Use of EGM08 model and shuttle radar topography mission data for geoid computation in the State of Rio de Janeiro,Brazil: A case study with Voronoi/Delaunay discretisations     

Newton Pereira dos Santos  Iris Pereira Escobar 《Studia Geophysica et Geodaetica》2010,54(2):239-255

The EGM08 geopotential model complete to degree and order 2159 was used in a remove-compute-restore (RCR) method for the geoid computation in the State of Rio de Janeiro, Brazil. Terrain and indirect effect corrections were computed using a 6-arcsec resolution DTE, derived from the TOPODATA Project (Shuttle Radar Topography Mission data) raised by the National Institute for Space Research. INPE, Brazil. We applied Voronoi/Delaunay discretisations for discrete Stokes integration. In these schemes, target area is partitioned into polygons/triangles, respectively, and the computation is carried out by point-wise numerical integration and no gridding is mandatory. For both procedures, the cells were produced using either observed gravity data combined with gridded Bouguer derived information. Particularly in Delaunay scheme, as the gravity anomalies are interpolated into the triangular cells, and geoid undulations are computed for their vertices, Stokes function singularity was gone. Externally estimated errors resulting from a comparison with GPS/leveling data were presented for both the schemes and classical ones, as well as for the EGM08 undulations. They yielded RMS differences equal to 0.105 m, 0.110 m, 0.110 m, 0.115 m and 0.228 m, respectively, for Voronoi, Delaunay, Voronoi/Delaunay with gridded-data alone and EGM08, computed between 32 GPS/leveling points.  相似文献   

Controlling factors and environmental implications of mercury contamination in urban and agricultural soils under a long-term influence of a chlor-alkali plant in the North–West Portugal     

A. Cachada  S. M. Rodrigues  C. Mieiro  E. Ferreira da Silva  E. Pereira  A. C. Duarte 《Environmental Geology》2009,57(1):91-98

This study aims at assessing the extent of total mercury (Hg) contamination in urban and agricultural soils under long-term influence of a chlor-alkali plant, located at about 1 km away from a town centre. Moreover, it aims at identifying the main factors controlling Hg contents’ distribution and associated potential hazards to environment and human health. The median value of total Hg for soil surface layer (0–10 cm) was 0.20 mg/kg (data ranging from 0.050 to 4.5 mg/kg) and for subsurface layer (10–20 cm) 0.18 mg/kg (data ranging from 0.046 to 3.0 mg/kg). The agricultural area showed higher Hg concentrations (ranging from 0.86 to 4.5 mg/kg) than urban area (ranging from 0.05 to 0.61 mg/kg), with some results exceeding target values set by the Dutch guidelines. Mercury concentrations observed in the studied area are more likely to be associated with the influence of the chlor-alkali plant and with the use of historically contaminated sludges and water from a nearby lagoon in agriculture, than to the impacts of urban development. The statistical correlations between Hg concentrations and soil properties suggest that anthropogenic metal sources should influence the spatial distribution more than the geological properties. Although the Hg emissions were drastically reduced 10 years ago, the area under influence of the chlor-alkali plant is still facing potential health and environmental threats arising from soil contamination.  相似文献   

Antioxidant and biotransformation responses in Liza aurata under environmental mercury exposure - relationship with mercury accumulation and implications for public health     

Guilherme S  Válega M  Pereira ME  Santos MA  Pacheco M 《Marine pollution bulletin》2008,56(5):845-859

This study was carried out in the Laranjo basin (Ria de Aveiro, Portugal), an area impacted by mercury discharges. Liza aurata oxidative stress and biotransformation responses were assessed in the liver and related to total mercury (Hg_t) concentrations. A seasonal fish survey revealed a sporadic increase in total glutathione (GSH_t) and elevated muscle Hg_t levels, although Hg levels did not exceed the EU regulatory limit. As a complement study, fish were caged for three days both close to the bottom and on the water surface at three locations, and displayed higher Hg_t levels accompanied by increased GSH_t content and catalase activity as well as EROD activity inhibition. The bottom group displayed higher hepatic Hg_t and GSH_t contents compared with the surface group. Globally, both wild and caged fish revealed that the liver accumulates higher Hg_t concentrations than muscle and, thus, better reflects environmental contamination levels. The absence of peroxidative damage in the liver can be attributed to effective detoxification and antioxidant defense.  相似文献   

Assessment of methylmercury production in a temperate salt marsh (Ria de Aveiro Lagoon, Portugal)     

Válega M  Lillebø AI  Pereira ME  Corns WT  Stockwell PB  Duarte AC  Pardal MA 《Marine pollution bulletin》2008,56(1):153-158

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Search for Spatial Structures at Scales Z∼ 1. III. The Effect of Lensing on QSO ?     

V.F. Litvin  S.A. Matveef  W.E. Pereira  V.V. Orlov 《Astrophysics and Space Science》1999,266(4):507-520

We carried out a search for peak in homogeneities in the distribution of matter – namely clumps and voids, within the range Z ∼ 1-3. We used a new method, based on the lensing of quasars by a combination of lenses, belonging to the above sought in homogeneities in the matter distribution. This work confirms the evidence of the existence of in homogeneities found by us earlier – of a clump (superattractor N.1), and of a void(supervoid). Besides, the existence of a new gigantic clump (superattractorN.2) was also discovered at Z ∼ 3. These clumps could well serve ascenters of the Bose-condensation in the early Universe; in particular –as Anselm's arion condensate, which leads to the formation of quasiperiodic structures with a period p ∼ 100-200 Mpc. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Effect of tidal flooding on metal distribution in pore waters of marsh sediments and its transport to water column (Tagus estuary, Portugal)   总被引：1，自引：0，他引：1  

Juan Santos-Echeandía  Carlos Vale  Miguel Caetano  Patrícia Pereira  Ricardo Prego   《Marine environmental research》2010,70(5):358-367

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A viscoplastic subloading soil model for rate‐dependent cyclic anisotropic structured behaviour          下载免费PDF全文

J. R. Maranha  C. Pereira  A. Vieira 《国际地质力学数值与分析法杂志》2016,40(11):1531-1555

This paper presents a new purely viscoplastic soil model based on the subloading surface concept with a mobile centre of homothety, enabling the occurrence of viscoplastic strains inside the yield surface and avoiding the abrupt change in stiffness of the traditional overstress viscoplastic models. This is required for overconsolidated soils. The model is formulated to reproduce the soil rate‐dependent behaviour under cyclic loading (changes in loading direction) and incorporates both initial and induced anisotropy, as well as destructuring. The model shows good qualitative response to some imposed three‐dimensional stress paths under quasi‐inviscid (elastoplastic) behaviour. Some of the main time‐dependent aspects of soil behaviour that the model is capable of reproducing were also illustrated. The capability of the model to adequately reproduce the results from an undrained triaxial test performed on stiff overconsolidated clays from the Lisbon region (Formação de Benfica), with an unloading–reloading deviatoric stress cycle at constant mean stress, that incorporates a series of staggered fast loading and creep stages, was evaluated. The model was able to reproduce well the main observed aspects of the time‐dependent stress–strain response and pore pressure evolution of a stiff overconsolidated clay under complex loading. The revised and generalised viscoplastic subloading surface concept is viable and can be applied to a consistent extension to viscoplasticity, including in the interior of the yield surface, of existing elastoplastic models formulated for soils and other materials. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Improving GSMaP V06 precipitation products over the Upper Tocantins River basin in the Brazilian Cerrado,based on local rain-gauge network     

Pereira  Rodrigo Moura  Bufon  Vinícius Bof  Maia  Felipe Cardoso Oliveira 《Theoretical and Applied Climatology》2022,148(3-4):1249-1260

Theoretical and Applied Climatology - Gridded precipitation products from remote sensing are currently available and could potentially enhance the use of precipitation data in regions with sparse...  相似文献   

Correction to: Observational Investigation of the Statistical Properties of Surface-Layer Turbulence in a Suburban Area of São Paulo,Brazil: Objective Analysis of Scaling-Parameter Accuracy and Uncertainties     

da Silveira  Lucas Cardoso  de Oliveira  Amauri Pereira  Sánchez  Maciel Piñero  Codato  Georgia  Ferreira  Maurício Jonas  Filho  Edson Pereira Marques  Božnar  Marija Zlata  Mlakar  Primož 《Boundary-Layer Meteorology》2022,185(2):197-197

Boundary-Layer Meteorology -  相似文献   

Mercury distribution in Douro estuary (Portugal)     

Ramalhosa E  Pereira E  Vale C  Válega M  Monterroso P  Duarte AC 《Marine pollution bulletin》2005,50(11):1218-1222

Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-3). The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm(-3), whereas for the more saline bottom waters it was about 65 ng dm(-3). The surface waters had maximum concentrations of total suspended particulate mercury of approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg g(-1). The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters.  相似文献