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1.
浙江煤山P/T之交碳同位素对有机碳埋藏的指示意义 总被引：5，自引：1，他引：4
根据碳酸盐碳同位素和有机(干酪根) 碳同位素记录, 结合碳循环模式, 计算得到了浙江煤山全球二叠系-三叠系界线层型剖面第23-40层的有机碳埋藏分数forg.在第23-24层和第27-29层下部出现forg的两个高峰值, 与绿硫细菌反映的两个缺氧环境条件相对应.在第25-26层和第32-34层出现两个forg低谷值, 与2-甲基藿烷指示的两次蓝细菌繁盛(第26层和第29层上部到第34层) 基本吻合.这些结果反映了forg与埋藏时的氧化还原条件密切相关.forg与总有机碳含量TOC的关系比较复杂, 一些TOC较高的层位(如第26层) forg却较低, 而一些TOC较低的层位(如第27层) forg却较高, 反映了原始生产力对TOC的重要贡献.根据原始生产力和forg得到的原始有机埋藏量, 可以校正现今测得的残余TOC.本次研究结果说明, 同步有机-无机碳同位素分析, 在建立一定碳循环模型的基础上, 计算有机碳埋藏分数, 可有效指示有机质埋藏状态, 进而为建立生物-环境-有机碳埋藏的耦合关系模型提供基础. 相似文献
2.
四川盆地广元地区大隆组有机质富集规律 总被引：12，自引：2，他引：10
四川盆地西北广元地区上二叠统大隆组主要为碳酸盐岩、硅质岩和页岩互层沉积.对四川广元长江沟剖面进行精细解剖的结果表明,大隆组中有机碳质量分数为0.16%~14.6%,有机碳质量分数与岩性关系密切,高有机碳质量分数赋存于黑色页岩和纹层状灰岩中,其中碳酸盐岩的有机碳质量分数与纹层厚度呈反比,即纹层厚度越大有机碳质量分数越低.大隆组优质烃源岩位于大隆组中部岩段,岩性组合为黑色页岩和硅质岩互层,间夹薄层状灰岩或纹层状灰岩.微量元素分析结果显示有机质的富集明显受控于沉积阶段及早期成岩阶段的氧化还原条件.综合分析表明大隆组烃源岩有机质富集受晚二叠世沉积环境、氧化还原条件、生物生产力、深部热液流体的影响,其中厌氧、缺氧环境是大隆组烃源岩发育的主控因素,高生物产率是有机质富集的前提条件. 相似文献
3.
根据碳循环模式,通过无机碳和有机碳碳同位素记录,半定量-定量地计算了贵州新民剖面晚二叠世有机碳埋藏分数forg,同时结合表征古海洋初级生产力的疑源类、藻类与菌孢的丰度值,详细分析了有机碳埋藏分数forg、古海洋生产力与岩石中保存的残余TOC之间的耦合关系。该研究发现新民剖面晚二叠世初级生产力较有机碳埋藏分数forg对残余TOC的贡献更大。但这一结果仍需进一步论证:新民剖面和煤山剖面forg与δ13Ccarb的高度相关性暗示forg主要受控于δ13Ccarb,而在Kump碳循环模型中忽略了晚二叠世火山活动对无机碳同位素组成的重要影响。 相似文献
4.
古海洋生产力指标研究进展 总被引：20，自引：1，他引：19
寻求反映古海洋生产力变化的指标是古海洋学研究的重要内容。生物沉积物、营养元素、微量元素和同位素、古生物资料等与古海洋生产力具有一定的关系,常用于古海洋生产力的重建工作:(1)生物沉积物主要包括有机碳、生物碳酸盐和生物硅质沉积等,其埋藏速率在很大程度上受到古海洋生产力的控制,常常用作古海洋生产力的替代性指标;(2)在地质时间尺度上,古海洋生产力主要受到大洋中营养元素可利用程度的控制,因此营养元素的相关记录可以提供古海洋生产力状况的重要信息;(3)海洋中某些微量元素的地球化学行为或者与有机质的改造有关,或者受到氧化还原条件变化的控制,或者受到某种浮游生物的生长的影响,从而能够直接或者间接地指示古海洋生产力的变化;(4)海相碳酸盐和有机质的碳同位素记录,海相有机物的氮同位素比值也用以再造古生产率等古海洋学参数;(5)可以利用对微体化石丰度值及其组合反映古生产力的变化。 相似文献
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6.
晚奥陶世全球海洋环境曾发生重要的改变,特别是赫南特冰期的气候变冷,造成了古海洋沉积物中多项地球化学指标出现异常现象,全球多地区出露的赫南特阶均记录了冰期时出现的碳、氮同位素异常,但对其产生机制的认识存在争议.四川盆地东南缘三泉剖面和双河剖面的奥陶系五峰组、观音桥段以及志留系龙马溪组的有机碳同位素、总氮同位素等地球化学指标测试结果显示,三泉剖面和双河剖面的赫南特阶观音桥段泥灰岩有机碳同位素和总氮同位素均出现正偏偏移,并可与其他地区奥陶系剖面进行对比.其中,三泉剖面δ13Corg值分布范围为?31.9‰ ～ ?27.9‰,自五峰组顶部开始偏重,在观音桥段达到峰值?27.9‰,偏移幅度约2‰;双河剖面 δ13Corg平均值为?30.1‰,观音桥段最大值为?29.1‰,向正偏移幅度约为1‰左右.这些变化特征揭示,晚奥陶世有机质的埋藏作用可能改变了海洋溶解无机碳库的碳同位素组成,并且引起赫南特冰期碳同位素异常.三泉剖面和双河剖面 δ15N平均值分别为1.4‰和1.1‰,冰期观音桥段 δ15N值正偏幅度在0.5‰～1‰之间,可能是由于长期的缺氧还原条件促进了海水的反硝化作用,而冰期时海平面下降限制了反硝化作用的强度,从而导致氮同位素出现正偏异常. 相似文献
7.
贵州二叠纪海相碳酸盐岩碳,氧同位素地球化学演化规律 总被引：14，自引：0，他引：14
以贵州罗甸二叠纪剖面为研究对象，详细讨论了海相碳酸盐岩的碳、氧同位素组成特点，及影响碳盐岩的δ＾１３Ｃ和δ＾１８Ｏ的主要因素。在此基础上系统阐述了整个二叠纪海相碳酸盐岩的δ＾１３Ｃ和δ＾１８Ｏ的演化与海平面升降的关系，第一次系统建立了二叠纪古海洋碳酸盐岩的碳、氧同位素演化曲线。 相似文献
8.
云南永善肖滩早寒武世早期碳氧同位素记录 总被引：14，自引：0，他引：14
本文对采自云南永善肖滩剖面下寒武统100余件碳酸盐岩样品的碳氧同位素进行了分析研究。在从灯影组白岩哨段上部至筇竹寺组玉案山段碳酸盐岩碳同位素变化曲线上,梅树村组小歪头山段底部δ13C值表现出显着负飘移。早寒武世梅树村期,碳同位素值缓慢增大,至大海段达到最大值。在筇竹寺组石岩头段底部,δ13C值表现为明显负飘移。在玉案山段,碳同位素又开始一个新的正飘移旋回。根据同位素资料,肖滩剖面下寒武统梅树村组小歪头山段至大海段地层相当于前托莫特阶地层,筇竹寺组石岩头段与托莫特阶地层对应,玉案山段与呵特达班阶下部地层对比。小歪头山段底部标志着寒武纪沉积已经开始。 相似文献
9.
基于系统碳氧同位素和有机碳测试,在充分论证样品测试数据有效性的基础上,对湘中坳陷地区泥盆系碳氧同位素特征展开分析,探讨了研究区地层对比、古海洋环境发育特征及其对富有机质页岩形成的影响.结果表明,湘中地区泥盆系δ13C受后期蚀变成岩作用影响较小.区内泥盆系δ13C表现出自下而上逐渐变轻,并在欧家冲组底部发生显著的负偏、之后向上逐渐增大的发育趋势.以上曲线与全球泥盆系碳氧同位素曲线相似,具有较为一致的变化趋势.区内泥盆系δ13C曲线形态及偏移程度与四川龙门山剖面、独山其林寨剖面、广西拉利剖面及欧美地台剖面可对比性强,可作为区内地层划分与对比、古海洋环境演化分析的依据.对比结果显示,区内棋梓桥组顶部-佘田桥组底部δ13C曲线与海平面变化存在差异,指示区域性地壳构造升降与全球海平面变化综合主导了区域的古水深变化.区内泥盆系δ13C正漂移与高TOC页岩具有良好对应关系,表明佘田桥组下部、孟公坳组上部富有机质页岩发育层段是大范围海侵阶段的产物,也是构成区内泥盆系页岩气勘探的主要目的层系. 相似文献
10.
通过对保山地块北部西邑地区下石炭统香山组和下二叠统丁家寨组详细的野外剖面实测与钻孔编录,并结合层序地层学、沉积相以及碳氧同位素分析结果认为,下石炭统香山组自下向上可分为三个岩性段,分别对应台前斜坡下部、台前斜坡上部、碳酸盐岩台地三种沉积环境。下二叠统丁家寨组为滨岸冰水沉积,下部为冰碛含砾钙质杂砂岩,发育落石构造。下石炭统香山组δ13CPDB值自下而上逐渐升高,环境可能较稳定,有机质埋藏增加。综合前人古地磁、生物区系对比、大地构造学等研究成果认为早石炭世保山地块较稳定,仍属冈瓦纳大陆北缘。丁家寨组冰碛含砾钙质杂砂岩结束后δ13CPDB值出现强烈负偏,与研究区冰期结束、早二叠世初次温度上升、大量玄武岩喷发等时限高度一致,共同说明了保山地块在早二叠世开始从冈瓦纳大陆北缘裂解出来,并开始向北漂移。该项研究的开展为探讨Submasu地块晚古生代的古海洋、古地理和气候演化具有重要意义,为全球同时期碳氧同位素数据库提供了新资料。 相似文献
11.
2030年前实现碳达峰、2060年前实现碳中和(简称“双碳”)是我国对国际社会的庄严承诺,已被纳入生态文明建设的总体布局。生态系统碳汇是实现“双碳”目标的重要手段,也是林业和草原实现高质量发展的必然要求。国际有关机构对全球森林、草地和湿地生态系统的碳储量和碳循环进行了评估。自1990年以来,附件一国家(指《联合国气候变化框架公约》附件一列出的经济合作发展组织中所有发达国家和经济转型国家)对本国的碳排放和碳汇进行估算,编制了年度温室气体清单; 我国也编制了5次国家温室气体清单。这些工作对我国开展应对气候变化的研究提供了基础。提出了如下建议: 在编制“双碳” 路线图和时间表时,既要考虑我国生态系统碳汇与能源和工业领域碳排放在区域空间分布和时间维度上的差异性,也要考虑生态系统同时所具有的碳汇和碳排放的特殊性; 生态系统碳汇是碳达峰的非选项,是碳中和的必选项; 生态系统碳汇要遵循国家实现“双碳”目标的基本原则,要将生态系统碳汇作为国家生态建设和保护工程的主要目标,提高碳汇计量和监测能力,完善市场和融资机制。 相似文献
12.
《Atmósfera》2014,27(2):165-172
In Mexico, approximately 7650 wildfires occur annually, affecting 263 115 hectares of land. In addition to their impact on land degradation, wildfires cause deforestation, damage to ecosystems and promote land use change; apart from being the source of emissions of toxic substances to the environment (i.e., hydrogen cyanide, black carbon and organic carbon). Black carbon is a short-lived greenhouse pollutant that also promotes snow and ice melting and decreased rainfall; it has an estimated global warming potential close to 5000.1 We present an estimate of the black carbon and organic carbon emissions from wildfires in Mexico from 2000 to 2012 using selected emission factors from the literature and activity data from local agencies. The results show average emissions of 5955 Mg/yr for black carbon and 62 085 Mg/yr for organic carbon. Black carbon emissions are estimated to be 14 888 Gg CO2 equivalent (CO2 eq) per year on average. With proper management of wildfires, such emissions can be mitigated. Moreover, improved air quality, conservation of ecosystems, improvement of visibility and maintenance of land use are a subset of the related co-benefits. Mitigating forest organic carbon emissions, which are ten times higher than black carbon emissions, would also prevent the morbidity and mortality impacts of toxic organic compounds in the environment. 相似文献
13.
在百万年时间尺度上,大气、海洋中的二氧化碳浓度(PCO2,二氧化碳分压)和长期变化主要受岩浆-变质脱碳作用和硅酸盐风化作用(消耗二氧化碳)控制。因此,地球表层主要构造活动带的构造-岩浆活动对长期碳循环具有重要的驱动作用。本文在总结已发表文献的基础上,系统评估了大陆弧,尤其是晚白垩世大陆弧的岩浆作用和剥蚀作用的碳通量,并以此为依据探讨了大陆弧演化对于全球长期碳循环的影响。大陆弧岩浆作用以周期性(几十万年至一百百万年)岩浆爆发(magmatic flare-ups)为特征。在一个周期内,大规模岩浆喷发会导致CO2排放量大幅度增加,促进温室效应。但同时,大规模的岩浆作用又会导致地壳增厚和和地表抬升,从而促进剥蚀作用、提高化学风化通量,进而增加CO2消耗量。对于单个的大陆弧来说,在其演化的不同阶段对于碳循环扮演着不同的角色：演化早期由于岩浆作用起主导作用,表现为净碳源;而在岩浆作用减弱或停止后,由于剥蚀作用的持续进行,表现为净碳汇。因此,从长周期和全球尺度上讲,大陆弧岩浆活动表现的“碳源属性”受到化学风化作... 相似文献
14.
Michel Bakalowicz 《Comptes Rendus Geoscience》2003,335(5):423-424
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Bruce Peterson Brian Fry Meredith Hullar Susan Saupe Richard Wright 《Estuaries and Coasts》1994,17(1):111-121
The distributions of dissolved organic carbon (DOC) and the natural carbon isotope ratio of DOC (DO13C) in estuaries reflect the predominant sources and sinks of organic matter from both allochthonous and autochthonous origins. The traditional view is that DOC in land-margin ecosystems reflects mainly the mixing of land-derived and oceanic DOC. However, this view is not consistent with the bulk of our data from a survey of DOC and DO13C distributions in estuaries on the East and Gulf coasts of the USA. While it is accurate that the DOC in estuaries includes material derived from land and from the ocean, the distributions of DOC and DO13C in several estuaries reflect additional DOC inputs from estuarine phytoplankton and tidal marshes. Even when DOC concentrations were distributed conservatively, the isotopic composition of the DOC revealed the existence of a dynamic cycle of DOC input and removal in some systems. 相似文献
17.
重庆地区岩溶地下河水溶解无机碳及其稳定同位素特征 总被引：6，自引：3，他引：3
稳定碳同位素是指示岩溶动力系统碳来源及转化的重要指标。为揭示重庆地区岩溶地下水中溶解无机碳基本特征和碳来源,本文对该地区63条岩溶地下河水样进行了水化学和碳同位素分析。研究结果表明,重庆地区地下河水溶解无机碳主要表现形式为HCO3-,雨季由于稀释作用其浓度低于旱季。重庆岩溶地下河水δ13C-DIC（V-PDB）旱季变化范围为-15.34 ‰～-5.89 ‰,雨季变化范围为-17.40 ‰～-4.23 ‰。根据δ13C同位素质量平衡方法,计算得到重庆地下河旱季碳酸盐岩溶蚀对DIC贡献为45.1 % ～79.7 %,雨季平均为34.6 %～82.1 % 。计算结果表明,在人类活动不断增强的情况下,岩溶水体DIC通量中碳酸盐岩溶解来源的DIC和其参与岩溶地下水δ13C值的形成并不一定是岩溶作用理论方程中所计算的50 %,而是有一定的变化范围。因此在计算岩溶作用碳汇时,建议通过δ13C值扣除碳酸盐岩溶蚀形成DIC的通量后再来推算岩溶作用形成的碳汇量。 相似文献
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It is recognized that karst processes are actively involved in the current global carbon cycle based on twenty years research, and the carbon sink occurred in karst processes is possibly an important part of “missing sink” in global carbon cycle. In this paper, an overview is given on karst carbon cycle research, and influence factors, formed carbon pools (background carbon sink) and sink increase potentials of current karst carbon cycle are analyzed. Carbonate weathering could contribute to the imbalance item (BIM) and land use change item (ELUC) in the global carbon cycle model, owing to its uptake of both atmospheric CO2 (carbon sink effect) and CO2 produced by soil respiration (carbon source reduction effect). Karst carbon sink includes inorganic carbon sink resulted from hydrogeochemical process and organic carbon sink generated by aquatic photosynthetic DIC conversion, forming relatively stable river (reservoir) water body or sediment carbon sink. The sizes of both sinks are controlled by terrestrial ecosystems and aquatic ecosystems, respectively. Desertification rehabilitation and carbon sequestration by aquatic plants are two effective ways to increase the carbon sink in karst area. It is estimated that the rate of carbon sink is at least 381 000 t CO2/a with vegetation restoration and afforestation in southwest China karst area, while the annual organic carbon sink generated by aquatic photosynthesis is about 84 200 t C in the Pearl River Basin. The development of a soil CO2 based model for assessment of regional dissolution intensity will help to improve the estimation accuracy of carbon sink increase and potential, thus provide a more clear and efficient karst sink increase scheme and pathway to achieve the goals of “double carbon”. With the deep investigation on karst carbon cycle, mechanism and carbon sink effect, and the improvement of watershed carbon sink measurement methods and regional sink increase evaluation approaches. Karst carbon sink is expected to be included in the list of atmospheric CO2 sources/sinks of the global carbon budget in the near future. 相似文献
19.
An experiment was carried out in two soils of oasis farmland and the surrounding desert at the southern periphery of the Gurbantonggut
Desert, in central Asia, to test the effects of land use on soil organic carbon (SOC) stock and carbon efflux in deep soil.
The result showed that although SOC content in the topsoil (0–0.2 m) decreased by 27% after desert soil was cultivated, total
carbon stock within the soil profile (0–2.5 m) increased by 57% due to the significant increase in carbon stock at 0.2- to
2.5-m depth, and carbon efflux also markedly increased at 0- to 0.6-m depth. In the topsoil, the carbon process of the oasis
was mainly dominated by consumption; in the subsoil (0.2–0.6 m) it was likely to be co-dominated by storage and consumption,
and the greatest difference in SOC stock between the two soils also lay in this layer; while in the deep layer (0.6–2.5 m)
of the oasis, with a more stable carbon stock, there was carbon storage dominated. Moreover, carbon stocks in the deep layer
of the two soils contributed about 65% of the total carbon stocks, and correspondingly, microbial activities contributed 71%
to the total microbial activity in the entire soil profile, confirming the importance of carbon cycling in the deep layer.
Desert cultivation in this area may produce unexpectedly high carbon stocks from the whole profile despite carbon loss in
the topsoil. 相似文献
20.
Particulate organic carbon found in sea foam and water samples from North Inlet, South Carolina, were examined for their δ13C isotopic composition. Sea foam particulate organic carbon (POC) δ13C values ranged from ?20.4 to ?24.6‰ (mean=?22.3‰) and water POC δ13C values ranged from ?21.0 to ?28.5‰ (mean= ?24.4‰). Temporal trends in sea foam and water POC indicate that δ13C values for both POC components are depleted in the colder months and enriched in the warmer months. Measurement of δ13C from potential sources for organic matter found in sea foam, combined with data on macroalgae productivity and phytoplankton biomass, indicates that macroalgae are the principal source of POC for sea foam in the colder months. In the warmer months, phytoplankton appear to be more important contributors. The observed water POC δ13C values were always depleted relative to foam POC δ13C values. This isotopic difference may result from chemical segregation during sea foam formation or may reflect DOC δ13C values from terrestrial origins. 相似文献