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Leito de drenagem: sistema natural para redução de volume de lodo de estação de tratamento de água; Draining beds: natural system for sludge volume reduction in the water treatment plant

ACHON, Cali Laguna; BARROSO, Marcelo Melo; CORDEIRO, João Sérgio
Fonte: ABES Publicador: ABES
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.83%
As Estações de Tratamento de Água (ETAs) tem funcionamento semelhante a uma indústria e podem em diversas etapas gerar resíduos que, na maioria das ETAs, são lançados nos corpos d’água sem tratamento. Neste trabalho avaliou-se o desempenho de Leitos de Drenagem, para o desaguamento de lodo, provenientes de ETAs de ciclo completo que empregam sulfato de alumínio e cloreto de polialumínio (PACl), como coagulantes. Analisou-se as características, a drenagem e secagem dos amostras de lodo e característica do drenado. Os Leitos de Drenagem mostraram-se eficientes para desaguamento e redução de volume de lodo de ETA, de forma natural, sem consumo de energia ou adição de produtos químicos. Obteve-se, aos sete dias, reduções da ordem de 87 % em volume para os lodos de PACl e 83 % para o lodo de Sulfato de Alumínio e teor de sólidos totais 28% e 31% respectivamente.; In this work the performance of Draining Beds for sludge dewatering was assessed. The sludge was provided from full cycle Water Treatment Plants (WTPs) that employ aluminum sulfate and polyaluminium chloride (PACl) as coagulants. The characteristics, drainage and drying of samples of sludge and characteristic of drained were analysed. The Draining Beds were shown to be efficient for dewatering and sludge volume reduction in the WTP...

Sphericity of apatite particles determined by gas permeability through packed beds

Pinto, Thiago César de Souza; Lima, Odair Alves de; Leal Filho, Laurindo de Salles
Fonte: SOC MINING METALLURGY EXPLORATION INC Publicador: SOC MINING METALLURGY EXPLORATION INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.83%
Because shape is an assessment of the three-dimensional form of a particle, it may be described in terms of sphericity (Psi), which is a measure of how closely a particle approaches a spherical configuration. In this study, Darcy`s law and the Kozeny-Carman model for fluid flow through porous media were applied to packed beds to determine the sphericity (Psi) of apatite particles. The beds were composed of glass spheres or particles of apatite (igneous from Brazil and sedimentary from the United States) of three classes of size (Class 1: -297 +210 mu m; Class 2: -210 +149 mu m; Class 3: -149 +105 mu m). Glass spheres were used to validate the model because of its known sphericity (Psi = 1.00). Apatite particles, either igneous or sedimentary, showed very close values for particle sphericity (Psi approximate to 0.6). Observations on particle images conducted by scanning electron microscopy illustrated that igneous (Psi = 0.623) and sedimentary (Psi = 0.644) particles of apatite of Class 2 predominantly exhibit elongated shape. The close value of particle sphericity (Psi approximate to 0.6) showed by either igneous or sedimentary apatite may be justified by the similarity in particle shape.; CNPq; CAPES

Influência das micro e macropropriedades dos lodos de estações de tratamento de águas no desaguamento por leito de drenagem; Influence of micro and macroproperties of sludge from water treatment plants in dewatering by draining beds

Barroso, Marcelo Melo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/04/2007 PT
Relevância na Pesquisa
36.92%
O estudo dos fatores intervenientes, micro e macropropriedades dos lodos de estação de tratamento de água (ETA), no desaguamento por sistemas naturais, com uso de leito de drenagem, constituiu o principal foco desta pesquisa. Assim, ensaios de desaguamento por leito de drenagem foram realizados com amostras de lodos de sulfato de alumínio e de cloreto de polialumínio (PA'CL') e monitoramento das variáveis climáticas. Os resultados comprovaram o desempenho do leito de drenagem para redução de volume, da ordem de 80% e 90% para os lodos de PA'CL' e sulfato de alumínio e teor de sólidos final respectivamente de 30 a 90%, sem consumo de energia. Na fase de drenagem, independente do tipo e volume de lodo aplicado, a vazão de drenagem foi maior quanto menor o valor da taxa de aplicação de sólidos - TAS (Kg/'M POT.2') (fração volumétrica de partículas). As variáveis analisadas, teor de sólidos, distribuição de tamanho de partículas, morfologia e composição das partículas entre outros, na massa de lodo bruto e desaguado indicaram diferentes mecanismos de secagem e conseqüente influencia na velocidade de secagem. O uso do fluxo de massa de água evaporada revelou-se adequado para avaliar a fase de secagem. O estudo das micro e macropropriedades do lodo mostram-se decisivos para balisarem pesquisas de desenvolvimento dos sistemas de desaguamento e de reúso dos lodos de ETAs.; The study of involved factors...

Utilização de leitos de drenagem no desaguamento de lodos anaeróbios.; Anaerobic sludge dewatering by modified drying beds.

Mortara, Fernando Cintra
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/09/2011 PT
Relevância na Pesquisa
36.92%
O método de desaguamento por leitos de drenagem foi desenvolvido por Cordeiro a partir do ano de 1993 (CORDEIRO, 2001) para o desaguamento de lodos de Estações de Tratamento de Água. A sua aplicação para lodos de lagoas de estabilização de esgotos foi feita por Fontana et al. (2007). Este trabalho teve por objetivo avaliar a utilização de leitos de drenagem no desaguamento de lodos produzidos em reatores UASB. Para tanto foram realizados ensaios em laboratório, utilizando testes do tempo de drenagem, para avaliar a influência de diferentes doses e tipos de polímeros no desaguamento do lodo. Alguns geotêxteis foram utilizados como meio filtrante nos funis de Buchner e também avaliados pelo teste do tempo de drenagem. Após escolhidas a manta e o polímero que apresentaram os melhores resultados em laboratório, foram desenvolvidos ensaios em escala piloto, com a utilização de três unidades cobertas de leitos de drenagem, cada um com dimensões de 1,58 m x 1,09 m por 0,5 m de altura. Para a avaliação do efeito das diferentes doses de polímero em escala piloto, foram utilizadas doses de polímero de 0 a 8 g/kg de sólidos totais (peso seco) e mantida a taxa de aplicação de sólidos em 15 kgST/m².ciclo (a concentração de sólidos no lodo foi de aproximadamente 27 g/L). Os resultados indicaram que com doses de polímero =2 g/kgST (peso seco) obtinha-se teor de sólidos no lodo de cerca de 13% após 1 dia e 20% após 10 a 15 dias. Para se atingir teor de sólidos de 25 a 30% o período de secagem necessário foi de cerca de 30 dias. Embora que mesmo sem a aplicação de polímeros o comportamento do lodo fosse semelhante ao de lodos condicionados com polímero...

Structural properties of beds packed with agro-industrial solid by-products applicable for solid-state fermentation: Experimental data and effects on process performance

Casciatori, Fernanda Perpetua; Laurentino, Carmem Lucia; Taboga, Sebastiao Roberto; Casciatori, Priscila Aparecida; Thomeo, Joao Claudio
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 214-224
ENG
Relevância na Pesquisa
36.83%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 08/55736-3; Processo FAPESP: 2011/07453-5; The knowledge of structural properties of beds packed with particles from agro-industrial solid wastes is important for modeling and simulation of heat and mass transfer in solid-state fermentation (SSF) in packed-bed bioreactors. This paper addresses the experimental determination of particle and bulk densities (rho(part) and rho(bulk)) and porosities (epsilon) of beds packed with sugar cane bagasse (SCB), wheat bran (WB) and orange pulp and peel (OPP) and with mixtures of them. The effects of moisture content (MC) and packing technique on structural properties were evaluated. Microscopic analysis of cell-size was performed and the porosity along the fermentation was determined, as well as the endoglucanase yields for different proportions of a medium composed by SCB/WB. Results showed that MC affects significantly rho(part), rho(bulk) and epsilon. For OPP and WB, epsilon ranged from 0.4 to 0.7, depending on MC, and for SCB from 0.7 to 0.9, depending on MC and packing technique. For the composed media SCB:OPP:WB (1:2:2, weight) and SCB:WB (7:3)...

Effect of tortuosity on transport properties of mixed granular beds

Mota, M.; Teixeira, J. A.; Bowen, William R.; Yelshin, Alexander
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2000 ENG
Relevância na Pesquisa
36.92%
The properties of binary mixed beds were investigated in a wide range of the particle size ratio δ . The relationship between tortuosity T, porosity ε, δ , and volume fraction of the large particle x_D in mixtures was analysed. Disregarding the tortuosity increase for the range of dense packing led to error in the permeability and diffusivity calculation. The tortuosity variation in the mixed beds must be taken into consideration for modelling transport phenomena in granular mixed beds as well as for building porous media with pre-selected properties. A model of the mixed bed porosity and tortuosity is proposed. The maximum packing tortuosity can be calculated as the product of monosized packing tortuosity both for large and small particle fractions.

Fluid Flow and Solid/Fluid Suspensions Flow in 3-D Packed Beds of Spheres: the effect of periodicity of fixed beds

Serrenho, Ana; Miguel, Antonio F
Fonte: TRANS. TECH. PUBLICATIONS, Switzerland, UK, USA Publicador: TRANS. TECH. PUBLICATIONS, Switzerland, UK, USA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.92%
A 3-D numerical study is performed to investigate the effects of periodicity (geometry) on flow of fluid and on flow of solid/fluid suspensions in packing arrangements of fixed beds of spheres. The porosity is fixed at 0.58 and the following packing arrangements are studied: simple cubic, face-centered cubic, hexagonal, rhomboedric hexagonal and tetragonal. Simulations are carried out at Reynolds numbers ranging from 0.1 and 50, and using solid suspensions with different sizes (0.2, 2 and 10 micron) and densities (200 and 2000 kg/m3). The effect of the periodicity on fluid flow characteristics (permeability and inertia parameter) and on the penetration efficiency of solid suspensions within the packed beds is analyzed and quantified.

Fluid Flow and Particles Transport in 3-D Packed Beds

Serrenho, A.; Miguel, A. F.
Fonte: Fluid Flow and Particles Transport in 3-D Packed Beds. Publicador: Fluid Flow and Particles Transport in 3-D Packed Beds.
Tipo: Aula
ENG
Relevância na Pesquisa
46.83%
A 3-D numerical study is performed to investigate the effects of periodicity (geometry) on fluid flow and particles transport through fixed beds of spheres. The following packing geometries are studied: cubic- orthorhombic simple, hexagonal, orthorhombic, rhombic-hexagonal, rhombic-pyramidal and tetragonal. The effect of the geometry both on fluid flow characteristics (permeability and inertia parameter) and transport of aerosol particles is studied. Simulations are carried out at Reynolds numbers ranging from 0.001 and 100. The transport of solid particle (size 0.2, 2 and 10 micron) with different temperatures is also analyzed.

Benthic Nematodes Assemblages as Indicators of Spatial Heterogeneity in Early Natural Recovery of Zostera Noltii Seagrass Beds.

Adão, Helena; Materatski, Patrick; Vafeiadou, Anna-Maria; Moens, Tom
Fonte: Association of Applied Biologists Publicador: Association of Applied Biologists
Tipo: Aula
ENG
Relevância na Pesquisa
36.83%
During 2008, Zostera noltii seagrass beds of the Mira estuary (SW coast of Portugal) suffered a total collapse. During 2009 symptoms of early recovery were observed. The availability of pre-collapse data and the sequence of sudden collapse followed by early and gradual recovery create a rare natural experiment on recovery and resilience of seagrass ecosystems. The principal goal of this study is to assess the evolution and resilience of the benthic nematodes assemblages during the natural recovery of the seagrass beds through analysis of the spatial and seasonal differences in structural and functional characteristics of the communities. The horizontal macroscale (km) and small scale variability will be evaluate. We hypothesize that the new environmental conditions of the early recovery, with sparsely distributed and small-sized seagrass patches, will increase the spatial heterogeneity of nematode communities and significantly affect community diversity, both taxonomic and functional. The sampling design was follows: Samples were collected in four “occasions”, (June, September, Dezember 2010 and February 2011), at randomly “stations” located over a distance 30 m, at two “sites”, 2km distance. In order to test the hypothesis that the composition of nematodes assemblages changes spatially and seasonally a two–way PERMANOVA analysis was performed based on matrix biodiversity indices including the Maturity Index (MI) and the Index of Trophic Diversity. Mean nematode densities varied between 2 ind. 10 cm-2 and maximum of 4735 ind. 10 cm-2 both at station B and 89 species were identified. The PCO ordination based on abundance and composition of nematode genera clearly reflected the discrimination of the two sites...

Development of a capacitive probe for water level measurement in filtration beds

Dias, Daniel Filipe Cristelo
Fonte: Universidade da Beira Interior Publicador: Universidade da Beira Interior
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
Relevância na Pesquisa
36.83%
Wastewater treatment processes by filtration (e.g. trickling filters, filter beds or constructed wetlands) are widely used for treating several types of wastewater, being a suitable solution for small urban agglomerates. Typically, the flow measurement is installed at the entrance of the plant (in the preliminary treatment) or at the entry of the filtration system, and there is no registration of flow rate in other points, which could be especially useful for the control of hydraulic loads and bed clogging and for evapotranspiration estimates. The existing water level meters are heavy to transport or difficult to setup in various points of filter beds and in addition may be an expensive technology for replication throughout the bed area. This work aimed to develop a light water level sensor, easy to transport and install, robust and with reliable readings, which could be installed at various points of a filtration treatment system. The developed sensor includes a capacitive probe, a data-logger and a computer interface. The system has a capacitive probe that changes depending on the water level. The capacitive value is measured with an appropriated method. The data-logger allows saving multiple records of capacity in time, while the interface can send data to a computer. Laboratory tests were conducted to determine the calibration curves that allow data to be converted from capacity to water height (or water level). These curves have been validated with laboratory measurements. The horizontal subsurface flow constructed wetland of Vila Fernando (Guarda) was used for experimental measurements of water level in 35 measuring points. Since at real scale there are adverse conditions that can interfere with either the probe or with the data-logger readings...

Community structure of the ichthyofauna associated with seagrass beds ( Halodule wrightii) in Formoso River estuary - Pernambuco, Brazil

Pereira,Pedro H.C.; Ferreira,Beatrice P.; Rezende,Sérgio M.
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2010 EN
Relevância na Pesquisa
36.83%
Seagrass beds are used by juvenile fishes in different ways, generally as nursery sites, shelter from predators, reducing competition and increasing availability of food resources, thus establishing a relationship of connectivity with other ecosystems. In the present study, the community structure of the ichthyofauna associated with seagrass beds on the Formoso River (Pernambuco - Brazil) was evaluated during the winter of 2008. Twenty-seven manual trawls (15 daytime and 12 nighttime) were performed, and a total of 358 fishes belonging to 18 families, 21 genus and 25 species were collected. The Catch Per Unit Effort (CPUE) by trawling average was 13.5 and 4.95 individuals per species per trawl. The most abundant families were Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) and Engraulidae (n = 19). Ecological indices for dial changes were always higher for the night period, confirming that such areas are used more frequently during this period. The need for measures to conserve these areas is emphasized, by its importance and vulnerability to human impacts.

A preliminary evaluation of shallow-water rhodolith beds in Bahia Magdalena, Mexico

Ávila,Enrique; Riosmena-Rodriguez,Rafael
Fonte: Universidade de São Paulo, Instituto Oceanográfico Publicador: Universidade de São Paulo, Instituto Oceanográfico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
37.1%
The aim of the present study was to describe the structure of shallow-water rhodolith beds from Bahia Magdalena, one of the most productive estuarine systems of the Mexican Pacific coasts. From September 2008 to May 2009 four rhodolith beds were found (between 1 and 3 m depth) and population descriptors such as rhodolith density, size classes, branch density, volume and weight were determined. The dominant rhodolith forming species was Lithophyllum margaritae. The size of beds ranged from 7,600 to 17,800 m2 approximately with densities from 42.2 to 215.9 ind.m-2. In these beds, L. margaritae shows fruticose and foliose growth forms, from which spherical forms were predominant (81-99%). Branch density (from 3.0 to 13.3 branches.cm-2) varied significantly (p < 0.05) among beds. The average volume (from 2.0 to 400 mL) and wet weight (from 32.4 to 84.8 g) was not significantly different among sites, but a significant positive correlation (r = 0.95, p < 0.05) was found between these parameters. The size of plants ranged from 2.0 to 11.5 cm with predominant size classes of 40.1-60 mm. Differences in rhodolith density, branch density and sphericity were attributed to possible differences in hydrodynamic conditions among sites. These beds were also a suitable habitat for high diversity of associated sponges. A non-metric multidimensional scaling (MDS) analysis using sponge species data revealed variability in the distribution of sponge assemblages among sites...

Evaluation of nursery function of mangroves and seagrass beds for tropical decapods and reef fishes: patterns and underlying mechanisms

Nagelkerken, I.
Fonte: Springer; Netherlands Publicador: Springer; Netherlands
Tipo: Parte de Livro
Publicado em //2009 EN
Relevância na Pesquisa
36.99%
Shallow-water tropical coastal habitats, such as mangroves and seagrass beds, have long been associated with high primary and secondary productivity. The ubiquitous presence of juvenile fish and decapods in these systems has led to the hypothesis that they act as nurseries. Earlier studies mainly focused on the faunal community structure of these systems, leaving us with little detailed insight into their potential role as nurseries. Habitats are considered nurseries if their contribution, in terms of production, to the adult population is greater than the average production of all juvenile habitats, measured by the factors density, growth, survival, and/or movement. High food abundance and low predation risk form the most likely factors that contribute to the attractiveness of tropical nursery habitats. Here, the current state of knowledge on nursery function of shallow-water coastal habitats, particularly mangroves and seagrass beds, is reviewed for each of the above-mentioned factors. Most data show that mangroves and/or seagrass beds have high densities of various fish species and some of their food items, and a lower predation risk for fish and decapods due to factors such as low predator abundance, high water turbidity, and complex habitat structure. In contrast...

Experimental observations on the different mechanisms for solid ejection in gas-fluidized beds

Almendros-Ibáñez, José Antonio; Sánchez-Delgado, Sergio; Sobrino, Celia; Santana Santana, Domingo José
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article Formato: application/pdf
Publicado em /03/2009 ENG
Relevância na Pesquisa
36.83%
This work presents an experimental study of the ejection velocity for different mechanisms of solid ejection in fluidized beds. The experiments were carried out in a 2D fluidized bed, where the bubble eruptions were recorded with a frequency of 250 frames per second using a high speed video camera with a resolution of 1.3 Megapixels. The results show that in isolated bubble eruption, the dome velocity is significantly reduced by the effect of a group of raining particles in the form of stalactites within the bubble. Higher velocities are observed when bubble coalescence takes place. If bubbles coalesce before the leading bubble breaks, the momentumof the trailing bubble together with the increase in the throughflowaccelerate the dome of the leading bubble. In contrast, when coalescence occurs after the breakage of the leading bubble, the wake of the trailing bubble is projected into the freeboard with a very high velocity (wake spike mechanism). The last observed mechanism, the jet spike mechanism, occurs when a stream of bubbles reaches the bed surface following the path opened by the previous bubbles. A cloud of particles moving upward is observed, although their velocities are not as high as in thewake spike mechanism due to the interchange of momentum during the collisions with other particles. Finally...

Numerical and experimental investigations on pseudo-2D gas fluidized beds

Hernández Jiménez, Fernando
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
37.04%
This dissertation is divided into seven chapters that study, numerically and experimentally, uidized beds of small thickness, i.e., pseudo two-dimensional (2D) gas fluidized beds. These types of fluidized beds are crucial for the understanding of the dynamics of gas-particle systems. In this regard, pseudo-2D fluidized bed systems typically have a transparent wall, to allow optical access to the system, and the volume of the bed possesses a small thickness to ensure that the visualisation is representative of the whole system. Additionally, the front and the rear walls restrict the motion of the solids, leading to different flow behaviour compared to fully three-dimensional (3D) systems. Therefore, a correct interpretation of the observations and numerical simulations of pseudo-2D beds is crucial for the understanding of the fluidization physics and the scale-up of the results to other types of beds (.....) ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------; El presente documento se divide en siete capítulos que estudian, tanto numérica como experimentalmente...

Heat transfer and thermal storage in fixed and fluidized beds of phase change materials

Izquierdo Barrientos, Maria Asunción
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
37.04%
Thermal energy storage is a key technology for energy conservation since many energy sources are intermittent in nature. Latent heat storage is considered one of the most efficient ways of storing thermal energy because, unlike sensible heat storage, it provides a high-energy storage density with a small temperature swing. There are available many storage techniques, including sensible and latent heat storage or a combination of both. Fixed and fluidized beds may be feasible technologies when the storing materials may be encapsulated in cans, spheres or microencapsulated in highly porous structures with protecting envelopes. This PhD thesis deals with thermal storage and heat transfer in fixed and fluidized beds with phase change materials (PCMs). The behavior of a bed with granular PCM as a thermal storage system is studied. Charging and discharging experiments are carried out and models for the transient response of the bed are developed for fixed and fluidized bed configurations. Moreover, a model for the heat transfer coefficient between the bed of PCM and an immersed surface is presented and validated with experimental measurements. The experimental studies are conducted in a cylindrical bed filled with granular PCM and with air as the working fluid. The bed has an internal diameter of 200 mm. The granular PCMs used consist of paraffin...

Rhodolith beds in Brazil: a new potential habitat for marine bioprospection

Amado-Filho,Gilberto M.; Pereira-Filho,Guilherme H.
Fonte: Sociedade Brasileira de Farmacognosia Publicador: Sociedade Brasileira de Farmacognosia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
36.92%
Rhodoliths are the free-living forms of a number of nongeniculate coralline algae. Rhodolith beds are a common feature of subtidal environments and have been recognized as important carbonate producers and paleoenvironmental indicators, as well as recognized as habitat-forming species. The rhodolith structure provides a hard three-dimensional substrate serving as microhabitat for a wide range of biodiversity, including commercially importance species. The largest known latitudinal occurrence range of rhodolith beds ais on the Brazilian coastal shelf from 2°N to 25°S. Despite their importance for the Brazilian benthic communities, only in the last decade sampling efforts allowed a more comprehensive understanding of the beds' distribution, their structure and associated communities, as well as data concerning the influence of environmental factors on rhodolith bed structure and dynamics. In this work, we review the available information on the biodiversity associated with the recently described Brazilian rhodolith beds of the continental shelf and oceanic islands, focusing on the associated organisms with potential for bioprospection research.

A preliminary evaluation of shallow-water rhodolith beds in Bahia Magdalena, Mexico

Ávila, Enrique; Riosmena-Rodriguez, Rafael
Fonte: Universidade de São Paulo. Instituto Oceanográfico Publicador: Universidade de São Paulo. Instituto Oceanográfico
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 01/12/2011 ENG
Relevância na Pesquisa
37.1%
The aim of the present study was to describe the structure of shallow-water rhodolith beds from Bahia Magdalena, one of the most productive estuarine systems of the Mexican Pacific coasts. From September 2008 to May 2009 four rhodolith beds were found (between 1 and 3 m depth) and population descriptors such as rhodolith density, size classes, branch density, volume and weight were determined. The dominant rhodolith forming species was Lithophyllum margaritae. The size of beds ranged from 7,600 to 17,800 m2 approximately with densities from 42.2 to 215.9 ind.m-2. In these beds, L. margaritae shows fruticose and foliose growth forms, from which spherical forms were predominant (81-99%). Branch density (from 3.0 to 13.3 branches.cm-2) varied significantly (p < 0.05) among beds. The average volume (from 2.0 to 400 mL) and wet weight (from 32.4 to 84.8 g) was not significantly different among sites, but a significant positive correlation (r = 0.95, p < 0.05) was found between these parameters. The size of plants ranged from 2.0 to 11.5 cm with predominant size classes of 40.1-60 mm. Differences in rhodolith density, branch density and sphericity were attributed to possible differences in hydrodynamic conditions among sites. These beds were also a suitable habitat for high diversity of associated sponges. A non-metric multidimensional scaling (MDS) analysis using sponge species data revealed variability in the distribution of sponge assemblages among sites...

Early Archean spherule beds: Chromium isotopes confirm origin through multiple impacts of projectiles of carbonaceous chondrite type: Comment and Reply

Glikson, Andrew
Fonte: Geological Society of America Inc Publicador: Geological Society of America Inc
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.92%
Three Early Archean spherule beds from Barberton, South Africa, have anomalous Cr isotope compositions in addition to large Ir anomalies, confirming the presence of meteoritic material with a composition similar to that in carbonaceous chondrites. The extra-terrestrial components in beds S2, S3, and S4 are estimated to be ∼1%, 50%-60%, and 15%-30%, respectively. These beds are probably the distal, and possibly global, ejecta from major large-body impacts. These impacts were probably much larger than the Cretaceous-Tertiary event, and all occurred over an interval of ∼20 m.y., implying an impactor flux at 3.2 Ga that was more than an order of magnitude greater than the present flux.

Oil-source correlation study of the Paleogene red beds in the Boxing sag of the Dongying depression, eastern China

Wang,Ying; Liu,Luofu; Meng,Jianghui; Jiang,Zhenxue; Gao,Yongjin; Liu,Shuhui
Fonte: Instituto de Geología, UNAM Publicador: Instituto de Geología, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
36.99%
We present a correlation study of the oil occurrence in the Paleogene red beds of the Boxing sag of the Dongying depression, eastern China. The reservoir includes the lower 4th Member of the Shahejie Formation (Es4¹) and 1st Member of the Kongdian Formation (Ek1). Sixteen source rock samples and 17 oil sand samples from the Boxing sag were collected and the biomarkers were analyzed to perform oil-source correlation. The results show that three oil types characterize the petroleum stored in the Paleogene red beds of the Boxing sag. The oil in Es4¹ is classified as Type A oil and is derived from the Es3¹ (lower 3rd Member of the Shahejie Formation) source rock, which was deposited in a freshwater-brackish lacustrine environment. The oil in Ek1 of the eastern sag (well Bo-8) is originated from the Es4u (upper 4th Member of the Shahejie Formation) source rock, characterized by saline-hypersaline lacustrine environment, and classified as Type B oil. The oil within Ek1 is a mixture of oil generated from both Es3¹ and Es4u source rocks and classified as Type C oil. The distribution of the different oil types in the Paleogene red beds in the Boxing sag is controlled by faults that connect the source rocks with the reservoir bed, which are here named "oil-source faults". The Paleogene red beds in the footwall blocks of these "oil-source faults" are the most promising oil and gas exploration target.