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"Utilização de duas variantes da fluorescência de raios X (EDXRF e TXRF) na determinação de chumbo em águas e sedimentos" ; Use of two variants of X-ray fluorescence (EDXRF and TXRF) in the determination of lead in waters and sediments

Moraes, Liz Mary Bueno de
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 13/12/2004 PT
Relevância na Pesquisa
36.66%
Este trabalho teve como objetivo principal a utilização de duas variantes da técnica analítica de fluorescência de raios X, dispersiva em energia - EDXRF e reflexão total TXRF, na determinação de Pb em amostras de águas superficiais e subterrâneas, e em sedimentos em suspensão e de fundo. Cinco amostras de cada matriz foram coletadas em uma área contaminada, nas proximidades da desativada fábrica de baterias Indústria Acumuladores Ajax Ltda., localizada no km 229 da rodovia Jaú-Ipaussu, em Bauru, SP. As variantes EDXRF com pré-concentração com APDC e medida direta por TXRF mostraram resultados satisfatórios na determinação de Pb em soluções-padrão e amostra certificada de água natural SRM1640, produzida pelo NIST, obtendo-se concentrações compatíveis com os valores esperados. A primeira técnica resultou em limite de detecção da ordem de 0,70 mg L-1, com tempo de análise de 300 s, melhor que a segunda técnica (4,46 mg L-1), em 200 s. Estas duas variantes também foram utilizadas para outros elementos químicos, como o Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn e Br, onde a EDXRF mostrou também melhores limites de detecção para todos os elementos. Para Ni, Cu e Zn, importantes na indústria de baterias, foram encontrados os limites de 0...

Distribuição dos metais pesados em sedimentos de fundo na bacia do alto Tietê: Fatores de enriquecimento e Classes de poluição; Distribution of heavy metals in bottom sediments in the basin of upper Tietê: Enrichment factors and Classes of pollution

Moraes, Graziela Meneghel de
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 12/08/2011 PT
Relevância na Pesquisa
46.46%
O Tietê é um importante rio para o estado de São Paulo, pois é considerado de grande potencial econômico, energético e de navegabilidade. A bacia do alto rio Tietê corresponde ao trecho da nascente em Salesópolis até o reservatório de Pirapora, passando pela região metropolitana de São Paulo. Por estar em uma região com grande pressão antrópica, o rio Tietê sofre grandes impactos ambientais associados ao lançamento de efluentes domésticos e industriais. Atualmente, um dos mais sérios problemas na área ambiental está relacionado à poluição química de natureza inorgânica em sedimentos fluviais, principalmente metais pesados. O presente estudo objetivou avaliar a distribuição dos principais metais pesados (Co, Cr, Cu, Zn, Cd, Ni e Pb) presentes nos sedimentos de fundo, em perfis de profundidade, nas estações de amostragem de Ponte Nova, Biritiba, Mogi das Cruzes e Pirapora ao longo da bacia do alto rio Tietê, identificando as ocorrências de origens naturais e antrópicas, levando em consideração diferentes critérios de toxicidade e biodisponibilidade. A determinação da concentração total dos metais de interesse, em perfil de profundidade, obtidas a partir do método da fusão alcalina permitiu avaliar os critérios de toxicidade considerando os valores-guia de qualidade de sedimentos VI...

Determination of net sediment transport patterns in Lirquén Harbor, Chile, through grain-size trend analysis: a test of methods

Ríos, Felipe; Ulloa, Raúl; Correa, Iran Carlos Stalliviere
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
46.41%
During June 1997, bottom sediment samples were collected at 76 stations on a rectangular grid in a small port (Lirquén Harbor, south-central Chile) facing siltation problems. The spatial changes in grain-size parameters, analyzed by using three different methodologies to infer net sediment transport paths, are compared with the measured water circulation of the study area and sediment dispersal patterns on aerial photographs. A Geographical Information System (GIS) is used to determine the degree of similarity between the results of the three grain-size trend methodologies. The results of this study confirm that because of its formulation and underlying assumptions, the McLaren-Bowles methodology tends to confuse the space-scale of sediment transport processes. In this way, the obtained transport patterns are in poor correlation with the observed hydrodynamics and aerial photographs and they seem to represent a combination of the spatial macroscale and mesoscale sediment transport processes existing in Concepcion Bay and in Lirquén Harbor, respectively. On the contrary, because the results yielded by the Gao-Collins and Le Roux methodologies correlate well with these studies, it is suggested that both methodologies be applied in combination to allow a better representation of local net sediment transport patterns...

Seasonal sediment transport pathways in Lirquen Harbor, Chile, as inferred from grain-size trends

Ríos, Felipe; Cisternas, Marcos; Le Roux, Jacobus; Correa, Iran Carlos Stalliviere
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
SPA
Relevância na Pesquisa
46.55%
En junio y diciembre de 1997 se realizaron dos campañas de muestreo sedimentológico en un puerto afectado por el embancamiento (Puerto Lirquén, Región del Biobío, Chile) con el fin de determinar la circulación sedimentaria del área de estudio a través de la aplicación de tres metodologías basadas en el análisis de los câmbios espaciales de los parámetros granulométricos de los sedimentos. Se estudia la relación entre los regímenes meteorológicos-oceanográficos y de transporte de sedimentos, los resultados de este análisis indican que la movilidad de los sedimentos está asociada a los eventos altamente energéticos que afectan a la Región. Los patrones de transporte obtenidos mediante las metodologías de McLaren-Bowles (1985), Gao-Collins (1992) y Le Roux (1994b), se comparan con el patrón residual de circulación de las aguas y con fotografías aéreas del área de estudio. Los resultados mostrados por las dos últimas metodologías reconocen una variación estacional en el patrón de transporte de sedimentos, concordando así con la variabilidad estacional de las condiciones meteorológicas y hidrodinámicas prevalecientes. Por lo tanto, se sugiere que los patrones de transporte obtenidos a través de las metodologías de Gao-Collins y Le Roux estarían representando la circulación de sedimentos a una mesoescala espacial. Sobre la base de los patrones de transporte de sedimentos inferidos...

The effect of depth and sediment type on the spatial distribution of shallow soft-bottom amphipods along the southern Portuguese coast

Carvalho, Susana; Cunha, Marina R.; Pereira, Fábio; Pousao-Ferreira, P.; Santos, M. N.; Gaspar, M. B.
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.59%
The present study provides updated information on amphipod assemblages of the southern Portuguese coast, the most south-western part of continental Europe. The influence of depth and sediment type on the spatial distribution of shallow soft-bottom amphipods was tested by means of univariate and multivariate methods. Samples were collected down to 40 m depth within areas ranging from very fine sand to gravel. The ratio between density and diversity was found to increase with depth and from coarser to finer sediments. Both physical variables tested were found to play a major role in structuring amphipod assemblages. However, some dominance of depth was evident as samples were mainly separated according to this variable. Moreover, while only 15 taxa were common to all depth levels, 35 were collected from all sediment types. Both depth and sediment type may override the potential effects of geographical location, as samples from different areas along the southern Portuguese coast were biologically related. A peculiar habitat was sampled in this study: a maerl bed, which was confirmed to be a hotspot of density. Nevertheless, this habitat did not harbor a distinct amphipod assemblage but some taxa such as Caprella spp., Lembos websteri...

A Bottom Sediment Distribution Map for the Portuguese Continental Shelf in ArcGis Format: Mapa da Distribuição de Sedimentos Superficiais da Plataforma Continental Portuguesa em Formato ArcGis

Silva, A.J.F.; Azevedo, M.R.; Martins, R.; Mamede, R.; Ricardo, F.; Magalhães, L.; Monteiro, P.; Bentes, L.; Gonçalves, J.M.S.; Quintino, V.; Rodrigues A.M.; Freitas, R.
Fonte: FCUL Publicador: FCUL
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
46.46%
This work presents a simplified map of the spatial distribution of surficial sediments and rock outcrops along the Portuguese continental shelf in ArcGIS format. Preliminary map preparation involved scanning, georeferencing and digitizing of pre-existing base maps from the Portuguese Hydrographic Institute and harmonization with other published and non-published cartographic information. Samples of soft bottom shelf sediments from nearly 500 sites, collected in the scope of the MeshAtlantic, RENSUB and ACOSHELF projects, were analyzed for grain-size and total organic matter. Grain-size analysis was performed using dry and wet sieving. The procedure includes chemical destruction of organic matter with H2O2, chemical dispersion with tetra-sodium pyrophosphate, separation of the mud fraction by wet sieving and dry sieving of both sand and gravel fractions. Raw grain-size data were expressed as weight percentages and classified according to a modified version of the Folk classification system. Grain size data for the whole set of samples were used to create a new sediment distribution map and develop an easy-to-use GIS interface, that will be available in the MeshAtlantic website, as part of a global broadscale habitat map for the Atlantic Area. Overall...

Survival of Escherichia coli in lake bottom sediment.

LaLiberte, P; Grimes, D J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1982 EN
Relevância na Pesquisa
46.59%
The survival of Escherichia coli in bottom sediment (Lake Onalaska, navigation pool no. 7, Mississippi River) was studied by using in situ dialysis culture of sterile (autoclaved) and unsterile sediment samples. Bags made from dialysis tubing were filled with either course sand sediment (28.8% fine) or organic, silty clay sediment (77.2% fine) and placed at the sediment-water interface. Bags representing sterile controls, unsterile uninoculated controls, autoclaved inoculated sediment, and unsterile inoculated sediment were studied during a 5-day period for each sediment type. Daily most-probable-number determinations indicated that E. coli populations in unsterile inoculated sediment fluctuated between 5.3 X 10(2) and 2.2 X 10(3) bacteria per g of silty clay and between 3.0 X 10(3) and 1.4 X 10(4) bacteria per g of sand. Autoclaved silty clay sediment inoculated with 1.0 X 10(6) bacteria per g increased to 2.2 X 10(8) bacteria per g in 3 days. During the same period, autoclaved sand sediment inoculated with 1.2 X 10(5) cells per g increased to 5.4 X 10(7) bacteria per g. By day 5, populations in both cultures had decreased by 1 log. The ability of E. coli to survive for several days in aquatic sediment in situ suggests that fecal coliforms in water may not always indicate recent fecal contamination of that water but rather resuspension of viable sediment-bound bacteria.

Bacteriological water quality effects of hydraulically dredging contaminated upper Mississippi River bottom sediment.

Grimes, D J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1980 EN
Relevância na Pesquisa
46.46%
Bacteriological effects of hydraulically dredging polluted bottom sediment in the navigation channel of the Upper Mississippi River (river mile 827.5 [about 1,332 km] to 828.1 [about 1,333 km]) were investigated. Bottom sediment in the dredging site contained high total coliform densities (about 6,800 most-probable-number total coliform index per g [dry weight] and 3,800 membrane filter total coliforms per g [dry weight]), and fecal coliforms comprised an average 32% of each total coliform count. Total coliform and fecal coliform densities in water samples taken immediately below the dredge discharge pipe were each approximately four times corresponding upstream values; fecal streptococcus densities were approximately 50 times corresponding upstream values. Correlation analysis indicated that mean turbidity values downstream to the dredging operation were directly and significantly (r greater than 0.94) related to corresponding total coliform, fecal coliform, and fecal streptococcus densities. Salmonellae and shigellae were not recovered from either upstream or downstream water samples. Turbidity and indicator bacteria levels had returned to predredge values within less than 2 km below the dredge spoil discharge area at the prevailing current velocity (about 0.15 m/s).

Consistent associations between hepatic lesions in English sole (Parophrys vetulus) and polycyclic aromatic hydrocarbons in bottom sediment.

Landahl, J T; McCain, B B; Myers, M S; Rhodes, L D; Brown, D W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1990 EN
Relevância na Pesquisa
46.57%
A consistent and statistically significant association between prevalence of hepatic neoplasms in free-living sole (Parophrys vetulus) and levels of anthropogenic polycyclic aromatic hydrocarbons in bottom sediment from sites of fish capture was documented in a series of studies conducted over a period of 7 years in Puget Sound, Washington. This result strengthens the evidence supporting a causal relationship between exposure to sediment-associated hydrocarbons and development of hepatic neoplasms in this bottom-dwelling marine fish species. Prevalences of two other distinct categories of idiopathic hepatic lesions-megalocytic hepatosis and steatosis/hemosiderosis-also showed consistent, statistically significant associations with polycylic aromatic hydrocarbon concentrations in bottom sediment, and association with prevalence of a third category (putatively preneoplastic foci of cellular alteration) approached statistical significance. On the basis of other studies, megalocytic hepatosis and foci of cellular alteration are both considered to be important precursor lesions in the stepwise histogenesis of hepatic neoplasms.

Assessment of Bioflocculant Production by Bacillus sp. Gilbert, a Marine Bacterium Isolated from the Bottom Sediment of Algoa Bay

Nontembiso, Piyo; Sekelwa, Cosa; Leonard, Mabinya V.; Anthony, Okoh I.
Fonte: Molecular Diversity Preservation International Publicador: Molecular Diversity Preservation International
Tipo: Artigo de Revista Científica
Publicado em 11/07/2011 EN
Relevância na Pesquisa
46.28%
The bioflocculant-producing potentials of a marine bacteria isolated from the bottom sediment of Algoa Bay was investigated using standard methods. The 16S rDNA sequence analysis revealed 98% similarity to that of Bacillus sp. HXG-C1 and the nucleotide sequence was deposited in GenBank as Bacillus sp. Gilbert with accession number HQ537128. Bioflocculant was optimally produced when sucrose (72% flocculating activity) and ammonium chloride (91% flocculating activity) were used as sole sources of carbon and nitrogen, respectively; an initial pH 6.2 of the production medium; and Mg2+ as cation. Chemical analysis of the purified bioflocculant revealed the compound to be a polysaccharide.

Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine

Butman, Bradford; Aretxabaleta, Alfredo L.; Dickhudt, Patrick J.; Dalyander, P. Soupy; Sherwood, Christopher R.; Anderson, Donald M.; Keafer, Bruce A.; Signell, Richard P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.78%
Cysts of Alexandrium fundyense, a dinoflagellate that causes toxic algal blooms in the Gulf of Maine, spend the winter as dormant cells in the upper layer of bottom sediment or the bottom nepheloid layer and germinate in spring to initiate new blooms. Erosion measurements were made on sediment cores collected at seven stations in the Gulf of Maine in the autumn of 2011 to explore if resuspension (by waves and currents) could change the distribution of over-wintering cysts from patterns observed in the previous autumn; or if resuspension could contribute cysts to the water column during spring when cysts are viable. The mass of sediment eroded from the core surface at 0.4 Pa ranged from 0.05 kg m−2 near Grand Manan Island, to 0.35 kg m−2 in northern Wilkinson Basin. The depth of sediment eroded ranged from about 0.05 mm at a station with sandy sediment at 70 m water depth on the western Maine shelf, to about 1.2 mm in clayey–silt sediment at 250 m water depth in northern Wilkinson Basin. The sediment erodibility measurements were used in a sediment-transport model forced with modeled waves and currents for the period October 1, 2010 to May 31, 2011 to predict resuspension and bed erosion. The simulated spatial distribution and variation of bottom shear stress was controlled by the strength of the semi-diurnal tidal currents...

Near-bottom circulation and dispersion of sediment containing Alexandrium fundyense cysts in the Gulf of Maine during 2010–2011

Aretxabaleta, Alfredo L.; Butman, Bradford; Signell, Richard P.; Dalyander, P. Soupy; Sherwood, Christopher R.; Sheremet, Vitalii A.; McGillicuddy, Dennis J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.71%
The life cycle of Alexandrium fundyense in the Gulf of Maine includes a dormant cyst stage that spends the winter predominantly in the bottom sediment. Wave-current bottom stress caused by storms and tides induces resuspension of cyst-containing sediment during winter and spring. Resuspended sediment could be transported by water flow to different locations in the Gulf and the redistribution of sediment containing A. fundyense cysts could alter the spatial and temporal manifestation of its spring bloom. The present study evaluates model near-bottom flow during storms, when sediment resuspension and redistribution are most likely to occur, between October and May when A. fundyense cells are predominantly in cyst form. Simulated water column sediment (mud) concentrations from representative locations of the Gulf are used to initialize particle tracking simulations for the period October 2010–May 2011. Particles are tracked in full three-dimensional model solutions including a sinking velocity characteristic of cyst and aggregated mud settling (0.1 mm s−1). Although most of the material was redeposited near the source areas, small percentages of total resuspended sediment from some locations in the western (~4%) and eastern (2%) Maine shelf and the Bay of Fundy (1%) traveled distances longer than 100 km before resettling. The redistribution changed seasonally and was sensitive to the prescribed sinking rate. Estimates of the amount of cysts redistributed with the sediment are small compared to the inventory of cysts in the upper few centimeters of sediment.

Variação espacial e sazonal de elementos maiores e traços no estuários do Rio Curimataú (RN), através de dados geoquímicos e de sensoriamento remoto

Garlipp, Adriana Baggio
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Geodinâmica e Geofísica; Geodinâmica; Geofísica Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Geodinâmica e Geofísica; Geodinâmica; Geofísica
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
46.61%
The Curimataú estuary is located in the oriental coast of Rio Grande do Norte State in Brazil. Its importance resides in the fact that this region possesses one of the last portions of preserved mangrove in the Rio Grande do Norte State. Nevertheless, it has been severely affected by many anthropogenic activities, as sugarcane monoculture and shrimp farming. Former works demonstrated that an accumulation of heavy metals is occurring in oysters in this estuary, and perhaps it could be explained by the input of metals in this ecosystem deriving from the shrimp farming. To better understanding the origin of these metals, bottom sediment samples, cores and suspended particulate matter were collected for a characterization of metal concentrations (Al, Ba, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn) and to determine the potentially bioavailable metals. Additionally, the enrichment ratio for each element analyzed was calculated. The mineralogical composition of sediment samples and cores were obtained by X-ray diffraction. Moreover, data of orbital remote sensing were used in order to detect and quantify suspended matter by applying a logarithmic algorithm. Geochemical data of bottom sediments and cores revealed that, excepting Ba and Pb, the elements analyzed presented concentrations characteristic of an unpolluted ecosystem (Al: 0...

Estimation of bottom backscattering strength from measured and modeled AN/SQS-53C reverberation levels

Scanlon, Gary Alexander.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 192 p. :|bill.
EN_US
Relevância na Pesquisa
36.7%
Hamilton type geoacoustic models were developed for Area Foxtrot, a NUWC test bed for emerging active sonar systems where the surface sediment type is highly spatially variable. Reverberation levels (RL) were modeled using the FEPE propagation model to augment the GSM propagation model because the bottom loss model in GSM did not estimate transmission loss accurately in shallow water. FEPE estimates reveal there is over a 15 dB difference between TL for sand and silt-clay sediments in Area Foxtrot. The comparison between modeled RL and measured RL (from a 1991 ASW exercise conducted by MUWC) enabled bottom scattering strength kernels to be developed for Area Foxtrot Bottom scattering strength was found to be a function of sediment type. Hard sand sediment has a bottom scattering strength which obeys Lambert's law (sin2 (theta)) while that of silt clay sediment is consistent with volume scattering (sin (theta)). The RLs in Area Foxtrot are azimuth-dependent and are a function of TL and bottom scattering strength (and hence bottom sediment type). Sonar beams steered towards the hard sand show higher.; U.S. Navy (U.S.N.) author.

BASIN-SCALE WAVES DYNAMICS AND SEDIMENT RESUSPENSION MECHANICS IN CENTRAL LAKE ERIE

Valipour, REZA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
46.61%
High-resolution physical and biogeochemical field data in central Lake Erie during the summers of 2008-2009 along with a three-dimensional numerical model were used to investigate the dynamics of basin scale waves and sediment resuspension mechanisms. In Chapter 2, the modal response of the Poincaré waves in the lake is assessed. The vertical mode-one Poincaré wave was found to be mostly dominant during the seasonal stratified period. The horizontal modal structure was also investigated in a sensitivity analysis, using the numerical model forced with real and idealized wind events. In Chapter 3, dynamics of bottom mixed layer (BML), primarily forced in the outer layer by surface seiches and Poincaré waves is studied for two 10-days representative intervals of weak and strong stratification. Shear velocity was calculated by least square fitting the well-known law-of-the-wall equation to observed near-bed velocity in a region of constant shear stress. Height of the BML is computed using water density (from water temperature) and compared with heights of logarithmic layer approximated using the law-of-the-wall equation and its modified form with buoyancy length scale term. Published equations for estimating BML heights are evaluated and modified for the lake. In Chapter 4...

An integrated GIS for sedimentological and geomorphological analysis of a lagoon environment. Barra de Cananeia inlet region, (Southeastern Brazil)

Conti, Luis Americo; Araujo, Carlos Alberto S.; Paolo, Fernando S.; Barcellos, Roberto L.; Rodrigues, Marcelo; Mahiques, Michel M.; Furtado, Valdenir V.
Fonte: SPRINGER; NEW YORK Publicador: SPRINGER; NEW YORK
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.61%
The aim of this work is to use GIS integration data to characterize sedimentary processes in a SubTropical lagoon environment. The study area was the Canan,ia Inlet estuary in the southeastern section of the Canan,ia Lagoon Estuarine System (CLES), state of So Paulo, Brazil (25A degrees 03'S/47A degrees 53'W). The area is formed by the confluence of two estuarine channels forming a bay-shaped water body locally called "Trapand, Bay". The region is surrounded by one of the most preserved tracts of Atlantic Rain Forest in Southwestern Brazil and presents well-developed mangroves and marshes. In this study a methodology was developed using integrated a GIS database based on bottom sediment parameters, geomorphological data, remote sensing images, Hidrodynamical Modeling data and geophysical parameters. The sediment grain size parameters and the bottom morphology of the lagoon were also used to develop models of net sediment transport pathways. It was possible to observe that the sediment transport vectors based on the grain size model had a good correlation with the transport model based on the bottom topography features and Hydrodynamic model, especially in areas with stronger energetic conditions, with a minor contribution of finer sediments. This relation is somewhat less evident near shallower banks and depositional features. In these regions the organic matter contents in the sediments was a good complementary tool for inferring the hydrodynamic and depositional conditions (i.e. primary productivity...

Comparative metagenomics of bathypelagic plankton and bottom sediment from the Sea of Marmara

Quaiser, Achim; Zivanovic, Yvan; Moreira, David; López-García, Purificación
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.52%
To extend comparative metagenomic analyses of the deep-sea, we produced metagenomic data by direct 454 pyrosequencing from bathypelagic plankton (1000 m depth) and bottom sediment of the Sea of Marmara, the gateway between the Eastern Mediterranean and the Black Seas. Data from small subunit ribosomal RNA (SSU rRNA) gene libraries and direct pyrosequencing of the same samples indicated that Gamma- and Alpha-proteobacteria, followed by Bacteroidetes, dominated the bacterial fraction in Marmara deep-sea plankton, whereas Planctomycetes, Delta- and Gamma-proteobacteria were the most abundant groups in high bacterial-diversity sediment. Group I Crenarchaeota/Thaumarchaeota dominated the archaeal plankton fraction, although group II and III Euryarchaeota were also present. Eukaryotes were highly diverse in SSU rRNA gene libraries, with group I (Duboscquellida) and II (Syndiniales) alveolates and Radiozoa dominating plankton, and Opisthokonta and Alveolates, sediment. However, eukaryotic sequences were scarce in pyrosequence data. Archaeal amo genes were abundant in plankton, suggesting that Marmara planktonic Thaumarchaeota are ammonia oxidizers. Genes involved in sulfate reduction, carbon monoxide oxidation, anammox and sulfatases were over-represented in sediment. Genome recruitment analyses showed that Alteromonas macleodii ‘surface ecotype'...

Distribuição de metais pesados nos sedimentos de fundo ao longo da bacia do Rio Tietê; Heavy metal distribution in the bottom sediments along Tietê River Basin

Mortatti, Jefferson; Hissler, Christophe; Probst, Jean-Luc
Fonte: Universidade de São Paulo. Instituto de Geociências Publicador: Universidade de São Paulo. Instituto de Geociências
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf
Publicado em 01/07/2010 POR
Relevância na Pesquisa
46.27%
Análises de metais pesados em sedimentos fluviais têm sido utilizadas para um melhor entendimento das cargas críticas e grau de toxicidade desses metais em função das influências antrópicas em bacias de drenagem, principalmente relacionados aos efluentes domésticos, industriais e agrícolas. O presente estudo reporta a distribuição de Cr, Cu, Ni, Zn e Pb nos sedimentos de fundo ao longo da bacia do rio Tietê, uma das regiões mais poluídas do sudeste do Brasil. Na parte alta da bacia de drenagem, as concentrações dos metais pesados se mostraram distribuídas na seguinte ordem decrescente Zn >; Cr >; Pb >; Ni >; Cu, enquanto que a jusante, na parte média da bacia (região sob forte influência antrópica) elevadas concentrações de Zn, Cu e Cr com 648, 200 e 183 μg g-1, respectivamente, puderam ser observadas. O potencial de biodisponibilidade dos metais pesados extraídos dos sedimentos de fundo do rio Tietê foi avaliado em função da análise por extração sequencial utilizada, a qual mostrou que na parte alta da bacia, a maioria dos metais pesados se mostrou mais concentrado na fração residual dos sedimentos, enquanto que à jusante, Zn, Cr e Ni se mostraram associados à fração biodisponível em mais de 60%...

Qualidade física e química da água e sedimentos de fundo da porção SW do reservatório de Biritiba-Mirim (SP) e sua implicação ambiental; not available

Sartori, Ana Carolina
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 13/10/2015 PT
Relevância na Pesquisa
46.46%
Essa dissertação teve como objetivo principal comparar parâmetros físicos e químicos da água e sedimentos de fundo em dez pontos delimitados do reservatório de Biritiba-Mirim, uma próxima à atividade agrícola e outra em que havia proteção de mata nativa. Como objetivo secundário, avaliar o uso e ocupação do solo no entorno do reservatório, utilizando imagens obtidas por sensoriamento remoto e também, discutir os parâmetros utilizados para delimitar a qualidade da água e sedimentos de fundo balizados pelos critérios do CONAMA, CETESB e MINISTÉRIO DA SAÚDE. A qualidade da água e sedimentos de fundo do reservatório foi determinada com base na coleta e análise laboratorial das amostras. Os resultados obtidos evidenciam variações nos parâmetros físico-químicos da água, pH e OD. As amostras CAL estão dentro dos valores referenciados pelos critérios estudados, mas algumas amostras CAS e os pontos de referência apresentaram os elementos alumínio, ferro e manganês em concentração acima do valor permitido pelas normativas em questão. As amostras CAL apresentaram-se mais com maior quantidade dos elementos químicos: fósforo, enxofre, potássio, manganês, cobre, zinco e chumbo do que as amostras CAS. Nas duas amostras retiradas do ponto de referência...

Contribution of food availability to the more rapid growth of the scallop, Euvola ziczac (Pteroida, Pectinidae) in bottom than in suspended culture

Hunauld,Patrick; Vélez,Anibal; Jordan,Noris; Himmelman,John H; Morales,Francisco; Freites,Luis; Lodeiros,César J
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2005 EN
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We conducted a 5-month experiment at Turpialito in the Golfo de Cariaco, Venezuela, to examine whether the previously reported more rapid growth of scallop Euvola ziczac in bottom compared to suspended culture can be attributed to more abundant or higher quality food resources near the sediment/water interface. The various body components (shell, muscle, digestive gland, gonad and remaining tissues) increased in size at a much greater rate for scallops maintained on the bottom, in partly buried cages at 5 m in depth, than in cages suspended at the same depth in the water column. Furthermore, survival was greater on the bottom. Food abundance and quality were examined by analyzing the seston collected in sediment traps at the sediment/water interface in the vicinity of the bottom cages and next to the suspended cages. Phytoplankton abundance (chlorophyll a) and the proportion of various fatty acids in the lipid fraction of the seston were similar on the bottom and in suspension. However, sestonic protein, lipid and carbohydrate levels, and the estimated energetic content of the seston, were higher on the bottom than in suspension, and probably contributed to the greater growth on the bottom. As the increase in the energetic content of the seston on the bottom compared to in suspension was less than the increase in growth (biomass) on the bottom compared to in suspension...