Publications by authors named "Renato C Cordeiro"

Coastal sedimentary systems are affected by continental and marine metal pollutant inputs associated with different hydrodynamic characteristics and geochemical processes. These include the formation of acid-volatile sulfides (AVS) within sediments, which affects metal bioavailability and associated aquatic biota toxicity risks. Physicochemical changes in these environments in the face of extreme natural or man-made environmental influences can dramatically alter metal bioavailability and toxicity through metal binding and immobilization as insoluble sulfides.

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Forest fragments from Amazon are important long-term carbon (C) reservoirs with an essential role in the global C balance. They are often impacted by understory fires, deforestation, selective logging and livestock. Forest fires convert soil organic matter into pyrogenic carbon (PyC), but little is known about its distribution and accumulation along the soil profile.

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Dredging activities cause sediment resuspension, which can change the bioavailability of nutrients such as phosphorus (P) in aquatic ecosystems due to remobilization. This study evaluated the remobilization of P in the solid and dissolved phase before and after sediment resuspension in the Meriti and Iguaçu River estuaries and the Rio de Janeiro and Niterói harbor in Guanabara Bay (Rio de Janeiro, Brazil). Three water and sediment samples were collected at each point.

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Article Synopsis
  • - The study examines the microbial diversity in sediments from Airo Lake, a floodplain lake in the Amazon, using metagenomics and biogeochemical analysis to understand the impact of the Negro River on the lake's environment.
  • - Three sediment layers were analyzed, revealing distinct microbiomes: older, deeper sediments had a higher abundance of specific bacteria like Burkholderia, while more recent layers contained different microbes like Thermococcus, indicating changes over time.
  • - A significant number of metagenome-assembled genomes (MAGs) identified in the older strata are linked to unknown taxa, suggesting potential new species, and show enrichment in sulfur cycle genes, highlighting the complexity of microbial interactions in this ecosystem.
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Article Synopsis
  • A large amount of carbon captured by terrestrial plants is stored in lake sediments, but there's limited data on this process in tropical rainforest lakes affected by human activities.
  • Researchers collected new data from 13 lakes in remote Amazon regions and added existing literature to analyze organic carbon burial in these lakes over the last 50-100 years.
  • The study reveals that humid tropical forest lakes are significant carbon sinks, storing about 80 Tg of carbon per year and highlights the importance of temperature and forest conservation in preserving these carbon reserves.
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The sediment contamination by trace metals in coastal aquatic ecosystems is a worldwide environmental problem, since metals can be toxic, persistent, and bioaccumulated. In case of natural events, such as storms, or anthropogenic activities, like dredging, the sediment resuspension to the water column occurs and can solubilize metals, probably increasing their bioavailability and consequently the risk to aquatic life. This study evaluated the bioavailability on reactive trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in estuarine sediments from Iguaçu and Meriti Rivers, both in the drainage basin of Guanabara Bay (Rio de Janeiro, Brazil).

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The Abrolhos bank is home of the richest coral reef system of the Southwestern Atlantic, where endemic coral species are found. It has been reported that Abrolhos' corals are under intense stress due to increasing of Marine Heat Waves during the last decades. Additionally, anthropic interventions along the adjacent coastal regions are a factor of concern since they contribute to the increase in the sediment load and to organic debris input in the reef domain.

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Article Synopsis
  • The study investigates microbial diversity in marine sediments of Guanabara Bay, Brazil, using metagenomics and biogeochemical tools across various sediment depths.
  • Findings reveal that methanogens dominate at shallower depths (1 mbsf), while sulfate-reducing microbes are more prevalent in deeper layers (4 mbsf).
  • A novel microbial order called Guanabacteria was discovered, showcasing distinct genetic traits relevant to sulfur and carbon cycles, highlighting the complex interactions and adaptations of microbial communities in impacted ecosystems.
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The study of the uptake and distribution of elements in marine environments is of great interest for understanding their pathways and accumulation. Here, we investigated in laboratory experiments the accumulation behavior of Cd in the sea anemone Bunodosoma caissarum and the mussel Perna perna. Specimens were incubated with isotopically enriched Cd in aquariums.

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Surface sediments were collected from Guanabara Bay, at 14 stations distributed in five sectors, over three sampling campaigns. Analyses of metals, grain size fractions and total organic carbon analyses were performed. The geo-accumulation index and the enrichment factor were estimated to assess contamination status based on background values.

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Mercury (Hg) has a complex biogeochemical cycle in aquatic environments. Its most toxic form, methylmercury (MeHg), is produced by microorganisms. This study investigated how the sea anemone Bunodosoma caissarum affects Hg distribution, methylation and volatilization in laboratory model systems.

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Article Synopsis
  • The study focused on identifying and monitoring pollution sources from domestic sewage and industrial wastes in rivers of the Guanabara Bay Basin, Brazil.
  • It assessed contaminant mass balance during low tide in the dry season, allowing for evaluation of pollution generation from various river segments.
  • The water quality analysis included metal levels and biochemical oxygen demand, yielding effective results for source identification and ranking of contaminated areas.
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The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (delta13C, 14C) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viração and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics.

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The Amazonian forest is, due to its great size, carbon storage capacity and present-day variability in carbon uptake and release, an important component of the global carbon cycle. Paleo-environmental reconstruction is difficult for Amazonia due to the scarcity of primary palynological data and the mis-interpretation of some secondary data. Studies of lacustrine sediment records have shown that Amazonia has known periods in which the climate was drier than it is today.

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