Distribuição sedimentar da Lagoa Rodrigo de Freitas através de sísmica de alta resolução

Neto, José Antônio Baptista; Silva, Cleverson Guizan; Dias, Gilberto Tavares de Macedo; Fonseca, Estefan Monteiro da

doi:10.1590/s0102-261x2011000100013

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…2 and 3). The behavior of these two types of echo-characters -with strong reflection and low penetration -is similar to other studies in different areas of Brazil (Catanzaro et al, 2004;Paolo & Mahiques, 2008;Veronez Jr et al, 2009a;Baptista Neto et al, 2011;Silva et al, 2014).…”

Section: Echo-character Typessupporting

confidence: 88%

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Geoacoustic Patterns of the Guaíba River Bottom and Subbottom and Their Relationship With Sedimentary and Hydrodynamic Processes

Scottá¹,

Andrade²,

Silva³

et al. 2019

Braz J Geophys

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ABSTRACT. This work aimed at studying the bottom and sub-bottom geoacoustics of the Guaíba River, whose echo patterns are related to hydrodynamic patterns and sedimentary processes. A total of 324 km of seismic transects were surveyed using the Stratabox high-frequency (10 kHz) profiler with concomitant imaging using a side-scan sonar in the northern and central areas of the Guaíba system. The records were interpreted with the aid of complementary data (bathymetry and bottom samples), and maps containing the spatial arrangement of echo-characters were developed. The echo-characters were classified into seven different types according to the presence of sediments controlled by the hydrodynamics of the system or modified by human action. In general, the echoes related to the deposition of fine sediments occurred in deeper areas, the navigation channel or surrounding areas. The echoes in the shallower areas presented strong acoustic reflectivity at sites with lower deposition of fine sediments and predominance of sandy sediments. The occurrence and morphology of asymmetric subaqueous dunes indicated a predominant north-to-south flow and a river behavior.Keywords: shallow geophysics, sedimentology, hydrodynamics, geoprocessing.RESUMO. Este trabalho tem por objetivo o estudo geoacústico de fundo e subfundo do rio Guaíba, cujos padrões de ecos são relacionados aos padrões hidrodinâmicos e aos processos sedimentares atuantes. Foram levantados 324 km de perfis sísmicos em extensão, com o perfilador de alta frequência (10 kHz) Stratabox e concomitante imageamento com Sonar de Varredura Lateral nas áreas Norte e Central do Guaíba. Os registros foram interpretados com o auxílio de dados complementares (batimetria e amostras de fundo) e foram confeccionados mapas com a disposição espacial dos eco-caráteres. Os eco-caráteres foram classificados em sete diferentes tipos, de acordo com a presença de sedimentos controlados pela hidrodinâmica do sistema ou modificados pela ação humana. De uma forma geral, os ecos relacionados à deposição de sedimentos finos ocorrem nas áreas mais profundas, no canal de navegação ou adjacências. Os ecos nas áreas mais rasas apresentam forte refletividade acústica, em locais com menor deposição de sedimentos finos e predomínio de sedimentos arenosos. A ocorrência e morfologia de dunas subaquosas assimétricas indicam um fluxo preponderante no sentido Norte – Sul e um comportamento fluvial do sistema aquático.Palavras-chave: geofísica rasa, sedimentologia, hidrodinâmica, geoprocessamento.

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Section: Echo-character Typessupporting

confidence: 88%

“…7). Baptista Neto et al (2011) also defined a similar echo using data from a similar equipment (10 kHz Stratabox) in Rodrigo de Freitas Lagoon, city of Rio de Janeiro, Brazil, and they associated it to dredging in the area.…”

Section: Echomentioning

confidence: 99%

Geoacoustic Patterns of the Guaíba River Bottom and Subbottom and Their Relationship With Sedimentary and Hydrodynamic Processes

Scottá¹,

Andrade²,

Silva³

et al. 2019

Braz J Geophys

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“…In Brazil, the presence of these features has been described by various authors such as VITAL and STATTEGGER (1997) in the lowest stretch of the Amazon River; FIGUEIREDO and NITTROUER (1995) and FIGUEIREDO et al (1996) in the Amazon submarine delta and COSTA and FIGUEIREDO (1998) on the Amazon Continental Shelf; BAPTISTA NETO et al (2011) in Rodrigo de Freitas Lagoon -Rio de Janeiro; BENITES et al (2015) in Saco do Mamangua, Rio de Janeiro; BAPTISTA NETO et al (1996), QUARESMA et al (2000) and CATANZARO et al (2004) in Guanabara Bay, Rio de Janeiro; WESCHENFELDER et al (2006) in Patos Lagoon -Rio Grande do Sul associated with low-lying paleotopographical features such as paleo river channels and/or valleys; SCHWARZER et al (2006) in the Rio Açu Canyon and FRAZÃO and VITAL (2007) in the Potengy estuary, both in Rio Grande do Norte; FÉLIX (2012) in the Bertioga Channel, São Paulo;andSOUZA et al (2011), DEMARCO et al (2012), GUESSER et al (2012) andWESCHENFELDER et al (2016) presented preliminary results for the North Bay and the Conceição Lagoon -on the Santa Catarina Coast (Figure 1). In summary, gas-charged sediment and exhaust gases escaping into the water column occur in Brazil on the continental shelf and in rivers, bays and lagoon systems, from north to south, normally associated with sediments rich in organic matter.…”

Section: Introductionmentioning

confidence: 88%

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

et al. 2016

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This paper presents the spatial distribution of shallow gas structures and classifies them on the basis of two different data sets of CHIRP seismic records, one from the Conceição Lagoon (CL) and the other from North Bay (NB), both on Santa Catarina Island, Southern Brazil. Side scan sonar data from the CL were used to facilitate the understanding. The sub bottom (SB) seismic data were processed and interpreted by means of the SeisPrho software, the side scan sonar (SSS) data by SonarWiz5 software and the spatial extension being measured with the help of GIS. The shallow gas structures were defined in accordance with their shapes in the seismic recordings (echo-character). At the CL, shallow gas accumulations were found in the form of seepages and features presenting shallow gas structures between the surface and 8.20 ms (around 12.3 m). Accumulations of gas were found in the form of Acoustic Blanking with Acoustic Plume, and also Black Shadows. Pockmarks were found on the lagoon floor and associated with gas seepages (average size diameter 0.97 ± 0.19 m and density from 54 to 242 units per 50 m2). In the NB three types of shallow gas features were found in the seismic profile, namely Acoustic Blanking, Turbidity Pinnacles and Intra-sedimentary plumes. The depth varied from the surface to 12.10 ms (around 18.15 m). In both environments, the gas is escaping from the sediment into the water column. The Pockmarks in the CL and the Acoustic Plume features and sediment rich in total sulfur in the NB validate these findings.

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“…The Rodrigo de Freitas Lagoon (22°57'02"-22°58'09"S, 43°11'09"-43°13'03"W) is a coastal and urban system situated in the Rio de Janeiro city, showing several recreational areas and high levels of human occupation on its margins (Enrich-Prast 2012). This estuarine system receives diffuse inputs of domestic sewage from vicinities or through inflowing of polluted rivers (Baptista-Neto et al 2011, Braz et al 2012. Most of the original perimeter of this lagoon was changed due to grounding (Enrich-Prast 2012).…”

Section: Study Sitementioning

confidence: 99%

Benthic macrofauna associated to the invasive bivalve Mytilopsis leucophaeata (Dreissenidae) in a coastal lagoon in Rio de Janeiro, Brazil

Rodrigues

Fernandes

Miyahira

et al. 2021

An. Acad. Bras. Ciênc.

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The invasion record for the estuarine bivalve Mytilopsis leucophaeata in Brazil is in Rio de Janeiro city, including the Rodrigo de Freitas Lagoon, where high densities of this invader were registered. This work aimed to (1) assess the composition and structure of the benthic macrofauna associated with this invader in Rodrigo de Freitas Lagoon, ( 2) analyze the spatiotemporal variation of richness, density and diversity of the associated benthic community, and (3) correlate changes on the density of the associated benthic species with some water quality variables and the density of M. leucophaeata. Clusters of M. leucophaeata were collected monthly (two years) in four sites. Nine taxa associated with M. leucophaeata were found; Heleobia sp. (Gastropoda) and Melita mangrovi (Amphipoda) showed the highest densities. The structure of the benthic macrofauna slightly differed among sampling sites, but not between dry and wet seasons. The water quality parameters, specifi c patterns of each taxon and high densities of M. leucophaeata contribute to variations in density of the associated species. Oscillations in the densities of M. leucophaeata and the native bivalve Brachidontes darwinianus suggest some agonistic relationship between them, such as a competition for space.

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Distribuição sedimentar da Lagoa Rodrigo de Freitas através de sísmica de alta resolução

Cited by 10 publications

References 6 publications

Geoacoustic Patterns of the Guaíba River Bottom and Subbottom and Their Relationship With Sedimentary and Hydrodynamic Processes

Geoacoustic Patterns of the Guaíba River Bottom and Subbottom and Their Relationship With Sedimentary and Hydrodynamic Processes

Shallow gas seismic structures: forms and distribution on Santa Catarina Island, Southern Brazil

Benthic macrofauna associated to the invasive bivalve Mytilopsis leucophaeata (Dreissenidae) in a coastal lagoon in Rio de Janeiro, Brazil

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