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Continental margins that exhibit high terrigenous input are generally located near deltas that are capable of transporting large quantities of sediments into the basin. However, in rare cases, high terrigenous sedimentation occurs in regions deprived of major riverine systems where the sedimentary pathway is enigmatic. One such case is the Neogene of the Pelotas Basin of Brazil and Uruguay, adjacent to the La Plata River mouth. Since the Miocene, anomalous sedimentation formed a giant progradational wedge, the Rio Grande Cone, one of the largest submarine fan-like features on Earth. To understand the Neogene evolution of the margin and the origins of the Rio Grande Cone, here we present a seismic-stratigraphic framework based on well-logs and 2D seismic data. Three depositional environments are identified: (1) on the shelf, upper Miocene to Pliocene fluvial channels delivered sand deposits on the mud-dominated shelf; (2) on the slope, sediment instability resulted in structural deformation and multiple phases of mass transport deposition and (3) on the lower slope and basin floor, large contourite drifts formed by sediment reworking. We classify the Rio Grande Cone as a megaslide complex, due to its depositional and structural setting. Local deltaic systems were active on the shelf in the Neogene, but the limited size of their paleo-drainage systems in comparison to the volume of sedimentation in the margin suggests that an additional sedimentary pathway existed. In this sense, the demise of an epicontinental sea over the La Plata Basin during the Neogene likely enabled the input of large volumes of fine sediments into the margin, via the La Plata plume water. We suggest that the desiccation of this epicontinental sea and the intensification of ocean currents since the middle Miocene explains the anomalous Neogene terrigenous influx into the SW Atlantic margin. [ABSTRACT FROM AUTHOR]

Between 2013 and 2017, we carried out nine field missions in the Lago Grande de Curuai floodplain, located in Pará state – North of Brazil – to collect samples for monitoring surface water quality. This site separated from the river by a narrow bank is composed of a network of channels and shallow lakes, a morphology shared by the floodplains of the lower Amazon. A multiparameter probe was used in situ to measure electrical conductivity, temperature, pH, dissolved oxygen, chlorophyll, turbidity, depth and a Secchi disk to estimate transparency. Water grab samples were analysed for suspended material, alkalinity, humic acid, phosphorus, nitrogen, carbon and chlorophyll. Sampling stations were distributed over the seven larger lakes in the floodplain and sampled at different periods of the hydrological cycle. The number of samples varied with the floodplain water level, with a minimum of 25 samples for each field visit. This data set is a collection of water quality data to assist in the limnological or biogeochemical studies of surface waters in Amazonian floodplain lakes, and the product of successive French‐Brazilian projects: (1) the Clim‐FABIAM 'Climate changes and Floodplain lake biodiversity in the Amazon Basin: how to cope and help the ecological and economic sustainability' funded by the French Foundation for biodiversity research (FRB), (2) the project Bloom‐ALERT –'Environmental sensitivity and population health vulnerability to cyanobacteria in the Amazon: towards shared indicators' funded by the French‐Brazilian research program GUYAMAZON 2014, and the project (3) 'Ecossistemas das várzeas e biodiversidade: Impactos das mudanças ambientais e climáticas considerando cenários de desenvolvimento sustentáveis' (Project number 490634/2013‐3) funded by the Brazilian National scientific Research Council CNPq. [ABSTRACT FROM AUTHOR]

New bathymetric and subsurface data from the Santos Basin, offshore southeast Brazil, reveal sharp lateral morphological variations facing the margin-parallel (along-margin) flow of the Antarctic Intermediate Water. The data, derived from 3D Pre-Stack Depth Migrated (PSDM) seismic reflection volumes, show on a ∼100 km long Southern segment slope gullies, mass transport deposits, and scars. These morphologies sharply shift laterally to a ∼50 km long Northern segment, typified by a smooth relief built of plastered contourite drifts with occasional elongated depressions. We examine this sharp lateral shift in the morphology of bottom current indicators in view of the hydrodynamical regime, sediment sources, and their distribution pattern. Results indicate that the sharp lateral morphological shift is attributed to (1) a 30° change in slope orientation, and (2) a northward increase in the across-margin velocity component of the Intermediate Water Boundary Current (IWBC). Subsurface data suggest this flow pattern has persisted since the mid-Miocene. In this case study, the lateral morphological shifts under contemporary hydrodynamic conditions emphasize the importance of understanding the coupling between ocean bottom currents and the seafloor in any marine environment. [Display omitted] • New bathymetric and subsurface data from the Santos Basin, offshore southeast Brazil • Sharp lateral shift from down- to along-slope dominated morphologies. • In between - mega slide tunnels shelf sediments to the deep Atlantic seafloor • Flow of Antarctic Intermediate Water along the slope regulates seafloor morphology. • Extent of coupling between ocean bottom current and seafloor is central for seafloor morphology analysis worldwide. [ABSTRACT FROM AUTHOR]

Pachycymbiola brasiliana is a marine snail found in the seas adjacent to the coasts of Brazil, Uruguay, and Argentina, whose eggshells are composed primarily of chitin. In this work, Pachycymbiola brasiliana eggshells were used to prepare films and their structural and physicochemical characteristics were investigated. The main focus was on their mechanical stability, water sorption, and methylene blue rejection. From the FTIR spectra, the bands corresponding to chitin were identified. The differential scanning calorimetric (DSC) data showed that the biopolymer has a glass transition temperature of around 32 °C. The morphological analysis was carried out by using SEM and XRD. The study of the films' mechanical stability showed an improvement with an increase in water activity. Regarding the methylene blue separation processes, a low permeation through the film and a rejection rate of 94 to 99% were demonstrated. Therefore, Pachycymbiola brasiliana eggshell can be considered a promising source of biopolymers for preparing biodegradable, non-toxic films with valuable separative properties. [ABSTRACT FROM AUTHOR]

An earthquake is a seismic event resulting from a sudden release of energy in the lithosphere, which produces waves that can propagate through the atmosphere into the ionosphere, causing ionospheric disturbances, and excites an additional electric field in the lower ionosphere. Two large-scale traveling ionospheric disturbances (LSTIDs) at daytime Turkey longitudes were found, with phase speeds of 534 and 305 m/s, respectively, after the second strong earthquake at 10:24 UT on 6 February 2023. During strong earthquakes, the equatorial ionospheric currents including the E-region equatorial electrojet (EEJ) and F-region ionospheric radial current (IRC) might be perturbed. At the Tatuoca station in Brazil, we observed a stronger-than-usual horizontal magnetic field associated with the EEJ, with a magnitude of ~100 nT. EEJ perturbations are mainly controlled by neutral winds, especially zonal winds. In the equatorial F-region, a wave perturbation of the IRC was caused by a balance of the electric field generated by the zonal winds at ~15° MLat, the F-region local winds driven by atmospheric resonance, and the additional polarization electric field. Our findings better the understanding of the complex interplay between seismic events and ionospheric current disturbances. [ABSTRACT FROM AUTHOR]

Signals recorded by two stations in the Brazilian region: [Fortaleza (3.74°S, 38.57°W) and Inconfidentes (22.31°S, 46.32°W)], receiving L1 transmissions from different geostationary satellites, were used to evaluate the amplitude scintillation index S4 and several characteristics of scintillation events (continuous record with S4 > 0.2) during nighttime hours (18:00 LT–02:00 LT) in the years 2014–2016. The effects from solar activity, season, and local time on the number of scintillation events per night, maximum scintillation, scintillation event duration, and spacing between consecutive events will be discussed. The results indicate that: (a) scintillation occurs from September to March in both links; (b) the most likely numbers of observed scintillation events per night were two or three, particularly during the first 2 years; (c) on average, the first scintillation event usually had larger maximum S4 values when compared to those of the later ones along the night; (d) the first scintillation event had a longer mean duration than the succeeding ones in a given night; (e) the durations of scintillation events, regardless of their numbers per night and the location, decreased with local time; (f) the opposite dependence of spacings between consecutive events on local time was observed; (g) the cumulative distribution functions of the scintillation onset time indicated a strong dependence on the dip latitude of the station; and (h) early occurrences of onset times are directly related to the increased probability of the occurrence of multiple scintillation events. Plain Language Summary: This study used radio signals from geostationary satellites collected from two ground‐based stations in distinct dip latitudes over Brazil to evaluate aspects of amplitude scintillation. The investigation focused on the number of occurrences and in their specific characteristics such as intensity, duration, and spacing between consecutive scintillation events. The early nighttime hours, when scintillation is more likely to affect the signals were considered during the months of September to March over the years of 2014–2016, covering varied seasonal and solar flux conditions. The findings indicate that scintillation events earlier in the night have larger S4 values and longer duration, being more severe for transionospheric signals. The results also show that earlier onset of scintillation events is likely to indicate multiple events over the night. These new findings contribute to the understanding of scintillation phenomenon and provide valuable insights for improving satellite‐based systems in equatorial and low‐latitude regions. Key Points: The first scintillation event has larger maximum S4 values and longer mean duration when compared to the subsequent eventsThe durations of the scintillation events decrease with local time. The spacing between consecutive events shows the opposite trend; andEarlier occurrences of onset times are related to the increased probability of the occurrence of multiple scintillation events [ABSTRACT FROM AUTHOR]