Understanding the impacts of land-use change on landscape-hydrological dynamics is one of the main challenges in the Northern Brazilian Cerrado biome, where the Amazon agricultural frontier is ...located. Motivated by the gap in literature assessing these impacts, we characterized the soil hydro-physical properties and quantified surface water fluxes from catchments under contrasting land-use in this region. We used data from field measurements in two headwater micro-catchments with similar physical characteristics and different land use, i.e. cerrado sensu stricto vegetation and pasture for extensive cattle ranching. We determined hydraulic and physical properties of the soils, applied ground-based remote sensing techniques to estimate evapotranspiration, and monitored streamflow from October 2012 to September 2014. Our results show significant differences in soil hydro-physical properties between the catchments, with greater bulk density and smaller total porosity in the pasture catchment. We found that evapotranspiration is smaller in the pasture (639 ± 31% mm yr-1) than in the cerrado catchment (1,004 ± 24% mm yr-1), and that streamflow from the pasture catchment is greater with runoff coefficients of 0.40 for the pasture and 0.27 for the cerrado catchment. Overall, our results confirm that conversion of cerrado vegetation to pasture causes soil hydro-physical properties deterioration, reduction in evapotranspiration reduction, and increased streamflow.
Heart rate recovery in 1 minute (HRR1) after the end of the 6-minute walk test (6MWT) is a non-invasive method of determining autonomic dysfunction. This parameter remains largely unexplored in ...pulmonary arterial hypertension (PAH) registries. We aimed to define the cut-off value and accuracy for abnormal HRR1 after the 6MWT and to investigate the association between HRR1 and clinical worsening in patients with PAH. This composite outcome was defined as first occurrence of all-cause death OR hospitalization from any cause OR disease progression characterized by decreased ≥ 15% in six-minute walking distance from baseline AND start of new specific PAH treatment or persistent worsening of World Health Organization functional class (WHO-FC). We performed a prospective cohort study that included 102 consecutive patients with PAH confirmed by right heart catheterization that underwent an 6MWT upon the diagnosis, recruited from September 2004 to April 2020 and followed up until April 2021 or death. The median HRR1 was 18 beats (IQR: 10-22), 50 and 52 PAH patients with <18 beats and ≥18 beats, respectively. The best cut-off for HRR1 to discriminate clinical worsening was 17 beats, with area under the curve (AUC) of 0.704 (95%CI: 0.584-0.824). The internal validation model by bootstrap showed an AUC of 0.676 (95%CI: 0.566-0.786) and the most accurate value was obtained in the seventh year of follow-up (AUC = 0.711; 95%CI: 0.596-0.844). Patients with an HRR1 <18 beats at baseline had a median event-free time of 2.17 years (95%CI: 1.82 to 2.52) versus 4.75 years (95%CI: 1.43 to 8.07) from those with ≥18 beats. In conclusion, a HRR1 value of less than 18 beats may be a reliable indicator of poor prognosis in patients with PAH.
Studies on the impacts of land-use and land-cover change on stream hydrochemistry in active deforestation zones of the Amazon agricultural frontier are limited and have often used ...low-temporal-resolution datasets. Moreover, these impacts are not concurrently assessed in well-established agricultural areas and new deforestations hotspots. We aimed to identify these impacts using an experimental setup to collect high-temporal-resolution hydrological and hydrochemical data in two pairs of low-order streams in catchments under contrasting land use and land cover (native vegetation vs. pasture) in the Amazon and Cerrado biomes. Our results indicate that the conversion of natural landscapes to pastures increases carbon and nutrient fluxes via streamflow in both biomes. These changes were the greatest in total inorganic carbon in the Amazon and in potassium in the Cerrado, representing a 5.0- and 5.5-fold increase in the fluxes of each biome, respectively. We found that stormflow, which is often neglected in studies on stream hydrochemistry in the tropics, plays a substantial role in the carbon and nutrient fluxes, especially in the Amazon biome, as its contributions to hydrochemical fluxes are mostly greater than the volumetric contribution to the total streamflow. These findings demonstrate that assessments of the impacts of deforestation in the Amazon and Cerrado biomes should also take into account rapid hydrological pathways; however, this can only be achieved through collection of high-temporal-resolution data.
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•Deforestation negatively impacts stream hydrochemistry in the Amazon and Cerrado.•High-temporal monitoring approaches reveal unaccounted environmental impacts.•Concentrations were higher in streams where the forest was replaced by pastures.•Stormflow is a substantial hydrological pathway for carbon and nutrient losses.
► In Brazilian agroscapes, riparian ecosystems often remain the last natural vegetation. ► In the riparian zone, gallery Forests and vereda wetlands store high quantities of carbon. ► Human impact ...(erosion) reduces these C stocks dramatically. ► Conservation of riparian wetlands will cause win-win situations due to ecosystem services provided by them, e.g. carbon storage, flood mitigation, provisioning of non-wood-products and support of biodiversity.
For climate mitigation it is important to identify and protect landscape units that have disproportionally large carbon storage (CS). Here we report on CS of the upper 30 and 60cm of soil in transects of vegetation types in stream valleys in the Brazilian Cerrado savanna, including Pasture, nearly native Cerrado vegetation, Vereda wetlands, and Gallery Forests. We chose three areas with varying types of human impacts in each of which three degraded and reference transects were compared. For the 60cm CS in undisturbed sites, maximum and average values per area were highest for Gallery Forest (360.0 and 206.5MgCha−1) and Vereda wetland (201.9 and 142.4MgCha−1), while those of Cerrado (57.7 and 52.7) and Pasture (62.3 and 52.7MgCha−1) were considerably lower. Variation between the three areas was high. In an area degraded by cattle trampling, losses in the upper 60cm compared to reference sites were highest in the carbon-rich vegetation types Vereda (72%) and Gallery Forest (71%) and lower in the carbon-poorer Pasture (33%) and Cerrado (7%). In areas degraded by fire or by erosion, results were less conclusive. Our data appeal to an improved conservation of riparian ecosystems of the Cerrado biome.
The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the ...flooding period and are particularly important to the regional ecosystem structure. Little soil CO₂ research has been conducted in this region. We evaluated soil CO₂ dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO₂ concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO₂ efflux and related environmental parameters. Soil CO₂ efflux during the study averaged 3.53 µmol CO₂ m⁻² s⁻¹, and was equivalent to an annual soil respiration of 1220 g C m⁻² y⁻¹. This efflux value, integrated over a year, is comparable to soil C stocks for 0-20 cm. Soil water potential was the measured parameter most strongly associated with soil CO₂ concentrations, with high CO₂ values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO₂ efflux from the tree island soil, with soil CO₂ dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO₂ efflux from soil. The annual flood arrives later, and saturates soil from below. While CO₂ concentrations in soil grew very high under both wetting mechanisms, the change in soil CO₂ efflux was only significant when soils were wet from above.
O uso da internet transcende o âmbito urbano, com investimentos públicos e privados levando a conectividade para pequenas comunidades rurais. Embora o acesso seja geralmente limitado à conexão Wi-Fi ...doméstica, o celular se tornou o principal meio de acesso para os residentes rurais. Isso tem criado oportunidades para a inclusão digital, especialmente durante a pandemia da Covid-19, quando o uso da internet se tornou essencial para o trabalho, a escola e o lazer. No entanto, junto com esses benefícios, surgem desafios, como o uso compulsivo de dispositivos móveis que podem afetar a saúde física e mental da população. Este estudo analisou o nível de dependência do telefone celular em 22 residentes de duas comunidades rurais no interior baiano, usando uma escala validada por King et al. (2019). Os resultados mostraram uma prevalência de níveis leve e moderado de dependência dos participantes. Isso sugere que a limitação do acesso cotidiano pode ser um elemento de proteção contra o uso excessivo. Além disso, este estudo destaca a necessidade de desenvolver e validar instrumentos de análise específicos para o contexto rural, a fim de compreender melhor o fenômeno da dependência digital nessas comunidades.
The transthoracic echocardiogram (TTE) plays a screening role in the diagnostic algorithm of pulmonary hypertension (PH). Studies have shown a significant disagreement between TTE measurements of the ...systolic pulmonary artery pressure (sPAP) and right atrial pressure (RAP) and those obtained by right heart catheterization (RHC).
To compare TTE measurements of sPAP and RAP with those obtained by RHC in patients being investigated for PH.
Patients referred to a PH reference center with a high or intermediate TTE probability of PH upon admission were submitted to RHC. The agreement between sPAP and RAP from both procedures was assessed through the Bland-Altman test. Differences of up to 10 mmHg for sPAP and 5 mmHg for RAP were considered within the variability of the test. Receiver Operating Characteristic (ROC) curve was constructed to determine the most accurate sPAP and Tricuspid regurgitation maximal velocity (TRV)values associated with the diagnosis of PH by RHC. The adopted level of statistical significance was 5%.
Ninety-five patients were included. The Bland-Altman analysis showed a bias of 8.03 mmHg (95% CI:-34.9-50.9) for sPAP and -3.30 mmHg (95% CI:-15.9-9.3) for RAP. AUC for sPAP and TRV measured by TTE for discrimination of probable PH were 0.936 (95% CI: 0.836-1.0) and 0.919 (95% CI: 0.837-1.0), respectively. However, only 33.4% of the echocardiographic estimate of sPAP and 55.1% of RAP were accurate, as compared to the measurements obtained by RHC.
TTE has a high discriminatory power as a screening diagnostic method for PH despite presenting disagreements between sPAP and RAP absolute values when compared to RHC measurements.
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