SIBI! EM BREVE O RIUFPA ESTARÁ LIBERADO! AGUARDEM!

Teses em Geologia e Geoquímica (Doutorado) - PPGG/IG

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/6341

O Doutorado Acadêmico pertence ao Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).

Navegar

Agora exibindo 1 - 20 de 22

Acesso aberto (Open Access)
Acúmulo e exportação de carbono, nitrogênio, fósforo e metais em canais de maré dos manguezais de Marapanim, Costa Norte Brasileira
(Universidade Federal do Pará, 2020-12-18) MATOS, Christiene Rafaela Lucas de; SILVA, José Francisco Berrêdo Reis da; http://lattes.cnpq.br/1338038101910673; https://orcid.org/0000-0002-8590-2462; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
In this study, we assessed the potential of intertidal mudflat sediments along mangrove forest to accumulate and export carbon, nutrients (N and P) and metals (Fe and Mn), in addition to examine the influence of the Amazonian seasonal rainfall patterns on the physicochemical conditions, diagenetic processes and exchange of nutrients and metals along the sediment-water interface (SWI) in intertidal mudflats fringed by pristine mangroves. The study was carried out in the Marapanim River estuarine system (northern Brazil), which is fringed by extensive areas of well-developed mangroves, part of the largest continuous and best preserved mangrove forest in the world, located approximately 200 km from west of the mouth of the Amazon River. The results of this work are presented in two articles. The first deals with the potential of stocks and accumulation of COT, NT and PT in intertidal mudflat sediments, in addition we investigate the potential sources of sedimentary organic matter (OM). The second assesses the influence of seasonal rainfall pattern on physicochemical properties, the diagenetic processes and the diffusive fluxes of nutrients at the SWI in the Marapanim mangrove creeks. During wet season the salinity values decreased as a consequence of the increase in rainfall, with a dilution-mixing zone in the top sediment (<15 cm). In the dilution-mixing zone, Fe (III) and Mn (IV) reduction are the dominant anaerobic respiratory processes in the sediments. The redox zonation of sediments oscillated in response to the rainfall patterns, with the highest concentrations of Fe2+ and Mn2+ in deeper sediment layers during the dry season. Under suboxic conditions, the mudflat sediments act as a source of Fe2+, Mn2+, NH4 +, and PO4 3- to the water column, and these fluxes were driven by rainfall. The results indicated that mangrove-fringed mudflats are quite effective in retaining carbon, nutrients and iron in sediment solid phases than exporting to the coastal waters, while can potentially be a significant contributor to the oceanic Mn cycle. The potential of these mangrove creeks to accumulate these elements is directly related to grain size, sources and susceptibility of OM degradation. In addition, temporal variability in pyrite formation revealed that the solid phase retention mechanisms are also susceptible to seasonal effects, with lower concentrations of chromium-reducible sulfur (CRS, mainly pyrite fraction) during the dry season. Therefore, we show that these seasonal variabilities implied substantial changes of physicochemical properties and the diagenetic processes, affecting the release of metals and nutrients from the SWI and their accumulation in the sediment.
Acesso aberto (Open Access)
A aplicação da cromatografia gasosa acoplada (GC-FID), isótopos estáveis, palinologia e razão C:N na reconstituição paleoambiental de manguezais do Estado da Bahia e Espírito Santo.
(Universidade Federal do Pará, 2024-07-30) SILVA, Fernando Augusto Borges da; ALBERGARIA-BARBOSA, Ana Cecília Rizzatti de; http://lattes.cnpq.br/2666263256585897; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702
Mangroves depend on ideal geomorphological, geochemical, and climatic factors to develop. Brazil, with its highly indented coastline under tropical and sub-tropical climate regimes, presents suitable conditions for the establishment of these ecosystems and distribution. The dynamics of these mangroves can be influenced by factors related to climatic variations and changes in hydrodynamic flow, resulting in modifications in sediment input and the origin of organic matter. These changes can be observed throughout the Holocene in different regions in of the country. On the northeast and southeast coast, the evolution of these ecosystems is associated with fluctuations in relative sea level (RSL) and sedimentary dynamics, while in the southern region, the change in the distribution of mangroves is a reflection of fluctuations in the RSL and climate changes caused by warming global. Recent studies seek to describe the evolution of these environments based on the elemental and isotopic characterization of organic matter. These constitute important tools in paleoenvironmental reconstruction. However, it is necessary to remember that the comparative analysis of the largest possible number of independent parameters is relevant as it adds value to the research and increases the reliability of the data to be analyzed, generating more precise information. Therefore, aiming to unravel the dynamics of organic matter in mangrove environments, as well as understanding movements of expansion and/or contraction of these ecosystems, analyzes of nalkanes were carried out using chromatography (GC-FID), associated with the sedimentary study, pollen data, isotopic and elemental analyses, synchronized with 14C and 210Pb dating, which allowed obtaining information about past biogeochemical processes and environmental changes during the Holocene and Anthropocene in the coastal plain at the mouth of the Itapicuru river (BA) and at the mouth of the Barra Seca and Jucu rivers (ES). Thus, the results of this research are presented in five scientific articles. The first, see chapter III, deals with the expansion of mangroves at the mouth of the Itapecuru river (BA) during the Anthropocene. The second scientific article (chapter IV) deals with the dynamics of mangroves at the mouth of the Barra Seca River, on the northern littoral of the State of Espírito Santo. The third article (chapter V) discusses the palynology tool used to understand the dynamics of coastal vegetation.The fourth article (chapter VI) presents the environmental changes that occurred at the mouth of the Jucu River, on the central coast of the State of Espírito Santo. Finally, the fifth article presents the results of n-alkanes analyses, compared with isotopic, elemental, palynological data, and 14C dating on the coastal plain of the Barra Seca River.
Acesso aberto (Open Access)
A dinâmica dos manguezais no Nordeste do Brasil: uma abordagem a partir de dados de sensores remotos e SIG.
(Universidade Federal do Pará, 2015-11-27) PEREIRA, Edson Adjair de Souza.; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; 3282736820907252
This study assesses the dynamics of mangroves in the northeastern Brazil in the last four decades from the classification of remote sensing images based on geographic objects (GEOBIA). This methodology combines spectral, temporal and spatial information of multi-temporal images to create consistent objects (mangrove areas) for a statistical analysis from classified images. The objective of this study was to evaluate the changes in mangrove forest cover in all states of the northeastern Brazil between 1975 and 2008, with regard to the increase or decrease mangrove areas in response to natural (erosion and accretion) and anthropogenic (Aquaculture / salinicultura) variations. In this study were processed and analyzed remote sensing images (RADAMBRASIL, ALOS PALSAR, TM Landsat and SRTM) from GEOBIA approach. During the studied period, there was a reduction of ~ 1,545 km2 mangrove forest area in 1975 to ~ 1480 km2 in 2008. This represents a net loss of ~ 65 km2, which is equivalent to a decrease of 13% in the mangrove forest area. Of the nine states studied, only Ceará and Pernambuco showed a gain in coverage of mangroves, while all others were reduced. Among the total mangrove forest area lost during the study period (~ 953 km2), the aquaculture/saliniculture ponds represent ~ 10%. Importantly, in the states of Rio Grande do Norte and Ceará the conversion of mangrove areas for aquaculture/saliniculture ponds already represent ~ 41% and 32% of the total area of mangrove lost, respectively. Therefore, it concludes that the methodology used to assess the dynamics of mangroves in northeastern Brazil from different sources of remote sensing data was extremely effective. New strategies for recovery and sustainable use of mangrove areas should be established in order to conserve this ecosystem for future generations.
Acesso aberto (Open Access)
Efeitos das mudanças climáticas nos limites austral e boreal dos manguezais americanos durante o Holoceno e Antropoceno
(Universidade Federal do Pará, 2021-09-08) RODRIGUES, Érika do Socorro Ferreira; KAM, Biu Liu; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
During the Holocene, mangrove distributions were primarily controlled by climate change and sea level fluctuations. In particular, low winter temperatures in the subtropical coastal areas limited these ecosystems to expand beyond 30°N and 28°S in the North and South Hemisphere. Therefore, under the continuous warming trend during the Anthropocene, mangroves are expected to migrate to more temperate regions previously occupied by saltmarshes (e.g., Spartina sp.). The purpose of this Thesis is evaluate the effects of climate changes and SLR fluctuations on the distribution of American mangroves along the Holocene and Anthropocene, based on satellite and drone images, sedimentary facies, diatoms, pollen, geochemistry (LOI, XRF, TOC , TN, TS, C: N, C: S, δ13C and δ15N) as well 210Pb and 14C datings .To achieve the aforementioned objectives, studies were conducted on the tropical coast of southeastern Brazil - south of the Espírito Santo State (20°41'S), the subtropical coastal regions located on the north (26°6'S) and south (28°29’ S) coast of Santa Catarina, and Louisiana littoral (29° 09' N). The results of this research are presented in four scientific papers. The first one (see, chapter II) deals with the effects of global warming on the establishment of mangroves in the Louisiana littoral (29° 09’ N) during the Holocene. The second scientific paper (see, chapter III) shows southward migration of the austral limit mangroves in South America, according to the increase in minimum winter temperatures in the Anthropocene (southern Santa Catarina coast, 28°29' S). The third manuscript (see, chapter IV) assesses the impacts of sea level rise on tropical mangroves in southeastern Brazil (southern Espírito Santo coast, 20°41'S) during the Holocene and Anthropocene, using a multi-proxy approach. The fourth scientific paper (see, chapter V) addresses the establishment of mangroves in the São Francisco do Sul Bay (north Santa Catarina coast , 26° 6'S), in response to global warming in the last 1000 years. The results indicated a marine transgression off the southern coast of Santa Catarina (28°29’ S) and the Louisiana littoral (29°09’ N) during early Holocene. This natural process converted a lake into lagoons colonized by herbs adapted to an estuarine environment. On the Brazilian tropical coast, the middle Holocene high sea-level stand (2-5 m above the current level) was decisive for the establishment of mangroves. This comportment was observed in an estuary located on the south coast of Espírito Santo (20°41'S) where a herbaceous plain was gradually replaced by a lagoon surrounded by mangroves between ~6300 cal yr BP and ~4650 cal yr BP. However, between ~ 4650 cal yr BP and 2700 cal yr BP the lagoon colonized by mangroves on its margins was converted to a tidal flat occupied by herbs, palms and trees/shrubs reflecting the reduction of estuarine influence in the late Holocene, according to with the fall and/or stabilization of the RSL. From the last thousand years there has been a significant decrease in the occurrence of mangrove pollen in the sediments of the tidal flats of southern Espirito Santo (390 cal yr BP (1560 AD) and 77 cal yr BP (1873 AD), probably caused by a RSL fall associated with Little Ice Age (LIA). Paleoclimatic studies have indicated temperature fluctuations during LIA (380 to 50 cal yr BP) and MCA – Medieval Warm Period (950 to 750 cal yr BP) in the late Holocene and consequent change in the Brazil southern vegetation. These climatic events probably influenced the appearance of the mangrove genera succession in the São Francisco do Sul Bay (north Santa Catarina coast, 26°6' S). The effects of the sea level fall and/or stabilization during late Holocene were recorded on the southern coast of Santa Catarina (Laguna, 28° 29 ′ S) through changes in coastal geomorphology. In this same period at the Louisiana coastline (29°09 ′ N), sandy sediments (overwash sediments) were deposited in these estuaries reflecting the gradual migration of these sediments towards land likely a result of storm events. The position of RSL on the southern Brazilian coast (Laguna, 28° 29 ′ S) and north american (Louisiana coast, 29° 09 ′ N) from the middle Holocene were the same presenting suitable physicochemical conditions for mangrove development, as occurred on the coast of Espírito Santo (~6300 cal yr BP) and São Francisco do Sul Bay (~1500 cal yr BP). However, no mangrove pollen grains were recorded in the sediments of the current austral (Laguna, 28° 29 ′ S) and boreal (Louisiana coast, 29° 09 ′ N) limit of American mangroves during the Holocene. During this time interval, there was a significant contribution of organic matter of estuarine source in tidal flats occupied by Spartina sp. Regarding to global warming and RSL rise during Anthropocene an increase mangrove pollen of Espírito Santo sedimentary cores (20° 40' S) reflected mangrove migration to topographically higher sandy plains previously dominated by herbaceous vegetation. Regarding Laguna mangroves (current southern limit of the American mangroves, 28° 29 ′ S), pollen analyzes, 14C and 210Pb datings indicated that the mangroves were established under estuarine influence between ~1957 and 1986 AD, represented by Laguncularia sp. trees. Spatio-temporal analyzes based on satellite and drone images indicated that mangroves have been expanding in recent decades with the introduction of new mangrove genera. In our study area in São Francisco do Sul Bay (north coast of Santa Catarina, 26°6' S), palynological analyzes and 14C dating revealed that mangroves were established around ~ 1500 cal yr BP represented by Laguncularia sp. followed by Avicennia sp. (~500 cal yr BP) and Rhizophora sp. in the last century. This mangrove succession genera were likely caused by a warming trend in South America during the late Holocene and Rhizophora sp. by warming during the Anthropocene. In relation to the mangroves located on the Louisiana littoral, historical records indicated the presence of small shrubs of Avicennia sp. at the beginning of the 20th century. Currently, remote sensing studies coordinated by Cohen (2021) indicate a latitudinal expansion of Avicennia sp. colonizing areas that were previously occupied by Spartina sp. after two decades of warm winters. Therefore, mangroves migrated from the tropics to temperate zones as winter minimum temperatures increased during the Holocene. The Laguna and Louisiana mangroves (currently South and North American mangroves limit) were only established in the early and mid-21st century, respectively. Such dynamics were likely caused by the natural global warming of the Holocene and intensified during the Anthropocene. This process also caused a RSL rise which resulted in the migration of mangrove from lowlands to new higher tidal flats.
Acesso aberto (Open Access)
A evolução dos manguezais nos litorais Nordeste e Sul brasileiros durante o Holoceno
(Universidade Federal do Pará, 2020-09-30) FREIRE, Neuza Araújo Fontes; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
It is possible that climate changes and sea level fluctuations (allogenic processes) are and will cause major changes in mangrove dynamics. However, other driving forces may be significantly affecting this system. Distinguishing allogenic and autogenic influence on mangroves is a challenging question, because mechanisms related to the natural dynamics of depositional environments (autogenic processes) have strong influences on the establishment and degradation of mangroves. Thus, impacts on mangroves caused by autogenic processes may be erroneously attributed to allogenic mechanisms. Therefore, it is imperative to identify the ‘fingerprint’ of global changes in modern mangrove dynamics. This thesis integrates palynological, geochemical, sedimentological data, 14C dating of sedimentary organic matter, geomorphological and vegetation data in order to evaluate the influence of autogenic and allogeneic processes on Brazilian mangroves during the Holocene. Tropical estuaries from Rio Grande do Norte and southern Bahia, and subtropical estuaries in northern and southern Santa Catarina estates with different climatic, geomorphological and oceanographic characteristics were studied. The Relative Sea-Level (RSL) along the Rio Grande do Norte reached modern level and stabilized at about 7,000 cal yr BP, allowing the mangrove establishment at the edges of the Ceará-Mirim River estuary until the nowadays. However, changes in the spatial distribution of mangroves have occurred since then due to channels dynamics in the region (autogenic processes). Considering the mangroves of the Jucuruçu River in southern Bahia, their horizontal and vertical distribution were controlled by the interactions of the changes in the RSL and fluvial discharge. Therefore, the dynamics of these estuarine mangroves during the Holocene was mainly controlled by changes in sea level and precipitation that affected fluvial discharge. These allogeneic mechanisms were the main drivers of the dynamics of these mangroves. However, during the last 600 years, factors intrinsic to the depositional system gained relevance by controlling the establishment and migration of mangroves by deposition and erosion of muddy tidal flats, abandonment and reactivation of channels (autogenic processes). In the case of Santa Catarina mangroves, the RSL rise up to the middle Holocene was decisive for the establishment of tidal flats appropriate for the expansion of saltmarshes. However, mangroves did not tolerate the Holocene low temperatures in the southern littoral of Santa Catarina. The pollen data indicate the establishment of mangroves with Laguncularia around 1,700 cal yr BP, followed by Avicennia and lastly Rhizophora trees, a cold less tolerant genus, around 650 cal yr BP in São Francisco do Sul, north of Santa Catarina. The mangroves of Laguna, south of Santa Catarina, composed of Laguncularia and Avicennia, were established in the current southern limit of the South American mangroves only in the last decades. No evidence was found for the presence of mangroves in Laguna during the Holocene. The establishment of these mangroves in the region probably started during the Anthropocene, as a consequence of the increase in minimum winter temperatures in southern Brazil. Considering changes in precipitation rates over drainage basins that feed mangrove estuaries, as well as trends in RSL rise and temperatures until the end of the 21st century, tropical estuarine mangroves will likely migrate to higher topographically sectors in the interior of the river valleys, where its extension will depend on the volume of river discharge interacting with the RSL rise. Subtropical mangroves are expected to expand to more temperate zones as minimum winter temperatures increase. This process should cause an increase in the diversity of mangrove species, such as the introduction of the Rhizophora genus in the current southern limit of the mangroves, positioned in Laguna-SC. However, in the case of high rates of RSL rise, the relatively new subtropical mangroves are also expected to migrate to topographically higher sectors of the coast.
Acesso aberto (Open Access)
Geomorfologia, mudanças na fonte de matéria orgânica e vegetação em planícies de maré próximas a foz do rio Amazonas durante o Holoceno
(Universidade Federal do Pará, 2011-11-11) GUIMARÃES, José Tasso Felix; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228; 8809787145146228
Geomorphological data, sedimentary facies, pollen, spores, carbon and nitrogen isotopes records, C/N ratio and radiocarbon dates allowed the identification and discussion about the relationship between the main morphological process, climatic signals and its influence on vegetation patterns of tidal flats near the mouth of the Amazon River during the last 5500 cal yr B.P. Therefore, data from the margin of Amazon River (Macapa site) indicate marine influence related to mangrove presence over a tidal mud flat between 5560 - 5470 cal yr BP and 5290 - 5150 cal yr BP. Afterward, the mangrove area shrank following the return of more humid conditions and increase of Amazon River discharge. A common reworking process of the tidal flat through the lateral migration of a meandering creek occurred in the study site, with later development of transitional vegetation under freshwater influence. Following the natural vegetation succession under stable climate and hydrological conditions, the expansion of varzea forests occurred since 600 - 560 cal yr BP until the present. Furthermore, regarding the tidal flats located west of the mouth of Amazon River (Amapa site), these stable conditions also allowed the mangrove maintenance over mudflats with deposition of marine organic matter during at least the last 2350 - 2300 cal yr BP. Processing and interpretation methods in optical and synthetic aperture radar (SAR) images, data of water salinity, maximum height of flood, historical rain series and sedimentary facies were used in the analysis of the morphological and geobotanical units, and its short-term changes to understand the main processes acting on the tidal flats downdrift of the Amazon River mouth (Calcoene site) during the last 30 years. Thus, the study area was subdivided in two main compartments: coastal plain and plateau. The coastal plateau presents a flat to gently undulated surface shaped by erosive process. Avulsion of alluvial channel and birdfoot feature possibly related to six deltaic lobes were also identified in this compartment. The vegetation is represented by varzea (flooded freshwater forests) and savannah. The coastal plain has an average length of 10 km, and it presents the tidal-fluvial channel, paleochannels, lakes, varzea, inundated field (herbaceous field), mangrove, chenier ridges, elongated tidal mud bars, tidal mud and mixed flat (non-vegetated). The sedimentary facies indicate tide and wave-dominated environments. The presence of lakes and lake belts, coexistence of herbaceous field and mangrove in the coastal plain may be related to silting and abandonment of tidal channels. The temporal analysis of these features indicates the savannah contraction, expansion of varzea and mangrove areas and formation of extensive mud tidal flats during drier period under the influence of El Nino. The wetter period under the influence of La Nina probably allowed the increase of varzea and lakes over the savannah areas, and the expansion of mangrove. Therefore, the decrease of rainfall index during El Nino may have reduced the Calcoene River inflow and favored an increase of tidal propagation, transport and deposition of mud along the tidal-fluvial channel and its secondary channels with subsequent development of mangrove and stabilization of muddy substrate near the coastline in La Nina. Considering a longer time scale during the mid and late Holocene, the analysis of morphology, sedimentary facies, palynological, carbon and nitrogen isotopes, C/N and radiocarbon data from tidal flats in the Calcoene site, indicates that vegetation development during the mid and late Holocene occurred influenced by the interaction relative sea-level and tidal channel dynamic. The data indicate a mud-rich tidal flat that presents alternations between supra and intertidal environments. The proximal portion of the tidal flat is related to the transitional sector between the costal plateau and plain and represents the final filling stage of the concave-up feature formed by the abandoned channel that contributed to water accumulation under very low energy flows, fern and other terrestrial vegetation establishment surrounding the formed lake since 5280 - 5160 cal yr BP. During the last 2840 - 2750 cal yr BP, the source of mud ceased and autochthonous organic material became prevalent as well as the increase in contribution of terrestrial organic matter (C3 plants), mainly represented by varzea vegetation. Herbaceous field already colonized the tidal flat at least during the last 3170 - 2970 cal yr BP. However, part of distal portion of the tidal flat related to the herbaceous field was covered by chenier ridges between 3170-2970 and 220-140 cal yr BP. The mangrove establishment, characterized by estuarine organic matter, Rhizophora and Avicennia pollen, occurred after 1350-1290 cal yr B.P and 220-140 cal yr B.P. on G3 and G2 site, respectively. This stacking pattern of sediments indicating a retrogradation, with distal facies over proximal facies, and gradual transition of herbaceous to mangrove sediment (e.g. G3 site) suggesting that the creation of accommodation space may be produced during an increase of wave action, tidal inundation frequency and evolution of secondary channels in the study site as a result of progressive relative sea-level rise. The integration of all these data suggests that the morphological process, vegetation patterns and sources of organic matter from tidal flats of Calcoene, Amapa and Macapa sites was influenced and conditioned by the interaction between relative sea-level, climatic and hydrological changes, and tidal channel dynamic during the Holocene.
Acesso aberto (Open Access)
Hidrodinâmica, transporte e proveniência sedimentar no baixo rio xingu e sua importância como “Tidal River” amazônico
(Universidade Federal do Pará, 2022-07-14) MEDEIROS FILHO, Lucio Cardoso de; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645; ASP NETO, Nils Edvin; http://lattes.cnpq.br/7113886150130994
This research is based on the investigation of the processes (geological and hydrodynamic) that govern the recent evolution of a large tributary of the lower Amazon, the Xingu River. The aim was to investigate its aspects of sedimentary evolution and hydrological flows, from already consolidated data on the filling of its ria and how its patterns of transport and sediment trapping, its seasonal and tidal effects have been established, in addition to understanding the role of the Amazon River as a regulator in the dynamics of its tributary. Hydrodynamic measurements of flow, velocity and water level along with bottom sediment and MPS samples were collected at 3 annual seasons (February, June and November). The results provided support for the investigation of the Xingu-Amazonas interaction and the evolution of the bottom morphology of the lower Xingu. The results suggest a filling of the ria both by the Xingu River, forming a prominent headwater delta, and the Amazon River, where tidal variations transport sediments upstream in the Xingu River. On the other hand, large areas in the central part of the ria indicate muddy sedimentation. Elementar geochemistry allowed us to trace part of the history of sediments and source rocks, together with the analysis of immobile elements (Al, Ti, Zr, Hf, Th) and rare earth elements (REE) because they are poorly fractionated during weathering processes. and they are concentrated in the bottom sediments to the detriment of the dissolved fraction of the rivers. The deposits preserved in the lower Xingu River, despite draining cratonic regions in higher areas, confirm that the bottom material is derived from heterogeneous sources with predominantly intermediate igneous compositions and that they underwent important recycling during fluvial transport. The hydrodynamic modeling allowed to indicate the fluvial discharge as the most relevant forcing for the muddy deposition dynamics in the Xingu estuary. From a numerical model, it was possible to extrapolate the flow and transport dynamics beyond the open boundaries, that is, the central portion of the ria, elucidating the interaction mechanism between river and tidal discharge and the associated sedimentary dynamics. The determination of the amplitudes and phases of the tidal components, whether of purely astronomical origin or resulting from shallow waters, as well as the average level and the hourly discharge proved to be fundamental for the understanding of the governing processes.
Acesso aberto (Open Access)
Ictiólitos da Formação Pirabas, mioceno do Pará, Brasil, e suas implicações paleoecológicas
(Universidade Federal do Pará, 2011-06-01) COSTA, Sue Anne Regina Ferreira da; RICHTER, Martha; http://lattes.cnpq.br/9381228195500524; ROSSETTI, Dilce de Fátima; http://lattes.cnpq.br/0307721738107549
The Pirabas Formation (Oligo-miocine), which is represented by carbonates deposits through the Brazilian Coastal Area between the States of Pará and Piauí, is recognized for its fossil richness. Among the many fossils paleoichthyofauna stands out for its abundance in outcrops, but the absence of stratigraphic and facies control of these fossil restricted their potential use in paleoenvironmental interpretations. The joint use of the technique of wet sieving for the recovery of ichthyoliths and microfacies and facies analysis of sediments taken from Pirabas Formation deposits, which were exposed in the B17 mine (Capanema-PA), allowed for the first time the use of vertebrate fossil for the elaboration of an interdisciplinary paleoenvironmental reconstruction model. The 3594 recovered ichthyoliths, along with the 5 facies associations and the 4 carbonate microfacies, led to the conclusion that these deposits of Pirabas Formation were formed in marine-marginal depositional system, with different environments genetically associated as shore face (surf zone), beach, lagoon, tidal channel and tidal delta, which would be part of an estuarine system with the influence of wave, marked by four different depositional cycles related to possible transgressiveregressive episodes. The estuarine environment was confirmed by the assembly of ichthyoliths, observing that this assembly is formed by both freshwater specimens, represented by the Characidae family, an unheard occurrence for the unit until then, as for marine specimens, for example, the sharks. Several dental types, possibly attributed to representatives of brackish waters, such as the genera Dasyatis and Sarpa, both equally registered for the first time, also strengthens the proposed environment. The distribution of the ichthyological community evidences palaeoenvironmental control, having registered their highest abundance in deposits of tidal channel. However, the influence of relative sea level resulted in the development of transgressive-regressive depositional cycles, which also exerted strong control on the stratigraphic distribution of the B17 Mine registered ichthyoliths, reinforcing the importance of interdisciplinary studies in refining palaeoecological reconstruction of this unit.
Acesso aberto (Open Access)
A influência marinha nas águas do lago Arari (ilha de Marajó-Pa) durante o Holoceno com base em indicadores biológicos e isotópicos.
(Universidade Federal do Pará, 2011-03-14) SMITH, Clarisse Beltrão; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228; 8809787145146228
This work aimed the paleoenvironmental reconstruct of the drainage basin area of the Lake Arari (Marajó Island-PA) during the last 7.250 yr B.P. There was performed the characterization of environment study, determining the current physico-chemical data of lake water and their botanical composition (phytoplankton and macrophytes). From the nine sediment cores sampled from the Lake Arari, herbaceous plain, and on the east coast of the Marajó Island, were analyzed the grains size, sedimentary structures, pollen, isotopic (_15N and _ 13C) and elemental (C/Nmolar) content that allowed the lito, bio and chemostratigraphy correlation between the sampling sites. The ages of events were determined by radiocarbon. The integrated analysis of these data allowed the identification of three phases: Phase 1, from 7.328-7.168 and 2.306-2.234 cal. yr B.P., the sediments are classified as clayey silt and sandy silt, showing predominantly lenticular and wavy structures with mangrove pollen and values of C/N molar ratio and _ 13C _ 15N compatible with a lagoonal depositional environment. In Phase 2, from 2.306-2.234 to ~500 cal. yr B.P., occurs a decrease in the energy flow, the sedimentary deposits present parallel lamination structure or massive deposits. Although the pollen data indicate the absence of mangroves in this phase, the isotope and elemental values continue to indicate preferential contribution of aquatic marine organic matter. In phase 3, from ~500 cal. yr B.P. to modern, is established the lake system, because the sediment deposition reflects relatively low energy flow and marine influence becomes progressively smaller with larger contribution of freshwater algae. Besides, occurs a slight increase in organic matter derived from terrestrial plants due to the expansion of the herbaceous plain, which it colonizes the Arari Lake's drainage. Currently the mangrove forests are restricted to east littoral area of the Marajó Island. According to the model proposed in this work, the decrease in marine influence, with consequences for the hydrodynamics, organic matter and vegetation of the study area, was produced by the interaction between the sea-level rise and river water discharge.
Acesso aberto (Open Access)
lndicadores de estabilidade da matéria orgânica em terras pretas nos sítios arqueológicos Jabuti e Jacarequara (Pará)
(Universidade Federal do Pará, 2015-09-02) SENA, Luciana Freitas de; KERN, Dirse Clara; http://lattes.cnpq.br/8351785832221386; 8351785832221386; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008; 1829861620854008
Environmental conditions in the Amazon region favor the weathering and decomposition of soil organic matter, making it depleted in nutrients and difficult agricultural use. But in the same region, areas that have been modified by human action preterit, known as Terra Preta Archaeological (TPA), have different properties, among which stands out the high stability of soil organic matter (SOM) that in some research it is attributed to interactions between the MOS and other soil constituents such as pyrogenic carbon and minerals from the soil. In this study were selected two archaeological sites in the state of Pará, the Jabuti, the cemetery housing type, located in the city of Bragança, and the Jacarequara, the sambaqui type, located in Barcarena, in order to assess the stability of organic matter TPA from soil extracted solutions (depths 30 and 80 cm) and own soil (collected during the implementation of extractors in December 2013) in areas of TPA and vicinity. The characterization of soil solutions was conducted in the period between March and June 2013, based on the macroscopic properties and the chemical indicators: dissolved carbon concentrations (organic, inorganic and total), determined by the combustion method; pH, Eh and conductivity. The SOM stability assessments in the solid phases of the TPA and surrounding areas (ADJ) were based on textural verification of soil chemical indicators (pH, organic carbon concentrations and Ca, K, P, Na, and Mg) and biological represented by the microbial biomass, determined by the method of irradiation / extraction and expressed in terms of carbon (Cbm) and nitrogen (Nbm). The results of the soil solutions showed that two sites in the pH values are higher in depth (80 cm), and at the site Jacarequara values were determined for this parameter up to 7.2, while the site Jabuti pH results do not exceed the value 6. The maximum values of Eh (mV), conductivity (μs) and dissolved organic carbon (mg L-1) in place Jacarequara, 30 cm deep were respectively +201 mV, 427 µs e 13 mg L-1 and in the area adjacent to this site, at the same depth the highest values were +128 mV, 72 µs e 23 mg L-1 for the same parameters. At the Jabuti site and its ADJ, in 30 cm deep, the respective maximum values of the same areas were Eh +108 mV and +96 mV; conductivity 138.87µs and 59.85µs, dissolved organic carbon 12 mg L-1 and 21.08 mg L-1. Comparing the areas of TPA and their ADJ, the data Eh and dissolved organic carbon refer to more stable components in soil areas of solutions of TPA, owing to the more oxidizing values and smaller dissolved organic carbon concentrations, the results conductivity, which is an indicator of the concentration of ions is higher in the TPA reporting the increased availability of nutrients. In both sites, soils presented sandy texture, both in the areas of TPA as the ADJ, the latter being more sandy. In the soil Jacarequara site and its ADJ in the range of 20 to 30 cm deep, the following values were obtained respectively: 119.82 g kg-1 and 20.34 g kg-1 for SOM; pHH2O equal to 6.8 and 4.9; 183 mg/dm3 and 5 mg/dm3 P (available); 39 mg/dm3 and 29 mg/dm3 K (exchangeable); 14.8 cmolc/dm3 and 0.7 cmolc/dm3 Ca (exchangeable); 0.1 cmolc/dm3 and 1.7 cmolc/dm3 Al (exchangeable), 181.26 μg g-1 and 88.74 μg g-1 of Cbm and 3.27 mg kg-1 and 1.91 mg kg-1 Nbm. In the soil of Jabuti site, the determined values were: 83.66 g kg-1 of MOS, pHH2O equal to 4.4; 55 mg/dm3 P (available); 59 mg/dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 4 cmolc/dm3 of Al (exchangeable); 92.56 mg kg-1 of Cbm and 1.41 mg kg-1 Nbm; in the area adjacent to this site, the values were: 13.13 g kg-1 of MOS, pHH2O equal to 4.6; 4 mg/dm3 P (available); 29 mg dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 1 cmolc/dm3 Al (exchangeable), 27.54 mg kg-1 of Cbm and 0.96 mg kg-1 Nbm. As well as other archaeological sites with TPA, Jacarequara and the Jabuti had significantly higher levels of nutrients compared to surrounding areas, with the exception of Ca element in Jabuti. In the sites, carbonaceous particles were investigated, showing no intrinsic results pyrogenic carbon. In areas of TPA, the results obtained from the soil analysis indicated positive correlation between the microbial biomass, organic matter and nutrients, which can be associated with better quality of the soil in these areas compared their ADJ, consistently with the data highlighted in the soil solutions. Comparing the two sites, the results indicate that the SOM in Jacarequara site shows more stable constituents.
Acesso aberto (Open Access)
Materiais construtivos e sua biodeterioração em fortificações da Amazônia
(Universidade Federal do Pará, 2017-03-29) NORAT, Roseane da Conceição Costa; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
Acesso aberto (Open Access)
Morfologia e análise da sucessão deposicional do vale inciso Quaternário de Marapanim, Norte do Brasil.
(Universidade Federal do Pará, 2009-11-03) SILVA, Cléa Araújo da; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; 3282736820907252
The coastal sector located eastward of the Amazon river mouth is characterized by several estuarine systems, that harbor large mangrove areas with approximately 7600 km2. The Marapanim Estuary is influenced by macrotidal regime with moderate waves influence. The morphological and morphostratigraphic aspects were investigated by using remote sensing images (i.e., Landsat-7 ETM+, RADARSAT- 1 Wide and SRTM) integrated with bathymetric and surface sediments data. Facies analysis of quaternary deposits was studied based on cores collected by vibracore and rammkersonde systems. These deposits were dating by AMSradiocarbon. The estuary was compartmentalized into estuary mouth, estuary funnel, and upstream estuary. The open-mouthed estuary (inner, middle and outer) is influenced by a mixedenergy in which both waves and macrotides play an important role in the hydrodynamic control, and transport and sediment. The data integration reflects an evolutive model of estuarine incised valley fill, defined by a basal surface that limits Quaternary deposits from Tertiary one, which are recovered by fluvial sands that constitute the lowstand system tract. The initial stage of the last transgression provided the trapping of fluvial sediments within the valley. Later, a transgressivemud deposits migrated over fluvial sediments to landward. Under stillstand sea level occurs widedevelopment of mud flat (freshwater swamp and mangroves), as well as its progradation toward the estuary mouth. Also, occur a transgressive pulse responsible for sandy deposits (beaches and dunes) that recover muddy deposits and provide the migration of this deposit to the elevated topographic level. The geological model proposed has application for the northeast coast of Pará, characterized by estuarine systems resulted by the last Holocene transgression.
Acesso aberto (Open Access)
Morfologia e dinâmica de médio (1958-2010) e curto (2007) períodos da planície costeira de Almofala, Município de Itarema, Ceará
(Universidade Federal do Pará, 2011-05-24) AGUIAR, Ponciana Freire de; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; https://orcid.org/0000-0001-7850-1217
This study also a morphologic and dynamic analysis in mid-term (1958-2004) and low-term (2007) to Almofala coastal plain (NW of Ceara, Northeast Brazil), including Almofala, Barreira and Torroes Beachs conditioned for high temperatures (>25ºC), media raining of 1172,21 mm, velocity winds of 5,5 m/s, mesotidal coast (media of 1,48 m), and height waves of 0,56 m. The objective also: (1) morphologic units and subunits identification (in scale 1:50000); (2) the evaluating shoreline changes by mid-term (1958-2010) and low-term (2007). The methodology consisted: (1) to compartment and subcompartment units, using the MDT and sloping map; (2) monitoring to coastal line in mid-term: with integration aerial photography’s and Quickbird images 46 years (1958/2004) and Landsat images, 33 years (1977/2010); (3) quantification and mapping to erosion and accretion zones; (4) morphosediment variability analysis by low-term (2007) to Almofala, Barreira and Torroes beachs; and (5) geoambiental zoning with vulnerability analysis and adjusting areas by using and occupation. In the PCA have this compartments and subdivisions: Plateaus (littoral “tabuleiros” with 8031957 m² and abrasion platform - 34654 m²; Coastal Plain (alluvial plain with 944912 m²; estuarine plain - lagune plain with 1449466 m², ebb-tidal plain 66696 m², tidal channels with 847036 m² and delta with 66696 m²; and sandy plain (coastal sandy dunes with 15343353 m² and beachs with 837031 m²). During period studied (1977/2010 - 33 years) the Almofala shoreline migrated so much, as continent direction as ocean direction: (1) section 3.1 -shoreline retreat of 785 m, with annual erosion rate of 13,15 m/years, retrograding -1,3 Km²/46 years (1958/2004), and addition of 570 m , prograding 888.045,47 m²/46 year, with annual rate of 6,3 m/year; (2) section 3.2 - the shoreline retreated 668 m, by erosion rate 12,24 m/year, retrograding -0,98 km²/ 33years (1977/2010), with addition 394 m, and accretion rate of 8m/year, prograding 0,37 km²/33years. The Almofala, Barreira and Torroes beachs behaved the beachs itself with RTR dominate wave. The parameter ε showed longshore bar and runnel to Almofala and Torroes beachs, with fine grain sizes (44%), and reflective to Barreira beach, with median grain sizes (29%). The parameter _ has stages lowtide terrace intermediate to Almofala beach and dissipative to Barreira and Torroes beachs. This beachs is semi-exposed by winds and waves, with erosion to Barreira (-64,5 m³) and Torroes (-72,1 m³) beachs, and acretion (62,83 m³) to Almofala beach (2007). The Torrões beach have high vulnerability by environmental risks (erosion), the Barreira beach have media as high vulnerability and the Almofala beach have media vulnerability to west and low vulnerability to east. The geoambiental map include: major APP’s areas, risky areas, appropriate occupation areas; and degraded areas for natural process (coastal erosion) and anthropic process to contribute with environmental planning and coastal management.
Acesso aberto (Open Access)
Morfologia e sedimentação em um estuário de macromaré e plataforma adjacente, margem equatorial brasileira
(Universidade Federal do Pará, 2025-06-30) MIRANDA, Artur Gustavo Oliveira de; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; https://orcid.org/0000-0003-0252-808X
Understanding morphosedimentary dynamics in macrotidal estuaries is a challenging task, particularly in large-scale systems where seabed morphology and sediment distribution are poorly constrained. This study presents an unprecedented investigation into the morphological changes and the spatial and seasonal variability of surface sediments in the São Marcos Estuary and its adjacent continental shelf. The objective was to assess multidecadal morphobathymetric evolution (1977–2022) and short-term sedimentary pattern modifications associated with climatic seasonality, characterized by a dry season and a rainy season (2020–2021). The 45-year analysis, based on comparisons of nautical charts, revealed a sediment transport pattern primarily controlled by ebb currents, which governs the evolution of key morphological features. A highly deflected subaqueous delta, developed in a marine environment dominated by macrotidal oceanographic processes, was identified on the inner continental shelf—this configuration deviates markedly from classical models of tidedominated deltas. The estuary exhibited morphological instability in the area seaward of the estuarine funnel—proximal to the São Luís Port Terminal—while the region landward of the funnel, including the lower estuary and the inner continental shelf, displayed relative morphological stability. Sediment budget analyses indicated a clearly negative sediment balance for both environments over the study period. The estuary experienced a net volume increase of 1.1 × 10⁹ m³, equivalent to 2.91 × 10¹² tm⁻³ of eroded sediments, with estimated erosion rates of 6.4 × 10¹⁰ tm⁻³/year and a volumetric erosion rate of 2.4 × 10⁷ m³/year. Similarly, the inner continental shelf recorded a net volume increase of 1 × 10⁹ m³, corresponding to 2.65 × 10¹² tm⁻³ of eroded sediments, with annual rates of 2.2 × 10⁷ m³/year for volume and 5.9 × 10¹² tm⁻³/year for sediment mass. Together, both environments accounted for a total net volume increase of 2.1 × 10⁹ m³, representing a total of 5.56 × 10¹² tm⁻³ of eroded sediments, with combined net erosion rates of 4.6 × 10⁷ m³/year and 1.23 × 10¹¹ tm⁻³/year, respectively. Sediment budget calculations across isobaths showed that the estuary experienced substantial sediment losses down to the -30 m isobath. Below this depth, however, sediment behavior was inverse, indicating sediment retention or accumulation. In contrast, the inner continental shelf exhibited a significant net volume increase up to the -25 m isobath, followed by a depositional regime with attenuated sediment accumulation down to the -45 m isobath. For sedimentary deposit characterization, 284 surface sediment samples were collected during the dry season and 281 during the rainy season. These samples were analyzed and spatially interpolated to quantify the percentages of mud (silt and clay), sand, organic matter, and calcium carbonate in both seasonal periods. Textural classifications of surface sediments were assigned based on the schemes proposed by Wentworth (1922), Shepard (1954), and Larsonneur (as modified by Dias, 1996). During the dry season, estuarine sediments were predominantly composed of fine and medium sand, while the adjacent continental shelf was mainly composed of medium sand. Sand accounted for approximately 70% of all dry season samples. In the rainy season, the estuary maintained a similar sediment distribution, with sand again dominant—fine sand being most abundant, followed by medium sand. The adjacent shelf showed a predominance of fine and medium sand, indicating that climatic seasonality exerted influence primarily over the continental shelf region. The intense tidal activity within the study area is the principal driver of the morphosedimentary dynamics of the São Marcos Estuary and its adjacent continental shelf.
Acesso aberto (Open Access)
Mudanças da cobertura, uso do solo e produção de minério de ferro em minas a céu abertona Austrália e no Brasil: um indicador de intensidade de explotação mineral
(Universidade Federal do Pará, 2023-05-26) SANTOS, Diogo Corrêa; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
Iron ore is a very important resource for the development of a nation. With technological, industrial and urban advances, especially in Asian countries, the demand for this resource has increased considerably in recent decades. Consequently, changes in land cover and use (LCLU) have occurred in the mined areas of countries with higher ore production. Australia and Brazil are the largest iron ore producers in the world. In 2019, they reached production amounts of 930 million tons (mt) and 480 mt, respectively. However, little is known about the extent of land required for iron ore exploitation at the scale of productive open-pit mines in these two countries. Therefore, this doctoral thesis aimed to (1) map the LCLU in time and space in iron mining areas in the countries with the highest production in the world; (2) estimate the area used for iron ore exploitation as well as the accumulated ore production from the 1980s to 2019; and (3) identify an indicator of mineral exploitation intensity and ore production in millions of tons per square kilometer (mt/km²) for the main iron mines in Australia and Brazil. Landsat 5 TM (1984 and 1986) and Sentinel-2B (2019) satellite images were processed to map LCLU in areas of open cast iron mines in the Pilbara region of Western Australia, Hamersley mineral province and in the regions of Carajás (PA), Corumbá (MS) and Quadrilátero Ferrífero, QF, (MG) in Brazil, using geographic object-based image analysis (GEOBIA). The values of iron ore production per mined area were extracted from the statistical yearbooks of mineral production in the two countries. The results showed that iron mining in Australia occupied an area of 41.45 km² in 1986 and was expanded to 875.06 km² by 2019. In Brazil, the extent of iron mining was 109.53 km² in 1984, and this area expanded to 295.75 km² in 2019. The overall accuracy and kappa index of the set of classified images were above 90%, indicating the excellent quality of the classification. The accumulated iron ore production data between 1984 and 2019 showed that Australia reached a total production of 8.4 billion tons of iron ore in this period in a mined area of 875.06 km², equivalent to 9.7 mt/km². Brazil reached a total production of 7.03 billion tons in an area of 297.75 km². The mineral exploitation intensity indicator showed that Brazil and Australia produced equivalents of 23.6 mt/km² and 9.7 mt/km², respectively, over the study period. The study concluded that (1) the area of mined soil increased in all the mines in the two countries analyzed between 1984 and 2019, with the largest expansion being detected in Australia; (2) the high production of iron ore in Australia and Brazil and the consequent LCLU changes are driven by high demand from Asian countries, especially China; and (3) according to the mineral exploitation intensity indicator, there was a better relationship between mineral production and mined area in Brazil than in Australia. This result allows us to confirm that the two countries, especially Brazil, reached extremely high levels of production in a proportionately small area. Finally, this doctoral thesis contributed to the understanding of the intensity of iron ore production and the consequent LCLU changes in these two countries in addition to contributing quantitative and specialized data on the extents of the main iron ore mines globally.
Acesso aberto (Open Access)
Ostracofauna da Formação Solimões (Atalaia do Norte, Amazonas, Brasil): taxonomia, implicações paleoambientais e bioestratigráficas.
(Universidade Federal do Pará, 2017-09-12) PEREIRA, Ana Paula Linhares; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; 4546620118003936
The study of the ostracods from the boreholes 1AS-7D-AM, 1AS-8-AM and 1AS-31- AM, drilled at the locality of Atalaia do Norte, in Amazonas State, Brazil, allowed to recognized 9 genera and 30 species; the eurialyne genera Cyprideis is the most abundant and diverse, with 19 known species and two new species described herein: C. atalaiensis sp. nov. and C. diction sp. nov. Other marine and/or transitional (Paracypris, Perissocytheridea, Rhadinocytherura, Pellucistoma and Skopaeocythere) and non-marine (Cypria, Cytheridella and Penthesilenula) genera have been found, as well as other microfossils (foraminifera, fishs, mollusks and palinomorphs) which have been used for the paleoenvironmental interpretations and biostratigraphy of the Solimões Formation. The integrated stratigraphic analisys of ostracods and palinomorphs in the boreholes 1AS-8-AM and 1AS-7D-AM allowed to date the sequence from Early Miocene to Late Miocene. Through the index fossils, were identified five palinological zones already proposed from the Neogene of western Amazon: Verrutricolporites, Early Miocene; Psiladiporites-Crototricolpites, Late Early Miocene to Early Middle Miocene; Crassoretitriletes, Middle Miocene; Grimsdalea, Late Middle Miocene to Early Late Miocene; and Astaraceae, Late Miocene. The distribution of the Cyprideis species allowed to recognize five zones corresponding to the palynological zones, four of which previously established, although its age limits have been changed in this study: C. aulakos, renamed as C. sulcosigmoidalis, from late Early Miocene to early Middle Miocene, C. caraione, Middle Miocene to early Late Miocene, C. minipunctata, late Late Miocene and C. cyrtoma Late Miocene. Furthermore, is proposed here a new ostracod zone: C. paralela, from Late Miocene. The biostratigraphic analysis, based on palinology and ostracods, as well as other microfossils reveals a sequence which starts at the Early Miocene, with influence of coastal environments attested by the presence of palinomorphs and foraminifera typically from mangrove. At the Middle Miocene, the paleoenvironments are characterized as fluvio-lacustrine with marine influence. Finally, in the Late Miocene although still marked by marine influence, predominate fluvio-lacustrine environment upward to the section.
Acesso aberto (Open Access)
A pluma do rio Amazonas: fonte: dinâmica e transporte de sedimentos para estuários e manguezais do litoral leste amazônico.
(Universidade Federal do Pará, 2024-06-14) SILVA, Ariane Maria Marques da; ASP NETO, Nils Edvin; http://lattes.cnpq.br/7113886150130994; https://orcid.org/0000-0002-6468-6158
The Southeastern Amazon Coastal Zone (SACZ) includes the largest mangroves belt in the world and more than 20 macrotidal estuaries. In this area, a large volume of fine sediments has been deposited during the Holocene, however, it is known that the local rivers are black water rivers, carrying small amounts of suspended sediment. Therefore, since decades the sources and transport mechanisms of fine sediments to estuaries and mangroves have been speculated and investigated. It was recently demonstrated the existence of an offshore source of muddy sediments to the mangroves. Due to its proximity, the Amazon River has been seen as the probable main source of sediments, where an average flow of 170x103 m3 .s-1 and suspended sediment concentrations in the order of 80 mg.L-1 would represent a nearly inexhaustible source of mud to both estuaries and mangroves. However, the provenance and transport processes by which the mud of the Amazon would reach the SACZ, providing mangrove progradation, are not yet understood, since the plume is mostly drifted to northwest. In this context, the sedimentary constitution of the inner continental shelf and its reworking must also be evaluated, as well as the possibility of mud supply to the east of the study region. The present study aimed to integrate and complement efforts on sediment dynamics in the estuaries (Mocajuba, Caeté and Gurupi) and mangroves of the SACZ, combining studies on the inner continental shelf. Therefore, tools and approaches from hydrodynamics, sedimentology and biogeochemistry were used to identify and understand the sources and transport mechanisms of muddy sediments for the sector, composing a distance gradient from the mouth of the Amazon River, as well as a gradient of the drainage basins size. The Mocajuba estuary presents quite peculiar aspects in terms of morphology and hydrodynamics. The morphology of the estuary is strongly influenced by structural evolution and faults caused by neotectonic events since the Neogene, resulting in deep and straight areas in the lower and middle portions of the estuary. The tide propagates into the estuary without significant deformations, as a result of the combination between inherited morphology and hydrodynamic aspects. Salinity showed higher values during dry seasons, while the concentration of suspended sediment was higher during rainy seasons. Estuarine circulation in Mocajuba is similar to fjord because of the deep, however, without salinity stratification. The estuarine turbidity maxima zone did not occur due to the high depth areas, low current velocities, and low suspended sediments concentration. However, a “high turbidity wedge” was observed near the mouth of the estuary, evidencing the Amazon River plume influence. The Caeté estuary is classified as a coastal plain, tide-dominated, with a semidiurnal regime and considerable variations during the spring and neap phases. From a scientific point of view, this is one of the most studied estuaries in the SACZ, including geology, geomorphology, hydrodynamics, sedimentology, geochemistry, biogeochemistry, ecology in general, among other studies areas. For this Thesis, the Caeté estuary was considered a “model estuary” due to its geographic location (regarding to the Amazon River mouth, Mocajuba and Gurupi estuaries distances), the hydrographic basin size and especially because of the data available in scientific articles that prove the influence of an offshore source of fine sediments. Gurupi is a typical coastal plain estuary, shallow, funnel-shaped, tide-dominated, but partially mixed. Salinity levels and suspended sediment concentrations were higher at the mouth and decreased upstream. The estuarine turbidity maxima zone was observed in both seasons, however, the increase in river discharge, during the rainy season, attenuated and displaced this zone seaward. The tide propagated asymmetrically, with hypersynchronous behavior near the mouth, being attenuated upstream. Regarding sedimentary organic matter, the data showed that estuarine samples present more negative δ13C values, as a result of stronger terrestrial and mangroves influences. The δ13C values of samples collected on the inner shelf showed less negative values, indicating a mixture between marine and mangrove carbon sources. Furthermore, the results showed that the size of the drainage basin of local rivers is also a relevant factor in the dynamics of organic matter. The Gurupi River, for example, is large enough to contribute organic and terrigenous sediments to the estuary and internal shelf. In summary, the SACZ estuaries are characterized by the macrotidal regime, subject to singular aspects of geology, geomorphology and the local river. In the Mocajuba estuary, inherited morphology had a strong influence on hydrodynamic and sedimentary processes. In the Gurupi estuary, the high river flow played a fundamental role in the estuarine dynamics.
Acesso aberto (Open Access)
O potencial do sensoriamento remoto SAR no mapeamento, discriminação de gêneros e estudo da dinâmica de floresta de mangue na região Amazônica.
(Universidade Federal do Pará, 2019-04-26) COUGO, Michele Ferreira; FERNANDES, Marcus Emanuel Barroncas; http://lattes.cnpq.br/8943067124521530; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
This dissertation examines the potential of data generated from SAR sensors to differentiate between mangrove genera using polarimetric data, biomass estimates based on forest structure, and by producing thematic mangrove forest maps, using multi-frequency SAR images. Polarimetric SAR data (Radarsat2), multi-frequency (bands X, C and L) were used to achieve this goal. The study area is the Ajuruteua Peninsula, located in the eastern sector of the Amazon Coastal Zone. Mangroves in this region are considered preserved with the following species present: Rhizophora mangle, Avicennia germinans, Avicennia schaueriana and Laguncularia racemose, where R. mangle is the dominant species in this region. Through the polarimetric image Radarsat-2, band C, the polarimetric response of the parcels, dominated by these two principal genera (Rhizophora e Avicennia), were analyzed. Through the analysis of the polarimetric response, we were unable to define a pattern per genus to allow for the differentiation of the genera using this parameter. Analysis of the scattering mechanism was conducted through polarimetric decomposition of the coherence and covariance matrix. In the H-α plane, all vegetation parcels were classified as zone 5 of average entropy, attributed to vegetation scattering, and as zone 6, also of average entropy, associated to an increase in the surface-level roughness. Only the field class presented an H value lower that the other classes, standing out from the others. The images of scattering mechanisms: double-bounce, volumetric and surface-level did not permit the separation of dominant genera in the region. Using annual time series images Sentinel1-A, the behavior of the σ° polarizations VV and VH were similar and did not present differences in relation to total biomass values. Variations in radar backscatter over the year were related to environmental conditions (precipitation and tidal regime), canopy alterations (phenology) and incidence angle. The σ° values were greater during the month of May to the end of August, and in the same period, σ°VH/σ°VV rate values were lower, which is a reflex of mangrove canopy dynamics in the region given that during this period leaf litter production is greater, despite modest oscillation (1.5 dB). The use of multi-frequency SAR images for Random Forest classification of the environments on the peninsula resulted in the best Kappa index, 0.53, for the model that included the Sentinel1-A and ALOS-PALSAR images, with a Kappa mangrove class of 0.90. The dwarf mangrove class presented a global disagreement (up to 10%) higher than the others, principally in types exchange with mangrove classes, hypersaline plains and others, being that the last two had the lowest Kappa indices per class in all the classifications. The mangrove class showed a global disagreement maximum of 5% and a Kappa index greater than 0.90 in all classifications. Based on the above considerations, we conclude that the mangrove genera approach, even with a greater n sample, did not produced significant differences to distinguish genera through polarimetric techniques, be them polarimetric responses or scatter techniques. Two advances can be identified in the study of mangroves using time-series Sentinel-1A: σ°VH/σ°VV polarization rate is related to canopy dynamics, and the use of trimester images, representing different seasons for the classification of mangrove forests. In addition, the potential of SAR images for mapping mangrove forests using time-series images from C and L bands through machine learning techniques is also recognized.
Acesso aberto (Open Access)
Radar de abertura sintética aplicado ao mapeamento e reconhecimento de zonas úmidas costeiras
(Universidade Federal do Pará, 2011-12-09) TEIXEIRA, Sheila Gatinho; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The use of SAR imaging to identify coastal wetlands under different acquisition configurations and different environmental conditions is a research topic at the forefront of knowledge in the field of remote sensing. In order to evaluate the potential of the use of SAR images in tropical coastal environments, an Environmental Protection Area of Baixada Maranhense was chosen to be investigated, given the state of preservation of the study area, where one can observe, mainly, mangrove ecosystems, fields salt marshes and fields flooded by fresh water. RADARSAT and ALOS PALSAR images in different imaging modes were acquired under different environmental conditions. In RADARSAT-1 Wide 1 images, it was possible to separate the mangroves and floodplains, in the dry and rainy seasons, especially when the images were acquired in conditions of zero precipitation, since with humidity in the system, the separation between these environments tends to decrease by the increase in backscattering. The influence of the high tide condition on the backscatter values of the RADARSAT-1 images was not verified. Contextual automatic classification based on frequency was able to separate mangroves from floodplains and water in both seasons from floodplains and water in both seasons. The RADARSAT-1 Wide and Fine images, acquired during the rainy season, under high rainfall, different tidal conditions and different incidence angles (20º - 47.8º) were transformed by the principal component analysis method, which attested that they are highly correlated. The backscatter analysis of these images showed a low separability for smaller incidence angles (20º to 31º), while in the images acquired at larger angles (41º to 47º) the separability is a little higher, when analyzing the mangrove environments and floodplains. In multipolarized RADARSAT-2 and PALSAR-HH images, acquired in the dry season, in areas of floodplain, saline and pasture grasslands, it was verified that the microtopography parameter HRMS, of the grassland areas, influenced about 49% of the values of σ0, of the image PALSAR-HH. For the RADARSAT-2 images, in the HV and VH polarizations, this influence was low, around 24% and 26%, respectively. In the parallel polarizations, the microtopography did not influence the zero sigma variations. Therefore, SAR images can be considered an excellent source of data for the recognition and monitoring of tropical coastal wetlands.
Acesso aberto (Open Access)
Taxonomia, paleobiogeografia, paleoecologia e bioestratigrafia (Ostracoda) do Oligo-Mioceno da Formação Pirabas (Pará, Brasil).
(Universidade Federal do Pará, 2015-07-14) NOGUEIRA, Anna Andressa Evangelista; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; 4546620118003936
The limit Oligo-Miocene is marked by one of the largest marine transgressions in the world recorded in the Pirabas Formation, a predominantly carbonate sequence exposed in the littoral northern Brazil. The identification of ostracods from 35 outcrops samples and 22 from the drill core FPR-160 Primavera, collected in the Pirabas Formation, trough an extensive survey of the literature as well as the comparative study with type material from Bold´s and Howe´s collections allowed the identification of 36 new species, 12 species left in “aff.” and three in “cf.”; and 27 species common to the Caribbean Neogene; two species recognized for other areas and more one species already described for the studied unit herein, as well as 38 in open nomenclature completing a record of a total of 119 species. This broad taxonomic study provided a robust database for the accuracy of paleoenvironmental, biostratigraphic and paleogeographic studies from this unit, and also to increase the record of the paleobiodiversity of Neogene Ostracods from North of Southwestern Atlantic. The taxonomic study of ostracods yielded approximately 23 families, 64 genera and 119 species. The facies association indicate from shallow marine plataformal to lagoonal environments, and the ostracods genera as Haplocytheridea, Cytheridea, and mainly, Perissocytheridea and Cyprideis genus, as well as benthic foraminifera of Ammonia and Elphidium genera indicated the salinity variation in the environments. The 27 common species to Caribbean units showed a tiny similarity compared to the large number of new species recorded to Pirabas unit. The irradiation, restriction and extinction of the ostracofauna in these regions, due to the tectonic and eustatic process in these regions, provided a new arrangement in the distribution and consequently the paleobiogeographics provinces. However, it is considered that the ostracofauna recorded to Pirabas unit is inserted in a new subprovince correlated to the Caribbean subprovinces. In Pirabas Formation, the record of the five species indexes Glyptobairdia crumena, (N5 / N6) and Neocaudites macertus (N4 and N5) inserted in Globigerinatella insueta Zone; and Pokornyella deformis (N6 to N16), Cytherella stainforthi (N2 to N5), Quadracythere brachypygaia (N3 to N6) in Globigerinoides trilobus Zones, Catapsydrax dissimilis and Catapsydrax stainforthi allowed to determinate the Late Oligocene to Early Miocene to Pirabas sequence. The more than 100 species recorded into this interval allowed the recognition of a Cytherella stainforthi zone which is subdivided in four subzones: Jugosocythereis pannosa, Quadracythere brachypygaia, Glyptobairdia crumena and Porkonyella deformis with limits marked by first and last occurrence along the succession. This new zonation is preliminarly calibrated with the zonal planktonic foraminifers, corresponding to N3 to N7 zones of Blow, included in the Chatian to Burdigalian ages, corroborating with Neogene ostracod biostratigraphy to the Caribbean region. Thus, this ostracod zonation is of great significance for local, intrabasinal and regional correlation, particularly where foraminiferal, nannofossil or palinomorfs control is poor due to the litoral caracteristc of the Pirabas sequence.