Be data from meltwater channels suggest that Jameson Land, east Greenland, was ice-covered during the last glacial maximum     

Lena Håkansson  Jason P. Briner  Ala Aldahan  Göran Possnert 《Quaternary Research》2011,76(3):452-459

Along the northeast Greenland continental margin, bedrock on interfjord plateaus is highly weathered, whereas rock surfaces in fjord troughs are characterized by glacial scour. Based on the intense bedrock weathering and lack of glacial deposits from the last glaciation, interfjord plateaus have long been thought to be ice-free throughout the last glacial maximum (LGM). In recent years there is growing evidence from shelf and fjord settings that the northeast Greenland continental margin was more extensively glaciated during the LGM than previously thought. However, little is still known from interfjord settings. We present cosmogenic ¹⁰Be data from meltwater channels and weathered sandstone outcrops on Jameson Land, an interfjord highland north of Scoresby Sund. The mean exposure age of samples from channel beds (n = 3) constrains on the onset of deglaciation on interior Jameson Land to 18.5 ± 1.3–21.4 ± 1.9 ka (for erosion conditions of 0–10 mm/ka, respectively). This finding adds to growing evidence that the northeast Greenland continental margin was more heavily glaciated during the LGM than previously thought.  相似文献   

异常压力对有机质的抑制作用及其石油地质意义   总被引：2，自引：1，他引：1  

李会军  吴泰然  郝银全  张秀珠  马宗晋 《沉积学报》2004,22(4):737-742

板桥凹陷异常压力发育,在板深35井中发现有机质的演化明显的受到了超压的抑制作用,具有和活化能、热导率、水动力等因素造成的热演化异常明显不同的特征。综合地质、地球化学分析表明,异常孔隙流体压力对有机质热演化的抑制作用是有条件的,在超压早期发育、高原始有机质丰度和高有机质热演化产物滞留的情况下超压对有机质的演化具有明显的抑制作用,超压对有机质演化的抑制作用在深层勘探方面具有重要的意义。  相似文献   

Drifting runoff periodicity during the 20th century due to changing surface water volume     

Anders Wörman  Göran Lindström  Anna Åkesson  Joakim Riml 《水文研究》2010,24(26):3772-3784

Fourier and wavelet analyses were used to reveal the dominant trends and coherence of a more than one‐century‐long time series of precipitation and discharge in several watersheds in Sweden, two of which were subjected to hydropower and intensive agriculture. During the 20th century, there was a gradual, significant drift of the dominant discharge periodicity in agricultural watersheds. This study shows that the steepness of the Fourier spectrum of runoff from the May to October period each year increased gradually during the century, which suggests a more predictable intra‐annual runoff pattern (more apart from white‐noise). In the agricultural watershed, the coherence spectrum of precipitation and runoff is generally high with a consistent white‐noise relationship for precipitation during the 20th century, indicating that precipitation is not controlling the drift of the discharge spectrum. In the hydropower regulated watershed, there was a sudden decrease of the discharge spectrum slope when regulation commenced in the 1920s. This study develops a new theory in which the runoff spectrum is related to the hydraulic and hydro‐morphological characteristics of the watershed. Using this theory, we explain the changes in runoff spectra in the two watersheds by the anthropogenic change in surface water volume and, hence, changes in kinematic wave celerity and water transit times. The reduced water volume in the agricultural watershed would also contribute to decreasing evaporation, which could explain a slightly increasing mean discharge during the 20th century despite the fact that precipitation was statistically constant in the area. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

The Phase A study of the ESA M4 mission candidate ARIEL     

Ludovic Puig  Göran Pilbratt  Astrid Heske  Isabel Escudero  Pierre-Elie Crouzet  Bram de Vogeleer  Kate Symonds  Ralf Kohley  Pierre Drossart  Paul Eccleston  Paul Hartogh  Jeremy Leconte  Giusi Micela  Marc Ollivier  Giovanna Tinetti  Diego Turrini  Bart Vandenbussche  Paulina Wolkenberg 《Experimental Astronomy》2018,46(1):211-239

ARIEL, the Atmospheric Remote sensing Infrared Exoplanet Large survey, is one of the three M-class mission candidates competing for the M4 launch slot within the Cosmic Vision science programme of the European Space Agency (ESA). As such, ARIEL has been the subject of a Phase A study that involved European industry, research institutes and universities from ESA member states. This study is now completed and the M4 down-selection is expected to be concluded in November 2017. ARIEL is a concept for a dedicated mission to measure the chemical composition and structure of hundreds of exoplanet atmospheres using the technique of transit spectroscopy. ARIEL targets extend from gas giants (Jupiter or Neptune-like) to super-Earths in the very hot to warm zones of F to M-type host stars, opening up the way to large-scale, comparative planetology that would place our own Solar System in the context of other planetary systems in the Milky Way. A technical and programmatic review of the ARIEL mission was performed between February and May 2017, with the objective of assessing the readiness of the mission to progress to the Phase B1 study. No critical issues were identified and the mission was deemed technically feasible within the M4 programmatic boundary conditions. In this paper we give an overview of the final mission concept for ARIEL as of the end of the Phase A study, from scientific, technical and operational perspectives.  相似文献   

Observation-based evaluation of surface wave effects on currents and trajectory forecasts     

R&#;hrs  Johannes  Christensen  Kai H&#;kon  Hole  Lars Robert  Brostr&#;m  G&#;ran  Drivdal  Magnus  Sundby  Svein 《Ocean Dynamics》2012,62(10):1519-1533

Knowledge of upper ocean currents is needed for trajectory forecasts and is essential for search and rescue operations and oil spill mitigation. This paper addresses effects of surface waves on ocean currents and drifter trajectories using in situ observations. The data set includes colocated measurements of directional wave spectra from a wave rider buoy, ocean currents measured by acoustic Doppler current profilers (ADCPs), as well as data from two types of tracking buoys that sample the currents at two different depths. The ADCP measures the Eulerian current at one point, as modelled by an ocean general circulation model, while the tracking buoys are advected by the Lagrangian current that includes the wave-induced Stokes drift. Based on our observations, we assess the importance of two different wave effects: (a) forcing of the ocean current by wave-induced surface fluxes and the Coriolis–Stokes force, and (b) advection of surface drifters by wave motion, that is the Stokes drift. Recent theoretical developments provide a framework for including these wave effects in ocean model systems. The order of magnitude of the Stokes drift is the same as the Eulerian current judging from the available data. The wave-induced momentum and turbulent kinetic energy fluxes are estimated and shown to be significant. Similarly, the wave-induced Coriolis–Stokes force is significant over time scales related to the inertial period. Surface drifter trajectories were analysed and could be reproduced using the observations of currents, waves and wind. Waves were found to have a significant contribution to the trajectories, and we conclude that adding wave effects in ocean model systems is likely to increase predictability of surface drifter trajectories. The relative importance of the Stokes drift was twice as large as the direct wind drag for the used surface drifter.

  相似文献   

Identifying burdens of coping with climate change: A typology of the duties of climate justice     

Göran Duus-Otterström  Sverker C. Jagers 《Global Environmental Change》2012,22(3):746-753

One of the central questions in climate change debates concerns fair burden-sharing, i.e. justice in the distribution of costs of undertaking climate-managing policies. In this paper it is argued that in order to distribute such costs justly, it is necessary to have a nuanced understanding of what types of burdens they represent. Climate managing policies are usually divided into responses that seek to reduce the concentration of greenhouse gases in the atmosphere (mitigation) and responses that seek to prevent harm arising from a changing climate (adaptation). Some have argued that there are normatively significant differences between mitigation and adaptation: that the two responses adhere to different logics and evoke different patterns of burden-sharing. This paper argues that the relevant distinction is instead between negative and positive climate duties, i.e. whether an agent has a duty to undertake climate-managing policies on account of the harm its excessive emissions are causing or simply on account of its ability to assist those in need. The paper offers a typology of the different mitigation and adaptation responses that can be sorted under the negative/positive distinctions. This way of conceptualizing the issue not only enables us to better address the burden-sharing question, offering a more nuanced understanding of the types of climate burdens that are ascribable to agents and pointing out the appropriate roles of contributory responsibility and ability. It also clarifies aspects of the climate negotiations, and explains why it matters whether adaptation finance transferred to vulnerable countries is portrayed as compensation for harmful emissions or simply as donor countries discharging their humanitarian duties.  相似文献   

Modelling cloud processing of aerosol during the ACE‐2 HILLCLOUD experiment     

Michael L. Flynn  Keith N. Bower  Thomas W. Choularton  Wolfram Wobrock  Jyrki M. Mäkelä  Bengt Martinsson  Göran Frank  Hans&#;Christen Hansson  Hans Karlsson  Paolo Laj 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):779-800

  相似文献   

永蓝高速公路K18+000～K18+350滑坡成因分析与防治措施研究   总被引：2，自引：0，他引：2  

李朋丽  林凯明  李家春  马保成  彭燃 《中国地质灾害与防治学报》2010,21(1):19-23

边(滑)坡灾害的预防和治理在高速公路建设运营中占重要地位。通过对永(州)蓝(山)高速公路K18+000～K18+350白泥坳隧道进口滑坡(简称白泥坳滑坡)的现场调查,从地层岩性、地形地貌、区域构造、气象水文与地下水及施工工序四个方面对滑坡的成因进行了详细研究。根据滑坡的地质构造及变形特征,结合钻孔及工程实地考察资料,分析了滑坡滑动面的可能位置。最后提出了以抗滑桩为主、辅以地表及地下排水设施的综合治理方案,以此达到加固正在发生变形的边坡、防止施工活动对坡体产生扰动导致古滑坡复活的目的。并结合工程实际,提出了抗滑桩及排水设施的施工工艺及流程,对施工过程中的注意事项作了详细说明,为施工提供了可靠依据。  相似文献   

天津地区主要河流表层沉积物中饱和烃的组成与分布特征   总被引：10，自引：1，他引：9  

张枝焕  陶澍  沈伟然  叶必雄  吴水平  施治  潘波  张震  李玉  丁立强 《地球化学》2004,33(3):291-300

根据不同环境功能区 9条河流表层沉积物样品中饱和烃污染物的分析结果,讨论了天津地区河流沉积物中饱和烃化合物的组成与分布特征,初步分析了饱和烃污染物的污染源.结果表明,不同河流表层沉积物中均分布有多种类型的饱和烃化合物,主要包括正构烷烃、无环类异戊二烯烷烃、异构与反异构烷烃、烷基环己烷和甾、萜类等.不同河流及同一河流不同河段的表层沉积物中可抽提有机物(EOM)、烃类化合物含量和饱和烃化合物的组成特征均存在明显的差别,其中北塘排污河(北排污河)和大沽排污河(南排污河)沉积物中 EOM的含量相对较高,海河及津北地区的潮白新河、蓟运河、永定新河、北京排污河的沉积物中 EOM的含量相对较低;北运河、南运河及大沽排污河巨各庄河段的沉积物中烃类化合物含量相对较高,海河、大沽排污河和北塘排污河表层沉积物中烃类污染物的含量相对较低.位于市区北部的河流,靠近市区的河段沉积物中 EOM含量有增加的趋势,而位于市区下游的河流,靠近市区的上游河段的沉积物中 EOM含量相对较高,下游河段的有所降低.河流中烃类污染物主要来源于矿物油及其衍生物、高等植物蜡和藻类的降解产物,不同河流及相同河流不同河段污染源的相对贡献存在明显的差别.  相似文献   

半滑舌鳎病原鳗利斯顿氏菌表型及分子特征研究半滑舌鳎病原鳗利斯顿氏菌表型及分子特征研究     

张晓君  秦国民  阎斌伦  徐静  毕可然  秦蕾 《海洋学报(英文版)》2009,28(5)

2008年12月，江苏赣榆某渔场养殖半滑舌鳎出现大量死亡，症状主要表现为：头部、鳃盖及鳍基出血， 尾鳍腐烂，腹腔膨胀并积有大量腹水，部分病鱼肠管脱出肛外。从病鱼肝脏、腹水中分离出大量优势生长的 细菌，人工感染试验证明其对半滑舌鳎有较强的致病性。对3株分离菌进行了形态特征、理化特性、胞外酶及溶血素活性等表型生物学性状检验；测定了代表菌株的16S rRNA和gyrB基因序列，分析了16 S rRNA和gyrB两种基因序列的同源性，并构建了系统发生树，比较了两种基因对分离菌的鉴定能力；结果表明gyrB基因用于细菌种间鉴定更具优越性；基于16S rRNA和gyrB基因的系统发育学分析表明分离菌与鳗利斯顿氏菌具有高同源性，根据分离菌的表型及分子特征，判定分离菌为利斯顿氏菌属（Listonella MacDonell and Colwell 1986）的鳗利斯顿氏菌\[Listonella anguillarum ( Bergeman 1909)MacDonell and Colwell 1986\]。胞外酶活性及溶血活性检测表明3株分离菌均具有淀粉酶、蛋白酶、卵磷脂酶等胞外酶活性，在含7%家兔脱纤血液营养琼脂培养基上呈β型溶血，PCR检测3株供试菌均可扩增出大小约493 bp的溶血素基因和大小约248 bp的金属蛋白酶基因。分离菌的耐药谱测定结果显示，对供试49种抗菌药物中的青霉素G等13种药物耐药，对羧苄青霉素等6种药物存在敏感与耐药的株间差异。  相似文献