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1.
黑碳被认为是除温室气体外对气候变暖贡献最大的辐射强迫因子.三极(北极、南极和青藏高原)地区是全球雪冰分布最集中的区域,沉积至雪冰中的黑碳可反映人类活动的历史变化,并可能导致反照率降低而影响物质能量平衡.通过系统回顾三极地区雪冰黑碳的研究方法、空间分布、时间变化及其造成的辐射强迫,得到的研究结果表明:由于处于不同的地理位... 相似文献
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3.
南极和北极地区在全球变化中的作用研究 总被引：23，自引：1，他引：23
近半个世纪的调查基本揭示了极地在地球系统中的作用。两极保持了世界 99%的冰川 ,相当于全球淡水的 78% ,全部融化将使地球海平面上升 70m。极区又是世界气候系统中最活泼的组成 ,通过其冰盖、大气和周围海域的强烈耦合过程而影响全球。同时 ,南极上空臭氧空洞的出现 ,北极地区冻土带的北移等都表明全球变化也在明显地影响着两极。中国 2 0年来对南极的考察过程中 ,建立两个南极科学考察站 ,拥有极地考察破冰船 ,1999年开展了中国首次北极科学考察 ,对南北极的区域特征及其在全球变化中的作用提出了新的认识。 相似文献
4.
北极海冰减退引起的北极放大机理与全球气候效应 总被引：5，自引：1，他引：4
自20世纪70年代以来,全球气温持续增高,对北极产生了深刻的影响。21世纪以来,北极的气温变化是全球平均水平的2倍,被称为"北极放大"现象。北极海冰覆盖范围呈不断减小的趋势,2012年北极海冰已经不足原来的40%,如此大幅度的减退是过去1 450年以来独有的现象。科学家预测,不久的将来,将会出现夏季无冰的北冰洋。全球变暖背景下北极内部发生的正反馈过程是北极放大现象的关键,不仅使极区的气候发生显著变化,而且对全球气候产生非常显著的影响,导致很多极端天气气候现象的发生。北极科学的重要使命之一是揭示这些正反馈过程背后的机理。北极放大有关的重大科学问题主要与气—冰—海相互作用有关,海冰是北极放大中最活跃的因素,要明确海冰结构的变化,充分考虑融池、侧向融化、积雪和海冰漂移等因素,将海冰热力学特性的改变定量表达出来。海洋是北极变化获取能量的关键因素,是太阳能的转换器和储存器,要认识海洋热通量背后的能量分配问题,即能量储存与释放的联系机理,认识淡水和跃层结构变化对海气耦合的影响。全面认识北极气候系统的变化是研究北极放大的最终目的,要揭示气—冰—海相互作用过程、北极海洋与大气之间反馈的机理、北极变化过程中的气旋和阻塞过程、北极云雾对北极变化的影响。在对北极海冰、海洋和气候深入研究的基础上,重点研究极地涡旋罗斯贝波的核心作用,以及罗斯贝波变异的物理过程,深入研究北极变化对我国气候影响的主要渠道、关键过程和机理。 相似文献
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H.Moses Chung Sheri W. Brand Patrick L. Grizzle 《Geochimica et cosmochimica acta》1981,45(10):1803-1815
Twenty crude oils from Paleozoic reservoirs in the Big Horn Basin. Wyoming were fractionated into light hydrocarbons, saturates, monoaromatics. diaromatics, polyaromatics-and-polars. and asphaltenes. Amounts and isotopic composition of each fraction were found to be internally consistent with the degree of maturation of the oil. confirming the established single source origin for these oils. A variation of approximately three per mil in the carbon isotopic composition of the whole oil and individual fraction was explained as being caused by maturation. The isotope-type-curves for these oils, the variations in isotopic composition as a function of compound group-type, were not found to be as simple as commonly believed. Other alteration processes, such as migration and deasphalting, might have influenced the pattern of the isotope distributions among fractions. The conservative nature of mass balance and subsequent isotope flows among various fractions of crude oil showed that the maturation of crude oil consists of consecutive processes leading from larger and more polar components into smaller and less polar components culminating in natural gas. Calculations were made to project the amount of condensates associated with the crude oils, and the amount of natural gas which had been generated from crude oils of a given maturity. 相似文献
6.
Angel Paniagua 《GeoJournal》2018,83(5):993-1004
The aim of this study is to place the current geographical debate on nature in the context of protected natural areas severely affected by depopulation processes, in which the daily lives of the inhabitants have been altered by changes in the traditional balance between human and non-human populations. A significantly humanized area within the Sierra Norte de Guadalajara National Park in central Spain is considered as an example. The qualitative methodology followed is based on documentary analysis and interviews with key inhabitants in the area, revealing narratives with a productive or consumer view of the nature. The national park appears as a container of a cultural nature, initially created by the traditional inhabitants, which generates an artificial, excessive nature and accelerates regressive sociodemographic dynamics. 相似文献
7.
我国极地海底观测系统的发展与展望 总被引：1，自引：0，他引：1
极地海洋特殊环境对观测技术提出了更高的要求.随着海底观测技术的日趋成熟,极地海底观测系统也得到了一定的发展,但后勤保障的高要求制约了系统的发展,目前广泛使用的仍是潜标系统.受国家高技术研究发展计划、国家海洋公益性行业科研专项经费项目和南北极环境综合考察与评估专项等支持,我国发展了极地在线近岸海洋环境监测系统、极地潜标和极地大型海—气耦合浮标等海床基观测系统,对我国的极地海洋学观测与研究做出了积极贡献.但总体而言,我国的极地海底观测仍未形成真正意义上的网络体系.未来有望在北冰洋太平洋扇区和南大洋普里兹湾率先建立海床基观测体系,系统观测并揭示该海域的环境变化特性. 相似文献
8.
南雄断裂构造剥离作用及其与铀成矿的关系 总被引：4，自引：2，他引：4
南雄断裂带下盘发育规模较大，平行于断裂走向的糜棱岩带，上盘为一中新生代盆地，随着地层时代的变新，沉积中心向断层一侧迁移。本文通过对断裂下盘糜棱岩带的剖面测量，对糜校岩中Ｓ－Ｃ面理、旋转碎斑和拉伸线理等各种韧性变形组构的详细研究，根据变形组构的运动学指向，结合断裂带内脆性构造岩及盆地中正断层的发育状况和展布特征，确定南雄断裂为一规模巨大的剥离断层。对剥离断层与铀成矿的关系本文也进行了初步探讨。 相似文献
9.
衡山变质核杂岩体西缘剥离断层及其对铀成矿的控制作用 总被引：6，自引：1，他引：6
衡山变质核杂岩体是由元古界深变质岩和燕山期复式花岗岩体组成，其西缘的界版剥离断层是区域深断裂的一部分，在断裂下盘山现糜棱岩－混合岩带具韧性变形特征，沿断裂已发现一些有意义的铀矿化，根据剥离断层控矿模式，提出在断裂上盘王冲－谢马冲地段寻找陡倾正断层与离断层交切处的隐伏铀矿的设想。 相似文献
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内陆河流域水文过程研究的一些科学问题 总被引：5，自引：0，他引：5
水科学研究的发展,对水文科学提出了新的挑战,即如何在流域、区域和全球尺度进行学科交叉、综合集成和协同研究,从而更全面地认识水在地球资源和环境变化中的作用,认识水圈及其与大气圈、岩石圈和生物圈的相互作用。为了解内陆河流域水文循环和水量平衡各分量之间的变化和转化关系及其与生态和环境之间的相互作用,以及对全球变化和人类活动的响应和反馈,基于内陆河流域上游山区径流形成区、中游人工绿洲水资源开发利用区和下游荒漠绿洲径流散失区的流域水文循环特征,从能水通量、生态和生物地球化学过程讨论了山区水文过程;从生态水文、尺度转换、阈值和反馈讨论了水文和植被的相互作用;从国外提出的关键作用带的概念讨论了内陆河流域地下水—土壤—植被作用层的水文过程。提出了开展内陆河流域水文过程观测和研究的基本框架。 相似文献
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In this paper the characteristics of surface radiative fluxes and cloud-radiative forcing are reviewed with a focus on the Arctic. Three aspects are addressed, including (i) changes in radiation flux over the global surface; (ii) characteristics of surface fluxes in the Arctic; and (iii) characteristics of cloud-radiative forcing in the Arctic. The clouds not only significantly reduce the peak summer radiative heating of the surface but also reduce the wintertime radiative cooling at the surface in higher latitudes. The downward longwave fluxes dominates the incident radiative fluxes in the Arctic during most of the year. Incoming shortwave fluxes are negligible during late fall, winter and early spring, and even during the midsummer the incoming shortwave fluxes are only slightly greater than the downward longwave fluxes. The total net surface radiative flux is negative for most of the year and only positive during midsummer in the Arctic. The global net cloud-radiative forcing is negative, but the cloud-radiative forcing is positive in the Arctic, showing a warming effect, except for a short period in mid-summer. Positive cloud-radiative forcing in the Arctic is attributed to the presence of snow and ice with high albedo and the absence of solar radiation during the polar night. 相似文献
12.
Ersi Kang Rensheng Chen Zhihui Zhang Xibin Ji Bowen Jin 《Frontiers of Earth Science》2008,2(4):384-392
The challenge is put forward to scientific hydrology by the advancement of water sciences; that is, how should we carry out
a multidisciplinary, integrated and cooperative research on hydrological processes in the basin, regional and global scales,
in order to better understand the role water plays in the changes of the natural resources and environment of the earth, and
to understand the hydrosphere and its interactions with the atmosphere, lithosphere and biosphere. How the changes and transformation
of the components of the water cycle and water balance occur in an inland river basin has yet to be understood. We also need
to understand what the interactions of water cycle, ecosystems and environment are, and what the responses and feedback of
the changes to global change and to human activities are. The water cycle in an inland river basin characterizes the runoff
generation region of the mountains upstream, the artificial oases region of water resources exploitation and utilization midstream
and the natural desert oases region of runoff dissipating downstream. The mountain hydrological processes are discussed from
water cycle, energy balance, water balance and ecological processes. The interactions of water and vegetation are discussed
in relation to ecohydrology, and the hydrological processes in the ground water-soil-vegetation layer are discussed from the
concept of the critical zone newly put forward abroad. The basic frame is put forward to carry out the field measurement,
experiment and studies of hydrological processes in a typical inland river basin.
__________
Translated from Advances in Earth Science, 2007, 22(9): 940–953 [译自: 地球科学进展] 相似文献
13.
湘东北长沙—平江断裂动力变质带的构造及地球化学特征 总被引：6，自引：0，他引：6
张文山 《大地构造与成矿学》1991,15(2):100-109
长沙—平江动力变质带是组成湘东北中生代地洼型拉伸构造型式的剥离断层带,其中的糜棱岩是大型韧性滑脱剪切作用的产物。文中重点阐述了糜棱岩的构造及地球化学特征及其成因意义,表明该断裂带的动力变质作用与大规模的地洼岩浆活动有着密切的生成联系,这可能是地洼构造演化的一个重要特征。 相似文献
14.
本文以青藏高原东缘的三级地貌(川西高原、龙门山和四川盆地)单元为基础,利用裂变径迹定年数据分区块研究了该地区的晚新生代以来的剥蚀速率。研究结果表明,晚白垩世以来青藏高原东缘经历了一个由平缓到突然加速的剥蚀过程,其转折点为中新世。在整个时间段内的平均剥蚀速率,川西高原为0.26mm/yr,龙门山为0.72mm/yr,四川盆地为0.20mm/yr。龙门山的剥蚀速率大约是川西高原的2.8倍,间接反映边缘山脉的隆升并不等同于高原内部的隆升,边缘山脉的隆升可能是构造隆升和剥蚀隆升相叠加的结果。 相似文献
15.
油气是重要的战略资源。其中天然气作为清洁能源,它曾经是,现在是,在可预期的未来——全球碳减排、中国碳达峰情景下,仍然是最重要的能源资源。能源进口渠道的多元化一直是中国缓解能源紧张的有效措施之一。北极地区油气资源丰富且以天然气为主,已发现的油气资源中绝大多数在俄罗斯,尤其是天然气。但是俄罗斯天然气生产的油气田80%以上已经进入北极圈。2012年,中俄合作开发北极亚马尔液化天然气项目正式启动,标志着中国参与北极油气资源开发利用取得重要进展,也事实上开启了中国主导的"丝绸之路经济带建设"和俄罗斯主导的"欧亚经济联盟建设"对接合作的进程。北极地区已发现的油气资源共计3289.4亿桶油当量,其中石油605.4亿桶（84.1亿吨）油当量,仅为全球已发现石油资源的2.5%;天然气41.4万亿立方米（约合2683亿桶,372.6亿吨油当量）,占全球已发现天然气资源的15.5%。北极地区已发现的油气总资源中绝大多数在俄罗斯,俄罗斯已发现的北极油气资源合计2905亿桶油当量（403.5亿吨）,占88.3%;其中天然气约39.47万亿立方米,约合2557.9亿桶（355.3亿吨）油当量,占北极地区已发现天然气总资源的95%以上。北极待发现的油气资源量也非常可观,约占世界待发现常规石油资源的15%;天然气占世界待发现常规天然气资源的30%,其分布也主要在俄罗斯。随着全球气候变暖和能源战略博弈,俄罗斯为确保其天然气出口及财政来源,必然要加大北极油气、特别是天然气的开采和开发,并通过北极航道运到中国和其他消费国。本文在概括分析北极油气资源分布特点、俄罗斯油气资源与北极战略及北方海航道通行能力的基础上,回顾了北极亚马尔液化天然气项目诞生、发展演变及其国际博弈的背景;概括介绍了中国成功介入北极油气资源项目这一标志性事件过程,并进一步提出了中国对北极油气资源利用战略举措的建议。 相似文献
16.
Shiv Mohan Singh Kumar Avinash Parmanand Sharma Ravindra Uttam Mulik Ajay Kumar Upadhyay Rasik Ravindra 《地学前缘(英文版)》2017,8(6):1339-1347
Cryoconite samples were collected from two different climatic domains i.e., the Sutri Dhaka glacier, western Himalaya India and Svalbard glaciers, the Spitsbergen, Arctic, to understand the elemental source and elemental deposition patterns. The data of geochemical analysis suggest that the Himalayan cryoconite samples accumulate higher concentrations as compared to the cryoconite samples of the Arctic glaciers. The concentration of lithophile elements (Cs, Li, Rb and U) was recorded higher in the cryoconite holes of the Himalayas, especially, in the lower to the higher parts of the glacier, whereas, lower concentrations were recorded in the Arctic samples. Chalcophile elements in the Himalayan cryoconites are enriched in As and Bi while the Arctic cryoconite samples show a higher concentration of Bi, Pb and As. The higher concentrations are responsible for influencing the ecosystem and in human health related issues. Siderophile elements (Co, Fe, Mn and Ni) show high concentrations in the Himalayan samples, whereas, the Arctic samples show minor variations and low elemental concentration in these elements, respectively. In addition, a few elements, such as Ag, Mg, and Ca show higher concentration in the Himalayan glacier samples. Ca also occurs in high concentrations in Arctic glacier samples. R-mode factor analysis of the Himalayas (Arctic) samples indicate that the elements are distributed in four (three) factors, explaining 89% (90%) of the variance in their elemental distribution. The Factor 1 suggests statistically significant positive loadings for most of the lithophile, chalcophile and siderophile elements of the “Himalayan” and the Arctic cryoconite samples. The sample-wise factor score distribution shows a considerable variation in the sampling locations along the glaciers of both the regions. Factors 2 and 3, demonstrate insignificant loading for most of the elements, except statistically significant positive loading in some of the elements of the both, Himalayan and Arctic “cryoconites”. The higher elemental concentration in the cryoconites of the Himalayan region may be an indicator of the natural processes and/or attributed to the rapid industrialization in the Asian countries. 相似文献
17.
首次依空间结构将青藏高原划分为外围高山、外缘高山、高原面高山、高原面及高原盆地等五种地貌体;厘清了高原不存在纬度地带性的误判,并结合作者前期高原苔原的论证,创建了高原苔原带谱体系及其三维仿真地带模型,分别为顶锥型(外围离散高山及高原面高山)、带型(外缘带状高山)和平面型(高原面).既具有一般高山苔原(alpine tundra)垂直带谱,又呈现高原山原苔原所特有的"复式三维地带性模式",在全球具有唯一性.首次编制了表征北极苔原与高原苔原关系的北半球苔原带模式图,指出长白山为东北亚高山苔原南界的论点不能成立,青藏高原苔原才是中国及东北亚苔原的南界.目前高原是第三极称谓皆无顶极生物带苔原带景观为前提,仅是高度上的寓意,从地理概念上明确了其与南北极并列的世界第三极定位. 相似文献
18.
南北极海区碳循环与全球变化研究 总被引：14，自引：1，他引：14
南北极是全球变化研究领域中十分重要的地区 ,也是世界大洋对全球变化反馈的一个重要窗口。文章论述了南北极海区碳循环研究的国内外研究动态 ,阐述了目前南大洋及北冰洋的生产力水平及碳收支平衡状态 ,讨论需要进一步研究的一些存在问题以及将来的发展方向。目前的研究表明 ,北极的生产力比历史上所认为的要高 ,在全球变化的作用下 ,其将成为越来越重要的碳汇区 ;南大洋主控着人为源CO2 的海气交换通量 ,而生产力所受到的限制也影响着其吸收CO2 的潜力。目前制约着对两极碳循环进一步认识所缺乏的资料包括 :极区碳汇的时空变异、南大洋的Fe限制及Fe假说、紫外增强对极区碳循环可能产生的影响等。今后研究的重点将集中在全球变化对两极碳循环的影响及其反馈 ,碳循环的机制及其动力学过程 ,以及通过碳循环人为干预全球变化的可行性。近年来 ,中国也十分重视极区碳循环的研究 ,取得了许多积极的成果。我们的研究结果表明 ,在 80°E～ 80°W之间 ,南大洋基本上是大气CO2 的汇 ,其中在 45°W～ 30°W及 10°W～ 10°E之间 ,是CO2 的强汇区。北冰洋的一些海区也表现为很强的碳汇区。计算得出 ,楚科奇海及其附近海区 7月到 9月CO2 吸收通量为 0 13g/ (m2 ·d) (碳 )。南大洋夏季CO2 吸收通量为 0 1g/ (m2 · 相似文献
19.
The evidence for the extent and timing of Weichselian glaciation in Arctic regions shows that: (1) there were no major marine ice domes in the Arctic at 18,000 B.P. but that glaciers were relatively limited in extent; (2) there were no extensive ice shelves at 18,000 B.P. as envisaged by Hughes, Denton & Grosswald(1977); (3) the major periods of glacier expansion were between 125,000 and 80,000 B.P., just prior to 45,000 B.P., and between 11,000 and 8,000 B.P., and thus that glacier fluctuations at the southern margins of the Laurentide and Fennoscandian ice sheets were out of phase with those in the Arctic which advanced during southern interstadials. Phases of glacier advance in the Atlantic sector of the Arctic can be identified in deep sea cores by the peaks in concentration of iceberg-dropped detritus and an increase in sedimentation rates, which are highest when sub-polar water penetrates to the north. The key to the temporal pattern of Arctic glaciation and its association with oceanic changes is given by the intimate association of present-day Arctic glacierisation with the two major low pressure troughs which penetrate the Arctic in the Atlantic sector and in Baffin Bay. The chronology of glaciation in the Atlantic sector is associated with the activity of these troughs and the related oceanic circulation. Cooling of the Arctic due to reduction in solar radiation at the end of the last interglacial, when the pack ice lay north of 75d?N in the Atlantic, produced ideal conditions for Arctic glacier growth, with moisture transported by a strong cyclonic flux into a cooling Arctic from a strong North Atlantic Drift current. A positive feedback loop involving ocean and atmospheric circulation and pack ice, caused movement of the polar front to the south, thus slowly cutting off the supply of moisture to the Arctic. Further cooling at 75,000 B.P. caused a rapid extension of the polar front south of 45d?N, effectively cut off the northward movement of surface currents on the North Atlantic, and produced a strong zonal oceanic and atmospheric circulation which starved Arctic glaciers of nourishment and caused their retreat, and initiated rapid build up of the Fennoscandian and Laurentide ice sheets. Subsequent extensions of Arctic glaciers were associated with limited northward movement of sub-polar water and associated Atlantic depressions. The expansion of glaciers within the Arctic between 11,000 and 8,000 B.P. was associated with the first and diachronous penetration of moisture into a still cool Arctic during decay of the two great ice sheets. 相似文献
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Yu. V. Barkhatov A. A. Tikhomirov S. A. Ushakova V. N. Shikhov S. I. Bartsev A. G. Degermendzhi 《Doklady Earth Sciences》2016,471(1):1168-1170
A sealed vegetation chamber was designed and constructed for physical simulation of climate conditions in the Subarctic zone during the spring–summer time. The small laboratory tundra-simulating ecosystem (TSE) was created for comparative evaluation of the rates of soil respiration and of the total balance of carbon fluxes in tundra ecosystems. The test experiment was performed to study the TSE response to a temperature rise in air and soil by 2°C in terms of the intensity of the СО2 flux. It was shown that this increase in temperature would cause a pronounced shift in the balance of СО2 production and utilization in the ecosystem from near-zero values to a stable generation of 24 μmol/h of CO2 per 1 kg of dry biomass. 相似文献