Although microorganisms play crucial roles in ecosystems, metagenomic analyses of soil samples are quite scarce, especially in the Southern Hemisphere. In this work, the microbial diversity of soil samples from an Atlantic Forest and Caatinga was analyzed using a metagenomic approach. Proteobacteria and Actinobacteria were the dominant phyla in both samples. Among which, a significant proportion of stress-resistant bacteria associated to organic matter degradation was found. Sequences related to metabolism of amino acids, nitrogen, and DNA and stress resistance were more frequent in Caatinga soil, while the forest sample showed the highest occurrence of hits annotated in phosphorous metabolism, defense mechanisms, and aromatic compound degradation subsystems. The principal component analysis (PCA) showed that our samples are close to the desert metagenomes in relation to taxonomy, but are more similar to rhizosphere microbiota in relation to the functional profiles. The data indicate that soil characteristics affect the taxonomic and functional distribution; these characteristics include low nutrient content, high drainage (both are sandy soils), vegetation, and exposure to stress. In both samples, a rapid turnover of organic matter with low greenhouse gas emission was suggested by the functional profiles obtained, reinforcing the importance of preserving natural areas.

No abstract

No abstract

The Xingu and Tapajós rivers in the eastern Amazon are the largest clearwater systems of the Amazon basin. Both rivers have "fluvial rias" (i.e., lake-like channels) in their downstream reaches as they are naturally impounded by the Amazon mainstem. Fluvial rias are widespread in the Amazon landscape and most of the sedimentary load from the major clearwater and blackwater rivers is deposited in these channels. So far, little is known about the role of Amazon rias as a trap and reactor for organic sediments. In this study, we used organic and inorganic geochemistry, magnetic susceptibility, diatom, and pollen analyses in sediments (suspended, riverbed, and downcore) of the Xingu and Tapajós rias to investigate the effects of hydrologic variations on the carbon budget in these clearwater rivers over the Holocene. Ages of sediment deposition (∼100 to 5,500 years) were constrained by optically stimulated luminescence and radiocarbon. Major elements geochemistry and concentration of total organic carbon (TOC) indicate that seasonal hydrologic variations exert a strong influence on riverine productivity and on the input and preservation of organic matter in sediments. Stable carbon isotope data (δ 13 C from −31.04 to −27.49‰) and pollen analysis indicate that most of the carbon buried in rias is derived from forests. In the Xingu River, diatom analysis in bottom sediments revealed 65 infrageneric taxa that are mostly well-adapted to slack oligotrophic and acidic waters. TOC values in sediment cores are similar to values measured in riverbed sediments and indicate suitable conditions for organic matter preservation in sediments of the Xingu and Tapajós rias at least since the mid-Holocene, with carbon burial rates varying from about 84 g m −2 yr −1 to 169 g m −2 yr −1 . However, redox-sensitive elements in sediment core indicate alternation between anoxic/dysoxic and oxic conditions in the water-sediment interface that may be linked to abrupt changes in precipitation. The variation between anoxic/dysoxic and oxic conditions in the water-sediment interface controls organic matter mineralization and methanogenesis. Thus, such changes promoted by hydrological variations significantly affect the capacity of Amazon rias to act either as sources or sinks of carbon.

No abstract

No abstract

This study aimed to analyze the perceptions of parents of children with clubfoot regarding the Ponseti method of treatment, and identify aspects of treatment that families found most difficult. Thirty families of children with clubfoot were treated with the Ponseti method over a 4-year period, and questionnaires were distributed at the conclusion of treatment. The most difficult components of treatment were identified. However, these challenges did not impact treatment outcome negatively. We hypothesize that a strong physician-patient relationship and high levels of parental education may decrease perceived difficulties of treatment with the Ponseti method.

Abstract. The Belo Monte hydropower complex located in the Xingu River is the largest run-of-the-river (ROR) hydroelectric system in the world and has one of the highest energy production capacities among dams. Its construction received significant media attention due to its potential social and environmental impacts. It is composed of two ROR reservoirs: the Xingu Reservoir (XR) in the Xingu's main branch and the Intermediate Reservoir (IR), an artificial reservoir fed by waters diverted from the Xingu River with longer water residence time compared to XR. We aimed to evaluate spatiotemporal variations in CO2 partial pressure (pCO2) and CO2 fluxes (FCO2) during the first 2 years after the Xingu River impoundment under the hypothesis that each reservoir has contrasting FCO2 and pCO2 as vegetation clearing reduces flooded area emissions. Time of the year had a significant influence on pCO2 with the highest average values observed during the high-water season. Spatial heterogeneity throughout the entire study area was observed for pCO2 during both low- and high-water seasons. FCO2, on the other hand, only showed significant spatial heterogeneity during the high-water period. FCO2 (0.90±0.47 and 1.08±0.62 µmol m2 d−1 for XR and IR, respectively) and pCO2 (1647±698 and 1676±323 µatm for XR and IR, respectively) measured during the high-water season were on the same order of magnitude as previous observations in other Amazonian clearwater rivers unaffected by impoundment during the same season. In contrast, during the low-water season FCO2 (0.69±0.28 and 7.32±4.07 µmol m2 d−1 for XR and IR, respectively) and pCO2 (839±646 and 1797±354 µatm for XR and IR, respectively) in IR were an order of magnitude higher than literature FCO2 observations in clearwater rivers with naturally flowing waters. When CO2 emissions are compared between reservoirs, IR emissions were 90 % higher than values from the XR during low-water season, reinforcing the clear influence of reservoir characteristics on CO2 emissions. Based on our observations in the Belo Monte hydropower complex, CO2 emissions from ROR reservoirs to the atmosphere are in the range of natural Amazonian rivers. However, the associated reservoir (IR) may exceed natural river emission rates due to the preimpounding vegetation influence. Since many reservoirs are still planned to be constructed in the Amazon and throughout the world, it is critical to evaluate the implications of reservoir traits on FCO2 over their entire life cycle in order to improve estimates of CO2 emissions per kilowatt for hydropower projects planned for tropical rivers.