The role of storm groups in the erosion of sandy coasts     

scar Ferreira 《地球表面变化过程与地形》2006,31(8):1058-1060

  相似文献   

Rainfall interception by an isolated evergreen oak tree in a Mediterranean savannah   总被引：1，自引：0，他引：1  

T. S. David  J. H. C. Gash  F. Valente  J. S. Pereira  M. I. Ferreira  J. S. David 《水文研究》2006,20(13):2713-2726

Redistribution of ground‐level rainfall and interception loss by an isolated Quercus ilex tree were measured over 2 years in a Mediterranean oak savannah. Stemflow, meteorological variables and sap flow were also monitored. Rainfall at ground level was measured by a set of rain‐gauges located in a radial layout centred on the tree trunk and extending beyond the crown limits. Interception loss was computed as the difference between the volume of rainwater that would reach the ground in the absence of the tree and the volume of water that actually fell on the ground sampling area (stemflow included). This procedure provided correct interception loss estimates, irrespective of rainfall inclination. Results have shown a clear non‐random spatial distribution of ground‐level rainfall, with rainwater concentrations upwind beneath the crown and rain‐shadows downwind. Interception loss amounted to 22% of gross rainfall, per unit of crown‐projected area. Stand interception loss, per unit of ground area, was only 8% of gross rainfall and 28% of tree evapotranspiration. These values reflect the low crown cover fraction of the stand (0·39) and the specific features of the Mediterranean rainfall regime (predominantly with few large storms). Nevertheless, it still is an important component of the water balance of these Mediterranean ecosystems. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Strategies to Make Methods Based on Flow Injection Analysis Greener     

Marcos Almeida Bezerra  Ricardo Erthal Santelli  Valfredo Azevedo Lemos  Juscelia Pereira dos Santos Alves  Bernardo Ferreira Braz  Luana Bastos Santos 《洁净——土壤、空气、水》2020,48(7-8)

The implementation of flow injection analysis (FIA) systems and correlated techniques in the laboratory routine provides an increase of analytical throughput and the reduction of risks of analyte losses and contamination. Naturally, it contributes to the reduction of reagent consumption and minimization of waste generation. This paper presents and discusses an overview of the main strategies adopted to make methods based on FIA systems more environmentally friendly, and offers a review of these methods that covers the period from January 2002 to December 2019. Strategies based on reagent management (adoption of procedures without reagents, replacement of toxic reagents, recycling and reuse of reagents and, use of immobilized reagents), the online waste treatment, and the improvements of FIA systems (flow system configurations that avoid reagent wastage, use of green detectors, automation, and miniaturization) are approached in this perspective.  相似文献   

Analysis of the impact of large scale seismic retrofitting strategies through the application of a vulnerability-based approach on traditional masonry buildings     

Tiago Miguel Ferreira  Rui Maio  Romeu Vicente 《地震工程与工程振动(英文版)》2017,16(2):329-348

The buildings’ capacity to maintain minimum structural safety levels during natural disasters, such as earthquakes, is recognisably one of the aspects that most influence urban resilience. Moreover, the public investment in risk mitigation strategies is fundamental, not only to promote social and urban and resilience, but also to limit consequent material, human and environmental losses. Despite the growing awareness of this issue, there is still a vast number of traditional masonry buildings spread throughout many European old city centres that lacks of adequate seismic resistance, requiring therefore urgent retrofitting interventions in order to both reduce their seismic vulnerability and to cope with the increased seismic requirements of recent code standards. Thus, this paper aims at contributing to mitigate the social and economic impacts of earthquake damage scenarios through the development of vulnerability-based comparative analysis of some of the most popular retrofitting techniques applied after the 1998 Azores earthquake. The influence of each technique individually and globally studied resorting to a seismic vulnerability index methodology integrated into a GIS tool and damage and loss scenarios are constructed and critically discussed. Finally, the economic balance resulting from the implementation of that techniques are also examined.  相似文献   

Wave observations from an array of directional buoys over the southern Brazilian coast     

Henrique Patricio Prado Pereira  Nelson Violante-Carvalho  Izabel Christina Martins Nogueira  Alexander Babanin  Qingxiang Liu  Uggo Ferreira de Pinho  Fabio Nascimento  Carlos Eduardo Parente 《Ocean Dynamics》2017,67(12):1577-1591

It is well known that the majority of buoy measurements are located around the US coast and along some Europeans countries. The lack of long-term and densely spaced in situ measurements in the Southern Hemisphere in general, and the South Atlantic in particular, hinders several investigations due to the lack of detailed metocean information. Here, we present an effort to overcome this limitation, with a dense network of buoys along the Brazilian coast, equipped with several meteorological and oceanographic sensors. Out of ten currently operational buoys, three are employed to present the main characteristics of waves in the Southern part of the network. For the first time, sensor characteristics and settings are described, as well as the methods applied to the raw wave data. Statistics and distributions of wave parameters, swell propagating events, comparison with a numerical model and altimeters and a discussion about the occurrence of freak waves are presented.  相似文献   

Insights about the formation of a complex impact structure formed in basalt from numerical modeling: The Vista Alegre structure,southern Brazil     

Marcos Alberto Rodrigues Vasconcelos  Fernanda Farias Rocha  Alvaro Penteado Crsta  Kai Wünnemann  Nicole Güldemeister  Emilson Pereira Leite  Júlio Csar Ferreira  Wolf Uwe Reimold 《Meteoritics & planetary science》2019,54(10):2373-2383

We present the outcomes of simulations of the formation of the Vista Alegre impact structure, Paraná Basin, Brazil. The target comprised a thick sequence of volcanic rocks of predominantly basaltic composition of the Serra Geral Formation that had been deposited on top of sedimentary rocks (sandstones) of the Pirambóia/Botucatu formations. The cratering process was modeled using the iSALE shock physics code. Our best‐fit model suggests that (1) the crater was originally ~10 km in size; (2) it was formed in ~115 s by a stony projectile of 1000 m in diameter, for an assumed impact velocity of 12 km s^?1; (3) target rocks underwent a peak pressure of ~20 GPa, in agreement with previous petrographic investigations of shock deformation. Furthermore, the model points out that the sedimentary strata below the layer of volcanic rocks were raised by ~650 meters at the central part of the crater, which resulted in the current partial exposure of the sandstones at the surface. The outcomes of our modeling suggest that parameters like cohesion and strength of the target rocks, after shock compression, determined the final morphology of the crater, especially the absence of a topographically prominent central peak. Finally, the results of the numerical modeling are roughly in agreement with gravity data over the structure, in particular with respect to the presence of the uplifted sedimentary strata, which are responsible for a low gravity signature at the center of the structure.  相似文献   

Spatiotemporal variability of vegetation due to drought dynamics (2012–2017): a case study of the Upper Paraíba River basin,Brazil     

Ferreira da Silva  Glauciene Justino  de Oliveira  Nádja Melo  Santos  Celso Augusto Guimarães  da Silva  Richarde Marques 《Natural Hazards》2020,102(3):939-964

Natural Hazards - Vegetation indices have been widely used for monitoring the spatiotemporal variables of vegetation and characterizing droughts, primarily in semiarid regions. Drought is a...  相似文献   

The trispectrum of the cosmic microwave background on subdegree angular scales: an analysis of the BOOMERanG data     

G. De Troia  P. A. R. Ade  J. J. Bock  J. R. Bond  A. Boscaleri  C. R. Contaldi  B. P. Crill  P. de Bernardis  P. G. Ferreira  M. Giacometti  E. Hivon  V. V. Hristov  M. Kunz  A. E. Lange  S. Masi  P. D. Mauskopf  T. Montroy  P. Natoli  C. B. Netterfield  E. Pascale  F. Piacentini  G. Polenta  G. Romeo  J. E. Ruhl 《Monthly notices of the Royal Astronomical Society》2003,343(1):284-292

  相似文献   

Nature and origin of the BIF-hosted São Bento gold deposit, Quadrilátero Ferrífero, Brazil, with special emphasis on structural controls     

Srgio Luiz Martins Pereira  Lydia Maria Lobato  Juliano Efigênio Ferreira  Eduardo Csar Jardim 《Ore Geology Reviews》2007,32(3-4):571

The orogenic banded iron formation (BIF)-hosted Au mineralization at São Bento is a structurally-controlled, hydrothermal deposit hosted by Archean rocks of the Rio das Velhas greenstone belt, Quadrilátero Ferrífero region, Brazil. The deposit has reserves of 14.3 t Au and historical (underground) production of 44.6 t Au between 1987 and 2001. The oxide-facies São Bento BIF is mineralized at its lower portion, where in contact with carbonaceous, pelitic schists, particularly in the proximity of sulfide-bearing quartz veins. Shear-related Au deposition is associated with the pervasive, hydrothermal sulfidation (mainly arsenopyrite) of the Fe-rich bands of the São Bento BIF. Auriferous, sulfide- and quartz-rich zones represent proximal alteration zones. They are enveloped by ankerite-dominated haloes, which reflect progressive substitution of siderite and magnetite within the BIF by ankerite and pyrrhotite, respectively. The São Bento BIF was intensely and extensively deformed, first into open, upright folds that evolved into tight, asymmetric, isoclinal folds. The inverse limb of these folds attenuated and gave way to sheath folds and the establishment of ductile thrusts. Mineralized horizons at São Bento result from early structural modifications imposed by major transcurrent and thrusts faults, comprising the Conceição, Barão de Cocais and São Bento shear zones. Dextral movement on the SW–NE-directed Conceição shear zone may have generated splays at a compressional side-stepping zone, such as the São Bento shear zone, which is the structural locus for the São Bento gold mineralization. Relaxation of the Conceição shear zone under more brittle conditions resulted in the development of dilatational zones where gold–sulfide–quartz veins formed. These structures are considered to have been generated in the Archean. Geochronological data are scarce, with Pb–Pb analyses of refractory arsenopyrite and pyrite from bedded and remobilized ore plotting on a single-stage growth curve at 2.65 Ga. A later compressional, ductile deformation of unknown age overprinted, rotated and flattened the original, N60E-directed structure of the whole rock succession, with development of planar and linear fabrics that appear similar to Proterozoic-aged structures. Fluid inclusion studies indicate low salinity, aqueous fluids, with or without CO₂ and/or CH₄, with extremely variable CO₂/CH₄ ratios, of probable metamorphic origin. Fluid evolution shows a paragenetic decrease in the carbonic phase from 10–15% to 5%, and increase in the H₂O/(CO₂ + CH₄) and CO₂/CH₄ ratios, suggesting important interaction with carbonaceous sediment. Trapping conditions indicate a temperature of 300 °C at 3.2 kbar.  相似文献   

Spatial variation in pore water geochemistry in a mangrove system (Pai Matos island, Cananeia-Brazil)     

X.L. Otero  T.O. Ferreira  P. Vidal-Torrado  F. Macías 《Applied Geochemistry》2006,21(12):2171-2186

Spatial variation in salinity, pH, redox potential, and in the concentrations of dissolved Mn, Fe²⁺ and sulphides in pore water were investigated in a mangrove system in the state of São Paulo (Brazil). Total organic C (TOC), S, Fe and Mn were analyzed in the solid phase, along with acid volatile sulphide (AVS), density of roots and percentage of sand. Five zones, situated along the length of a 180 m transect were considered in the study. Four of these were colonized by different species of vascular plants (Spartina, Laguncularia, Avicennia and Rhizophora) and were denominated soils; the other was not colonized by vegetation, and was denominated sediment. The results indicated important differences between the physicochemical conditions of the pore water in the vegetated zones and the sediment. In the former, two geochemical environments were identified, based on soil depths. The upper 20 cm contained the largest quantity of roots, and the conditions were oxic (Eh > 350 mV) or suboxic (Eh: 100–350 mV), acidic, and with high concentrations of Fe and Mn in the pore water. Below this depth, the soil became anoxic, the concentration of sulphides (HS⁻) increased significantly and the concentrations of dissolved Fe and Mn decreased significantly. The total S and the AVS fraction increased with depth, while TOC concentrations decreased, indicating that the decreases in Fe and Mn were due to the precipitation of metal sulphides. However, clear differences among the vegetated zones were not observed. The sediment was always anoxic, but with low concentrations of sulphide in the interstitial water, and was neutral or slightly alkaline. As in the soils, the concentrations of sulphides and total S increased significantly with depth, indicating that the conditions favoured the synthesis and stability of metal sulphides.  相似文献