Shallow gas occurrence in a Brazilian ría (Saco do Mamanguá, Rio de Janeiro) inferred from high-resolution seismic data

Benites, Mariana; Alves, Daniel Pavani Vicente; Maly, Mascimiliano; Jovane, Luigi

doi:10.1016/j.csr.2015.08.022

Cited by 23 publications

(25 citation statements)

References 45 publications

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“…Mean monthly precipitation over a 20-year period varied from 64.1 to 170.5 mm as reported by Brazil's National Hydrometeorological Network operated by the Geological Survey of Brazil 1 . The innermost and shallower inlets of the Bay (e.g., Saco do Mamanguá Ría; Benites et al, 2015) are rapidly affected by the local wind field and by continental freshwater drainage from surrounding coastal-plain watersheds, particularly the Paraty Mirim river. Drainage is usually low, however, even during rainy summer seasons, so the yearround salinity fluctuations are slight, varying from 34 to 35 (Signorini, 1980).…”

Section: Study Areamentioning

confidence: 99%

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

et al. 2019

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The autotrophic plankton assemblage along the subtropical coastal embayments of the South Brazil Bight is dominated by the cyanobacterium Synechococcus. This investigation aims to assess its contribution to the total carbon metabolism within the planktonic system of Mamanguá Ría, a subsystem of the Bay of Ilha Grande, southeast Brazilian coast. We hypothesized that photosynthetic carbon fixation by cyanobacteria does not support the plankton metabolism inside the Ría. Net community production (NCP) was calculated from differences between gross community production (GCP) and dark community respiration rates measured by in situ incubations using the oxygen light-and-dark technique. Our results reveal the carbon budget inside the Ría is not balanced by autotrophic production. The deficit of net ecosystem production throughout the year ranged from 0.5 to 1.5 mg m −2 d −1 below what is necessary to sustain local plankton metabolism. We argue that the offset between daily GCP and total community respiration may be balanced by grazing of nano-heterotrophs on heterotrophic bacteria. Our conclusions apply to the majority of the meso-oligotrophic Brazilian inner shelf waters away from estuarine plumes and upwelling systems.

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Section: Study Areamentioning

confidence: 99%

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

et al. 2019

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“…XANES measurements have been performed on MTB to study the synthesis of biogenic magnetite from a phosphate-rich ferric hydroxide precursor (Fdez-Gubieda et al, 2013;Baumgartner et al, 2013;, but no previous analyses have been performed on biogenic magnetite isolated from natural sediment. We use our results from M. australis spectra as an internal standard to compare XANES data from natural isolated magnetic particles from recent sediment from Mamangu a Ría (Ilha Grande Bay, Brazil; Benites et al, 2015) to confirm the presence of MTB and the state of the magnetite they produce. XANES data are integrated with transmission electron microscope (TEM) observations and a range of magnetic measurements.…”

Section: Introductionmentioning

confidence: 99%

Fingerprints of partial oxidation of biogenic magnetite from cultivated and natural marine magnetotactic bacteria using synchrotron radiation

Rodelli

Jovane

Roberts

et al. 2018

Environ Microbiol Rep

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Magnetotactic bacteria are a multi-phyletic group of bacteria that synthesize membrane-bound magnetic minerals. Understanding the preservation of these minerals in various environments (e.g., with varying oxygen concentrations and iron supply) is important for understanding their role as carriers of primary magnetizations in sediments and sedimentary rocks. Here we present X-ray near edge structure (XANES) spectra for Fe in magnetotactic bacteria samples from recent sediments to assess surface oxidation and crystal structure changes in bacterial magnetite during early burial. Our results are compared with a XANES spectrum of cultivated Magnetofaba australis samples, and with magnetic properties, and indicate that oxidation of magnetite to maghemite increases with depth in the sediment due to longer exposure to molecular oxygen. These results are relevant to understanding magnetic signatures carried by magnetofossils in oxic sediments and sedimentary rocks of different ages.

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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: 99%

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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Shallow gas occurrence in a Brazilian ría (Saco do Mamanguá, Rio de Janeiro) inferred from high-resolution seismic data

Cited by 23 publications

References 45 publications

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

Fingerprints of partial oxidation of biogenic magnetite from cultivated and natural marine magnetotactic bacteria using synchrotron radiation

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

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