O MCTI convida para o Evento de Monitoramento "Marco 01 do Programa Ciência no Mar: gestão de riscos e desastres" que ocorrerá em 11 de maio, de 9h-18h.
O evento apresenta os resultados das pesquisas sobre óleo no mar realizadas na Chamada Emergencial de 2019 e na Chamada nº6/2020, totalizando 18 projetos de pesquisa. Entre eles, o GT Óleo do INCT AmbTropic II, num acordo com o INCT PRO-OCEANO e INCT MAR-COI.
Saiba mais sobre os projetos que serão apresentados: http://ciencianomar.mctic.gov.br/desastres-maritimos/
Transmissão: https://www.youtube.com/channel/UCaiWZ4i1MwY2Oq6buLP1vIA
Um trabalho recentemente publicado na revista Marine Geology (IF: 3.04) pelo GT1.1 (Deltas e Erosão da Linha de Costa) intitulado "Effects of Holocene climate changes and anthropogenic river regulation in the development of a wave-dominated delta: The São Francisco River (eastern Brazil)" de autoria de José Maria Landim Dominguez e Junia Kacenelenbogen Guimarães, discute os efeitos das mudanças climáticas durante o Holoceno e da regulação antropogênica do rio São Francisco no desenvolvimento do seu delta e conclui que a construção do delta ocorreu em pulsos associados a períodos mais úmidos na bacia hidrográfica. O artigo também discute as causas da erosão severa que afeta a desembocadura fluvial nas última décadas.
Modelo evolutivo do delta do São Francisco, durante o Holoceno
Erosão da linha de costa durante o periodo 1960-2020 no delta do São Francisco ABSTRACT
The São Francisco River is the fourth longest river in South America and one of the most regulated. Severe coastalerosion has affected the delta shoreline since 1985, leading to the complete destruction of Cabeço village be- tween 1997 and 1999. In this study, we mapped and radiocarbon dated the beach ridge sets occurring on the delta plain and performed a detailed analysis of the delta shoreline changes since 1960. During the Holocene, the delta plain construction was punctuated and took place during episodes of higher river discharges coincident with Bond events 4, 2 and 1 and periods of higher precipitation in the river basin, as reconstructed by δ18O measurements in cave speleothems. The last major episode of delta construction apparently ended at approxi- mately 1.0 ka cal. BP. Since that time, riverine sediment input has been just sufficient to maintain the shoreline. A comparison of historical maps and aerial photographs showed that from 1853 to 1960, the shoreline at the river mouth remained in approximately the same position. A decrease in rainfall in combination with river regulation, particularly after 1985, triggered extensive erosion at the delta shoreline. This erosion was not caused by sediment retention behind the major dams but instead resulted from changes in the backwater/drawdown effects deriving from river regulation. Shoreline erosion mostly affected the river mouth. The mobilized sediments caused progradation of the downdrift shoreline. Updrift of the river mouth, the shoreline remained stable, as it had already reached an equilibrium orientation in which the net longshore transport was zero
O trabalho completo pode ser acessado em: https://doi.org/10.1016/j.margeo.2021.106456
O GT3.0 (Variabilidade Climática, Ciclos Biogeoquímicos e Fluxo de CO2 no Oceano Atlântico Tropical) publicou em abril de 2021 um novo artigo na Frontiers in Marine Science (IF: 3.661) intitulado "Surface Circulation and Vertical Structure of Upper Ocean Variability Around Fernando de Noronha Archipelago and Rocas Atoll During Spring 2015 and Fall 2017" de autoria de Alex Costa da Silva, Alexis Chaigneau, Alina N. Dossa, Gerard Eldin, Moacyr Araujo e Arnaud Bertrand
ABSTRACT
Using current, hydrographic and satellite observations collected off Northeast Brazil around the Fernando de Noronha Archipelago and Rocas Atoll during two oceanographic cruises (spring 2015 and fall 2017), we investigated the general oceanic circulation and its modifications induced by the islands. In spring 2015, the area was characterized by lower SST (26.6◦C) and deep mixed-layer (∼90 m). At this depth, a strong current shear was observed between the central branch of the eastward flowing near-surface South Equatorial Current and the westward flowing South Equatorial Undercurrent. In contrast, in fall 2017, SST was higher (∼28.8◦C) and the mixed-layer shallower (∼50 m). The shear between the central South Equatorial Current and the South Equatorial Undercurrent was weaker during this period. Interestingly, no oxygen- rich water from the south (retroflection of the North Brazil undercurrent) was observed in the region in fall 2017. In contrast, we revealed the presence of an oxygen-rich water entrained by the South Equatorial Undercurrent reaching Rocas Atoll in spring 2015. Beside these global patterns, island wake effects were noted. The presence of islands, in particular Fernando de Noronha, strongly perturbs central South Equatorial Current and South Equatorial Undercurrent features, with an upstream core splitting and a reorganization of single current core structures downstream of the islands. Near islands, flow disturbances impact the thermohaline structure and biogeochemistry, with a negative anomaly in temperature (−1.3◦C) and salinity (−0.15) between 200 and 400 m depth in the southeast side of Fernando Noronha (station 5), where the fluorescence peak (>1.0 mg m−3) was shallower than at other stations located around Fernando de Noronha, reinforcing the influence of flow-topography. Satellite maps of sea- surface temperature and chlorophyll-a confirmed the presence of several submesoscale features in the study region. Altimetry data suggested the presence of a cyclonic
O artigo foi acessado no formato "Open Access"e pode ser acessado no seguinte "link": https://doi.org/10.3389/fmars.2021.598101