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1.
MATTHEW J. AMESBURY KEITH E. BARBER PAUL D. M. HUGHES 《Boreas: An International Journal of Quaternary Research》2011,40(1):161-174
Amesbury, M. J., Barber, K. E. & Hughes, P. D. M. 2010: The methodological basis for fine‐resolution, multi‐proxy reconstructions of ombrotrophic peat bog surface wetness. Boreas, 10.1111/j.1502‐3885.2010.00152.x. ISSN 0300‐9483. The need for Holocene peat‐based palaeoclimatic records of increased temporal resolution has been widely identified in recent research. The often rapid growth rates of ombrotrophic bogs, when combined with fine‐resolution (i.e. millimetre‐scale) sampling, provide an as yet largely unexploited potential to derive sub‐decadal palaeoclimatic data from this proxy‐archive. However, multi‐proxy, fine‐resolution analyses require changes to standard methodologies, and the application of sampling techniques that are new to peat‐based palaeoclimate research. A peat sampler was custom‐built to allow precise and replicable millimetre‐scale subsampling. Subsequent methodological testing revealed that, irrespective of sample thickness (i.e. resolution), halving the standard sample volume used for plant macrofossil (from 4 cm3 to 2 cm3) and testate amoebae (from 2 cm3 to 1 cm3) analyses and the sample weight used for peat humification analysis (from 0.2 g to 0.1 g dried peat) did not affect the interpretation of the results. A contiguous 1‐mm sampling resolution for plant macrofossil analysis was also tested, but it was found that contiguous 5‐mm samples provided a more reliable background record to fine‐resolution testate amoebae and peat humification analyses. Based on these findings, a standardized and systematic methodological approach was developed, using the custom‐built peat slicer to take millimetre‐scale samples that provide enough sample material for both testate amoebae and peat humification analyses to be performed at 1‐mm resolution. This approach will facilitate the testing of the palaeoclimatic reliability of multi‐proxy, fine‐resolution peat‐based records. 相似文献
2.
This special feature: Genetic Structure and Adaptation in Coastal Ecosystems emphasizes the importance of research focused on population genetic structure and evolutionary change for understanding estuarine
and coastal communities. Many studies have examined the effect of environmental gradients on community-level patterns in estuarine
habitats; however, relatively little is known about the role of genetically based adaptation (the heritable response to these
environmental gradients) in these organisms. This special feature presents 11 studies that use a variety of approaches including
ecophysiology, ecological genetics, molecular markers, and patterns of gene expression occurring within these populations.
These studies provide examples of the role of genetic diversity and adaptation across a diversity of estuarine and coastal
environments, and highlight the temporal and spatial scales at which adaptation impinges upon management. This collection
of papers is especially timely, given the increasing importance of understanding and predicting the response to global climate
change in order to effectively manage these communities. 相似文献
3.
Warren C. Jochem Kelly Sims Edward A. Bright Marie L. Urban Amy N. Rose Phillip R. Coleman Budhendra L. Bhaduri 《Natural Hazards》2013,68(3):1325-1342
In recent years, uses of high-resolution population distribution databases are increasing steadily for environmental, socioeconomic, public health, and disaster-related research and operations. With the development of daytime population distribution, temporal resolution of such databases has been improved. However, the lack of incorporation of transitional population, namely business and leisure travelers, leaves a significant population unaccounted for within the critical infrastructure networks, such as at transportation hubs. This paper presents two general methodologies for estimating passenger populations in airport and cruise port terminals at a high temporal resolution which can be incorporated into existing population distribution models. The methodologies are geographically scalable and are based on, and demonstrate how, two different transportation hubs with disparate temporal population dynamics can be modeled utilizing publicly available databases including novel data sources of flight activity from the Internet which are updated in near-real time. The airport population estimation model shows great potential for rapid implementation for a large collection of airports on a national scale, and the results suggest reasonable accuracy in the estimated passenger traffic. By incorporating population dynamics at high temporal resolutions into population distribution models, we hope to improve the estimates of populations exposed to or at risk to disasters, thereby improving emergency planning and response, and leading to more informed policy decisions. 相似文献
4.
本文对加速溶剂萃取仪(ASE300)和快速索氏抽提仪提取的氯仿沥青“A”及由其分离出的饱和烃、芳烃、胶质和沥青质组分做了详细对比.结果表明:多数情况下ASE300抽提出的氯仿沥青“A”的量比快速索氏抽提仪抽提出的量略多,主要是胶质和沥青质量的增加;不同抽提装置得到的饱和烃和芳烃组分的色谱-质谱谱图高度一致,定量结果的相对偏差在5％以内.各组分的稳定碳同位素分析精度±0.5‰.所有的地化参数表明ASE300完全可以替代快速索氏抽提仪,从而降低消耗、提高分析效率. 相似文献
5.
MODIS是新一代遥感技术,其遥测数据与其他单独的遥感平台(如NOAA和Land Sat)所获得的数据相比,具有免费、较高时间分辨率(0.5d)、空间分辨率(250m)和光谱分辨率(波谱范围0.4～14μm,36个光谱通道)等优势和特点.详细介绍了国内外的研究现状,着重对MODIS在洪水过程和洪灾范围实时动态监测、冰川和积雪、降水、植被、土壤水分、蒸发、水文模型、水质等方面的应用和研究进展进行了评述,指出MODIS在水文水资源中具有广阔的应用前景. 相似文献
6.
The fine structure of the FeI λ 532.4185-nm line of neutral iron is studied with high spatial (0.5″) and temporal (9.3 s) resolution using observations of a quiet region at the center of the solar disk. The character of the line asymmetry depends strongly on the nature of the velocity field, i.e., on whether it is due to convective or wave motions. The magnitude of the asymmetry due to acoustic waves is comparable to that due to convective motions. The propagation of acoustic waves in moving granules and intergranular lanes is studied by solving a system of hydrodynamical equations in a three-dimensional model for the solar atmosphere. The temporal variations in the bisector of the line synthesized in a non-LTE approximation agree well with the observational data. 相似文献
7.
介绍了目前在国际壳幔作用及动力学研究中普遍使用的Piston-Cylinder高温高压实验技术的主要工作原理、结构、样品装置设计及主要技术指标.通过分析Piston-Cylinder高温高压实验技术在大洋和大陆板块俯冲深部过程的流体活动、基性岩石部分熔融作用、岩浆活动机制及约束条件等壳幔相互作用研究中的应用实例,认为引进该项实验技术对于我国科技工作者开展高温高压条件下壳幔动力学研究以及缩短我国实验岩石学技术手段与国际间的差距具有重要意义. 相似文献
8.
Paleoclimate research is essential to determine the natural variability of climate and to place the current climate change into its natural context. The current need is to generate the highest temporal resolution paleoclimatic reconstructions possible in order to assess the natural variability of the climate system, but also to test the ability of numerical models to simulate conditions different from the ones observed with the relatively short instrumental records. In this paper, we show that CAT-scan analysis of sedimentary sequences, with its 1 mm downcore resolution, can be used to identify millennial to seasonal cycles in sedimentary sequences. In examples from the St. Lawrence Estuary, Eastern Canada, spectral analysis of the CAT-scan data from Holocene postglacial sediments revealed millennial- to centennial-scale oscillations possibly associated with either solar variability, changes in relative sea-level or tidal amplitude. Similarly, spectral analysis of Holocene and Sangamonian glaciomarine sequences revealed decadal- to annual-scale oscillations with periods close to the one previously associated with the North Atlantic Oscillation (NAO), whereas spectral analysis of the CAT-scan data from the Sangamonian rhythmites possibly revealed seasonal cycles. 相似文献
9.
Friedrich Wieneke Dr. 《GeoJournal》1991,24(1):71-76
Coastal research is structured here according to its main topics, and remote sensing systems are valued accordingto their usefulness for these different topics. Mainly, coastal research requires a high spatial resolution in combination with a high temporal resolution power. Therefore, satellite-borne systems are less suited than airborne systems. High altitude photography combines advantages of both systems, but substances may best be detected by non-photographic techniques. 相似文献
10.
地质年代学为地球与行星科学研究提供时间坐标,以定量解析地质过程先后关系和时间尺度。历经百余年发展,定年技术在研究对象、测试效率、空间分辨率和时间分辨率等维度均得到大幅度提高,地质年代学研究已从仅提供时代约束过渡到更加强调对地质过程时间尺度与节律的研究,进而约束地质事件的驱动机制和互馈机理。然而,基于放射性同位素衰变的绝对定年技术精度存在物理极限,不能无限提高,且其时间分辨率一般随年龄增加而变差,难以满足深时地质研究的高时间分辨率需求,发展时间分辨率不受绝对年龄约束的相对定年技术是地质年代学的重要发展方向。本文围绕扩散年代学这一具有重要发展前景的相对定年技术,在系统回顾其理论模型和测量技术的基础上,重点对制约扩散年代学准确性和精确性的问题,如扩散系数的不确定性、扩散初始条件假设、浓度曲线的测试质量以及误差评估等进行了探讨。本文还对扩散年代学近年来在岩浆储存与运移、成矿时间尺度与节律和变质过程等领域取得的部分重要进展予以评述。精确的扩散系数是开展扩散年代学研究的前提,以石英中的Ti为例,不同实验给出的扩散系数差异超过3个数量级,据此计算的花岗岩岩浆在固相线上的储存时间从几十年变化到百万年尺度,显著影响我们对岩浆储存状态的理解。高质量的元素浓度剖面测量是扩散年代学的关键,因石英Ti含量的高空间分辨率精准测量较为困难,CL灰度常被作为Ti含量的替代指标,但这需要考虑Al等元素对CL灰度的影响,并严格评估Ti含量校正曲线和扩散剖面空间尺度不匹配对定年结果的影响。高温变质过程U Pb定年通常给出较为离散的表观年龄,并被解释为变质过程具有较长的持续时间,这一定程度上可以通过高温下同位素体系因扩散引起的不封闭予以解释。展望未来,进一步完善扩散年代学在高温体系中的研究,拓展在中低温条件下的应用,并与绝对定年深度结合,是扩散年代学的重要发展方向,也是实现深时地质研究高时间分辨率解析的必由之路。 相似文献
11.
To test the potential for developing sub‐decadal resolution records of ombrotrophic bog surface wetness (BSW), selected abrupt climate events were identified in cores from four sites in north‐west Europe and time‐slices over each event were investigated at 2–5‐mm resolution using peat humification, testate amoeba and plant macrofossil analyses. Age–depth models based on radiocarbon, spheroidal carbonaceous particle and tephra dates were applied and the error in these models was used to determine the effective temporal sampling resolution, which in most cases was sub‐decadal. Fine‐resolution results revealed some inconsistencies in the co‐variability of individual proxies and there was a lack of correspondence between some results from adjacent cores. However, we found evidence of abrupt shifts in BSW occurring over ca. 5–20 years, indicating a more rapid proxy response than identified in previous research. To maximize potential temporal resolution and produce reliable sub‐decadal BSW data in future research, we recommended that peat‐based studies should obtain the best possible chronological control, focus on sites with high species diversity and rapid accumulation rates and perform replicate coring, or use open peat sections where the stratigraphy can be clearly seen, to assess intra‐site differences in microtopography. Site‐specific factors should be a primary consideration in the selection of sites for future fine‐resolution research. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）副矿物U-Th-Pb定年技术为精确厘定地质演化历史、探讨成岩成矿等重要地质作用过程提供重要的时间参数,是地质年代学快速发展的重要技术支撑.总结了LA-ICP-MS副矿物U-Th-Pb定年技术在元素分馏校正、非基体匹配分析、标准样品研发、普通铅校正、高空间分辨率及高效率分析等方面取得的重要进展.展望未来,需更进一步深入探讨和研究元素分馏及基体效应机理,研发更多种类的高质量副矿物标样,建立更多更准确、更精密、更高空间分辨率及更高效的LA-ICP-MS副矿物U-Th-Pb定年新方法和新技术,以实现从更微观和更精细的角度探讨地质问题,并持续为高效解决地球与行星科学研究领域重大科学问题提供关键支撑. 相似文献
13.
本文应用改进的水分平衡模型研究了不同气候变化情景下中国未来地表径流的变化。结果表明:基于不同的气候变化情景模拟所得的地表径流变化在空间上有差异,总体上,中国未来的地表径流将增加;长江上游地区的地表径流春季下降但在夏季增加,而下游地区的则相反,夏季径流下降而春季径流剧增;气溶胶对地表径流变化方面有影响,但在各个气候变化情景下缺乏一致性。 相似文献
14.
橄榄石集合体的简单剪切形变实验研究 总被引：1，自引：1，他引：0
本文利用高精度Paterson气体介质变形装置对富铁橄榄石集合体(Mg_(0.5),Fe_(0.5))_2SiO_4进行了高温简单剪切变形试验.试验在温度1473K和围压300MPa的条件下进行,差应力为64～153MPa,应变率为10~-5～10~-3s~-1.一共进行了三组试验,试件的剪切变形量分别为89%,131%和200%,通过对变形后试件的反射光学显微结构分析,得到富铁橄榄石集合体动态重结晶的微观机制,由结晶各向异性分析给出晶格最优取向和波速各向异性的分布及随应变的增加而表现出的演化特征. 相似文献
15.
Arun Mondal Deepak Khare Sananda Kundu Sandip Mukherjee Anirban Mukhopadhyay Surajit Mondal 《地学前缘(英文版)》2017,8(3):425-436
Digital Elevation Model (DEM) is one of the important parameters for soil erosion assessment. Notable uncertainties are observed in this study while using three high resolution open source DEMs. The Revised Universal Soil Loss Equation (RUSLE) model has been applied to analysis the assessment of soil erosion uncertainty using open source DEMs (SRTM, ASTER and CARTOSAT) and their increasing grid space (pixel size) from the actual. The study area is a part of the Narmada river basin in Madhya Pradesh state, which is located in the central part of India and the area covered 20,558 km2. The actual resolution of DEMs is 30 m and their increasing grid spaces are taken as 90, 150, 210, 270 and 330 m for this study. Vertical accuracy of DEMs has been assessed using actual heights of the sample points that have been taken considering planimetric survey based map (toposheet). Elevations of DEMs are converted to the same vertical datum from WGS 84 to MSL (Mean Sea Level), before the accuracy assessment and modelling. Results indicate that the accuracy of the SRTM DEM with the RMSE of 13.31, 14.51, and 18.19 m in 30, 150 and 330 m resolution respectively, is better than the ASTER and the CARTOSAT DEMs. When the grid space of the DEMs increases, the accuracy of the elevation and calculated soil erosion decreases. This study presents a potential uncertainty introduced by open source high resolution DEMs in the accuracy of the soil erosion assessment models. The research provides an analysis of errors in selecting DEMs using the original and increased grid space for soil erosion modelling. 相似文献
16.
酸解烃方法过去主要用在常规油气地球化学勘查中。近几年通过对海底天然气水合物地球化学勘查试验研究,发现该方法也能应用其中。酸脱气过程是酸解烃方法的最重要组成部分,它直接影响到该方法的最后测试结果。为满足当前海洋地质调查中沉积物取样特点,笔者等在前人工作基础上对酸解烃方法中酸脱气装置进行了改进。通过一系列条件试验,确定了在改进后装置下酸脱气过程中最佳的样品粒度、盐酸浓度、反应时间等条件。通过平行性试验和准确性试验,证明该酸脱气装置所得到的数据基本可靠,结果符合部颁标准。 相似文献
17.
Vertical profiles of suspended fine sediment concentration, tidal current velocity, and salinity were measured in May 1994 in the Changjiang Estuary. High resolution concentration profiles were obtained by using a 0.5-MHz acoustic suspended sediment, monitor. High temporal and spatial resolution acoustic profiling of fine suspension concentration provides both the instantaneous vertical profile of concentration and information on the continuous dynamic processes of fine sediment erosion, transport, and deposition. Calibrated acoustic images revealed 1) highly stratified suspensions, 2) resuspension of the cohesive mud, bed, and 3) re-entrainment of the near-bed high concentration suspensions by turbulent shear flow. Within the near-bed high concentration suspensions, two different frequencies of highly episodic resuspension processes were identified: high frequency resuspension, lasting, a few seconds low frequency resuspension, lasting a few minutes. The highest concentrations, associated with low velocity and high salinity, were found close to the cohesive mud bed. Lutoclines were persistent features during the measurements. 相似文献
18.
颗粒土的微观力学行为（如土颗粒的运动与破碎等）决定着其宏观应力-应变行为,如应变局部化、应力硬化等。为研究颗粒土的微观力学行为,开发了一台微型三轴试验装置。它的轴向加载系统由伺服控制的步进转动马达与涡轮传动的减速器组成,围压由GDS压力控制器提供,压力室采用高透光率,高强度的轻质材料制成。借助于X射线显微CT及图像处理分析技术,该装置能实现对干砂土微尺寸试样（直径为8 mm,高度为16 mm）在三轴剪切条件下微观特性的无损检测。采用该三轴试验装置对粒径为0.60～1.18 mm 的LBS（Leighton Buzzard sand）试样在1.5 MPa的围压下进行了试验。结果显示,试验装置测得应力-应变曲线合理,显微CT 图像特征清晰,能够用于颗粒土体微观土力学行为的试验研究。 相似文献
19.
XIAO Zhijie LIAN Bin CHEN Jun H. Henry Teng 《中国地球化学学报》2007,26(3):252-258
A simple apparatus was designed to effectively isolate magnetotactic bacteria from soils or sediments based on their magnetotaxis. Through a series of processes including sample incubation, MTB harvesting, isolation, purification and identification, several strains of bacteria were isolated from the samples successfully. By Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray Analysis (EDXA), these bacteria were certificated to be magnetotactic bacteria. The phylogenetic relationship between the isolated magnetic strains and some known magnetotactic bacteria was inferred by the construction of phylogenetic tree based on 16SrDNA sequences. This apparatus has been proven to have the advantages of being inexpensive, simple to assemble, easy to perform and highly efficient to isolate novel magnetotactic bacteria. The research indicated that the combined approach of harvesting MTB by home-made apparatus and the method of plate colony isolation could purify and isolate magnetotactic bacteria effectively. 相似文献
20.
疏松质石笋碳酸盐的精确微区取样 总被引：2，自引：1，他引：1
高分辨率极端气候事件是古气候研究中的一个热点。作为重要的古气候信息载体之一的石笋,以其每年几十到几百微米的生长速率,为提取高分辨率古气候代用指标提供了可能。而可靠的微区取样则是石笋高分辨率分析的重要前提。本文利用美国New Wave微区取样装置,对微区取样技术在石笋碳酸盐中的应用进行了探讨。在年层并非平直的疏松质石笋表面,于40 μm取样步长内,成功获得了平均质量约为100 μg的石笋微区分析样品。所获得的年内分辨率样品可同时提供微量元素分析和稳定同位素分析。重点讨论了石笋微区取样过程中必须注意的样品固定和取样参数设置等关键问题,提供了有效收集石笋微区样品和避免样品交叉污染的方法。 相似文献