Showing papers by "Ane Alencar published in 2023"

The drivers and impacts of Amazon forest degradation

Abstract: Approximately 2.5 × 106 square kilometers of the Amazon forest are currently degraded by fire, edge effects, timber extraction, and/or extreme drought, representing 38% of all remaining forests in the region. Carbon emissions from this degradation total up to 0.2 petagrams of carbon per year (Pg C year−1), which is equivalent to, if not greater than, the emissions from Amazon deforestation (0.06 to 0.21 Pg C year−1). Amazon forest degradation can reduce dry-season evapotranspiration by up to 34% and cause as much biodiversity loss as deforestation in human-modified landscapes, generating uneven socioeconomic burdens, mainly to forest dwellers. Projections indicate that degradation will remain a dominant source of carbon emissions independent of deforestation rates. Policies to tackle degradation should be integrated with efforts to curb deforestation and complemented with innovative measures addressing the disturbances that degrade the Amazon forest. Description Losing the Amazon The Amazon rainforest is a biodiversity hotspot under threat from ongoing land conversion and climate change. Two Analytical Reviews in this issue synthesize data on forest loss and degradation in the Amazon basin, providing a clearer picture of its current status and future prospects. Albert et al. reviewed the drivers of change in the Amazon and show that anthropogenic changes are occurring much faster than naturally occurring environmental changes of the past. Although deforestation has been widely documented in the Amazon, degradation is also having major impacts on biodiversity and carbon storage. Lapola et al. synthesized the drivers and outcomes of Amazon forest degradation from timber extraction and habitat fragmentation, fires, and drought. —BEL Two Reviews spotlight the threats of ongoing deforestation and degradation in the Amazon. BACKGROUND Most analyses of land-use and land-cover change in the Amazon forest have focused on the causes and effects of deforestation. However, anthropogenic disturbances cause degradation of the remaining Amazon forest and threaten their future. Among such disturbances, the most important are edge effects (due to deforestation and the resulting habitat fragmentation), timber extraction, fire, and extreme droughts that have been intensified by human-induced climate change. We synthesize knowledge on these disturbances that lead to Amazon forest degradation, including their causes and impacts, possible future extents, and some of the interventions required to curb them. ADVANCES Analysis of existing data on the extent of fire, edge effects, and timber extraction between 2001 and 2018 reveals that 0.36 ×106 km2 (5.5%) of the Amazon forest is under some form of degradation, which corresponds to 112% of the total area deforested in that period. Adding data on extreme droughts increases the estimate of total degraded area to 2.5 ×106 km2, or 38% of the remaining Amazonian forests. Estimated carbon loss from these forest disturbances ranges from 0.05 to 0.20 Pg C year−1 and is comparable to carbon loss from deforestation (0.06 to 0.21 Pg C year−1). Disturbances can bring about as much biodiversity loss as deforestation itself, and forests degraded by fire and timber extraction can have a 2 to 34% reduction in dry-season evapotranspiration. The underlying drivers of disturbances (e.g., agricultural expansion or demand for timber) generate material benefits for a restricted group of regional and global actors, whereas the burdens permeate across a broad range of scales and social groups ranging from nearby forest dwellers to urban residents of Andean countries. First-order 2050 projections indicate that the four main disturbances will remain a major threat and source of carbon fluxes to the atmosphere, independent of deforestation trajectories. OUTLOOK Whereas some disturbances such as edge effects can be tackled by curbing deforestation, others, like constraining the increase in extreme droughts, require additional measures, including global efforts to reduce greenhouse gas emissions. Curbing degradation will also require engaging with the diverse set of actors that promote it, operationalizing effective monitoring of different disturbances, and refining policy frameworks such as REDD+. These will all be supported by rapid and multidisciplinary advances in our socioenvironmental understanding of tropical forest degradation, providing a robust platform on which to co-construct appropriate policies and programs to curb it. An overview of tropical forest degradation processes in the Amazon. Underlying drivers (a few of which are shown in gray at the bottom) stimulate disturbances (timber extraction, fire, edge effects, and extreme drought) that cause forest degradation. A satellite illustrates the attempts to estimate degradation’s spatial extent and associated carbon losses. Impacts (in red and insets) are either local—causing biodiversity losses or affecting forest-dweller livelihoods—or remote, for example, with smoke affecting people’s health in cities or causing the melting of Andean glaciers owing to black carbon deposition. Credit: Alex Argozino/Studio Argozino

Brazilian Amazon indigenous territories under deforestation pressure

Abstract: Abstract Studies showed that Brazilian Amazon indigenous territories (ITs) are efficient models for preserving forests by reducing deforestation, fires, and related carbon emissions. Considering the importance of ITs for conserving socio-environmental and cultural diversity and the recent climb in the Brazilian Amazon deforestation, we used official remote sensing datasets to analyze deforestation inside and outside indigenous territories within Brazil's Amazon biome during the 2013–2021 period. Deforestation has increased by 129% inside ITs since 2013, followed by an increase in illegal mining areas. In 2019–2021, deforestation was 195% higher and 30% farther from the borders towards the interior of indigenous territories than in previous years (2013–2018). Furthermore, about 59% of carbon dioxide (CO 2 ) emissions within ITs in 2013–2021 (96 million tons) occurred in the last three years of analyzed years, revealing the magnitude of increasing deforestation to climate impacts. Therefore, curbing deforestation in indigenous territories must be a priority for the Brazilian government to secure these peoples' land rights, ensure the forests' protection and regulate the global climate.

Metabolic Profiling of Murine Macrophages Exposed to Silver Nanoparticles at Dose and Time Dependencies

Abstract: The macrophage time‐dependent metabolic profile changing basal metabolism triggered by nanoparticles can be obtained and used to improve wound healing treatments. Herein this study demonstrates that metabolic status responds systematically to cytotoxicity manipulation, providing an interesting way of cellular control. Nuclear magnetic resonance (NMR) based metabolomics and cytotoxic assays are used to study RAW 264.7 cells exposed to AgNPs at different concentrations and incubation times. Cytotoxicity data show a slight decrease in cellular expansion rates accompanied by morphological changes in cells. Metabolomics show that despite the glycolytic activity of treated and non‐treated cells remains unchanged; however, only the treated cells present a rich Citrate environment signaling up‐regulation of Tricarboxylic‐Acid‐Cycle (TCA). Cells choose aerobic routes instead of anaerobic ones to produce energy and self‐regulate their amino acid metabolism to balance TCA. Choline metabolism is down‐regulated once its sub‐products, Betaine and Glycine, are reduced, thus compromising Creatine synthesis. Phospholipid metabolism is down‐regulated due to the decreasing of Phosphocholine and Sn‐Glycerol‐3‐PC, in agreement with the cytotoxicity results. Pyroglutamate decreases in treated cells, signaling different levels of oxidative stress. These analytical tools can characterize AgNPs‐treatments, even distinguishing dose and time dependencies. Therefore, the fine‐tuning of exposition parameters can modulate cellular activity to achieve better wound healing.

Health impacts of smoke exposure in South America: increased risk for populations in the Amazonian Indigenous territories

Abstract: Smoke particulate matter emitted by fires in the Amazon Basin poses a threat to human health. Past research on this threat has mainly focused on the health impacts on countries as a whole or has relied on hospital admission data to quantify the health response. Such analyses do not capture the impact on people living in Indigenous territories close to the fires and who often lack access to medical care and may not show up at hospitals. Here we quantify the premature mortality due to smoke exposure of people living in Indigenous territories across the Amazon Basin. We use the atmospheric chemistry transport model GEOS-Chem to simulate PM2.5 from fires and other sources, and we apply a recently updated concentration dose-response function. We estimate that smoke from fires in South America accounted for ∼12 000 premature deaths each year from 2014–2019 across the continent, with about ∼230 of these deaths occurring in Indigenous lands. Put another way, smoke exposure accounts for 2 premature deaths per 100 000 people per year across South America, but 4 premature deaths per 100 000 people in the Indigenous territories. Bolivia and Brazil represent hotspots of smoke exposure and deaths in Indigenous territories in these countries are 9 and 12 per 100 000 people, respectively. Our analysis shows that smoke PM2.5 from fires has a detrimental effect on human health across South America, with a disproportionate impact on people living in Indigenous territories.

Biochemical Response of Human Endothelial and Fibroblast Cells to Silver Nanoparticles

Abstract: Bactericidal and antimicrobial properties of silver nanoparticles, AgNPs, in addition to their cytotoxic effects, have been investigated to properly modulate cell biochemistry processes in order to improve the healing of wounds. Herein, we studied the cytotoxicity and metabolic profiling of two human cell lineages, fibroblast FN1 and endothelial HUV-EC-C, planning doses of AgNPs, and incubation times. Cytotoxicity assays showed consistent decrease in proliferation rates, viable cell number, and average surface areas. Metabolomics and nuclear magnetic resonance were successfully used to characterize changes in metabolic events triggered by silver treatments. Endo- and exometabolome revealed biochemical changes induced on treated cells compared to controls. For instance, glycolytic pathway is up-regulated due to the elevation in glucose consumption; however, the consequent elevation in pyruvate production seems to be wasted by cells to generate energy by aerobic means that are choosing to oxidize it to acetate. Aminoacid metabolism is down-regulated, signalizing the protein degradation mechanism. Tricarboxylic acid cycle is down-regulated once succinate was left over in the culture media. Concurrently, the ketogenic pathway is up-regulated due to the excess of acetone. Changes in pyroglutamate metabolism were detected indicating up-regulation of glutathione biosynthesis used to equilibrate the effects induced by oxidative stress, in accordance with the N-acetylcysteine finds. Phospholipid metabolism is down-regulated, as revealed by the changes in O-phosphocholine and Sn-glycerol-3-PC levels, signaling reduction in the cellular proliferation rates. To the best of our knowledge, this is the first report describing AgNP-induced changes in the UDP-GlcNAc levels, which plays an essential role in modifying nucleocytoplasmic proteins.