Publications by authors named "Nathan Barros"

In the face of intense urban expansion, the assessment of water quality plays a crucial role in environmental preservation. Here, we evaluated aquatic genotoxicity in three locations with different degrees of urbanization using Tradescantia pallida var. purpurea and Daphnia magna as bioindicators.

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TB/HIV coinfection poses a complex public health challenge. Accurate forecasting of future trends is essential for efficient resource allocation and intervention strategy development. This study compares classical statistical and machine learning models to predict TB/HIV coinfection cases stratified by gender and the general populations.

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The ability of freshwater bacteria to secrete extracellular vesicles (EVs) upon interaction with viruses remains to be established. Here, we investigated for the first time if freshwater virus-infected bacteria release EVs in both natural ecosystems and virus-like particles (VLPs)-enriched cultures. We performed a systematic study using transmission electron microscopy to visualize viruses and EVs at high resolution and single-cell imaging analyses to quantitate nascent EVs at the surface of gram-negative bacteria.

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Article Synopsis
  • - Proposed hydropower dams in the Amazon Basin need careful consideration of environmental trade-offs, as the ecosystem services provided by this diverse area can be affected differently depending on dam placements.
  • - Multiobjective optimization is utilized to find a balance that minimizes negative impacts on essential aspects like river flow, fish diversity, and greenhouse gas emissions while still achieving energy production targets.
  • - Uncoordinated dam construction has led to lost ecosystem benefits, highlighting the need for collaborative approaches among Amazonian countries to better manage hydropower development across the entire region.
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Anaerobic biodigestion figures as a sustainable alternative to avoid discharge of cattle manure in the environment, which results in biogas and biofertilizer. The anaerobic bioconversion of biomass to methane via anaerobic biodigestion requires a multi-step biological process, including microorganisms with distinct roles. Here, the dynamics of acidogenic bacterial populations by classical microbiology, as well as biogas productivity by gasometer and chromatography, in the anaerobic co-digestion process were studied.

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Despite substantial advances in quantifying greenhouse gas (GHG) emissions from dry inland waters, existing estimates mainly consist of carbon dioxide (CO) emissions. However, methane (CH) may also be relevant due to its higher Global Warming Potential (GWP). We report CH emissions from dry inland water sediments to i) provide a cross-continental estimate of such emissions for different types of aquatic systems (i.

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Caffeine is a contaminant frequently detected in water bodies. Growth trends in both human population and caffeine consumption per capita are expected to exacerbate the occurrence of caffeine in freshwaters. Yet the effects of caffeine on native fish fauna are poorly understood.

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In Brazil, environmental occurrence of micropollutants, such as pharmaceuticals, is rarely studied, and these compounds are not part of national water quality guidelines. In this study, we evaluated the occurrence of micropollutants in the Paraibuna River, located in the southeast region of Brazil, which is the most populated region of the country. Surface water samples were taken every 3 months for 1.

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While providing protein for a fast-growing human population, the ongoing boom in global aquaculture comes with environmental costs. Particularly, the intense greenhouse gas (GHG) emissions reported for several aquaculture systems are a source of concern. Still, we argue that actual emissions could be multiple times higher than currently thought.

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Increased periods of prolonged droughts followed by severe precipitation events are expected throughout South America due to climate change. Freshwater sediments are especially sensitive to these changing climate conditions. The increased oscillation of water levels in aquatic ecosystems causes enhanced cycles of sediment drying and rewetting.

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Run-of-river dams are often considered to have lower environmental impacts than storage dams due to their smaller reservoirs and low potential for flow alteration. However, this has been questioned for projects recently built on large rivers around the world. Two of the world's largest run-of-river dams-Santo Antônio and Jirau-were recently constructed on the Madeira River, a major tributary to the Amazon River in Brazil.

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Caffeine is one of the most consumed substances, and it has been largely detected in aquatic ecosystems. We investigated the trends in caffeine consumption over three decades and its relationships with gross domestic product (GDP) and human development index (HDI) to understand global patterns and to identify potential hotspots of contamination. The total caffeine consumption is increasing mainly due to population growth.

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Article Synopsis
  • Hundreds of dams have been proposed in the Amazon basin, presenting a considerable opportunity for renewable hydropower, but with potential high greenhouse gas (GHG) emissions.
  • The carbon intensity of proposed hydropower projects varies significantly, with upland dams showing comparable emissions to solar and wind energy, while some lowland dams may produce more GHGs than fossil fuels.
  • A multi-objective optimization framework indicates that effective, low-carbon hydropower development in the Amazon requires careful site selection for dams, focusing on higher elevations and smaller streams, alongside consideration of GHG emissions and social-ecological impacts.
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Reservoir sediment can work as both sink and source for contaminants. Once released into the water column, contaminants can be toxic to biota and humans. We investigate potential ecological risk to benthic organisms by metals contamination in six reservoirs in Southeast Brazil.

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Methane (CH) emissions from lakes are the largest of the emissions from freshwater ecosystems. We compile open water CH emission estimates from individual lakes from all over the world and consider the three main emission pathways: diffusive; ebullitive; and storage. The relationships between emissions, environmental variables, lake characteristics and methodological approaches are investigated for the measurements from 297 lakes.

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Freshwater reservoirs are a known source of greenhouse gas (GHG) to the atmosphere, but their quantitative significance is still only loosely con- strained. Although part of this uncertainty can be attributed to the difficulties in measuring highly variable fluxes, it is also the result of a lack of a clear accounting methodology, particularly about what constitutes new emissions and potential new sinks. In this paper, we review the main processes involved in the generation of GHG in reservoir systems and propose a simple approach to quantify the reservoir GHG footprint in terms of the net changes in GHG fluxes to the atmosphere induced by damming, that is, 'what the atmosphere sees.

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On November 2015, one of Brazil's most important watersheds was impacted by the mine waste from Fundão dam collapse in Mariana. The mine waste traveled over 600 km along the Doce River before reaching the sea, causing severe devastation along its way. Here we assessed trace element concentrations and cytogenotoxic effects of the released mine waste.

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The magnitude of diffusive carbon dioxide (CO) and methane (CH) emission from man-made reservoirs is uncertain because the spatial variability generally is not well-represented. Here, we examine the spatial variability and its drivers for partial pressure, gas-exchange velocity (k), and diffusive flux of CO and CH in three tropical reservoirs using spatially resolved measurements of both gas concentrations and k. We observed high spatial variability in CO and CH concentrations and flux within all three reservoirs, with river inflow areas generally displaying elevated CH concentrations.

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Methane (CH) strongly contributes to observed global warming. As natural CH emissions mainly originate from wet ecosystems, it is important to unravel how climate change may affect these emissions. This is especially true for ebullition (bubble flux from sediments), a pathway that has long been underestimated but generally dominates emissions.

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Collectively, reservoirs created by dams are thought to be an important source of greenhouse gases (GHGs) to the atmosphere. So far, efforts to quantify, model, and manage these emissions have been limited by data availability and inconsistencies in methodological approach. Here, we synthesize reservoir CH, CO, and NO emission data with three main objectives: (1) to generate a global estimate of GHG emissions from reservoirs, (2) to identify the best predictors of these emissions, and (3) to consider the effect of methodology on emission estimates.

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Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (CO2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic carbon (C) fluxes in warm waters. We test the hypothesis that a warm eutrophic system is a source of both CO2 and CH4 to the atmosphere, and that atmospheric emissions are larger than the burial of OC in sediments.

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In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized.

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Planktonic organisms dominate waters in ponds, lakes and oceans. Because of their short life cycles, plankters respond quickly to environmental changes and the variability in their density and composition are more likely to indicate the quality of the water mass in which they are found. Planktonic community is formed by numerous organisms from distinct taxonomic position, ranging from 0.

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