High resolution investigation of the 7 μm region of the ethane spectrum     

Carlo di Lauro  Franca Lattanzi  Linda R. Brown  Keeyoon Sung  Jean Vander Auwera  Arlan W. Mantz  Mary Ann H. Smith 《Planetary and Space Science》2012,60(1):93-101

Building upon previous studies, we re-investigated the ethane spectrum between 1330 and 1610 cm^?1 by combining unapodized spectra obtained at room temperature with a Bruker Fourier transform spectrometer (FTS) in Brussels and at 131 K with a Bruker FTS in Pasadena. The maximum optical path differences (MOPD) of the two datasets were 450 and 323.7 cm, corresponding to spectral resolutions of 0.0020 and 0.0028 cm^?1, respectively. Of the 15,000 lines observed, over 4592 transitions were assigned to the ν₆ (at 1379 cm^?1), ν₈ (at 1472 cm^?1), ν₄+ν₁₂ (at 1481 cm^?1) and 2ν₄+ν₉ (at 1388 cm^?1) bands, and another 1044 transitions were located for the ν₄+ν₈?ν₄ hot band (at 1472 cm^?1). Our new analysis included an improved implementation of the Hamiltonian calculation needed to interpret the complex spectral structures caused by numerous interactions affecting these four modes of vibration. From these results, we created the first line-by-line database containing the molecular parameters for over 20,000 ¹²C₂H₆ transitions at 7 μm.  相似文献   

Detecting and Enumerating New Building Structures Utilizing Very‐High Resolution Imaged Data and Image Processing     

DongMei Chen  Douglas Stow  Scott Daeschner  Linda Tucker 《国际地球制图》2013,28(1):71-84

Abstract

Information on the number and type of new building structures is required by urban and transportation planners and the real estate industry. The goal of this paper is to explore the potential of high resolution imagery for meeting public and private sector demands for information on new buildings. The value of 1 m, 5 m, and 10 m panchromatic and 1 m color scanned aerial photography images acquired in 1997 and 1998 for a study area within the City of San Diego, California is assessed for general change detection and building enumeration. Both semi‐automated and interactive change‐detection approaches are evaluated. We demonstrate that interactive, visual‐based approaches appear to be the most accurate (within 1% of actual count) and efficient approach for generating information on the number of new buildings associated with single family residential land use. More automated approaches to detecting and enumerating image microfeatures may be useful as enhancements for visual‐based assessments and may be practical in areas composed mostly of large buildings associated with commercial and industrial land use. The highest accuracy for automated approaches was an undercounting of 11% for residential buildings and overcounting of 20% for those associated with commercial and industrial land use.  相似文献   

A Parcel Shape Index for Use in Land Consolidation Planning   总被引：1，自引：0，他引：1  

Demetris Demetriou  Linda See  John Stillwell 《Transactions in GIS》2013,17(6):861-882

Area shape analysis has been a subject of focus for research in geography and other disciplines for many years. However, existing area shape indices present significant weaknesses for the analysis of land parcels in an agricultural context as they do not measure shape in an appropriate, reliable or explicit manner. This article presents a new parcel shape index (PSI) which integrates six geometric parameters through multi‐attribute decision‐making, combined with value functions for parameter standardization. The superior performance of the new PSI in relation to three existing indices is demonstrated through a case study area in Cyprus. The methodology can be applied in other contexts aimed at assessing the quality of a particular shape compared to an optimum.  相似文献   

VASCULAR PLANTS OF MOUNTAIN TALUS SLOPES,MT. RAE AREA,ALBERTA, CANADA     

Linda J. Kershaw  James S. Gardner 《自然地理学》2013,34(3):218-230

The vascular flora of talus slopes in the Mt. Rae area, Canadian Rocky Mountain Front Ranges, is discussed in the context of edaphic and geomorphic conditions. Thirteen talus slopes were sampled systematically for the presence of vegetation, and vascular plants were identified to the species level. Such talus slopes are generally considered relatively sterile and too unstable for the development of distinctive flora. The presence of vegetation is usually taken as an indicator of slope stability. A total of 77 species with boreal and arctic affinities was identified. Most plants display growth forms suitable to the unstable and xeric talus substrate with Schroeter's Schuttstrecker and Schuttdecker forms being most common. Although areal coverage by plants is sparse, a large number of species with morphological characteristics suitable for the talus environment suggests that the presence of plants should not be regarded as an absolute indicator of slope stability. Rather, these plants may represent a long-term equilibrium assemblage characteristic of active talus slopes in a mountain environment.  相似文献   

SOIL DEVELOPMENT AND SPATIAL VARIABILITY ON GEOMORPHIC SURFACES OF DIFFERENT AGE     

Linda R. Barrett  Randall J. Schaetzl 《自然地理学》2013,34(1):39-55

Twenty-four soil pedons on each of four sandy lake terraces in northwestern lower Michigan that ranged in age from 3000 to 11,000 years BP were studied to assess trends in soil morphological variability with time. After verifying the general uniformity of parent materials within and between the four surfaces, we examined temporal trends in the spatial variability of soil color, cementation, horizon thickness and development. E horizons attained high color values (lightness) by 3000 years and changed little after that time, whereas B horizons continued to get darker with time. Cementation within B horizons increased in strength and amount with time, as did B horizon thickness. Soils ≥4000 years old had deeper eluvial zones but much greater variabilities in the thickness of that zone than did younger soils. Soil development increased with time, but spatial variability in degree of development also increased with time. These patterns are best explained by invoking spatially random soil mixing upon a surface that is otherwise undergoing podzolization. [Key words: podzolization, chronofunction, Michigan, soil variability, soil genesis.]  相似文献   

Culturing of the first 37:4 predominant lacustrine haptophyte: Geochemical,biochemical, and genetic implications     

Jaime L. Toney  Susanna Theroux  Robert A. Andersen  Annette Coleman  Linda Amaral-Zettler  Yongsong Huang 《Geochimica et cosmochimica acta》2012

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The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition     

Bruno Malaizé  Elsa Jullien  Amandine Tisserand  Charlotte Skonieczny  E. Francis Grousset  Frédérique Eynaud  Catherine Kissel  Jérôme Bonnin  Svenja Karstens  Philippe Martinez  Aloys Bory  Vivianne Bout-Roumazeilles  Thibaut Caley  Xavier Crosta  Karine Charlier  Linda Rossignol  José-Abel Flores  Ralph Schneider 《Quaternary Research》2012,77(1):182-191

A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ¹⁸O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ¹³C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ¹³C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ¹³C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ¹⁸O and δ¹³C values of deep waters.  相似文献   

Strengthened East Asian summer monsoons during a period of high-latitude warmth? Isotopic evidence from Mio-Pliocene fossil mammals and soil carbonates from northern China     

Benjamin H. Passey  Linda K. Ayliffe  Anu Kaakinen  Zhaoqun Zhang  Jussi T. Eronen  Yanming Zhu  Liping Zhou  Thure E. Cerling  Mikael Fortelius 《Earth and Planetary Science Letters》2009,277(3-4):443-452

The East Asian monsoons have fluctuated in concert with high-latitude warmth during the past several hundred thousand years, with humid summer monsoon-dominant climates characterizing warm intervals, including interglacials and interstadials, and arid winter monsoon-dominant climates characterizing cool intervals, including glacials and stadials. Of the states comprising the mid-Pleistocene to recent climatic regime, interglacials are most similar in terms of high latitude ice volumes and temperatures to those extant during the late Miocene and early Pliocene. Thus, an important question is whether Mio-Pliocene climates in northern China were analogous to a hypothetical ‘prolonged interglacial state,’ with increased summer monsoon precipitation and expansion of forest and steppe environments at the expense of desert environments.We utilize new and previously published carbon isotopic data from fossil teeth and soil carbonates to place constraints on paleovegetation distributions and to help infer the behavior of the monsoon system between ～ 7 and 4 Ma. We find that plants using the C₄ photosynthetic pathway—which today are largely grasses found in regions with warm season precipitation—were present in northern China by late Miocene time, demonstrating that the C₄ expansion in China was not significantly delayed compared to the global C₄ event. During the late Miocene–early Pliocene interval, soil carbonate and tooth enamel δ¹³C data indicate: 1) that nearly pure C₃-plant ecosystems existed in the southern Chinese Loess Plateau (CLP), and therefore ecosystems there were dominated by woody dicot, herbaceous dicot, or cool-season grass vegetation (or a combination of these), and 2) that the CLP was characterized by a pattern of northward-increasing C₄ vegetation and aridity. Utilizing a broadened conceptual model for interpreting δ¹³C data, and citing independent faunal, floral, and lithostratgraphic data, we suggest that these patterns reflect northward expansion of forest and steppe ecosystems and relatively humid monsoon climates during the late Miocene and early Pliocene. An important implication of this interpretation is that the forcing mechanism illuminated by the temporal correlation during the Pleistocene between warm high latitudes and strong East Asian summer monsoons is a robust feature of the Eurasian tectonic–climatic system that predates the Plio-Pleistocene climatic reorganization.  相似文献   

Newly recognized hosts for uranium in the Hanford Site vadose zone     

Joanne E. Stubbs  Linda A. Veblen  David C. Elbert  James A. Davis 《Geochimica et cosmochimica acta》2009,73(6):1563-234

Uranium contaminated sediments from the U.S. Department of Energy’s Hanford Site have been investigated using electron microscopy. Six classes of solid hosts for uranium were identified. Preliminary sediment characterization was carried out using optical petrography, and electron microprobe analysis (EMPA) was used to locate materials that host uranium. All of the hosts are fine-grained and intergrown with other materials at spatial scales smaller than the analytical volume of the electron microprobe. A focused ion beam (FIB) was used to prepare electron-transparent specimens of each host for the transmission electron microscope (TEM). The hosts were identified as: (1) metatorbernite [Cu(UO₂)₂(PO₄)₂·8H₂O]; (2) coatings on sediment clasts comprised mainly of phyllosilicates; (3) an amorphous zirconium (oxyhydr)oxide found in clast coatings; (4) amorphous and poorly crystalline materials that line voids within basalt lithic fragments; (5) amorphous palagonite surrounding fragments of basaltic glass; and (6) Fe- and Mn-oxides. These findings demonstrate the effectiveness of combining EMPA, FIB, and TEM to identify solid-phase contaminant hosts. Furthermore, they highlight the complexity of U geochemistry in the Hanford vadose zone, and illustrate the importance of microscopic transport in controlling the fate of contaminant metals in the environment.  相似文献   

Hafnium Isotope Characteristics of Palaeoarchaean Zircon OG1/OGC from the Owens Gully Diorite,Pilbara Craton,Western Australia          下载免费PDF全文

Anthony I. S. Kemp  Jeffrey D. Vervoort  Katarina E. Bjorkman  Linda M. Iaccheri 《Geostandards and Geoanalytical Research》2017,41(4):659-673

We report Hf isotope data for 3467 Ma igneous zircons from the Owens Gully Diorite of the Pilbara Craton. These zircons, designated OG1 or OGC, have simple, well‐defined U‐Pb age systematics. Measurements obtained by single crystal dissolution yield a moderate range in ¹⁷⁶Hf/¹⁷⁷Hf (mean 0.280633 ± 34) and ¹⁷⁶Lu/¹⁷⁷Hf (mean 0.00119) that translate into initial (3467 Ma) ¹⁷⁶Hf/¹⁷⁷Hf values that are equivalent within measurement uncertainty (mean 0.280554 ± 7, ε_Hf = +0.6 ± 0.2, 2s). Laser ablation analysis yielded clustered initial ¹⁷⁶Hf/¹⁷⁷Hf ratios (mean 0.280560 ± 20, 2s) indistinguishable from those obtained by solution analysis. The antiquity and moderately high ¹⁷⁶Lu/¹⁷⁷Hf of these zircons result in significant corrections for radiogenic ingrowth of ¹⁷⁶Hf (to 6 ε_Hf units). Depth profiling by concurrent Pb‐Hf isotope determination reveals trends to lower ²⁰⁷Pb/²⁰⁶Pb in several crystals, although these are not accompanied by shifts in ¹⁷⁶Hf/¹⁷⁷Hf. We conclude that zircons from the Owens Gully Diorite are homogeneous for Hf isotopes at the scale of sampling and within the uncertainty limits of the measurement techniques employed. Zircon OG1/OGC would appear to be an ideal quality monitor for laser ablation Hf isotope determination in ancient zircons, and for laser ablation techniques where Hf isotope and age information are determined concurrently or simultaneously.  相似文献