全球变化与陆地生态系统研究：回顾与展望   总被引：16，自引：2，他引：16  

傅伯杰  牛栋  赵士洞 《地球科学进展》2005,20(5):556-560

全球变化与陆地生态系统相互关系的研究是国际地圈－生物圈计划（IGBP）的核心研究计划之一，也是整个全球变化的研究核心领域之一。该计划自上世纪八十年代启动以来，已经取得了一系列重要的研究成果，对于推动全球变化研究发挥了重要作用。中国学者在全球变化与陆地生态系统研究领域也开展了许多工作并取得了重要成绩。按照我国科学技术和社会经济发展的需求，本文提出了未来我国在该领域的研究重点，包括（1）中国陆地生态系统重要生命元素的代谢及其耦合机制研究；（2）全球变化敏感区域或重要样带上陆地生态系统对全球变化的影响研究；（3）我国的C、N、P、S生物地球化学循环与全球变化的关系研究；（4）发展中国特色的区域植被动态模型。  相似文献   

The granite-upper mantle connection in terrestrial planetary bodies: an anomaly to the current granite paradigm?   总被引：2，自引：0，他引：2  

Bernard Bonin  Jean Bbien 《Lithos》2005,80(1-4):131-145

Granite formed in the terrestrial planets very soon after their accretion. The oldest granite-forming minerals (4.4 Ga zircon) and granite (4.0 Ga granodiorite) indicate conditions resembling the present-day ones, with the presence of oceans and external processes related to liquid water. As a result, the current granite paradigm states that granite is not issued directly from the melting of the mantle. However, a granite-upper mantle connection is well established from several pieces of evidence. Tiny micrometre- to millimetre-sized enclaves of granite-like glassy and crystalline materials in Earth's mantle rocks are known in oceanic and continental areas. Earth's mantle-forming minerals, such as olivine, pyroxene, and chromite, can contain silicic materials, either as glass inclusions or as crystallised products (quartz or tridymite, sanidine, K-feldspar, and/or plagioclase close to albite end-member). Importantly, the same evidence is amply found in some types of meteorites, whether they are primitive, such as ordinary chondrites, or differentiated, such as IIE irons, howardite–eucrite–diogenite (HED), and Martian shergottite–nakhlite–chassignite (SNC) achondrites. Although constituting apparently an anomaly, the granite-upper mantle connection can be reconciled with the current granite paradigm by recognising that the conditions prevailing in the formation of granite are not only necessarily crustal but can occur also at depths in mantle rocks. Unresolved problems to be explored further include whether tiny amounts of granitic material within terrestrial mantles may be hints of greater abundances and more direct mantle involvement, and what role can be played by granite trapped within the upper mantle in lithosphere buoyancy.  相似文献   

A new combined European permanent network station coordinates solution     

N. Panafidina  Z. Malkin  R. Weber 《Journal of Geodesy》2006,80(7):373-380

The EUREF [International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe] network of continuously operating GPS stations (EPN) was primarily established for reference frame maintenance, and also plays an important role for geodynamical research in Europe. The main objective of this paper is to obtain an independent homogeneous time series of the EPN station coordinates, which is also available in SINEX format. A new combined solution of the EPN station coordinates was computed. The combination was performed independently for every week, in three steps: (1) the stated constraints on the coordinates were removed from the individual solutions of the Analysis Centers; (2) the de-constrained solutions were aligned to ITRF2000; (3) the resulting solutions were combined using the Helmert blocking technique. All the data from GPS weeks 900 to 1302 (April 1997–December 2004) were used. We investigated in detail the behavior of the transformation parameters aligning the new combined solution to ITRF2000. In general, the time series of the transformation parameters show a good stability in time although small systematic effects can be seen, most likely caused by station instabilities. A comparison of the new combined solution to the official EUREF weekly combined solution is also presented.  相似文献   

Thermosteric Effects on Interannual and Long-term Global Mean Sea Level Changes     

J. L. Chen  C. R. Wilson  B. D. Tapley  X. G. Hu 《Journal of Geodesy》2006,80(5):240-247

We investigate global mean sea level (MSL) changes and different geophysical contributions at interannual and long-term (decadal) time-scales. Thermosteric effects of global MSL changes are estimated from ocean temperature anomaly data for the period 1955–2003 from the World Ocean Database 2001 (WOD01), plus additional data processed through June 2004. Estimates based on WOD01 show significant differences to previously published results based on similar temperature anomaly data from the World Ocean Database 1998 (WOD98), especially during the period overlapping with the TOPEX/Poseidon satellite altimeter mission. During this period (1993–2004), the WOD01-estimated thermosteric contribution of global MSL change is less than half of the estimate from WOD98 (1.3 ± 0.1 vs. 3.0 ± 0.6 mm/year), as compared to the rate of 2.6 ± 0.06 mm/year observed by satellite altimeters. The larger uncertainty in ocean temperature profiles and incomplete data collection in WOD98, especially in the later years (1997 and 1998) appear to be the major error sources to the overestimated steric effects by WOD98. During the entire 50-year period, the steric effect on global MSL change amounts to about 0.34–0.39 (±0.05) mm/year. Strong interannual and decadal variability exists in estimated thermosteric contributions to the global MSL change, and (surprisingly) the thermosteric effect does not show any pronounced contribution to the strong interannual variability during the 1997/1998 El Niño/La Niña event. Our analysis based on the National Centers for Environmental Prediction reanalysis atmospheric model and the National Oceanic and Atmospheric Administration Climate Prediction Center global land data assimilation system indicates that atmospheric water vapor and terrestrial water storage changes show strong interannual variability that is well correlated with observed global MSL change, and could have significant effects on interannual global MSL changes.  相似文献   

地热异常区与降水异常区及地形变速率的关系   总被引：1，自引：0，他引：1  

马柱国 《高原气象》1996,15(3):311-317

利用我国１９５４－１９９３年的季距平３．２ｍ地温资料，对“地热涡”的空间分布规律进行了统计分析。结果表明：一般其高频区与地形变速率绝对值的大值区对应，与降水异常的高频区基本对应，但中心位置大多偏离２００ｋｍ左右；其低频区与地形变速率弱的地区对应，与降水异常的低频区亦基本对应。  相似文献   

华南亚热带山地土壤有机质更新特征定量研究   总被引：12，自引：3，他引：12  

陈庆强  孙彦敏  沈承德  彭少麟  易惟熙  姜漫涛  李志安 《地理科学》2002,22(2):196-201

选择鼎湖山自然保护区森林植被带（SL）、灌丛一草甸过渡带土壤剖面（GC）进行薄层取样，根据土壤有机质^14C放射性水平，运用模型计算土壤有机质更新速率（m）。结果表明上部0－10cm土层有机质更新速率（m）最高；向下,m锐减；剖面下部m值极低，这说明土壤有机质由不同更新周期（T）组分构成。表层快循环组分占绝对优势，向下，慢循环组分为主，剖面下部为稳定组分。根据m、有机碳含量、有机碳含量、土壤容重、土层厚度计算有机质更新CO2产量，表层0－10cm层段CO2产量约为整个剖面的98％。SL剖面m值及有机质更新CO2产量均明显大于GC剖面相应值。分析表明在同一气候植被是制约土壤有机质更新及CO2产量的第一要素，这为通过绿化加强土壤碳汇功能提供重要依据。  相似文献   

氮输入对陆地生态系统碳循环关键过程的影响   总被引：12，自引：3，他引：9  

彭琴  董云社  齐玉春 《地球科学进展》2008,23(8):874-883

碳氮作为陆地生态系统最关键的两大生源要素,它们在自然界的循环过程中不仅各自对全球变暖做出重要贡献,而且两者的循环过程显著耦合,互相影响各自的作用和效果。从氮元素对植物光合作用、呼吸作用以及土壤呼吸作用影响的角度入手,综述了氮输入对陆地生态系统碳固定和碳排放这两个碳循环关键过程的影响特征和机理,分析了陆地生态系统碳源汇对氮素变化响应的不确定性,在此基础上对未来的相关重点研究方向进行了探讨和展望。  相似文献   

Description of Ecosystem of the Lower Odra and the Odra Estuary     

J. C. Chojnacki 《洁净——土壤、空气、水》1999,27(5):257-267

Environmental conditions of the lower river Odra and its estuary show a high variability of chemical and biological parameters, related to the dynamics of the river, its mouth area, the Lake Dabie-Szczecin Lagoon system, and the Pomeranian Bay. Water chemistry, affected by the total sum of industrial, urban, and agricultural pollution discharged from the direct drainage area is discussed. This pollution load influences the composition and ecological structures of terrestrial, frequently unique, phytal communities associated with aquatic areas, phyto- and zooplankton, benthos, fish fauna, and avifauna. The current status of the terrestrial and aquatic ecosystems is described; elements of cultural infrastructure existing within the Lower Odra Valley in Western Pomerania are mentioned as well.  相似文献   

川东南焦石坝页岩气区现今地温场特征   总被引：2，自引：1，他引：1       下载免费PDF全文

李春荣  饶松  胡圣标  汪集旸  魏志红  黄庆球  胡东风  郭旭升 《地球物理学报》2017,60(2):617-627

四川盆地是我国重要的含油气区,关于盆地现今地温场的工作,前人已经做过一些研究.而对于近年来页岩气勘探取得突破性进展的川东南焦石坝地区,现今地温场的研究工作甚少.本文基于川东南高陡褶皱带焦石坝页岩气区新增的3口钻井的稳态测温数据和118块岩石样品热导率数据,计算了研究区的地温梯度和大地热流值.结合前人的研究成果,编制了研究区大地热流等值线图.结果表明,焦石坝页岩气区地温梯度介于24~34℃/km,大地热流值介于60~70mW·m~(-2)之间,与川中古隆起相似,属于地温高异常区.地温高异常缘于隆起区相对高的岩石热导率引起的浅部热流的重新分配.其次,与位于研究区东侧边界的齐岳山大断裂在燕山和喜山期的构造引起的热液活动有关.焦石坝页岩气区地温高异常对页岩气的解吸附速率具有促进作用,对提高采收率具有一定意义.  相似文献   

Survival of a proto-atmosphere through the stage of giant impacts: the mechanical aspects   总被引：2，自引：0，他引：2  

Hidenori Genda  Yutaka Abe 《Icarus》2003,164(1):149-162

When a giant impact occurs, atmosphere loss may occur due to global ground motion excited by a strong shock wave traveling in the planetary interior. Here, the relations between the ground motion and the amount of the lost atmosphere are systematically investigated through calculations of a spherically one-dimensional atmospheric motion for various initial atmospheric conditions. The fraction of the lost atmosphere to the total mass of the atmosphere is found to be controlled only by the ground velocity and, insensitive to the initial atmospheric conditions. Unlike the previous studies (Ahrens, 1990, Origin of the Earth, H.E. Newson, J.H. Jones (Eds.), pp. 211-227; Ahrens, 1993, Annu. Rev. Earth Planet. Sci. 21, 525-555; Chen and Ahrens, 1997, Phys. Earth Planet. Inter. 100, 21-26); the estimated loss fraction for the giant impact is only 20%. Significant escape occurs only when the ground velocity is close to the escape velocity. Thus, most of the atmosphere should survive the giant impact. The cause of the difference from previous estimates is discussed from energetic and dynamic points of view. Moreover, if our estimates are applied to the atmosphere of the impactor planet, a significant fraction of it is carried to the target planet. Survival of the proto-atmosphere has very important effects on the origin and evolution of the terrestrial planets' volatile budget.  相似文献