Climate controls on rainfall isotopes and their effects on cave drip water and speleothem growth: the case of Molinos cave (Teruel,NE Spain)     

Ana Moreno  Carlos Sancho  Miguel Bartolomé  Belén Oliva-Urcia  Antonio Delgado-Huertas  Mª José Estrela  David Corell  Juan Ignacio López-Moreno  Isabel Cacho 《Climate Dynamics》2014,43(1-2):221-241

The interpretation of stable isotopes in speleothems in terms of past temperature variability or precipitation rates requires a comprehensive understanding of the climatic factors and processes that influence the δ¹⁸O signal in the way through the atmosphere to the cave, where carbonate precipitates acquiring its final isotopic composition. This study presents for the first time in the Iberia Peninsula an integrated analysis of the isotopic composition of rainfall (δ¹⁸O_p) during 2010–2012 years and, through a detailed monitoring survey, the transference of the primary isotopic signal throughout the soil and epikarst into the Molinos cave (Teruel, NE Spain). Both air temperature and amount of precipitation have an important effect on δ¹⁸O_p values, clearly imprinting a seasonal variability modulated by an amount effect when rainfall events are more frequent or intense. Air mass history and atmospheric circulation influences are considered through the study of weather types, synoptic-scale climate patterns and large-scale atmospheric circulation indexes (North Atlantic Oscillation and Western Mediterranean Oscillation) revealing a dominant source effect on δ¹⁸O_p values in this region where tropical North Atlantic and Western Mediterranean are the two moisture source regions. A delay of 2–3 months occurs between the dripwater oxygen isotopic composition (δ¹⁸O_d) respect to δ¹⁸O_p values as a consequence of large residence time in the epikarst. Limited calcite precipitates are found from winter to spring when δ¹⁸O_d values are less negative and dripwater rates are constant. This study suggests that NE Iberian δ¹⁸O_calcite proxy records are best interpreted as reflecting a combination of parameters, not just paleotemperature or paleorainfall and, if extending present-day situation towards the recent past, a biased signal towards winter values should be expected in Molinos speleothem records.  相似文献   

Evaluation of three simulation approaches for assessing yield of rainfed sunflower in a Mediterranean environment for climate change impact modelling     

J. García-López  Ignacio J. Lorite  R. García-Ruiz  J. Domínguez 《Climatic change》2014,124(1-2):147-162

The determination of the impact of climate change on crop yield at a regional scale requires the development of new modelling methodologies able to generate accurate yield estimates with reduced available data. In this study, different simulation approaches for assessing yield have been evaluated. In addition to two well-known models (AquaCrop and Stewart function), a methodological proposal considering a simplified approach using an empirical model (SOM) has been included in the analysis. This empirical model was calibrated using rainfed sunflower experimental field data from three sites located in Andalusia, southern Spain, and validated using two additional locations, providing very satisfactory results compared with the other models with higher data requirements. Thus, only requiring weather data (accumulated rainfall from the beginning of the season fixed on September 1st, and maximum temperature during flowering) the approach accurately described the temporal and spatial yield variability observed (RMSE?=?391 kg ha^?1). The satisfactory results for assessing yield of sunflower under semi-arid conditions obtained in this study demonstrate the utility of empirical approaches with few data requirements, providing an excellent decision tool for climate change impact analyses at a regional scale, where available data is very limited.  相似文献   

Observations of the Hubble Deep Field South with the Infrared Space Observatory– II. Associations and star formation rates     

Robert G. Mann  Seb Oliver  Ruth Carballo  Alberto Franceschini  Michael Rowan-Robinson  Alan F. Heavens  Maria Kontizas  David Elbaz  Anastasios Dapergolas  Evanghelos Kontizas  Gian Luigi Granato  Laura Silva  Dimitra Rigopoulou  J. Ignacio Gonzalez-Serrano  Aprajita Verma  Steve Serjeant  reas Efstathiou  Paul P. van der Werf 《Monthly notices of the Royal Astronomical Society》2002,332(3):549-574

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Pollen‐ and diatom based environmental history since the Last Glacial Maximum from the Andean core Fúquene‐7, Colombia     

Maria Isabel Vélez  Henry Hooghiemstra  Sarah Metcalfe  Ignacio Martínez  Herman Mommersteeg 《第四纪科学杂志》2003,18(1):17-30

The late Pleistocene–Holocene ecological and limnological history of Lake Fúquene (2580 m a.s.l.), in the Colombian Andes, is reconstructed on the basis of diatom, pollen and sediment analyses of the upper 7 m of the core Fúquene‐7. Time control is provided by 11 accelerator mass spectrometry (AMS) ¹⁴C dates ranging from 19 670 ± 240 to 6040 ± 60 yr BP. In this paper we present the evolution of the lake and its surroundings. Glacial times were cold and dry, lake‐levels were low and the area was surrounded by paramo and subparamo vegetation. Late‐glacial conditions were warm and humid. The El Abra Stadial, a Younger Dryas equivalent, is reflected by a gap in the sedimentary record, a consequence of the cessation of deposition owing to a drop in lake‐level. The early Holocene was warm and humid; at this time the lake reached its maximum extension and was surrounded by Andean forest. The onset of the drier climate prevailing today took place in the middle Holocene, a process that is reflected earlier in the diatom and sediment records than in the pollen records. In the late Holocene human activity reduced the forest and transformed the landscape. Climate patterns from the Late‐glacial and throughout the Holocene, as represented in our record, are similar to other records from Colombia and northern South America (the Caribbean, Venezuela and Panama) and suggest that the changes in lake‐level were the result of precipitation variations driven by latitudinal shifts of the Intertropical Convergence Zone. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Surface density profiles of collisionless disc merger remnants     

Thorsten Naab  Ignacio Trujillo 《Monthly notices of the Royal Astronomical Society》2006,369(2):625-644

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Spectral dating of high-redshift stellar populations     

Ignacio Ferreras  Sukyoung K. Yi 《Monthly notices of the Royal Astronomical Society》2004,350(4):1322-1329

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Characterization of Colliery Spoils in León: Potential Uses in Rural Infrastructures     

Joaquín Ferreras Cadierno  Manuel Ignacio Guerra Romero  Andrés Juan Valdés  Julia Mª Morán del Pozo  Julia García González  Desirée Rodríguez Robles  José Vallepuga Espinosa 《Geotechnical and Geological Engineering》2014,32(2):439-452

One of the bases of sustainable development is the responsible management of natural resources, and this is the approach which has been adopted by developed countries as regards management of all kinds of waste, through the establishment of management strategies based on prevention, reuse and recycling. This article present the results of a physical, chemical and geotechnical characterization of colliery spoils stored in slag heaps in the Ciñera-Matallana coal mining area in León, Spain. The primary objectives of this research were to determine the suitability of this mining waste for use as granular material in rural and civil engineering infrastructures and to classify it according to national and international road construction standards. On the basis of the results obtained, they are proposed several possible uses (foundation and core layers in track and road embankments, granular sub-base for light traffic and top layers of embankments), although it should be noted the need for mechanical treatments as crushing or sieving and the recommendation of use of sulphate resistant cement to avoid the possible problems.  相似文献   

Methodological proposal to assess groundwater contamination danger: study case of Bajo Cauca aquifer (Colombia)     

Teresita Betancur  Carlos Palacio  Jorge Ignacio Gaviria  María Rueda 《Environmental Earth Sciences》2013,70(1):315-328

Interaction between vulnerability and contaminating charge was used in order to determine the groundwater contamination danger. The result of danger being adapted to the scale of impact on human or animal health and ecosystems is known as “risk”. Index and overlapping methodologies such as EPNNA, DRASTIC, SINTACS, GOD AVI, and Ekv were used and compared to evaluate vulnerability. Contaminating charge to the subsoil, which is generated from specific human activity, has four characteristics: kind of contaminant, means of disposal, intensity, and duration. Interaction among these characteristics obtains a Contaminating Charge Index. In the Bajo Cauca Antioqueño region, over 150,000 inhabitants require ground water for meeting their basic needs at home, for cattle breeding activities, and for irrigation. For this region, an assessment of the groundwater contamination of the free aquifer, as well as an estimation of its impact and the danger this contamination may pose to ecosystems or communities has been performed. Analysis of the interaction between vulnerability and threat allows for the creation of danger and risk maps.  相似文献   

Mitigation of lateral ground displacements of liquefied soils with underground barriers     

Ignacio Arango 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1067-1073

Analyses of damage data from earthquakes in the last 35 years show that very high financial losses have resulted from cases where liquefaction of soils was associated with ground lateral displacements towards a free boundary such as a shoreline, a river channel, or an open trench. Lateral displacements in excess of 10 m have been documented in the literature [Bartlett and Youd, J. Geotech. Engng, ASCE 121 (1995) 316]. In fact, in many cases, displacements amounting to only a fraction of this number are capable of causing considerable disruption to man-made works. Several factors contribute to the extent of lateral spreading: surface and subsurface geometry, soil characteristics, and intensity of ground motion.

Ground displacements can be minimized or even arrested in practice with an underground structure properly designed to counter the driving forces, gravity and inertia combined. Mitchell et al. suggested practical guidance for the design of such structures, or barriers, in 1998 [Geotech. Spec. Publ. 75 (1998) 580]. However, to date there is no standard procedure to carry out the analysis of such barriers. The paper describes several recent designs of underground barriers that have been constructed in highly seismic environments. Three types of underground barriers are described: clay fill, a grid of structural piles, and a grid of cement-treated soil. The design of the cement-treated cell barrier is discussed in detail as it accounts for the most unfavorable combination of all forces acting on the structure: lateral stresses induced by liquefied soil, hydrodynamic effects, inertia forces, and loss of ground.  相似文献   

Low-ionization galaxies and evolution in a pilot survey up to z=1     

Edmond Giraud  Jorge Melnick  Hernan Quintana  Fernando Selman  Ignacio Toledo  Paula Zelaya 《中国天文和天体物理学报》2011,11(3)

We present galactic spectroscopic data from a pencil beam of 10.75×7.5 centered on the X-ray cluster RXJ0054.0-2823 at z=0.29.We study the spectral evolution of galaxies from z=1 down to the cluster redshift in a magnitude-limited sample at R≤23,for which the statistical properties of the sample are well understood.We divide emission-line galaxies into star-forming galaxies,Low Ionization Nuclear Emission line Regions(LINERs) ,and Seyferts by using emission-line ratios of[OII],Hβ,and[OIII],and derive stella...  相似文献