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991.
Ryan Plummer Danuta de Grosbois Derek Armitage Rob C. de Loë 《Global Environmental Change》2013,23(4):749-763
Assessing vulnerability related to water is a global concern and especially important to populations experiencing multiple exposures and sensitivities. Approaches are required that span social and physical concerns, and that bridge multiple types and forms of knowledge. This research investigates the water vulnerability of three First Nation communities in Ontario, Canada. A collaborative process was used to build an integrative understanding of water vulnerability, develop an associated instrument, and undertake the community scale assessments. Results from the assessment provided communities with a comprehensive overview of water vulnerability, and pointed to gaps in knowledge and specific areas where attention was needed. Conducting assessments at a community scale following the methodology employed in this research responds to the need for integration and context sensitivity when engaging in water vulnerability assessments and introduces innovations to existing assessment tools. A holistic approach to water vulnerability assessment provided decision-makers with the context-specific details and empirical insights they require to prioritize issues and allocate resources. 相似文献
992.
Sabine Schmidt Hélène Howa Aurelia Mouret Fabien Lombard Pierre Anschutz Laurent Labeyrie 《Continental Shelf Research》2009,29(8):1044-1052
As a part of the ANR-Forclim experiment, particle mass fluxes and sedimentation processes were investigated on the slope of Aquitanian margin of the Bay of Biscay, between the canyons of Cap-Breton and Cap-Ferret. Interface sediments were collected along a depth transect from 145 to 2000 m; simultaneously a mooring line was deployed at the deepest station (WH, 2000 m) with two traps (800 and 1700 m) for a 16-month period (June 2006–November 2007). 210Pb activities of settling particles and of interface sediments were determined to study transport processes of particles. Sediment and mass accumulation rates, calculated from excess 210Pb profiles in the sediment column, show the expected decreasing trend with depth, as usually observed on margins. Mean particulate mass fluxes at 800 and 1700-m depth at site WH are, respectively, 27 and 70 g m?2 a?1.The 210Pb budget points out events of temporary high lateral input of particles. The comparison of mass and 210Pb fluxes between the water column and the seabed indicates that lateral transport plays an important role in particle accumulation on the Aquitanian margin. Regarding the objectives of the ANR-Forclim program, which aims to improve significantly the interpretation of fossil foraminifera signals, as a proxy for hydrological changes in the North Atlantic ocean, these results highlight advection processes must be considered when interpreting fluxes of foraminifers on the Aquitanian margin. 相似文献
993.
Gabriëlle J. M. De Lannoy Julie Ufford Alok K. Sahoo Paul Dirmeyer Paul R. Houser 《水文研究》2011,25(4):634-649
Land surface models are typically constrained by one or a few observed variables, while assuming that the internal water and energy partitioning is sensitive to those observed variables and realistic enough to simulate unobserved variables. To verify these assumptions, in situ soil climate analysis network (SCAN) observations in the Lower Mississippi Basin (2002–2008) are analysed to quantify water and energy budget components and they are compared to Community Land Model (CLM3·5) simulations. The local soil texture is identified as a major indicator for water storage characteristics and the Normalized Difference Vegetation Index shows potential as a drought indicator in summer months. Both observations and simulations indicate a regime where, except in some summer months, evapotranspiration controls soil moisture. CLM simulations with different soil texture assignments show discharge sensitivity to soil moisture, but almost no impact on evapotranspiration and other energy balance components. The observed and simulated water budgets show a similar partitioning. However, the SCAN observed water balance does not close because of precipitation measurement errors, unobserved irrigation, lack of specific storage change measurements and errors in the computed actual evapotranspiration. The simulated heat flux partitioning differs from that ‘observed’, with a larger (resp. smaller) fraction of net radiation being used by latent (resp. sensible) heat flux, and unobserved freeze and thaw events. The comparison between observations and model simulations suggests that a consistent observation collection for multiple variables would be needed to constrain and improve the full set of land surface variable estimates. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
994.
Jackie Despriée Pierre Voinchet Hélène Tissoux Jean-Jacques Bahain Christophe Falguères Gilles Courcimault Jean Dépont Marie-Hélène Moncel Sophie Robin Marta Arzarello Robert Sala Laurent Marquer Erwan Messager Simon Puaud Salah Abdessadok 《Quaternary Science Reviews》2011,30(11-12):1474-1485
This paper records the findings from c. 80 prehistoric sites that have been discovered in the alluvial deposits of the rivers Creuse, Cher, and Loir, tributaries of the middle Loire River, over the period since 1981. These deposits comprise river terrace aggradations formed during successive glacial–interglacial cycles which have recorded climate and environment during Quaternary time. The systematic dating of these river deposits by Electron Spin Resonance (ESR) applied to optically bleached sedimentary quartz has resulted in the establishment of a chronological framework for the evolution of these rivers during Lower and Middle Pleistocene (between 1.7 Ma and 130 ka). Evidence for Early Palaeolithic (Mode 1) industries with an in situ context (workshops, soils) in the highest aggradations indicates that Hominins were present in the study area, near the geographical centre of France (47°N), around 1.1 Ma. Examination of the sites indicates that Human occupations were located along valley bottom sites during temperate episodes. Subsequently, after a gap of several hundred thousand years industries with handaxes appear in the Middle Loire Basin in the interval between 700 and 600 ka, and then continuously from 400 ka. These two phases of settlement produced industrial assemblages with clear differences in their responses to the supplies of raw materials and in the modes of making flakes. 相似文献
995.
Recent archeological and geoarcheological investigations have corroborated the notion of close interaction between man and environment in our study area during historical times. The riparian Sárk?z, forming an interface between two major geographical regions of Transdanubia and the Great Hungarian Plains, has been continuously inhabited for the past 8000 years. Settlements were generally confined to areas above 90.5?C91m ASL, with the exception of a few drier periods. This elevation can therefore be regarded as the margin of human settlement. The lower-lying areas correspond to the actual floodplain inundated for the major part of the year from which lag-surfaces stand out as island-like natural highs hosting the settlements themselves. The endowments and settlement pattern persisted from the Neolithic onwards until the terminal Modern Age, when measures aimed to ordain the area substantially altered the natural landscape. 相似文献
996.
The dissipation test evaluation method presented here employs: (i) a point-symmetric, linear, coupled consolidation model with a new boundary condition and a new time factor, (ii) an automatic and mathematically precise, non-linear, inverse problem solver which includes some reliability testing methods and a kind of regularization technique, and (iii) a method to identify the initial condition.The evaluation method is equally applicable to pore water pressure data displaying monotonic or non-monotonic time variation, with the only difference that the initial condition is identified differently during the inverse problem solution.The necessary testing time is very short provided that the pore water pressure is measured well above the tip. This is attributed to the ability of the one-dimensional, linear consolidation model to account for the geometry and the unloading effects that occur when steady penetration of the static cone penetrometer ceases. 相似文献
997.
Gaëlle SAUNIER Franck POITRASSON Bertrand MOINE Michel GREGOIRE Abdelmadjid SEDDIKI 《Meteoritics & planetary science》2010,45(2):195-209
Abstract– Although iron isotopes are increasingly used for meteorites studies, no attempt has been made to evaluate the effect of terrestrial weathering on this isotopic tracer. We have thus conducted a petrographic, chemical, and iron isotopic study of equilibrated ordinary chondrites (OC) recovered from hot Moroccan and Algerian Saharan deserts environment. As previously noticed, we observe that terrestrial desertic weathering is characterized by the oxidation of Fe‐Ni metal (Fe0), sulfide and Fe2+ occurring in olivine and pyroxene. It produces Fe‐oxides and oxyhydroxides that partially replace metal, sulfide grains and also fill fractures. The bulk chemical compositions of the ordinary chondrites studied show a strong Sr and Ba enrichment and a S depletion during weathering. Bulk meteoritic iron isotope compositions are well correlated with the degree of weathering and S, Sr, and Ba contents. Most weathered chondrites display the heaviest isotopic composition, by up to 0.1‰, which is of similar magnitude to the isotopic variations resulting from meteorite parent bodies’ formation and evolution. This is probably due to the release of isotopically light Fe2+ to waters on the Earth’s surface. Hence, when subtle Fe isotopic effects have to be studied in chondrites, meteorites with weathering grade above W2 should be avoided. 相似文献
998.
Zoltán Makó Ferenc Szenkovits Júlia Salamon Robert Oláh-Gál 《Celestial Mechanics and Dynamical Astronomy》2010,108(4):357-370
This paper provides a study of the stable and unstable regions around the smaller primary in the framework of the spatial
elliptic restricted three-body problem. The definitions and methods used to determine stable and unstable regions are extended
to three dimensions. New results concerning the stable and unstable regions around Mercury are obtained in the Sun–Mercury
system. 相似文献
999.
S. Surblé S. Heathman P. E. Raison D. Bouëxière K. Popa R. Caciuffo 《Physics and Chemistry of Minerals》2010,37(10):761-767
The structural behavior under pressure of three lanthanide pyrochlore zirconates Ln2Zr2O7 (Ln3+ = Ce, Nd and Gd) has been investigated by X-ray diffraction up to 50 GPa. For all three compounds, a symmetry reduction from
cubic to monoclinic is observed under increasing pressure dependant on a pressure value that increases with the ionic radius
of the lanthanide ions, r
Ln. The cubic and monoclinic phases coexist over a wide pressure range which increases with r
Ln. The zero-pressure bulk modulus of the cubic phase, B
0, and its pressure derivative, B
0′, have been determined by fitting the experimental compressibility curves to the Birch–Murnaghan equation of state. 相似文献
1000.
Partitioning of Se, As, Sb, Te and Bi between monosulfide solid solution and sulfide melt - Application to magmatic sulfide deposits 总被引:1,自引:0,他引:1
Hassan M. Helmy Chris Ballhaus Raúl O.C. Fonseca 《Geochimica et cosmochimica acta》2010,74(21):6174-6179
The chalcogenes (S, Se, Te), semimetals (As, Sb) and the metal Bi are important ligands for noble metals and form a wide range of compositionally diverse minerals with the platinum-group elements (PGE). With the exception of S, few experimental data exist to quantify the behavior of these elements in magmatic sulfide systems. Here we report experimental partition coefficients for Se, Te, As, Sb, and Bi between monosulfide solid solution (mss) and sulfide melt, determined at 950 °C at a range of sulfur fugacities (fS2) bracketed by the Fe-FeS (metal-troilite) and the Fe1−×S-Sx (mss-sulfur) equilibria. Selenium is shown to partition in mss-saturated sulfide melt as an anion replacing S2−. Arsenic changes its oxidation state with fS2 from predominantly anionic speciation at low fS2, to cationic speciation at high fS2. The elements Sb, Te, and Bi are so highly incompatible with mss that they can only be present in sulfide melt as cations and/or as neutral metallic species. The partition coefficients derived fall with increasing atomic radius of the element. They also reflect the positions of the respective elements in the Periodic Table: within a group (e.g., As, Sb, Bi) the partition coefficients fall with increasing atomic radius, and within a period the elements of the 15th group are more incompatible with mss than the neighboring elements of the 16th group. 相似文献