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21.
René Laprise Leticia Hernández-Díaz Kossivi Tete Laxmi Sushama Leo Šeparović Andrey Martynov Katja Winger Michel Valin 《Climate Dynamics》2013,41(11-12):3219-3246
Following the CORDEX experimental protocol, climate simulations and climate-change projections for Africa were made with the new fifth-generation Canadian Regional Climate Model (CRCM5). The model was driven by two Global Climate Models (GCMs), one developed by the Max-Planck-Institut für Meteorologie and the other by the Canadian Centre for Climate Modelling and Analysis, for the period 1950–2100 under the RCP4.5 emission scenario. The performance of the CRCM5 simulations for current climate is discussed first and compared also with a reanalysis-driven CRCM5 simulation. It is shown that errors in lateral boundary conditions and sea-surface temperature from the GCMs have deleterious consequences on the skill of the CRCM5 at reproducing specific regional climate features such as the West African Monsoon and the annual cycle of precipitation. For other aspects of the African climate however the regional model is able to add value compared to the simulations of the driving GCMs. Climate-change projections for periods until the end of this century are also analysed. All models project a warming throughout the twenty-first century, although the details of the climate changes differ notably between model projections, especially for precipitation changes. It is shown that the climate changes projected by CRCM5 often differ noticeably from those of the driving GCMs. 相似文献
22.
Modeling stream-aquifer interactions in a shallow aquifer, Choele Choel Island, Patagonia, Argentina 总被引:3,自引:1,他引:2
A groundwater/surface-water interaction model was developed for the shallow alluvial aquifer of the Choele Choel Island in
Patagonia, Argentina. In this semiarid climate, agriculture is sustained by an irrigation/drainage system. During the irrigation
season, seepage losses through unlined distribution canals in irrigated fields contribute to elevated groundwater levels,
jeopardizing fruit productivity in some areas. Moreover, high stream stages during the irrigation season interfere with groundwater
drainage. The model utilized MODFLOW and its stream package, and was successfully calibrated for a historical irrigation season.
Modeling results indicate that drainage through streams is significantly higher than drainage through artificial drains. The
stream/aquifer relationship proved very responsive to water table rises caused by irrigation. This response manifested as
changes in the gaining/losing character of stream reaches. A synthetic run aimed at isolating the effect of streamflow changes
on groundwater levels showed that the effect of higher streamflows dissipates toward the interior of the island, disappearing
completely at the island center. Even though some results were qualitative, the model helped to provide a better understanding
of the coupled system to elucidate some of the causes of a rising water table on the island.
相似文献
Leticia B. RodríguezEmail: |
23.
Jordi Llorca Julia Roszjar Julia A. Cartwright Addi Bischoff Ulrich Ott Andreas Pack Silke Merchel Georg Rugel Leticia Fimiani Peter Ludwig José V. Casado David Allepuz 《Meteoritics & planetary science》2013,48(3):493-513
We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse‐grained basaltic shergottite, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe‐rich olivine (approximately 4.5 vol%), large Ca‐phosphates, including both merrillites and Cl‐apatites (approximately 3.4 vol%), minor amounts of silica or SiO2‐normative K‐rich glass, pyrrhotite, Ti‐magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26–96En5–50Wo2–41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41–49An39–58Or1–7 in composition, but some can be as anorthitic as An93. Olivine (Fa91–96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for Martian interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35–65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography, and mineral chemistry, suggesting a possible launch‐pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma. 相似文献
24.
Groundwater capture processes under a seasonal variation in natural recharge and discharge 总被引:1,自引:1,他引:0
"Capture" is the increase in recharge and the decrease in discharge that occurs when pumping is imposed on an aquifer system
that was in a previous state of approximate dynamic equilibrium. Regional groundwater models are usually used to calculate
capture in a two-step procedure. A steady-state solution provides an initial-head configuration, a set of flows through the
boundaries for the modeled region, and the initial basis for the capture calculation. The transient solutions provide the
total change in flows through the boundaries. A difference between the transient and steady-state solutions renders the capture
calculation. When seasonality is a modeling issue, the use of a single initial hydraulic head and a single set of boundary
flows leads to miscalculations of capture. Instead, an initial condition for each season should be used. This approach may
be accomplished by determining steady oscillatory solutions, which vary through the seasons but repeat from year to year.
A regional groundwater model previously developed for a portion of the San Pedro River basin, Arizona, USA, is modified to
illustrate the effect that different initial conditions have on transient solutions and on capture calculations.
Received, September 1996 · Revised, October 1997 · Accepted, October 1997 相似文献
25.
Leticia Lescano Francisco Locati Jorge Sfragulla Silvina Marfil Aldo Bonalumi Pedro Maiza 《Environmental Earth Sciences》2017,76(18):631
In this work, a talc and vermiculite mine from the province of Córdoba (Argentina) was investigated with special emphasis on the occurrence of asbestiform and non-asbestiform phases. The meta-ultramafic rock was studied by a multimethodological approach, complementing field studies with petrographic-mineralogical, compositional and morphological analyses. Samples were examined by stereomicroscopy, polarizing light microscopy, SEM–EDS, XRD, DSC-TGA and FTIR. Complementary, compositional and textural analyses were performed with FE-SEM–EDS and EPMA. Talc-rich veins with a laminar and fibrous appearance were at first recognized. However, the fibrous morphology observed both in the field and by microscopy is due to an apparent habit because of the sample orientation. To avoid erroneous interpretations, studies by secondary electron images (SEM) are fundamental to carrying out this type of analysis. Tremolite was identified in different zones of the outcrop; however, only ~40% of the crystals located in the vermiculite zone have dimensions to be considered as asbestiform fibres in the range of respirable particles. In these types of complex deposits affected by superimposed metamorphic, igneous and deformational events, multimethodological approaches are necessary to develop models of occurrence of asbestiform morphologies that may be applicable to other with similar characteristics. 相似文献
26.
Sharon M. Valverde-Esparza Alejandro Ramírez-Rojas E. Leticia Flores-Márquez Luciano Telesca 《Acta Geophysica》2012,60(3):833-845
The non-extensivity approach based on the Tsallis entropy has been applied to seismicity that occurred from 1988 to 2010 along
the Mexican South Pacific coast. We analyzed four different regions, characterized by different subduction patterns. Our results
indicate a possible correlation between the non-extensive parameters and the seismicity pattern associated with the inclination
angle of each subduction region. 相似文献
27.
28.
Claudio Gaucher Robert Frei Farid Chemale Jr Dirk Frei Jorge Bossi Gabriela Mart��nez Leticia Chiglino Federico Cernuschi 《International Journal of Earth Sciences》2011,100(2-3):273-288
Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Río de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pérez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492?±?4?Ma, U?CPb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429?±?21?Ma, U?CPb on zircon) at the top. The Mina Verdún Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U?CPb LA-ICP MS zircon age of 1,433?±?6?Ma is reported here for lapilli-tuffs at the base of the Mina Verdún Group (Cerro de las Víboras Formation). This age shows that the Mina Verdún Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20?Ga, as shown by K?CAr and Ar?CAr ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pérez Terrane to the remainder of the RPC along the Sarandí del Yí megashear. We report a U?CPb LA-ICP MS zircon age (upper intercept) of 3,096?±?45?Ma for metatonalites of the La China Complex (Nico Pérez Terrane), which yield a lower intercept age of 1,252?Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested. 相似文献
29.
Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vannamei) were investigated.This involved an examination of growth performance,glutamate dehydrogenase(GDH) and Na+-K+ ATPase mRNA expression,,and GDH activity in muscles and gills.Three experimental diets were formulated,containing 25%,40%,and 50% dietary protein,and fed to the shrimp at a salinity of 25.After 20 days,no significant difference was observed in weight gain,though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels.Subsequently,shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5,respectively,and sampled at weeks 1 and 2.Shrimp fed with 40% protein at 25 in salinity(optimal conditions) were used as a control.Regardless of the salinities,shrimp fed with 50% dietary protein had significantly higher growth performance than other diets;no significant differences were found in comparison with the control.Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks.Ambient salinity change also stimulated the hepatosomatic index,which increased in the first week and then recovered to a relatively normal level,as in the control,after 2 weeks.These findings indicate that in white shrimp,the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism.Increased dietary protein level could improve the osmoregulation capacity of L.vannamei with more energy resources allocated to GDH activity and expression. 相似文献
30.
P. Muniz N. Venturini M. Hutton N. Kandratavicius A. Pita E. Brugnoli L. Burone F. García-Rodríguez 《Journal of Sea Research》2011,65(1):38-50
A study on the benthic ecosystem health was performed to assess the environmental quality of Montevideo coastal zone, in view of the construction of a new sanitation system. Data were compared to previous research undertaken 10 years ago, and biochemical composition of organic matter, heavy metals, organic matter, phytopigments, benthic diatoms, macrofauna community structure and a biotic index (AMBI) were used as proxies. Results indicate an environmental quality-gradient, with the worst conditions within the inner stations of Montevideo Bay and an improvement towards the adjacent coastal zone. Higher levels of chromium, lead, phaeopigments, organic biopolymers and poor benthic macrofauna and diatom communities, characterised the hypertrophic innermost portion of Montevideo Bay. Data indicated a clear deterioration of the adjacent coastal zone comparatively to that observed 10 years ago. The complementary use of approaches not applied before (benthic diatoms and organic biopolymers) with those formerly applied improve our assessment of the trophic status and the environmental health of the area. 相似文献