215 resultados para Brazil Paraná
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Este estudo é parte do monitoramento limnológico empreendido pela Companhia Energética do Estado de São Paulo (CESP) durante o processo de enchimento do reservatório de Porto Primavera (Usina Hidrelétrica Engenheiro Sérgio Motta). Este reservatório, localizado no alto rio Paraná, entre os Estados de São Paulo e Mato Grosso, é o quarto maior do país. A primeira etapa de enchimento do lago começou em dezembro de 1998 e a segunda em março de 2001. Amostras para a análise da comunidade bentônica e das características sedimentológicas foram coletadas trimestralmente entre agosto de 1999 e novembro de 2001 e também em agosto de 2002 (11 campanhas). As coletas foram feitas em 13 estações de amostragem distribuídas no reservatório e em uma localizada a jusante da barragem. 128 táxons de invertebrados foram encontrados, sendo Mollusca, Annelida, Insecta e Nematoda os grupos dominantes durante praticamente todos os meses analisados. A classe Insecta foi a melhor representada, com 9 diferentes ordens, dentro das quais os Diptera contribuíram com a ocorrência de 63 táxons. A espécie exótica de bivalve Corbicula fluminea foi registrada em todas as estações de amostragem mostrando sua grande capacidade para colonizar novos habitats em regiões neotropicais. Variações consideráveis na densidade da fauna foram observadas para os diferentes períodos e locais analisados. A densidade máxima (média de 7812 ind.m-2) foi registrada no centro do reservatório enquanto que as densidades mínimas foram registradas na zona lacustre próxima à barragem (média de 9 ind.m-2). A maior riqueza de espécies por local/período (24 táxons) foi encontrada no trecho superior do reservatório (trecho fluvial). A diversidade máxima foi observada nas zonas superior e central do reservatório, com valores de 3.82 e 3.86 (bits.ind-1) no início (agosto/1999) e final (agosto/2002) do processo de enchimento, respectivamente. Não foi encontrado um padrão de distribuição dos grupos faunísticos que pudesse estar associado com a textura granulométrica dos diferentes locais amostrados. Por outro lado, constatou-se a diminuição, ou mesmo a não ocorrência de organismos, nas estações com elevada concentração de matéria orgânica (>40%) em baixo estado de degradação (grandes detritos vegetais). Tal fato pode estar relacionado com a falta de depósitos de sedimentos, dificultando a fixação de organismos da fauna bentônica, bem como com condições químicas mais redutoras em função da intensidade dos processos de decomposição da fitomassa inundada.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Diamictites interbedded with marine shales and turbidites onlap the eastern border of the Parana Basin (Southern Brazil). These poorly sorted sediments were deposited during the Permo-Carboniferous glaciation, and their matrix-supported clasts show no preferred orientation. These massive rocks have been studied using anisotropy of magnetic susceptibility (AMS) and grain shape fabric. Hysteresis loops and thermomagnetic measurements show that AMS depends mostly on the paramagnetic clays, but fine ferromagnetic particles also contribute to the anisotropy. The coarse silt to sand grain preferred orientation study supports the use of AMS in describing the diamictite fabric, at least regarding the orientation of the foliation. AMS and grain shape data reveal subhorizontal to weakly inclined magnetic and grain shape foliation parallel to the regional bedding. The magnetic lineations are normally scattered within the foliation plane in agreement with the oblate AMS ellipsoids found in these rocks. Both fabric patterns are consistent with deposition by subaqueous mudflows that were resedimented downslope, with elastic supply from continental sources. The off-vertical grain shape foliation poles suggest that the deposition of diamictites was controlled by the depocentre topography of the Rio do Sul sub-basin.
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A study of the characteristics and distribution of the soil humus fractions in representative ecosystems of central Brazil was carried out with special emphasis on the comparison between the soils under virgin vegetation-Cerrado-and those subjected to cultivation. In spite of the contrasted vegetation and cultural practices in the sites studied, the soil humus showed analogous characteristics: there was a negligible amount of plant residues, the humic and fulvic acids amounted to approximately 70% of the total organic carbon, and about 40% of these humic substances were in extremely stable association with the soil mineral fraction, the HCl-HF treatment being required for their extraction. The stability of such organo-mineral complexes increased slightly in the cultured sites. The study of the humic acid fraction showed increased oxidation and aromaticity in most of the cultivated sites: the lowest values for the IR alkyl vibrations and H/C atomic ratios and the highest ones for the optical density at 465 nm were observed in sites transformed into orchards, whereas the above changes were small in those used as pasture. The 14C NMR spectra confirmed that the proportion of polyalkyl structures decreased in the humic acids of soils subjected to cultivation, as opposed to that of carboxyl groups. In spite of the high stability inferred for the organic matter throughout the wide area examined, the samples from the original Cerrado as well as from those transformed into pastures showed, in laboratory conditions, higher mineralization rates than those from the sites subjected to cultivation. This is partly attributed to the decreased proportions of extractable humic substances in the latter. © 1992.
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The Paraná Basin is a Western Gondwanan cratonic basin that is better defined as the Paraná depositional site, since it has a diverse history as a basin. Sedimentation started in the Ordovician-Silurian, followed by extensive marine Devonian deposition. A Late Paleozoic/ Triassic facies cycle wedge was clearly built during Pangean time. The Early Cretaceous was characterized by extensive basaltic lava flows immediately before the break-up of Pangea. Following these rifting and drifting processes, the basin's structural framework was totally rebuilt, generating new depositional sites in the Late Cretaceous to Tertiary. Based on more recent data, at least two different basins may be defined during the evolution of what was once considered a unique basin. Nevertheless, even if considered as a single basin, the sedimentary pile of the Paraná Basin has considerable economic potential, until now exploited only rudimentarily, except for its groundwater resources. Aggregates, limestones, clays, industrial sands, gems, dimension stones, hydrocarbons, coal, peat, and uranium are some of the potential mineral resources of this basin. Copyright © 1997 by V. H. Winston & Son, Inc. All rights reserved.
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Trichilia catigua A. Juss. - Meliaceae has been traditionally used as a tonic and digestive medicine. Some Brazilian pharmaceutical firms use this species to produce phytopharmaceuticals and alcoholic beverages. The aim of this work is to determine its geographical distribution and characterise the environments where catuaba is found in the state of Paraná, in order to support the domestication strategy for the agricultural production of this species. Based on the literature, botanical collections and field observations it was established, that five species of the genus occurring in Paraná, which were identified as T casaretti, T catigua, T claussenii, T elegans, T pallida and another supposed to be T pattens. Trichilia catigua occurs within a wide but defined strip in the state. By evaluating data of climate; soil types; natural vegetation formations; mean, maximum and minimum temperatures; relative humidity; rainfall; altitudes and evapotranspiration the strip may be localised above latitude 25° in the central and Eastern regions of the state and above latitude 26° in South-western Parana. In general, T catigua was found to occur on fertile, organic-matter-rich soils and predominantly under forest canopies.
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Interviews were conducted with fáfia (Pfaffia glomerata (Spreng.) Pedersen) collectors from the municipal districts of Querência do Norte and Porto Rico, where enterprises and buyers of this plant are concentrated. The results allowed us to conclude that both the adults and children make collection. Each adult collects from 50 to 150 kg of roots/day, depending on the collection area, for about 8 months/year. Collections mostly occur all over the year, but the activity becomes more intense from May to August. All families are not exclusively dedicated to fáfia collection and also develop other rural activities. They have been collecting fáfia for 2 to 13 years, indicating that an intensive exploitation has been present in the region for over a decade. During collection, no plant part is used for replanting the species. The roots are commercialised by regional buyers. The price of the roots varies from US $ 0.07 to US $ 0.13/kg and average gain is about US $ 2,055/family/year, representing a considerable profit for the collectors.
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Monthly samples were taken from April 1992 to March 1993 of fish assemblages present in six permanent lagoons and four ponds, fragmented from them during the drought period and during the terminal phases of desiccation, to evaluate changes in their diversity, abundance and dominance. Their relationships with hydrological and environment conditions were examined. A total of 63 fish species were identified. Species composition and abiotic factors were heterogeneous among the different water bodies. The proportion of piscivores and oxygen concentration were the determining factors for structuring the assemblages. The impact of piscivory upon fish diversity was neutral at the beginning and negative at the end of the dry season. In the terminal phase of desiccation, diversity was higher in ponds that contained a moderate proportion of piscivores than in these containing a higher proportion.
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Alluvial paleosoil horizons from the 3 to 4 m high banks of the Paraná River were used to reconstruct the palaeoenvironmental history and palaeohydrological regime of the river. The bank consists of a Middle to Late Holocene sequence of sandy to silty clay layers of overbank deposits. The paleosoil horizon is located to a depth of 1.95 m from the top of the bank and is recognized as a guide horizon throughout the floodplain of the Upper Paraná River floodplain. Analyses of organic matter (δ13C and humic/fulvic acids), palynology (pollen and charcoal fragments), magnetic susceptibility, micromorphology, x-ray diffraction and 14C dating were conducted for samples from two representative profiles of the study area. Two phases were characterized in the history of the river: 1) An older phase, of stability in fluvial hydrology (stasis) with low frequency of floods, which produced conditions for soil development (14C 1700 ± 70 yr. BP). At this period, the predominance of herbaceous vegetation (determinated by pollen and δ13C analyses) suggests a climate less humid than the present one, and 2) A second phase, when climate changed to the present conditions of humidity (annual rain fall of 1600 rum) and characterized by the predominance of C3 plants. Under this new hydrological regime, the river developed an agradational floodplain, with a depositional sedimentary rate of 1.2 mm.y-1. © 2006 Gebrüder Borntraeger.
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A new Hypoptopomatinae, Corumbataia britskii, is described based on specimens recently collected in a tributary of the upper Rio Paraná basin, Mato Grosso do Sul State, Brazil. Corumbataia britskii differs from its congeners by having a more depressed head profile (vs. a more rounded head profile in C. cuestae and C. tocantinensis), by having a more developed and conspicuous tuft of enlarged odontodes on the tip of the supraoccipital (vs. its reduced condition found in C. cuestae and C. tocantinensis), and by heaving a partially enclosed arrector fossae (vs. an almost completely enclosed arrector fossae in C. cuestae and C. tocantinensis). Copyright © 2007 Magnolia Press.
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Twenty-two 14C datings were performed at the central sector of the Paraná coast to define Holocene regressive barrier evolution. The barrier Pleistocene substratum was ascribed an age between 40 400 and 30 000 yr BP, but it can also represent the penultimate sea level highstand during marine isotope stage 5e. The Holocene barrier samples provided ages between 8542-8279 and 2987-2751 cal yr BP, and showed at least six age inversions that were related to age differences between in situ or low-distance transported shells or trunk fragments, and high-distance transported vegetal debris, wood fragments and organic matter samples. The regressive Holocene barrier age was 4402-4135 cal yr BP near the base, and 2987-2751 cal yr BP near the top. Most of the vegetal remains were transported by ebb tidal currents from the estuaries to the inner shelf below wave base level during the mid-Holocene highstand; they were transported onshore by storm waves and littoral currents during the sea level lowering after the sea level maximum, and were deposited mainly as middle shoreface swaley cross-stratification facies. © 2008.