Review: The Yucat��n Peninsula karst aquifer, Mexico     

Peter Bauer-Gottwein  Bibi R. N. Gondwe  Guillaume Charvet  Luis E. Mar��n  Mario Rebolledo-Vieyra  Gonzalo Merediz-Alonso 《Hydrogeology Journal》2011,19(3):507-524

The Yucatán Peninsula karst aquifer is one of the most extensive and spectacular karst aquifer systems on the planet. This transboundary aquifer system extends over an area of approximately 165,000? km² in México, Guatemala and Belize. The Triassic to Holocene Yucatán limestone platform is located in the vicinity of the North American/Caribbean plate boundary and has been reshaped by a series of tectonic events over its long geologic history. At the end of the Cretaceous period, the Yucatán Peninsula was hit by a large asteroid, which formed the Chicxulub impact crater. The Yucatán Peninsula karst aquifer hosts large amounts of groundwater resources which maintain highly diverse groundwater-dependent ecosystems. Large parts of the aquifer are affected by seawater intrusion. Anthropogenic pollution of the aquifer has been increasing over the past few decades, owing to relentless economic development and population growth on the Peninsula. This review summarizes the state of knowledge on the Yucatán Peninsula karst aquifer and outlines the main challenges for hydrologic research and practical groundwater-resources management on the Peninsula.  相似文献   

The study of metal contamination in urban topsoils of Mexico City using GIS   总被引：1，自引：0，他引：1  

María Teresa Rodríguez-Salazar  Ofelia Morton-Bermea  Elizabeth Hernández-Álvarez  Rufino Lozano  Victor Tapia-Cruz 《Environmental Earth Sciences》2011,62(5):899-905

This research presents and discusses information concerning the spatial distribution of heavy metals (Pb, Cu, Zn, Ba, Co, Cr, Ni and V) in the urban environments of Mexico City using geographical information system and statistical analysis. Superficial soil samples (n = 146) were analyzed. The highest contamination indices were found in the north and center zone of the metropolitan area. In contrast, the surrounding rural fields show a lower impact grade. The higher concentrations of Pb, Cu, Zn and Ba were observed as being related to high vehicular traffic, nevertheless other elements such as Co, Cr, Ni and V do not show anthropogenic influence and their content can be attributed to the parental rock. The results are compared with previous surveys carried out in 2003 in order to evaluate temporal deposition trends. No changes were found on reported concentrations except for Cu and Zn, whose concentration has increased in later years. The results suggest that spatial distribution analysis and results in comparison with previous studies could be useful for the management and sustainable development of the metropolitan area of Mexico City.  相似文献   

Territorial dynamics and boundary effects in a protected area of the Central Iberian Peninsula     

Paloma de las Heras  Paloma Fernández-Sañudo  Nieves López-Estébanez  María José Roldán 《Central European Journal of Geosciences》2011,3(1):1-11

We analysed the main changes in land use over a 21 year period within the perimeter of a Protected Natural Area (PNA) and outside this perimeter. The area is characterised by its Mediterranean mid-mountain landscape and its piedmont, which extends almost as far as the city of Madrid. We employed cartography of land use and plant formation from 1980 and 2001. We identified land uses and their changes in this time period in order to determine the principal territorial dynamics (scrub encroachment, urban development, forest encroachment, new pastures and new crops). Subsequently, we performed a comparative analysis between the changes inside and those outside the protected area. The results show that there is a boundary effect between the protected area and the surrounding zone, which is more notable in the areas where urban development has intensified. This kind of research serves to establish whether or not a PNA contributes to protecting and conserving natural resources as compared to what occurs in the unprotected surrounding area, which tends to be subjected to more aggressive dynamics.  相似文献   

Volcanic ash forecast during the June 2011 Cordón Caulle eruption   总被引：1，自引：0，他引：1  

Estela Collini  María Soledad Osores  Arnau Folch  José G. Viramonte  Gustavo Villarosa  Graciela Salmuni 《Natural Hazards》2013,66(2):389-412

We modelled the transport and deposition of ash from the June 2011 eruption from Cordón Caulle volcanic complex, Chile. The modelling strategy, currently under development at the Argentinean Naval Hydrographic Service and National Meteorological Service, couples the weather research and forecasting (WRF/ARW) meteorological model with the FALL3D ash dispersal model. The strategy uses volcanological inputs inferred from satellite imagery, eruption reports and preliminary grain-size data obtained during the first days of the eruption from an Argentinean ash sample collection network. In this sense, the results shown here can be regarded as a quasi-syn-eruptive forecast for the first 16 days of the eruption. Although this article describes the modelling process in the aftermath of the crisis, the strategy was implemented from the beginning of the eruption, and results were made available to the Buenos Aires Volcanic Ash Advisory Centers and other end users. The model predicts ash cloud trajectories, concentration of ash at relevant flight levels, expected deposit thickness and ash accumulation rates at relevant localities. Here, we validate the modelling strategy by comparing results with satellite retrievals and syn-eruptive ground deposit measurements. Results highlight the goodness of the combined WRF/ARW-FALL3D forecasting system and point out the usefulness of coupling both models for short-term forecast of volcanic ash clouds.  相似文献   

Effect of the addition of granitic powder to an acidic soil from Galicia (NW Spain) in comparison with lime   总被引：1，自引：1，他引：0  

Benita?Silva  Remigio?ParadeloEmail author  Nuria?Vázquez  Eduardo?García-Rodeja  María?Teresa?Barral 《Environmental Earth Sciences》2013,69(2):429-441

The impact of diffuse pollution, agricultural land use and climate change on the long-term response of subsurface–surface water quality is not well understood, but is a prerequisite for evaluation of water management options. The goal of this study is to model geochemical evolution of water chemistry from the infiltration through soil into the unsaturated zone, transport through bedrocks and granular aquifers to a river in order to identify zones of steep concentration gradients and high dynamics under transient flow conditions. A numerical model was constructed comprising a 2-D 1,500 m × 150 m vertical cross-section of typical sedimentary rock formations, a glacio-fluvial quaternary gravel aquifer in the valley and soil layers. The model coupled saturated/un-saturated flow and reactive transport under steady state and transient conditions. Geochemical interactions, include intra-aqueous kinetic reactions of oxygen with dissolved organic matter, as well as kinetics of carbonate dissolution/precipitation. This model section was chosen to provide insight in to the principal processes and time scales affecting water chemistry along different flow paths. The numerical simulator MIN3P was used, a finite volume program for variably saturated subsurface flow and multi-component reactive transport. The results show that subsurface water residence times range from approximately 2 to 2,000 years. Different zones are to be expected with respect to the development of mineral equilibria; namely, purely atmospherically influenced, as well as open and closed system carbonate dissolution. Short-term responses to daily averaged changes in precipitation, however, are only visible to some extent in the shallower and near-river parts of flow system and solute loads. This can most likely be explained by directional changes in flow paths, indicating that equilibrium geochemical condition predominate at the hillslope scale, i.e. water quality depends on transport pathways rather than on kinetic effects. The extent of reducing conditions is controlled by the presence of organic-rich layers (i.e. peat deposits), the dissolution kinetics of aquifer organic matter and the subsequent mixing with oxygenated water by hydrodynamic dispersion.  相似文献   

Bloom of Scrippsiella trochoidea (Gonyaulacaceae) in a shrimp pond in the southwestern Gulf of California, Mexico     

Gárate-Lizárraga I  Band-Schmidt CJ  López-Cortés DJ  Muñetón-Gómez Mdel S 《Marine pollution bulletin》2009,58(1):145-149

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Macroinvertebrate patterns along environmental gradients and hydrological connectivity within a regulated river-floodplain     

Belinda Gallardo  Mercedes García  Álvaro Cabezas  Eduardo González  María González  Cecilia Ciancarelli  Francisco A. Comín 《Aquatic Sciences - Research Across Boundaries》2008,70(3):248-258

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Tectono-sedimentary evolution of Jurassic–Cretaceous diapiric structures: Miravete anticline,Maestrat Basin,Spain     

Jaume Vergés  Yohann Poprawski  Ylènia Almar  Peter A. Drzewiecki  Mar Moragas  Telm Bover-Arnal  Chiara Macchiavelli  Wayne Wright  Grégoire Messager  Jean-Christophe Embry  David Hunt 《Basin Research》2020,32(6):1653-1684

Integration of extensive fieldwork, remote sensing mapping and 3D models from high-quality drone photographs relates tectonics and sedimentation to define the Jurassic–early Albian diapiric evolution of the N–S Miravete anticline, the NW-SE Castel de Cabra anticline and the NW-SE Cañada Vellida ridge in the Maestrat Basin (Iberian Ranges, Spain). The pre shortening diapiric structures are defined by well-exposed and unambiguous halokinetic geometries such as hooks and flaps, salt walls and collapse normal faults. These were developed on Triassic salt-bearing deposits, previously misinterpreted because they were hidden and overprinted by the Alpine shortening. The Miravete anticline grew during the Jurassic and Early Cretaceous and was rejuvenated during Cenozoic shortening. Its evolution is separated into four halokinetic stages, including the latest Alpine compression. Regionally, the well-exposed Castel de Cabra salt anticline and Cañada Vellida salt wall confirm the widespread Jurassic and Early Cretaceous diapiric evolution of the Maestrat Basin. The NE flank of the Cañada Vellida salt wall is characterized by hook patterns and by a 500-m-long thin Upper Jurassic carbonates defining an upturned flap, inferred as the roof of the salt wall before NE-directed salt extrusion. A regional E-W cross section through the Ababuj, Miravete and Cañada-Benatanduz anticlines shows typical geometries of salt-related rift basins, partly decoupled from basement faults. These structures could form a broader diapiric region still to be investigated. In this section, the Camarillas and Fortanete minibasins displayed well-developed bowl geometries at the onset of shortening. The most active period of diapiric growth in the Maestrat Basin occurred during the Early Cretaceous, which is also recorded in the Eastern Betics, Asturias and Basque-Cantabrian basins. This period coincides with the peak of eastward drift of the Iberian microplate, with speeds of 20 mm/year. The transtensional regime is interpreted to have played a role in diapiric development.  相似文献   

CPLat: first operational experimental processing center for SIRGAS in Argentina     

María Paula Natali  M. Müller  L. Fernández  C. Brunini 《Journal of Geodesy》2009,83(3-4):219-226

The SIRGAS permanent GPS network which is in fact the IGS network densification for the American continent, consists today of more than 200 stations covering the continent and islands. It is currently processed by the IGS RNAAC SIR centre at Deutsches Geodätisches Forschungsinstitut producing weekly free solutions relying on IGS final orbits and EOP that contribute to the ITRF through IGS. By August 2006, the SIRGAS Working Group I had accepted five proposals for experimental processing centers within the region that would collaborate with IGS RNAAC SIR. One of them, Centro de Procesamiento La Plata (CPLat) in Argentina, began processing 60 stations on October 2006. By January 2007 CPLat reached operational capability, delivering weekly free solution SINEX files, with an internal consistency of 1.5 mm average for the horizontal components, and 3 mm in the vertical. Comparisons with IGS global and IGS RNAAC SIR weekly solutions were taken as external consistency indications, showing average RMS residuals of 1.8, 2.4 and 5 mm for the north, east, and vertical component, respectively. Analysis and comparison of adjusted solution time series from CPLat and other processing centers has proved to be highly valuable for solution QC, namely detection and identification of station anomalous behavior or modelling problems. These procedures will ensure the maintenance of the performance specifications for CPLat solutions. Action is being taken in order to guarantee the continuity of this effort beyond the experimental phase.  相似文献   

A densification mechanism to model the mechanical effect of methane hydrates in sandy sediments     

Maria De La Fuente  Jean Vaunat  Héctor Marín-Moreno 《国际地质力学数值与分析法杂志》2020,44(6):782-802

Recent pore-scale observations and geomechanical investigations suggest the lack of true cohesion in methane hydrate-bearing sediments (MHBSs) and propose that their mechanical behavior is governed by kinematic constrictions at pore-scale. This paper presents a constitutive model for MHBS, which does not rely on physical bonding between hydrate crystals and sediment grains but on the densification effect that pore invasion with hydrate has on the sediment mechanical properties. The Hydrate-CASM extends the critical state model Clay and Sand Model (CASM) by implementing the subloading surface model and introducing the densification mechanism. The model suggests that the decrease of the sediment available void volume during hydrate formation stiffens its structure and has a similar mechanical effect as the increase of sediment density. In particular, the model attributes stress-strain changes observed in MHBS to the variations in sediment available void volume with hydrate saturation and its consequent effect on isotropic yield stress and swelling line slope. The model performance is examined against published experimental data from drained triaxial tests performed at different confining stress and with distinct hydrate saturation and morphology. Overall, the simulations capture the influence of hydrate saturation in both the magnitude and trend of the stiffness, shear strength, and volumetric response of synthetic MHBS. The results are validated against those obtained from previous mechanical models for MHBS that examine the same experimental data. The Hydrate-CASM performs similarly to previous models, but its formulation only requires one hydrate-related empirical parameter to express changes in the sediment elastic stiffness with hydrate saturation.  相似文献