Aplicação de Modelo de Tendência Direcional de Transporte ao Longo de uma Ilha-Barreira: Restinga da Marambaia (RJ, SE Brasil)

Diferentes métodos de estudo foram desenvolvidos para definir os padrões de transporte de sedimentos, sendo um deles o modelo de tendência direcional de transporte de sedimentos (GSTA), que se baseia na análise da variabilidade espacial dos parâmetros granulométricos – média (μ), desvio-padrão (σ) e assimetria (Sk). Neste trabalho, o complemento GisedTrend, que opera em ambiente de Sistema de Informações Geográficas (SIG), foi implementado para analisar a dinâmica sedimentar da margem interna da restinga da Marambaia. Esta feição isola parcialmente a baía de Sepetiba do oceano adjacente, localizando-se no litoral sul do estado do Rio de Janeiro. Os resultados mostram que os sedimentos da área emersa da ilha-barreira são predominantemente compostos por areias médias bem selecionadas, enquanto que as amostras coletadas a partir da isóbata de 2 m exibem progressivo afinamento em direção às áreas mais profundas, de areia fina para silte fino, tornando-se mal selecionadas na mesma direção. Quatro casos de tendência direcional foram avaliados e os resultados permitiram identificar áreas de remoção e acumulação de sedimentos, bem como inferir os mecanismos responsáveis pelos padrões observados, como correntes geradas pelo vento, marés e dispersão de plumas de sedimentos em suspensão

UTILIZAÇÃO DE IMAGENS DE SATÉLITE LANDSAT PARA ANÁLISE DA VARIABILIDADE MORFOLÓGICA DE PONTAIS ARENOSOS NA PLANÍCIE COSTEIRA DE CARAVELAS (NE DO BRASIL)

Em áreas extensas o levantamento de dados geológicos e oceanográficos de forma multitemporal e sinótica envolve altos custos financeiros, bem como tempo necessário para sua realização. No Brasil, observa-se a fragmentação das informações disponíveis acerca dos ecossistemas costeiros e oceânicos, em grande parte devido à combinação de sua grande extensão territorial e a escassez de recursos, contexto no qual a aplicação de técnicas de sensoriamento remoto pode ser a chave para acelerar a aquisição de uma ampla gama de dados ao longo do litoral. Neste artigo, imagens de satélite adquiridas com os sensores Landsat TM e ETM+ foram empregadas como ferramentas no estudo da variabilidade temporal da morfologia costeira em áreas caracterizadas por forte dinâmica sedimentar. Foram utilizadas cinco imagens multiespectrais entre os anos de 1987 e 2001, realizando-se o mapeamento da linha de costa ao longo da planície costeira de Caravelas (BA). O trabalho foca em quatro setores da área de estudo que apresentaram substanciais mudanças morfológicas durante o período de 15 anos: a Ponta do Catoeiro, a foz dos rios Jucuruçu e Itanhém e a ilha Pontal do Sul. Esta última, foi a única área em que se observou predomínio de processos erosivos, que resultaram em um significante decréscimo em sua área subaérea (~458.291 m2). Os outros três setores apresentaram tendência de progradação, relacionada ao crescimento lateral dos pontais arenosos da ordem de 1,2 a 1,3 km e aumento da área subaérea. Comparações entre os resultados aqui reportados e os de outros estudos conduzidos na área de estudo mostram que o uso de imagens de satélite na caracterização de mudanças geomorfológicas em regiões com presença de pontais arenosos é altamente recomendado e produz resultados confiáveis

Spatio-temporal morphological variability of a tropical barrier island derived from the Landsat collection

Barrier islands are low-lying elongated, narrow sandy deposits, usually parallel to the coastline, separated from the continent by a lagoon. Due to their low elevation above sea level, barrier islands are environments susceptible to drastic morphological changes depending on the meteo-oceanographic conditions to which they are subjected. This work presents the morphological changes between 1985 and 2021 in “Restinga da Marambaia”—a 40 km long barrier island on Brazil’s Southeastern coast. One hundred thirty-four scenes from the Landsat collection were processed, enabling the quantification of the barrier island area. Additionally, the rates of change in the position of the shorelines facing the Atlantic Ocean, Sepetiba Bay, and Marambaia Bay were computed. The barrier island’s total area and the central sector’s width present significant seasonal variability, which is maximum during the austral fall and winter seasons. On the shores facing the Atlantic Ocean and Sepetiba Bay, it is noted that the central and far eastern sectors show an erosional trend. In contrast, the coastline is more stable on the shore facing Marambaia Bay. The seasonal variations of the barrier island area occur during a period of low rainfall and more energetic waves associated with local winds, which produce coastal currents, transporting the available sediments

Variações das forçantes hidrodinâmicas junto a um campo de dunas subaquáticas na Baía da Guanabara - RJ

Guanabara Bay (RJ) is a depositional coastal system where large subaqueous sand dunes occur in response to the hydrodynamic conditions prevailing on its central channel. Current velocity measurements, taken 1 meter above the bottom, allowed the computation of shear stresses during the period comprised between October 1994 and June 1995. Shear stress is expressed in terms of its associated shear velocity (u*). Assuming that the surface sediment is mainly composed of medium sands, the critical shear velocity for sedimentary particles with mean diameter of 0.25mm (lower limit of medium sands), was calculated and yielded a u*cr equal to 0.91 cm.s-1. It was estimated that the shear velocity exceeded the critical value during 64% of the duration of the measurements. When frontal systems reach the study area, the combined effect of strong winds and long period waves potentially increase sediment mobilization and transport. Thus, tidal currents can be considered the most important forcing mechanisms for this portion of Guanabara Bay sediment dynamics.A Baía de Guanabara (RJ) é um sistema costeiro deposicional onde dunas arenosas subaquáticas de grande tamanho ocorrem em resposta às condições hidrodinâmicas predominantes no seu canal central. Séries temporais da velocidade e direção das correntes foram coletadas a 1 metro do fundo entre outubro de 1994 e junho de 1995. As velocidades de cisalhamento junto ao fundo (u*) foram calculadas e o valor crítico necessário para o transporte de partículas sedimentares com diâmetro médio de 0,25 mm (limite inferior de areias médias), foi ultrapassado durante cerca de 64% do intervalo amostral. Durante a passagem de sistemas frontais, o efeito conjunto dos ventos fortes e ondas de longo período aumenta o potencial de remobilização e transporte sedimentar desta porção da Baía de Guanabara

ARQUITETURA E EVOLUÇÃO DEPOSICIONAL DA SUCESSÃO SEDIMENTAR PLEISTOCENO TARDIO-HOLOCENO (ÚLTIMOS ~20 Ka) DA BAÍA DE SEPETIBA (RJ): Architecture and Depositional Evolution of the Latest Pleistocene-Holocene (last ~20ky) Sedimentary Succession of Sepetiba Bay (RJ)

The Sepetiba Bay, western coastal area of Rio de Janeiro state, consists of an embayment where estuarine conditions prevail, due to its limited contact to open ocean being isolated by a barrier island of ~40 km extent - restinga da Marambaia. The present study aims at investigating the stratigrahic evolution of the bay’s infilling units, based on seismic anlysis of ~800 km of high-resolution reflection seismic profiles. Seismic analysis was coupled with previously dated horizon on the Rio de Janeiro continental shelf (14C AMS), as well as with recently-dated sedimentary evolutional stages of the Marambaia barrier island (14C AMS/OSL). Integration of all results revealed the existence of a transgressive-highstand sedimentary sucession (up to 30 m thick) composed of units U2-U5 which testifies the onset and evolution of estuarine conditions in the Sepetiba area: an open ocean estuarine system (deposition of unit U2) progressively envolved into more isolated estuarine conditions (depositions units U3-U4), until attaining the configuration of a low energy estuarine environment no longer in direct connection with the open sea (deposition of Unit U5) related to the constructional phases of the Marambaia barrier island itself.   Palavras-chave: Transgressive deposition; Paleoestuarine system; Latest Pleistocene-Holocene transgression.A baía de Sepetiba, localizada na costa oeste fluminense, consiste de um embaiamento onde predominam condições estuarinas com contato limitado ao oceano aberto, devido à presença da restinga da Marambaia - uma ilha-barreira de ~40 km de comprimento. O presente estudo visa o detalhamento da evolução estratigráfica do preenchimento sedimentar da baía, baseado na análise de ~ 800 km de linhas sísmicas de alta resolução, correlacionada a dados de datação de horizonte sísmico na plataforma continental (14C AMS) e de estágios de evolução da restinga da Marambaia (14C AMS/LOE). A integração dos resultados revelou a existência das unidades U2-U5 - uma sucessão sedimentar transgressiva e de mar alto de até ~30 m de espessura, que testemunha a implantação de um sistema estuarino aberto na região em direta conexão com o mar (deposição de U2), que evoluiu para condições estuarinas progressivamente mais isoladas (deposição das unidades U3 e U4) até atingir uma configuração de ambiente estuarino de baixa energia sem conexão direta com o mar (deposição da unidade U5), similar às condições do sistema deposicional atual. Os diferentes ambientes estuarinos, revelados pela fácies sísmicas das unidades U2-U5, estão diretamente correlacionados às diferentes fases de construção e/ou fechamento da restinga da Marambaia. Palavras-chave: Deposição transgressiva; Paleosistema estuarino; Transgressão Pleistoceno Tardio-Holoceno

Correction : Chaparro et al. Incidence, Clinical Characteristics and Management of Inflammatory Bowel Disease in Spain: Large-Scale Epidemiological Study. J. Clin. Med. 2021, 10, 2885

The authors wish to make the following corrections to this paper [...]

Incidence, Clinical Characteristics and Management of Inflammatory Bowel Disease in Spain : Large-Scale Epidemiological Study

(1) Aims: To assess the incidence of inflammatory bowel disease (IBD) in Spain, to describe the main epidemiological and clinical characteristics at diagnosis and the evolution of the disease, and to explore the use of drug treatments. (2) Methods: Prospective, population-based nationwide registry. Adult patients diagnosed with IBD-Crohn's disease (CD), ulcerative colitis (UC) or IBD unclassified (IBD-U)-during 2017 in Spain were included and were followed-up for 1 year. (3) Results: We identified 3611 incident cases of IBD diagnosed during 2017 in 108 hospitals covering over 22 million inhabitants. The overall incidence (cases/100,000 person-years) was 16 for IBD, 7.5 for CD, 8 for UC, and 0.5 for IBD-U; 53% of patients were male and median age was 43 years (interquartile range = 31-56 years). During a median 12-month follow-up, 34% of patients were treated with systemic steroids, 25% with immunomodulators, 15% with biologics and 5.6% underwent surgery. The percentage of patients under these treatments was significantly higher in CD than UC and IBD-U. Use of systemic steroids and biologics was significantly higher in hospitals with high resources. In total, 28% of patients were hospitalized (35% CD and 22% UC patients, p < 0.01). (4) Conclusion: The incidence of IBD in Spain is rather high and similar to that reported in Northern Europe. IBD patients require substantial therapeutic resources, which are greater in CD and in hospitals with high resources, and much higher than previously reported. One third of patients are hospitalized in the first year after diagnosis and a relevant proportion undergo surgery

Historical evolution of seafront occupation in France (Bay of Biscay) and Brazil (Rio de Janeiro) face to coastal erosion vulnerability and risks (19th - 21th centuries)

Large-scale anthropic intervention in the coastal zone started mainly in the 19th century due to the need to accommodate increasingly larger ships in the port areas, and to the diffusion of the value of beaches as places for sea-bathing. Throughout the 20th century, urban growth of coastal areas increased, and it is where, nowadays, some of the largest cities in the world are established. Also, several popular tourist destinations are found in the coastal areas, creating a huge flux of people. In this work is presented the historic evolution of the coastal zone occupation in the city of Rio de Janeiro (Brazil) and in the Bay of Biscay (France) with emphasis on its influence on the natural dynamics of sandy beaches, and on their vulnerability and risks to coastal erosion. The historic review starts in the early 19th century and extends until our days, focusing on the transformations caused by the urban development and tourism-related activities, and thei

Análise comparativa entre sensores remotos e dados in situ no estudo de sedimentos em suspensão: aplicação à plataforma continental do estado do Rio de Janeiro

The analysis of suspended particulate matter (SPM) distribution is an important tool for the environmental monitoring of coastal zones. When present in high concentrations, these components may cause important changes in several processes throughout the water column, such as water quality, supply of nutrients, and the dispersion of pollutants and pathologic agents. The objective of this study is to construct regional algorithms to estimate the concentration of suspended sediment from satellite images and to compare the estimated values with those obtained in situ. To carry out this work, two data sets of SPM concentrations collected during two oceanographic cruises, performed in June 2010 and January 2011 were combined with satellites images collected by MODIS and MERIS sensors. Several atmospheric corrections were considered for each sensor in order to verify their performance. The values of SPM concentration obtained in situ were correlated with the radiometric data for each product for generate the algorithms. The algorithms generated from the regression curves between the concentration of SPM and the radiometric data, were applied to daily and monthly images to determine the best algorithm, and the spatial and temporal variability of the sediment plume. Among the results obtained, it was found that, in general, the sensor MERIS underestimated the reflectance data, while MODIS overestimated these values. In this study it was observed that the variability of the plume near Cabo de São Tomé (22°S/41°W) is the result of the combined influence of the wind pattern, the wave field, coastal upwelling and the Brazil Current.Pages: 7874-788

Image1_Spatio-temporal morphological variability of a tropical barrier island derived from the Landsat collection.TIF

Barrier islands are low-lying elongated, narrow sandy deposits, usually parallel to the coastline, separated from the continent by a lagoon. Due to their low elevation above sea level, barrier islands are environments susceptible to drastic morphological changes depending on the meteo-oceanographic conditions to which they are subjected. This work presents the morphological changes between 1985 and 2021 in “Restinga da Marambaia”—a 40 km long barrier island on Brazil’s Southeastern coast. One hundred thirty-four scenes from the Landsat collection were processed, enabling the quantification of the barrier island area. Additionally, the rates of change in the position of the shorelines facing the Atlantic Ocean, Sepetiba Bay, and Marambaia Bay were computed. The barrier island’s total area and the central sector’s width present significant seasonal variability, which is maximum during the austral fall and winter seasons. On the shores facing the Atlantic Ocean and Sepetiba Bay, it is noted that the central and far eastern sectors show an erosional trend. In contrast, the coastline is more stable on the shore facing Marambaia Bay. The seasonal variations of the barrier island area occur during a period of low rainfall and more energetic waves associated with local winds, which produce coastal currents, transporting the available sediments.</p