Showing papers by "José Antônio Baptista Neto published in 2007"

Análise multivariada de dados ecológicos da baía de Guanabara- RJ, com base em foraminíferos bentônicos

Abstract: Guanabara bay is an estuary environment situated in the seaboard of Rio de Janeiro state, under the coordinates 22o 40' and 23o 00'S and 43o 00' and 43o 20'W. Nowadays, it has an approximate area of 377 km2, it has had a reduction of 91 km2 since the discovery of Brazil, being considered one of the most polluted seacoast regions of the country. The environmental monitoring of Guanabara bay becomes increasingly necessary in order to be capable of taking effective measures in its management. Therefore, the use of bioindicator organisms, like foraminifera, is an excellent tool because of their rapid response to environmental changes. The goal of this paper is to apply statistical analyses to the biotic data (benthic foraminifera), aiming to observe how they behave in Guanabara bay. In November 1999, samples of bottom sediment were collected along Guanabara bay; 52 of them distributed along all the bay were used in this study. They were treated and classified according to the pattern methodology for foraminifera. For the numerical ecology, grouping analysis and indicating species analysis (ISA) were done using the programs Statistica 6.0 and PCORD. Through the grouping analysis, it was observed the formation of groups in both samples and species. ISA showed what species is the best one to indicate the actual state of Guanabara bay - Ammonia tepida. The multivaried ecological analyses had an optimal response in the evaluation of patterns of pollution in Guanabara bay, based on benthic foraminifera.

Caracterização textural dos sedimentos superficíais de fundo e dinâmica sedimentar na baía de guanabara, rio de janeiro

Abstract: Ninety-two bottom surface sediment samples were collected in the Guanabara bay using a van-Veen sampler. They were analyzed for grain size distribution and organic matter. From the association between the bottom morphology and sediment characteristics, it was possible to establish the sedimentary dynamics. This allowed a division of the bight into three sedimentary zones: a south, sand-dominated zone of relatively high wave and current energy, a north zone characterized by very calm conditions and clay/mud deposition, and a central zone of mixed sedimentary characteristics. Palavras-chaves: Sediment Dynamic, Guanabara Bay, Texture

Spatial distribution of clay minerals in guanabara bay sediments and its relationship with the estuary hydrodynamics

Abstract: Ninety-two samples were collected in the Guanabara Bay bottom sediments. After grainsize analyses, clay mineral identification was performed in twenty-five samples located in the inner section of the bay where fine sediment deposition predominates. Kaolinites (mean=73%), illites (mean=16%) and smectites (mean=11%) were the group of clay minerals identified. The clay minerals identified showed detrital characteristics which indicate an absence of recent authigenic processes within the surface sediments of the bay. Smectites showed a preferential setting towards the region of higher salinity values. Its lowest abundance (0.15%) was observed near the rivers where the average salinity was 14 whereas its highest abundance (17%) was observed at the most downstream station with average salinity of 32. An inverse relationship between kaolinites and smectites relative abundance was also observed from the inner region towards the more saline region of the bay.

Avaliação da poluição antrópica usando padrão de distribuição de espécies de foraminíferos provenientes de testemunhos da baía de Guanabara, RJ

Abstract: This work presents a study of benthic foraminifera recovered from three cores collected near the Paqueta island, in the Guanabara bay, Rio de Janeiro, southeastern Brazil. The cores have different sizes and were subsampled in centimetric intervals. The recovered benthic foraminiferal assemblages were thoroughly identified, in order to carry out an ecological study towards reconstructing the environmental evolution of the studied area during the recent historical period and assessing the response of the foraminiferal assemblages to the locally occurring natural and/or anthropogenic impacts. The microfaunal distribution results were correlated with the sedimentological and TOC (Total Organic Carbon) data to understand the environmental trends and evaluate the varying patterns of human-related pollution in the area. 14C isotopic date was taken at the bottom of one core, to help for the local sediment accumulation rates. Species diversity values were low in all samples, whereas the TOC values were commonly high, increasing dramatically upwards across the cores. The dominant species in that area of the Guanabara bay were Ammonia tepida, Elphidium spp. and Buliminella elegantissima. Patterns of the distributions of these species confirm the influence of the anthropogenic pollution toward the top of the cores.

Análise dos foraminíferos bentônicos de dois testemunhos na região nordeste da Baía de Guanabara

Abstract: Guanabara bay receives a large amount of industrial and domestic sewage, which contributes for its environmental degradation. For monitoring those environmental changes, two cores from the northeastern area of the bay were analized. They were subsampled in centimeter intervals and the laboratory treatment followed specific methodology for foraminifera. Foraminifera are much sensitive microorganisms as to environmental changes as to anthropogenic ones, thus they are useful as pollution indicators. The results show low values of diversity, however, a higher diversity in the core T15, between Paqueta island and Sao Goncalo than in the core T14, at Sao Goncalo south region. Both of them presented Ammonia tepida as a dominant species human pollution bioindicator, and Buliminella elegatissima as bioindicator of high levels of organic matter.

Análise dos Foraminíferos Bentônicos de Dois Testemunhos na Região Nordeste da Baía de Guanabara Benthic Foraminifera Analysis in Two Cores from the Northeastern Area of Guanabara Bay

Abstract: Guanabara bay receives a large amount of industrial and domestic sewage, which contributes for its environmental degradation. For monitoring those environmental changes, two cores from the northeastern area of the bay were analized. They were subsampled in centimeter intervals and the laboratory treatment followed specific methodology for foramini fera. Foraminifera are much sensitive microorganisms as to environmental changes as to anthropogenic ones, thus they are useful as pollution indicators. The results show low values of diversity, however, a higher diversity in the core T15, between Paqueta island and Sao Goncalo than in the core T14, at Sao Goncalo south region. Both of them presented Ammonia tepida as a dominant species human pollution bioindicator, and Buliminella elegatissima as bioindicator of high levels of organic matter.