引起了p(CO2)和FCO2的总体升高;蓄水过程水域生态系统逐渐完善,浮游植物生长对p(CO2)和FCO2的影响逐渐显现。  相似文献   

10.
Marine carbon cycle of the South China Sea is an important part of global carbon cycle. Researches on the air-sea CO2 flux in the South China Sea will help us understand the global carbon cycle and improve the global carbon system parameter database. This paper concisely summarized the changes of partial pressure of CO2 (pCO2), air-sea CO2 fluxes (FCO2), and related environmental factors in four regions in domains in the South China Sea. The low-salinity area of the upper reaches of the Pearl River estuary in the northern of South China Sea shelf area acted as a strong source of atmospheric CO2, with high pCO2(405.3~810.6 Pa)all year round. The lower area of the Pearl River estuary (salinity > 33.7) acted as a weak sink of CO2 in winter, with relatively low pCO2 (35.2~37.0 Pa). The northern slope/basin in the South China Sea acted as a source of CO2 in warm seasons with a relatively high pCO2 (45.0 Pa), and acted as a sink of CO2 in cold seasons with a relatively low pCO2 (34.7 Pa). The west of the Luzon Strait acted as a sink of CO2 in spring, while it acted as a source of CO2 in other seasons, with relative high pCO2 (38.4~47.5 Pa) in winter. The central/southern basin in the South China Sea acted as sources of CO2, with relative high pCO2 (41.0 Pa) all the year. Generally, the estimation of annual sea-air CO2 fluxes showed that most domains in the South China Sea served as weak sources of atmospheric CO2. In the future, more researches should be focused on the time-series of sea surface pCO2 and the remote sensing of the sea-air CO2 fluxes.  相似文献   

11.
青藏高原北部植物叶片碳同位素组成的空间特征   总被引:25,自引:5,他引:25  
测定了青藏高原北部13个地点101份草本植物叶片碳同位素组成(δ13C值), 结果发现, 植物叶片δ13C值的分布范围在-29.2‰~-23.8‰之间, 平均值约为-26.89‰, 明显低于全球高海拔植物叶片δ13C值(-2.6‰) ; 而植物叶片δ13C值随海拔和经、纬度的变化趋势与其它同类报道相似:随着海拔的升高和经、纬度的降低, 植物叶片δ13C值呈现升高趋势. 叶片δ13C值也随土壤含水量和土壤温度的变化而变化:土壤含水量越高, 土壤温度越低, 植物叶片δ13C值越小, 但它们之间的相关关系不具统计学意义. 初步分析表明, 大气压力 (CO2分压)和温度的协同变化导致了叶片δ13C值随着海拔变化的分布格局, 而温度和相对湿度的变化是引起叶片δ13C值的经、纬度效应的主要因子.  相似文献   

12.
Global climate change has been one of the most concerned environmental problems in the world since the 1980s. Since stable carbon composition (13C) in plant tissues can record abundant information on climate changes, it has been widely used as an important climate proxy in global change studies and becomes a powerful tool for obtaining paleoclimate information, understanding paleoenvironment reconstruction and modern climate change, and predicting future climate trends. However, a lot of potential uncertainties have always involved in the reconstruction of paleoclimate and paleoenvironment by carbon isotope of the past period sediment or fossils. Among them, the most dominant uncertainty is due to our poor understanding of the relations between carbon isotope ratios of plants and climatic factors and the climatic and environmental significance indicated by modern plant 13C. This may limit the application of plant 13C in the study of climatic and environmental changes. Based on the Summary of plant 13C fractionation and carbon isotope distribution of different photosynthetic plants, the effects of environmental factors, e.g., temperature, precipitation, atmospheric CO2 concentration, and altitude on terrestrial plant 13C and their relationships were reviewed in this paper, and the response mechanism of plant 13C to climate changes were also analyzed. Furthermore, the current existing problems and the future prospects in carbon isotope study were discussed. It is pointed out that strengthening some studies such as the response of C4 plants 13C to climate environmental parameters, the transformation relation of different scale plant 13C, intersection and permeation of related disciplines, and various proxies and scientific method, will undoubtedly make us have a more accurate understanding of the climate history and eventually broaden the development of the field during the process of global change study by plant carbon isotope techniques.  相似文献   

13.
碳质气溶胶(或颗粒物)作为大气气溶胶的重要组成,对环境、气候和人类健康造成了巨大的危害。其主要组成成分有机碳和元素碳具有不同的来源特征,且对人类健康和气候系统的影响也具有明显的差异。放射性碳同位素(14C)不仅能定性区分生物源和化石源,还能定量分析不同来源对有机碳和元素碳的贡献比率。重点评述了放射性碳同位素法对气溶胶源解析的技术原理、分离测试方法以及在我国应用的研究进展;最后提出了国内研究应加强的领域和利用放射性碳同位素法研究大气气溶胶的发展趋势。  相似文献   

14.
Abuse of fossil energy resources results in the excessive discharge of greenhouse gases, especially CO2, enhancing the trend of global climate warming. Carbon sequestration is an important method to lower the increasing rate of CO2 concentration in the atmosphere. Marine carbon sequestration is a novel idea for reducing CO2 emission, and its reservoir mainly includes seawater and submarine sediment, which not only possess a great potential capacity of carbon sequestration, but also have high safety in relation to continental reservoirs. In this paper, we expounded the technique principle and mechanisms of marine carbon sequestration, potential capacity and time duration of marine carbon sequestration, main factors influencing marine carbon sequestration, CO2 injection technique, impacts on marine biota from over emission of CO2 and technique monitoring the leakage of CO2. Finally, a prospect of marine carbon sequestration was proposed, and its hot topics were accordingly pointed out.  相似文献   

15.
A. Demény  S. Harangi 《Lithos》1996,37(4):335-349
Processes of carbonate formation have been related to C and O isotopic compositions in the Mesozoic alkali basalt (Mecsek Mts.) and lamprophyre (Transdanubian Range) suites of Hungary. In the studied magrnatic rocks, carbonates are present as ocelli, amygdales, xenoliths, veins and groundmass carbonate. C and O isotope studies of these types of carbonate have yielded information on the origin of the carbonates and indicated the following processes of formation that determined the δ13C and δ18O values of the carbonates:(1)Crystallization of magmatic carbonate. Textural characteristics and δ13C values suggest formation of magmatic carbonate in alkali basalt and lamprophyre dikes, whereas the δ18O compositions of these carbonates indicate low temperature oxygen isotope exchange with magmatic fluids.(2) Assimilation of sedimentary carbonate by silicate magmas. Even completely recrystallized amygdales and ocelli of basalts and lamprophyres have preserved their sedimentary δ13C values. In contrast, variations in the extent of mobilization and isotope exchange with magmatic fluids are reflected in differences in the ranges of the δ18O values of amygdales, ocelli and veins, and can be attributed to different amounts of fluids involved in the magmatic events.(3) Low temperature alteration of magmatic rocks caused only 18O-enrichment in the carbonate amygdales of basalts and the groundmass carbonates of lamprophyres, indicating that no externally-derived CO2 was present in the alteration fluids.(4) Degassing of magma and magmatic fluid. Correlations between δ13C and δ18O data, magma crystallization depths and amygdale sizes in the alkali basalts suggest that CO2 degassing has been responsible for the negative δ13C and positive δ18O shifts observed. A similar trend was found in the lamprophyres, but the extent of the δ18O shift indicates that in these rocks H2O degassing also played an important role.  相似文献   

16.
The δ13C of organic matter bound within the crystal lattice of foraminiferal calcite tests may provide a potential tracer of the isotopic composition of the surface water primary photosynthate. Using δ13C of the organic matter extracted from the crystal lattice and the calcite test, it is theoretically possible to estimate the paleo-surface water pCO2. We have tailored this technique initially for the subpolar planktonic foraminifera species Globigerina bulloides. Initial surface water pCO2 estimates from deep-sea core BOFS 5K (50°41.3′N, 21°51.9′W, water depth 3547 m) indicate that the northeast Atlantic Ocean may have been a greater sink for CO2 during the last glacial than during the Holocene. Greatly reduced benthic foraminifera abundances, especially phytodetritus feeders, in BOFS 5K during the last glacial indicates low surface productivity. This rules out a productivity-driven CO2 sink. The enhanced glacial CO2 sink must, therefore, have results from a southwards shift of the centre of deep water formation.  相似文献   

17.
概述了国内外14C和13C技术在大气碳质气溶胶源解析中应用的研究进展,指出14C在碳质气溶胶源解析研究中具有不可替代的独特优势,联合采用14C和13C技术有利于解决多种排放源的区分问题;随着碳质气溶胶组分分离技术的进步,对有机碳(0C)和黑碳(BC)等组分中14C的研究获得重要进展;除需深入研究13C的分馏机制外,建立各种排放源在不同区域的δ13C值域“特征谱”的重要性也日益突出;结合14C和13C以外的其他示踪剂、模型和分析方法将提供更多关于气溶胶来源的信息,并减小来源贡献率估算的不确定性.  相似文献   

18.
对取自赣南地区10个温泉的地热气体进行了气体化学成分及氦、碳、氖同位素组成的分析。该区地热气体可分为CO2型和N2型两种类型。CO2型地热气体分布在赣南东南部地区,主要成分是CO2,占总体积96.47%以上,二氧化碳气体的δ13C值为 -5.50‰~-3.49‰(PDB),平均为 -4.66‰,为幔源无机成因,其氦同位素组成为1.36~2.27 Ra,具有明显的幔源成因特征,最高约有28.2%的氦源于地幔,其N2-Ar-He关系研究表明,该型地热气体中的氮源于地幔-地壳-大气混合成因。研究揭示该区CO2型地热气体属幔源无机成因气,是地幔脱气作用的产物。N2型地热气体分布在赣南西部地区,N2含量占91.04%以上,其中二氧化碳气体的δ13C值为 -23.7‰~-12.6‰,平均为 -17.82‰,为壳源有机成因,其氦同位素组成为0.06~0.13 Ra,具有明显的壳源放射性成因特征,3He/4He 与 4He/20Ne关系和He-Ar-N2关系研究表明,N2型温泉气主要来源于大气,并有壳源气体的贡献。  相似文献   

19.
重庆雪玉洞洞内CO2浓度之高,在国内外皆罕见,但此洞穴系统碳循环特征及控制因素仍不清楚.利用土壤二氧化碳分压(PCO2-soil)、洞内大气二氧化碳分压(PCO2-cave)、地下河水二氧化碳分压(PCO2-eq)、方解石饱和指数(SIc)、地下河水溶解无机碳同位素(δ13CDIC)等指标来研究雪玉洞洞内CO2浓度变化、控制因素以及地下河对洞内碳循环的影响.结果表明:雪玉洞上覆PCO2-soil雨季高,旱季低;降雨量是控制上覆PCO2-soil的重要因子.雪玉洞PCO2-cave变化规律明显,暖季高,冷季低;温度变化导致洞内外气流频繁交换是PCO2-cave突变的重要原因,地下河水CO2脱气能够在短时间内让PCO2-cave上升到较高值.雨季由于土壤CO2效应,地下河水具有低SIc、高PCO2-eq特性,矿化度较高,并且部分月份地下河水具有溶蚀性;旱季由于土壤CO2效应及降雨较少,地下河水呈现高SIc、低PCO2-eq特性,矿化度较低,以沉积为主.   相似文献   

20.
重点分析了研究区潜水、浅层承压水、泉水及地表水δD、δ18O的分布特征,并对5组水文钻探井地下水样品进行分析.潜水δD变化范围为-97.32‰~-67.51‰,平均值为-80.34‰;δ18O为-15.85‰~-10.66‰,平均值为-12.08‰.浅层承压水δD为-111.93‰~-68.38‰,平均值为-84.79‰;δ18O为-16.01‰~-10.52‰,平均值为-12.30‰.泉水δD为-102.06‰~-71.63‰,平均值为-84.10‰;δ18O为-14.21‰~-9.70‰,平均值为-12.24‰.地表水δD为-90.53‰~-60.99‰,平均值为-72.58‰;δ18O在-13.20‰~-9.54‰,平均值为-11.21‰.地下水δ13C为-9.4‰~-5.6‰,平均值为-8.3‰,极差为3.8‰.结果表明:地下水与地表水均起源于当地大气降水.潜水与浅层承压水水力联系较强,潜水与浅层承压水属于同一含水系统.与浅层承压水相比,深层承压水年龄较大,在20 ka左右,属于沉积埋藏水.深层承压水与浅层承压水的水力联系较弱.潜水与浅层承压水的δ13C值较为接近,且接近大气CO2的δ13C值-7‰.研究区地下水中碳的主要来源为大气CO2.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号