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41.
de Abreu Corrêa A Albarnaz JD Moresco V Poli CR Teixeira AL Oliveira Simões CM Monte Barardi CR 《Marine environmental research》2007,63(5):479-489
The State of Santa Catarina produces the greatest quantity of edible mollusks in Brazil. To guarantee sanitary qualify, mollusk cultures should be monitored for contamination by pathogenic microorganisms. A self-purification or "depuration" system that eliminates Salmonella enterica serovar Typhimurium contamination from oysters has been developed and evaluated. The depuration process occurred within a closed system, in which 1000 L of water was recirculated for 24 h. The water was sterilized with ultraviolet (UV) light, chlorine, or both together. Oysters (Crassostrea gigas) artificially contaminated with S. typhimurium were harvested every 6 h. Samples of oyster tissue were excised and both the presence and numbers of bacteria were determined. Combined UV light and chlorine treatments resulted in total elimination of bacteria within 12 h. Polymerase chain reaction detected bacteria in water exposed to the three treatments. This pioneering study is the first of its kind in Brazil and represents a major contribution to commercial mollusk culture in this country. 相似文献
42.
Alcides Nobrega Sial Claudio Gaucher Marinho Alves da Silva Filho Valderez P. Ferreira Marcio M. Pimentel Luiz D. Lacerda Emmanoel V. Silva Filho Wilker Cezario 《Precambrian Research》2010
Two cap carbonates overlying glaciogenic diamictites crop out extensively in the eastern Vaza Barris Domain of the Sergipano Belt, northeastern Brazil. They are represented by carbonates of the Jacoca Formation, resting on top of diamictite of the Ribeiropolis Formation, and by the Olhos D’Agua Formation (carbonates, organic-rich towards the top), which overlies diamictite of the Palestina Formation. These two sequences were deformed and metamorphosed at sub-greenschist facies-conditions during the Brasiliano cycle (650–600 Ma). 相似文献
43.
This study investigates the mean kinematic characteristics of the tropical Atlantic easterly disturbances in January-March(JFM),April-June(AMJ),July-September(JAS)and October-December(OND)from 1968-1998.For each season,the preferential tracks of these disturbances in the 3-10-day band periods were computed and spatialized,as well as their associated wavelength,velocity and main period,which lies between 3-5 days and between 6-9 days depending on the track and the season. Two main tracks are highlighted over the Atlantic Ocean.During OND and JFM these two tracks are well separated and located in each hemisphere around 15°S and 12.5°N.From AMJ to JAS these tracks migrate northward;in JAS,they merge into one over the northern tropical Atlantic along 17.5°N.The associated wavelength fields exhibit a meridional gradient,with large wavelengths(greater than 4000 km) around the equator,between 5°N and 5°S,and smaller wavelengths outside of this latitude band(between 2500-3500 km).The phase speed is also found to exhibit poleward decreasing values from 12-6 m s-1. Over the north Atlantic track,6-9-day disturbances were found to occur from January to May and approximately from October to December.From June to September,the 3-5-day waves dominate the synoptic activity.Over the south Atlantic track,between May and August the synoptic variability is mainly explained by the 3-5-day disturbances but from January to April and from September to December both 3-5-day waves and 6-9-day waves can occur. 相似文献
44.
45.
Ana Araujo Richard W. Carlson José C. Gaspar Luiz A. Bizzi 《Contributions to Mineralogy and Petrology》2001,142(2):163-177
Mafic rocks representative of the alkaline magmatism of the Alto Paranaíba Province in southwestern Minas Gerais, Brazil were studied by means of petrography, mineral, whole-rock and isotope geochemistry with the objective of better understanding this Cretaceous magmatism and the characteristics of the magma sources. Because of the variety and complexity of lithotypes examined in this research and the paucity of detailed studies of these Brazilian rocks in the literature, this study also attempts to establish parameters that allow for a clear distinction between kimberlite and kamafugite. Fifty-two occurrences are described and classified as kimberlite or kamafugite. Among the kamafugites, both ugandite (characterized by the presence of leucite) and mafurite (with kalsilite) end members have been characterized. Mineral compositions were found to be efficient in distinguishing between kimberlites, mafurites and ugandites in the province, primarily on the basis of phlogopite composition. The Re-Os isotope systematics permitted a better understanding of the relation of the sublithospheric mantle source to the magmatism in the region. Kimberlites, mafurites and ugandites have different 187Os/188Os ratios (0.117 to 0.129, 0.127 to 0.145 and 0.142 to 0.147, respectively). The Rb-Sr and Sm-Nd isotope systematics failed to indicate first-order differences between kamafugites and kimberlites, whilst 206Pb/204Pb ratios for the kimberlites are higher than those for the other rock types. Kimberlite and kamafugite isotopic compositions appear to be related to the mixture of at least two dominant mantle components: one with an isotopic signature similar to that of lithospheric peridotites, i.e., with 187Os/188Os ratios of the order of 0.118, similar to those observed in mantle-derived xenoliths entrained in kimberlites intruded in the Kaapvaal, Wyoming, and Siberian cratons; another with higher 187Os/188Os ratios of the order of 0.135, within the range of ratios reported for pyroxenite veins in alpine-type peridotites and ocean island basalts. Different melting depths of heterogeneous lithospheric sources by a mantle plume are suggested to explain the isotopic characteristics of the Alto Paranaíba Alkaline Province alkaline rocks. 相似文献
46.
Luiz Antonio Pierantoni Gamboa Philip D. Rabinowitz 《Earth and Planetary Science Letters》1981,52(2):410-418
A broad zone of linear, mappable basement structures is observed north and northeast of the Rio Grande Rise in the South Atlantic Ocean. These structures lie along the same flow line as the Sa?o Paulo Ridge, the Florianopolis High, and onshore lineaments, suggesting that they all comprise the same tectonic trend: the Rio Grande fracture zone. The morphology developed along this fracture zone during the early opening of the South Atlantic Ocean formed a barrier to open ocean circulation during the Aptian and allowed the formation of extensive evaporite deposits to the north of it. 相似文献
47.
Luiz Alberto Ribeiro Mendonça Horst Frischkorn Marlúcia Freitas Santiago Josué Mendes Filho 《Environmental Geology》2005,47(8):1045-1053
Measurements of the environmental isotopes carbon-14 and oxygen-18 and of the electrical conductivity in ground water, together with MODFLOW-88 (DOS) simulations of pumping tests, were used to achieve a detailed understanding of the functioning of an aquifer in the area of a well field. The methodology was applied in the sedimentary basin of the Cariri region, in the south of Ceará State in Brazil. Localized hydraulic connections between adjacent aquifer units could be detected, and mixing ratios for the contributions from the units involved were determined. Cone of depression simulations for a three-year drought period revealed well interference and a drastic lowering of the piezometric level, thereby explaining the hydrogeologic changes and transformations in vegetation that were observed in the area of the well field. The combined use of the modeling tools and the geochemical field observations is shown to provide more detailed insight into the conceptual model of the groundwater flow system. 相似文献
48.
Otávio C. Acevedo Osvaldo L. L. Moraes Gervásio A. Degrazia Luiz E. Medeiros 《Boundary-Layer Meteorology》2006,119(1):41-55
The determination of nocturnal surface fluxes in low wind conditions is a major problem for micrometeorological studies. The
eddy correlation technique, extensively used in field measurements, becomes inappropriate if not enough turbulent activity
exists. At the same time, the phenomenon of turbulence intermittency is responsible for the existence of localized events
of short duration within which a large fraction of the total nighttime scalar exchange occurs. The scalar flux within a certain
intermittent event varies considerably depending on the window used for the flux calculation. In many cases, events with very
different time durations occur in the same night, and therefore, the proper determination of the surface flux would require
averaging within data windows of different sizes for each event. In this work, the surface exchanges of temperature, moisture
and carbon dioxide are analysed at a micrometeorological tower at southern Brazil. Intermittent turbulence is a common occurrence
at the location. The analysis shows that the fluxes vary with turbulence intensity and the estimation technique. A variable-window
size method for flux estimation is suggested and shown to cause an increase in the magnitude of the nocturnal surface fluxes 相似文献
49.
Dr. Bruce Forsberg Dr. Jose Marcus Godoy Dr. Reynaldo Victoria Dr. Luiz Antonio Martinelli 《GeoJournal》1989,19(4):399-405
A 210Pb chronology of sedimentation in a small floodplain lake in the Jamari river basin (Rondonia, Brazil) provided insight into the relationship between development and erosion in the Brazilian Amazon. Positive correlations between increased sedimentation in the lake and levels of deforestation and mining in the Jamari basin suggested a major increase in erosion associated with these activities. This increase in erosion could diminish agricultural yields in the basin and significantly reduce the useful life of a hydro-electric plant recently built on the river. 相似文献
50.
Reynaldo L. Victoria Dr. Luiz A. Martinelli Jeffrey E. Richey Dr. Allan H. Devol Dr. Bruce R. Forsberg Dr. Maria N. G. Ribeiro 《GeoJournal》1989,19(1):45-52
Soil samples were collected on the floodplains of the Amazon River and its principal Brazilian tributaries during dry, early rising water, and early falling water periods. The concentrations of basic cations and pH in these alluvial soils were always higher than those in the more common terra firme soils while the concentrations of aluminum were generally lower. Among the alluvial soils, those from the main channel floodplain were generally higher in basic cations and pH, and lower in aluminum than those from the tribuary floodplains. The concentrations of basic cations in soils along the main channel floodplain decreased downstream. No significant difference was found in the levels of basic cations, pH, or aluminum between sampling periods. 相似文献