References of "Sarmento, H"
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See detailInfluence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake
Amaral, JH; Borges, Alberto ULiege; Melack, JM et al

in Science of the Total Environment (2018), 630

We investigated plankton metabolism and its influence on carbon dioxide (CO2) dynamics in a central Amazon floodplain lake (Janauacá, 3°23′ S, 60°18′ W) from September 2015 to May 2016, including a period ... [more ▼]

We investigated plankton metabolism and its influence on carbon dioxide (CO2) dynamics in a central Amazon floodplain lake (Janauacá, 3°23′ S, 60°18′ W) from September 2015 to May 2016, including a period with exceptional drought. We made diel measurements of CO2 emissions to the atmosphere with floating chambers and depth profiles of temperature and CO2 partial pressure (pCO2) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism. Overnight community respiration (CR), and gross primary production (GPP) rates were higher in clear chambers and positively correlated with chlorophyll-a (Chl-a). CO2 air-water fluxes varied over 24-h periods with changes in thermal structure and metabolism. Most net daily CO2 fluxes during low water and mid-rising water at the wind exposed site were into the lake as a result of high rates of photosynthesis. All other measurements indicated net daily release to the atmosphere. Average GPP rates (6.8 gC m−2 d−1) were high compared with other studies in Amazon floodplain lakes. The growth of herbaceous plants on exposed sediment during an exceptional drought led to large carbon inputs when these areas were flooded, enhancing CR, pCO2, and CO2 fluxes. During the period when the submerged herbaceous vegetation decayed phytoplankton abundance increased and photosynthetic uptake of CO2 occurred. While planktonic metabolism was often autotrophic (GPP:CR > 1), CO2 out-gassing occurred during most periods investigated indicating other inputs of carbon such as sediments or soils and wetland plants. [less ▲]

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See detailSpatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake
Forsberg, BR; Amaral, JH; Barbosa, P et al

Poster (2015, December 14)

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See detailPRESSÃO PARCIAL (PCO2) E FLUXO DE DIÓXIDO DE CARBONO (CO2) EM AMBIENTES DE VÁRZEA AMAZÔNICOS
Amaral, JHF; Barbosa; Kasper, D et al

Conference (2015, July 12)

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See detailProduction of dissolved organic matter by phytoplankton and its uptake by heterotrophic prokaryotes in large tropical lakes
Morana, C; Sarmento, H; Descy, J-P et al

Poster (2014, April 27)

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See detailLake Kivu: food web structure and energy flows
Descy, J-P; Sarmento, H; Isumbisho, P et al

Conference (2013, August 04)

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See detailTeleconnections between ecosystem productivity and climate indices in a tropical great lake
Darchambeau, François ULiege; Borges, Alberto ULiege; Sarmento, H et al

Poster (2013, April 07)

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See detailNovel photosynthetic CO2 bioconvertor based on green algae entrapped in low-sodium silica gels
Rooke, J. C.; Léonard, Alexandre ULiege; Sarmento, H. et al

in Journal of Materials Chemistry (2011), 21(4), 951-959

A photosynthetic bioreactor for CO2 assimilation has been designed using silica sol-gel immobilisation technologies with the chlorophyta Botryococcus braunii (Kützing) and Chlorella vulgaris (Beijerinck ... [more ▼]

A photosynthetic bioreactor for CO2 assimilation has been designed using silica sol-gel immobilisation technologies with the chlorophyta Botryococcus braunii (Kützing) and Chlorella vulgaris (Beijerinck). The living hybrid gels formed revealed a mesoporosity that enabled diffusion of nutrients and gases, promoting the light and dark photosynthetic reactions from within the bulk of the material. To determine the efficiency of the photosynthetic bioreactor in terms of CO 2 remediation, the activity and viability of the encapsulated cells have been monitored through oximetry, 14C assimilation, pulse amplitude modulation fluorimetry and confocal microscopy, revealing a long term productivity of living hybrid materials capable of photosynthetic processes for at least 80 days. Structural and textural properties of the gels were established through 29Si MAS-NMR and N2 physisorption respectively. © 2011 The Royal Society of Chemistry. [less ▲]

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See detailNovel photobioreactors based on microalgae immobilized in silica gels obtained by "Chimie douce" for biofuel production
Léonard, Alexandre ULiege; Rooke, J.; Sarmento, H. et al

in Abstracts of Papers - American Chemical Society (2010)

A new generation of photobioreactors for the clean production of green biofuels is described. It is based on the smart combination of living and inanimate, namely microalgae encapsulated in porous silica ... [more ▼]

A new generation of photobioreactors for the clean production of green biofuels is described. It is based on the smart combination of living and inanimate, namely microalgae encapsulated in porous silica gels. Such hybrid materials would allow for the controlled exploitation of photosynthesis to assimilate atmospheric CO2 and convert it into useful energy sources by using sunlight. The use of biocompatible routes for the immobilization of cyanobacteria has extended the duration of survival up to 40 weeks. [less ▲]

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See detailCyanobacteria immobilised in porous silica gels: Exploring biocompatible synthesis routes for the development of photobioreactors
Léonard, Alexandre ULiege; Rooke, J. C.; Meunier, C. F. et al

in Energy and Environmental Science (2010), 3(3), 370-377

With the aim of designing photobioreactors (PBR) based on a smart exploitation of microalgae for the production of biofuels and metabolites of interest, this paper describes a novel approach where ... [more ▼]

With the aim of designing photobioreactors (PBR) based on a smart exploitation of microalgae for the production of biofuels and metabolites of interest, this paper describes a novel approach where cyanobacteria are entrapped within highly porous silica matrices. With this concept, it would be possible to work with a constant population of organisms for a continuous (and increased) photoproduction of metabolites, in contrast to "one-shot" uses of liquid cultures. Different hybrid materials based on porous silica gels are described with a special emphasis on finding the most appropriate immobilisation conditions for prolonged cell survival. It is found that an aqueous route based on acid-exchanged sodium silicate combined with the use of silica nanoparticles as a gel-strengthening species shows the best results with a high primary production rate post immobilisation and a preservation of the photosynthetic pigments of up to 35 weeks. Oxygen production, though very low, could be evidenced up to 17 weeks after entrapment, demonstrating the suitability of using porous silica matrices in PBR design. © 2010 The Royal Society of Chemistry. [less ▲]

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See detailHybrid photosynthetic materials derived from microalgae Cyanidium caldarium encapsulated within silica gel
Rooke, J. C.; Léonard, Alexandre ULiege; Meunier, C. F. et al

in Journal of Colloid and Interface Science (2010), 344(2), 348-352

Cyanidium caldarium (Tilden) Geitler SAG 16.91 has been encapsulated within a porous silica host structure to target novel photosynthetic hybrid materials suitable for use in solar cells or CO2 fixation ... [more ▼]

Cyanidium caldarium (Tilden) Geitler SAG 16.91 has been encapsulated within a porous silica host structure to target novel photosynthetic hybrid materials suitable for use in solar cells or CO2 fixation. C. caldarium cells are both thermophilic and acidophilic; on account of these tolerances the hybrid materials could be employed in more extreme heat conditions. TEM highlights that the external cell membrane can remain intact after encapsulation. The images reveal an alignment of silica gel around the external membrane of the cell, providing evidence that the cell wall acts as both a nucleation and polymerisation site for silica species and that the silica scaffold formed by the aggregation of colloidal particles, generates a porosity that can facilitate the transport of nutrients towards the cell. Epifluorescence microscopy and UV-visible spectroscopy have revealed the preservation of photosynthetic apparatus post-immobilisation. Productivity studies showed how the presence of silica nanoparticles within the matrix can adversely interact with the exterior cellular structures preventing the production of oxygen through photosynthesis. © 2009 Elsevier Inc. All rights reserved. [less ▲]

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See detailPhotosynthesis within porous silica gel: Viability and activity of encapsulated cyanobacteria
Rooke, J. C.; Léonard, Alexandre ULiege; Sarmento, H. et al

in Journal of Materials Chemistry (2008), 18(24), 2833-2841

In the framework of designing novel bioreactors, the encapsulation of photosynthetic cyanobacterial strains of the genus Synechococcus, PCC 6301, PCC 7002 and Cyanothece PCC 7418, within mesoporous silica ... [more ▼]

In the framework of designing novel bioreactors, the encapsulation of photosynthetic cyanobacterial strains of the genus Synechococcus, PCC 6301, PCC 7002 and Cyanothece PCC 7418, within mesoporous silica networks has been achieved via the acidification of aqueous colloidal silica precursors at ambient temperature. The effect of the silica matrix on the external membrane of the cells has been studied. The viability of the cells over a three month duration has been assessed using transmission electron microscopy, epifluorescence microscopy, UV-visible spectroscopy and high-performance liquid chromatography. The bioactivity of the encapsulated cyanobacteria was detected via the assimilation of NaH14CO3. Although most cells entrapped within the silica gel remain undivided, some cells continued to divide even when there was limited space. TEM studies have revealed an interaction between the silica gel and the cell membrane. HPLC studies highlight that the photoactive pigments in PCC 6301 and PCC 7002 can be preserved for up to 12 weeks whilst PCC 7418 lost its photosynthetic pigments after two weeks post-immobilisation. These results suggest that certain strains of cyanobacteria are able to photosynthesise within a hybrid gel yielding the possibility of novel photobioreactors. © The Royal Society of Chemistry 2008. [less ▲]

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