Ordinary kriging and indicator kriging in the cartography of trace elements contamination in São Domingos mining site (Alentejo, Portugal)     

M.T. Tavares  A.J. Sousa  M.M. Abreu   《Journal of Geochemical Exploration》2008,98(1-2):43

The abandoned pyrite mine of São Domingos, in the southeast Portugal is still an acid mine drainage generator and a source for trace elements pollution. This study aims to evaluate and map the soils and sediments chemical pollution. With this purpose three test sites located in the vicinities of the mine were sampled for soils, sediments and mining waste materials. The samples were analysed for pH, organic carbon, iron oxides and total content of As, Cu, Cr, Hg, Pb, Sb, U, Zn, Mn, S, Fe Al, Ca, K, Mg and P. The hyperspectral image of the test sites was acquired using the aero transported sensor HymapTM. Chemical analysis and hyperspectral images data were processed to estimate the contamination maps by multivariate data analysis, ordinary kriging, cokriging and indicator kriging methodologies.The test sites located downstream the mine open pit, are highly contaminated mainly in As, Hg, Pb and Sb, but no contamination was found in the third test site, upstream the mining site. The acid mining drainage seems to be the main spreading agent of chemical contaminants mostly originating from the mine waste materials. Factorial analysis and the geostatistical methodologies allowed several approaches for the contamination cartography of mining areas.  相似文献   

Factors Affecting <Emphasis Type="Italic">Pisidium amnicum</Emphasis> (Müller, 1774; Bivalvia: Sphaeriidae) Distribution in the River Minho Estuary: Consequences for its Conservation     

Ronaldo Sousa  Pedro Morais  Carlos Antunes  Lúcia Guilhermino 《Estuaries and Coasts》2008,31(6):1198-1207

The bivalve Pisidium amnicum (Müller 1774) is a common species in several European freshwater ecosystems. However, few Iberian watersheds are colonized by this species, and the River Minho estuary is possibly the Iberian aquatic ecosystem with the larger population. In October 2004–2007, investigations on spatial and temporal variations in P. amnicum abundance and biomass were carried out at 16 sites along the River Minho tidal freshwater wetlands. Mean abundance and biomass per site ranged from 0 to 750 ind m⁻² and 0 to 7.42 g AFDW m⁻², respectively. A clear decrease in the spatial distribution, abundance, and biomass was observed during the 4-year assessment. Furthermore, a stepwise multiple regression model showed that organic matter and conductivity explained 50.2% of the variation in P. amnicum abundance (R ² = 0.502, F _{[2, 15]} = 7.569, p = 0.005). Ecological knowledge is essential to the implementation of future conservation plans for P. amnicum, and the results of this study are of paramount importance to identify habitats that should be protected in order to preserve this species and provide scientific reference that may be useful in the development of management and/or restoration plans.  相似文献   

Recognising na-tech events in Brazil: moving forward     

José Carlos de Moura Xavier  Wilson Cabral de Sousa Junior 《Natural Hazards》2016,82(1):493-506

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Point source radiation in inhomogeneous anisotropic structures     

Ivan Pšenčík  Telesson Neves Teles 《Pure and Applied Geophysics》1996,148(3-4):591-623

The ray formulae for the radiation from point sources in unbounded inhomogeneous isotropic as well as anisotropic media consist of two factors. The first one depends fully on the type and orientation of the source and on the parameters of the medium at the source. We call this factor the directivity function. The second factor depends on the parameters of the medium surrounding the source and this factor is the well-known geometrical spreading. The displacement vector and the radiation pattern defined as a modulus of the amplitude of the displacement vector measured on a unit sphere around the source are both proportional to the ratio of the directivity function and the geometrical spreading.For several reasons it is desirable to separate the two mentioned factors. For example, there are methods in exploration seismics, which separate the effects of the geometrical spreading from the observed wave field (so-called true amplitude concept) and thus require the proposed separation. The separation also has an important impact on computer time savings in modeling seismic wave fields generated by point sources by the ray method. For a given position in a given model, it is sufficient to calculate the geometrical spreading only once. A multitude of various types of point sources with a different orientation can then be calculated at negligible additional cost.In numerical examples we show the effects of anisotropy on the geometrical spreading, the directivity and the radiation pattern. Ray synthetic seismograms due to a point source positioned in an anisotropic medium are also presented and compared with seismograms for an isotropic medium.  相似文献   

Changes in the Wetlands of Andalusia (Doñana Natural Park, SW Spain) at the End of the Little Ice Age     

Arturo Sousa  Pablo García-Murillo 《Climatic change》2003,58(1-2):193-217

The Little Ice Age is a climatic period still insufficiently known. This ignorance is more marked in the case of Andalusia (southern Spain), where only recent works throw any light on the topic. Our studies, primarily from the perspective of botany and changes in the plant landscape, reveal the effects that this period had in these latitudes, and in particular on the Doñana Natural Park (SW Spain). This work shows an aridization in climatic conditions coinciding with the end of the Little Ice Age. The results corroborate the most recent theses on this period in Spain. Furthermore, the effects on the marsh areas studied lead us to conclude that the interpretation of the Little Ice Age in these southern latitudes should be different to that normally given for more northerly latitudes – much better known and more studied than the Mediterranean regions.  相似文献   

Seismic Vulnerability of Historical Constructions: A Contribution   总被引：1，自引：0，他引：1  

Carlos Sousa Oliveira 《Bulletin of Earthquake Engineering》2003,1(1):37-82

Earthquakes are known to be natural hazards that have affected tremendously historical constructions. Unfortunately, as far as earthquake impacts are concerned, there are no world statistics to compare the suffering of populations or of the building stock and their evolution in time, with the damage inflicted to the stock of historical constructions. Lately, a great effort has been placed on engineering developments: (i) to better understand the seismic behaviour of historical construction and (ii) to assess the benefits of different techniques for reinforcing these structures. However, a great deal of discussion is still going on the type of reinforcement that should be applied, how effective it is and how much it costs. Research is needed for helping in these decisions, by providing a more precise framework in this field. The aim of this review is to make an overall insight on some of the available methods for assessing seismic vulnerability of historical constructions and on how to use them in the case of occurrence of an earthquake. Given this occurrence, the objective is to minimize the effects of aftershocks, avoid hurried demolition made under extreme pressure and help shore-up parts in risk of falling. The final aim is also to help in the definition of strategies for the repair of the damaged patrimony, or as a measure to prevent damage in future earthquakes for the most vulnerable cases. The paper is illustrated with the presentation of several examples published in the literature where the author participated. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Thermal expansion of granitoids     

Siegfried Siegesmund  Luís Sousa  Christian Knell 《Environmental Earth Sciences》2018,77(2):41

The thermal rock properties are particularly important for natural stones whenever a temperature change may occur, which becomes particularly important when different materials are combined on any architectural structure. The thermal expansion of a rock is dependent on the coefficients of the expansion of the individual rock-forming minerals and the rock fabric. A systematic study on 65 different stones, mostly granitoids and others magmatic rocks, most of them are often used as dimensional building stones, was performed. Temperature and moisture are very important parameters in the natural environment. Therefore, the thermal expansion, and in addition the thermohygric expansion on selected examples, was measured. The data were also discussed considering the effect of the mineralogy and the temperature. A modeling approach was introduced to show how the mineralogy and the related single crystal properties affect the thermal properties and how good a simple calculation can help to characterize the measured thermal expansion of a rock. The directional dependence of the thermal expansion was also discussed and explained based on detailed rock fabric measurements. In this study, the bowing of granitoid samples was tested and compared with bowing phenomena of granitoid facade panels. The slabs were cut in different directions and were studied under different conditions of temperatures and water saturation. It could be clearly documented that the temperature and the moisture have a control on the bowing behavior. The implication of our data is that thermal expansion depends greatly on wetting and drying, i.e., the thermal cracking is characterized by the residual strain observed after cooling to room temperature. The sensitivity to the thermal cracking has a significant control on the application in architectural constructions.  相似文献   

Towards a framework for geospatial tangible user interfaces in collaborative urban planning     

Valérie Maquil  Ulrich Leopold  Luís Moreira De Sousa  Lou Schwartz  Eric Tobias 《Journal of Geographical Systems》2018,20(2):185-206

The increasing complexity of urban planning projects today requires new approaches to better integrate stakeholders with different professional backgrounds throughout a city. Traditional tools used in urban planning are designed for experts and offer little opportunity for participation and collaborative design. This paper introduces the concept of geospatial tangible user interfaces (GTUI) and reports on the design and implementation as well as the usability of such a GTUI to support stakeholder participation in collaborative urban planning. The proposed system uses physical objects to interact with large digital maps and geospatial data projected onto a tabletop. It is implemented using a PostGIS database, a web map server providing OGC web services, the computer vision framework reacTIVision, a Java-based TUIO client, and GeoTools. We describe how a GTUI has be instantiated and evaluated within the scope of two case studies related to real world collaborative urban planning scenarios. Our results confirm the feasibility of our proposed GTUI solutions to (a) instantiate different urban planning scenarios, (b) support collaboration, and (c) ensure an acceptable usability.  相似文献   

Earthquake early warning for Portugal: part 1 - Where does it matter?     

Silva  Vitor  Taherian  Amir  Oliveira  Carlos Sousa 《Bulletin of Earthquake Engineering》2022,20(11):5545-5565

Bulletin of Earthquake Engineering - In the last five centuries, Portugal was affected by several earthquakes of strong magnitude (M &gt; 7) that caused widespread destruction and a...  相似文献   

Guest editorial: old masonry under seismic loading     

Carlos Sousa Oliveira  Anibal Costa 《Bulletin of Earthquake Engineering》2012,10(1):1-5

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