963 resultados para coastal environments
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A Baía do Guajará (Região Metropolitana de Belém-PA) faz parte do estuário Amazônico e é o acidente geográfico que mais sofre com a influência urbana. Com base nisto objetivou-se neste trabalho realizar um estudo sobre as condições de sanidade da zona estuarina da Baía do Guajará, diagnosticando o efeito dos lançamentos de efluentes na qualidade do corpo hídrico utilizando a ictiofauna como indicador ecológico. Foram selecionadas cinco estações de coletas considerados contaminadas (4 localizadas no canal principal e 1 nos igarapés) e três referências (2 no canal principal e 1 no igarapé) que foram visitados em 4 ocasiões para coleta da ictiofauna e parâmetros ambientais. Foram capturados 567 indivíduos de 40 espécies, a maioria foi Siluriformes. A abundância relativa em número (CPUEn) no canal principal apresentou maiores valores em dezembro (S/C). Nos igarapés foi observada variação significativa entre as estações de coleta. A maioria das espécies, tanto nos igarapés como canal principal foram consideradas acessórias e ocasionais. Esta fauna visitante utiliza a área para reprodução, berçário e alimentação. Esta escolha se deve à disponibilidade alimentar e a possibilidade de obter refúgio contra predadores e parasitas. Quanto à diversidade, no canal principal, os resultados foram semelhantes entre os períodos e estações de coletas não apresentando variação significativa. Nos igarapés houve variação significativa apenas para as estações de coleta. Através da análise multivariada foi observado que houve uma distinção da ictiofauna que habita o canal principal da baía do Guajará da que habita os igarapés. As espécies capturadas no canal em grande parte apresentaram hábitos migratórios, movimentando-se entre os ambientes límnico-estuarino e estuarino-costeiro. Já nos igarapés a maioria apresentou hábito límnico, com indivíduos que realizam apenas pequenas migrações dentro dos igarapés. Para o canal principal a coleta de dezembro apresentou diferença altamente significativa. Nos igarapés houve variação significativa entre as estações de coleta. A análise do BIO-ENV não identificou nenhum fator abiótico podendo influenciar a estrutura da ictiofauna. Apesar de os resultados terem mostrado que a ictiofauna do canal não está sendo afetada diretamente pela contaminação urbana da cidade de Belém, registra-se, um fenômeno de bio-estimulação (fonte alimentar), que pode ser um sinal de inicio de poluição orgânica e pode provocar a eutrofização do ambiente podendo causar danos irreparáveis ao ambiente e à população que o utiliza.
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Os aspectos morfodinâmicos relacionados à erosão ou acresção da linha de costa são alguns dos assuntos analisados na gestão das zonas costeiras que vêem sendo tratada em todo mundo no sentido de monitorar e proteger essas zonas. Esta tese objetiva analisar o comportamento da morfodinâmica costeira de Salinópolis, relacionando-o ao uso da orla oceânica. A área de estudo foi compartimentada em três setores: Oeste (praias da Corvina e do Maçarico), Central (praia do Farol Velho) e Leste (praia do Atalaia). A metodologia consistiu na: (a) aquisição e tratamento de imagens multitemporais (1988-2001-2013) do satélite Landsat 5 TM, 7 ETM e 8 OLI; (b) aplicação de entrevistas/questionários com banhistas, (c) aquisição de dados de campo durante as estações chuvosa (26, 27, 28/04/2013) e menos chuvosa (04, 05, 06/10/2013); e (d) análise laboratorial para o tratamento dos dados adquiridos em campo (topografia das praias estudadas, amostragem de sedimentos superficiais das mesmas e com o uso de armadilhas, e medições oceanográficas de ondas, marés, correntes e turbidez). Foram feitas as representações gráficas dos perfis topográficos das praias, calculados os parâmetros estatísticos granulométricos de Folk & Ward (1957), as taxas do transporte sedimentar nas praias e os parâmetros morfométricos de Short & Hesp (1982), estes últimos foram calculados com o intuito de relacioná-los aos estados morfodinâmicos de praias propostos por Wright & Short (1984) e Masselink & Short (1993). Para a classificação da costa oceânica de Salinópolis em termos de uso e ocupação foi utilizado o decreto nº 5.300 de 7 de dezembro de 2004. A partir das pesquisas sobre a urbanização na costa e das obras situadas nos ambientes costeiros foi utilizada uma matriz proposta por Farinaccio & Tessler (2010) que lista uma série de impactos ambientais, e o quadro de geoindicadores do comportamento da linha de costa proposto por Bush et al. (1999), para a identificação de locais com vulnerabilidade à erosão ou acresção. Para as condições oceanográficas em cada praia e periculosidade ao banho nas mesmas, foram integralizados os dados de ondas, de correntes, de morfodinâmica praial e questionários aplicados com banhistas. Atualmente, a orla oceânica de Salinópolis possui diferentes características quanto à utilização e conservação, abrangendo desde a tipologia de orlas naturais (Classe A) até orlas com urbanização consolidada (Classe C). A primeira ocorre nos extremos da área de estudo e, a segunda, na região da sede municipal. Quatro tipos de praias foram identificados segundo a exposição marítima e o grau das condições oceanográficas: tipo 1 (Maçarico), tipo 2 (Corvina), tipo 3 (Farol Velho) e tipo 4 (Atalaia). O trecho de costa com maiores impactos ambientais e com elevada erosão costeira localiza-se na praia do Farol Velho. O grau de periculosidade ao banho foi de 4 (praia do Maçarico) a 7 (praia do Atalaia) – médio a alto grau de risco. As praias de Salinópolis apresentam declives suaves (< 1,5°), grandes variações na linha de costa entre as estações do ano (9,6 a 88, 4 m) e volume sedimentar variável dependendo do grau de exposição das praias ao oceano aberto. Predominou o estado morfodinâmico dissipativo (Ω>5,5) para estas praias, mas com ocorrência do estado de banco e calha longitudinais (4,7<Ω<5,5) no setor oeste. As macromarés na área de estudo apresentaram altura máxima de 5,3 m (Setor Central, durante a estação menos chuvosa) e mínima de 4 m no mesmo setor, durante a estação chuvosa. As correntes longitudinais foram mais intensas no setor leste (>0,45 m/s) durante as duas estaçoes do ano. As alturas de ondas foram também maiores no setor leste (máximo de 1,05 m durante a maré enchente na estação menos chuvosa) e os períodos de ondas foram mais curtos (<4,5 s) no setor oeste. A média granulométrica obtida dos sedimentos coletados na face praial apresentou escala mais freqüente entre 2,6 a 2,8 phi, indicando a predominância de areia fina. O grau de seleção predominante dos sedimentos foi de 0,2 a 0,5 phi (muito bem selecionados e bem selecionados), e da assimetria foi de positiva (0,10 a 0,30) e de aproximadamente simétrica (-0,10 a 0,10). O grau de curtose variou desde muito platicúrtica (<0,67) a muito leptocúrtica (1,50 a 3,00). Foram observados eventos de acresção sedimentar da estação chuvosa a menos chuvosa. De 22/07/1988 a 28/08/2013 (25 anos) também houve predomínio de acresção, onde o avanço médio linear da linha de costa foi de 190,26 m. O recuo médio linear obtido para toda área de estudo foi de -42,25 m. Áreas com maior erosão são pontuais: divisas das praias da Corvina e Maçarico, e Farol Velho e Atalaia. Os traps portáteis indicaram uma maior quantidade de sedimentos transportados longitudinalmente na estação menos chuvosa (Mín. 280 g/m3: enchente, setor oeste; Máx. 1098 g/m3: vazante, setor leste). Nos traps de espraiamento, o balanço entre a quantidade de sedimentos entrando e saindo nas praias foi menor no setor central (Mín. 80 g/m3: vazante, estação menos chuvosa; Máx. 690 g/m3: enchente, estação menos chuvosa). A circulação costeira sedimentar é proveniente, principalmente, do efeito das marés, com direção governada pela enchente e vazante dos rios que atravessam a costa. Os dados indicam o transporte longitudinal de sedimentos da ilha de Atalaia e rio Sampaio para o setor oeste e as margens das faixas praiais.
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Fossil fuels are the main energy sources of the modern industrial age. Very sophisticated processes have been developed to extract these resources, due to increased demand on a global scale, as the extraction of oil. However, the complexity of these processes can cause accidents such as the release of oil to seas and oceans. In this context, this study proposes to carry out the implementation of a system of information to charts of environmental sensitivity to oil and prepare maps of vulnerability to oil for the city of Caraguatatuba-SP. The implementation of the database with geographical information of coastal environments was appropriate to be provided by the Internet, allowing wide access of data. The maps of vulnerability are important tool developed for the Individual Emergency Plans, because they were developed in operational scale, appropriate to actions to combat oil.
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The intense urbanization in coastal environments can cause environmental changes due to the susceptibility of these areas. It is therefore of utmost importance to understand the environmental quality of coastal area and the geomorphological features are essential to make it possible, as well as the geomorphological maps that are used as an instrument to analyze the relief. However, there is no standardization among the geomorphological mapping techniques, since the proposals vary according to the taxonomy of the relief, the adopted scale and the objective of the researcher. This paper aims to carry out geomorphological mappings of sectors of the city of Mongaguá, in São Paulo state, according to the conceptions of Verstappen and Zuidam (1975) and Gustavsson, Kolstrup and Seijmonsbergen (2006), seeking to verify the possibilities and constraints that each one can provide for environmental management. Verstappen and Zuidam’s design (1975) is a classical international bibliography proposal indicating the symbols and colors that will be used to represent the relief according to the origin shape of the geomorphological features; Gustavsson, Kolstrup and Seijmonsbergen's conception (2006) is a latest international proposal which also uses symbols and colors that can be combined to represent various forms of relief, coming from different origins. The mappings in this research are although not presented as a mainstream map, but as a cartographic representation in which the symbols are superimposed on the digital ortophoto map to provide the reader an association between symbolism and the relief represented. The result is a comparative analysis among the symbols that were used in each mapping, in which is discussed what design is the most appropriate, considering the adopted scale and the geomorphological features of the mapped area
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Pós-graduação em Geografia - IGCE
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Using distributions of benthic Foraminifera and bottom-water variables (depth, salinity, temperature, oxygen, suspended matter, organic matter, phosphate, silicate, nitrite, and nitrate), we investigated movements of water masses on the South Brazilian Shelf (27-30 degrees S) and assessed the seasonality of continental runoff on the distribution of shelf water masses. The data were obtained from water and sediment samples collected in the austral winter of 2003 and austral summer of 2004 in three transects. The terrestrial nutrient input was significantly reduced at stations away from the coast, but high values of nutrients were maintained in subsurface waters due the presence of South Atlantic Central Water (SACW) at greater depths. At shallow sampling stations the influence of freshwater runoff was related to (1) the dominance of calcareous benthic Foraminifera, such as lagoon-related Pseudononion atlanticum, Hanzawaia boueana, Bulimina marginata, Bolivina striatula, Elphidium poeyanum, together with several agglutinated species, including Arenoparrella mexicana, Gaudryina exilis, and Trochammina spp., common in coastal environments subject to wide salinity fluctuations. In contrast, smaller forms and higher species diversity characterized the assemblage at offshore stations. In winter, the presence of Buccella peruviana and Uvigerina peregrina at Santa Marta Cape suggest the possible transport of those species of Subantarctic Shelf Waters (SASW) origin. Foraminifera associated to Subtropical Shelf Water (STSW) were dominated by Globocassidulina subglobosa in both seasons. In summer, the occurrence of U. peregrina in the shallower stations suggested the influence of SACW nutrients brought up by upwelling of deeper waters. (C) 2008 Elsevier Ltd. All rights reserved.
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Seabob shrimp Xiphopenaeus kroyeri is a marine species that lives in shallow waters of coastal environments, often impacted by polycyclic aromatic hydrocarbons (PAH) pollution. In the present study, seabob shrimp were exposed for 96 h to benzo[a]pyrene (BaP) at the nominal concentrations of 100, 200, 400 and 800 microg.L-1. Animals of the control groups were exposed either to clean water or to the BaP-carrier (DMSO). At the end of the exposures, muscle tissues were sampled for BaP uptake assessment and hepatopancreas and hemolymph for EROD enzyme activity and hemocytes DNA damage, respectively. EROD activity and DNA damage increased significantly as a function of BaP exposure concentrations. Significant correlations between BaP uptake and both EROD activity and DNA damage suggest that they can be used as suitable tools for integrated levels of study on the biomarkers of PAH exposure.
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The genus Codium comprises c. 125 species widely distributed in marine coastal environments throughout the world. Due to morphological plasticity, the taxonomic delimitation of Codium species can be difficult. Sequences of the first exon of the large subunit of RUBISCO (rbcL) have been used in the molecular delimitation of species and for phylogenetic purposes. In the present study, we complement previous morphological work on Brazilian Codium species with molecular systematics. Based on the partial rbcL sequences, seven species are recognized along the Brazilian coast: C. decorticatum, C. intertextum, C. isthmocladum, C. profundum, C. spongiosum, C. taylorii and the new species Codium pernambucensis. Ten unique sequences were obtained among the samples examined, which we used in combination with previously published sequences to infer molecular phylogenies using various methods. The resulting trees showed three principal monophyletic groupings: Clade A with species having a prostrate habit, not branched, and mostly with small, grouped utricles; Clade B primarily consisting of upright species with cylindrical branches and large individual utricles; and Clade C composed of upright species with cylindrical branches that are slightly flattened, and have intermediate-sized individual utricles. The Brazilian species grouped with morphologically similar taxa from other geographic localities, and are present in all three main clades. A new sprawling species, Codium pernambucensis is described based on morphology and molecular analyses.
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Green roof mitigation of volume and peak flow-rate of stormwater runoff has been studied extensively. However, due to the common practice of green roof fertilization, there is the potential for introduction of nutrients into local bodies of water. Therefore, this study compares green roof runoff quality with the water quality of precipitation and runoff from a bare shingle roof. The runoff from a demonstration-scale extensive green roof was analyzed during the summer of 2011 for its effect on runoff volume and analyzed during eleven storm events in the fall and winter for concentrations of copper, cadmium, zinc, lead, nitrogen species, total nitrogen, total organic carbon, sulfate, orthophosphate, and other monovalent and divalent ions. The green roof reduced the overall volume of runoff and served as a sink for NO3 - and NH4 +. However, the green roof was also a source for the pollutants PO4 3-, SO4 2-, TOC, cations, and total nitrogen. Metals such as zinc and lead showed trends of higher mass loads in the bare roof runoff than in precipitation and green roof runoff, although results were not statistically significant. The green roof also showed trends, although also not statistically significant, of retaining cadmium and copper. With the green roof serving as a source of phosphorous species and a sink for nitrogen species, and appearing to a retain metals and total volume, the life cycle impact analysis shows minimum impacts from the green roof, when compared with precipitation and bare roof runoff, in all but fresh water eutrophication. Therefore, the best environments to install a green roof may be in coastal environments.
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La Provincia de Río Negro, a través de su Constitución y de leyes específicas, adhiere “a los principios que sustentan el desarrollo sustentable de conformidad con la Carta de Naciones Unidas." En la costa marítima de Río Negro existen poblaciones relativamente densas y en aumento básicamente por la inmigración en busca de nuevos horizontes laborales. Los conflictos ambientales que se presentan son comunes a otras zonas costeras: contaminación de las aguas costeras por insuficiente o falta de servicios de tratamiento de aguas residuales, modificación, para desarrollo urbano, industrial y comercial, de hábitats críticos para el sostenimiento de pesquerías, vida silvestre, desarrollo de infraestructura costera inapropiada o mal diseñada que favorece procesos erosivos acelerados y/o interrumpen procesos ecológicos básicos, ocupación espacial desordenada que impide el acceso público a playas y otros terrenos públicos, manejo inapropiado de desechos sólidos, incumplimiento de la legislación en la zona costera; generación de conflictos intersectoriales, desarrollo desordenado de infraestructura con altos costos socioeconómicos, crecimiento de la frontera agropecuaria, deterioro de los suelos (sobrepastoreo, desertificación), introducción de especies exóticas, etc. En Río Negro se han relevado, aunque a diferente escala y muchas veces en forma discontinua, la mayor parte de los ambientes costeros considerados de mayor interés desde el punto de vista ecológico y/o productivo. Ejemplo de productos de estos estudios son las Areas Naturales Protegidas de Punta Bermeja, Caleta de Loros, Bahía de San Antonio, Complejo Islote Lobos y Puerto Lobos, así como la Reserva Pesquera Golfo San Matías. Sin embargo, la información se halla dispersa, por lo que la mayor parte de las veces no se puede contar con un panorama actualizado y globalizador que permita la toma de decisión en forma ágil y un real manejo de las especies y/o de su ambiente. Por ello se considera necesario g enerar un Plan de Manejo de la Costa Marítima de Río Negro, esto es, una clasificación del territorio de acuerdo a su grado de sensibilidad ecológica, expresado en unidades cartográficas ambientales, y estableciendo pautas de manejo para las mismas. Se optó por un Sistema de Inventario y Planificación de Recursos, adaptado a un método de Planificación Participativa en el que se involucra en forma directa, a través de encuentros y talleres, a los diferentes estamentos provinciales, municipales, centros de investigación, organizaciones no gubernamentales ambientalistas, organizaciones intermedias, especialistas. Para la Evaluación de los Elementos e identificación de Zonas de Mayor Sensibilidad Ecológica se utilizó un Método de Evaluación de Riesgos que permite cartografiar grado de Amenazas, Vulnerabilidad y Riesgo.
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Methane is a powerful greenhouse gas and its biological conversion in marine sediments, largely controlled by anaerobic oxidation of methane (AOM), is a crucial part of the global carbon cycle. However, little is known about the role of iron oxides as an oxidant for AOM. Here we provide the first field evidence for iron-dependent AOM in brackish coastal surface sediments and show that methane produced in Bothnian Sea sediments is oxidized in distinct zones of iron- and sulfate-dependent AOM. At our study site, anthropogenic eutrophication over recent decades has led to an upward migration of the sulfate/methane transition zone in the sediment. Abundant iron oxides and high dissolved ferrous iron indicate iron reduction in the methanogenic sediments below the newly established sulfate/methane transition. Laboratory incubation studies of these sediments strongly suggest that the in situ microbial community is capable of linking methane oxidation to iron oxide reduction. Eutrophication of coastal environments may therefore create geochemical conditions favorable for iron-mediated AOM and thus increase the relevance of iron-dependent methane oxidation in the future. Besides its role in mitigating methane emissions, iron-dependent AOM strongly impacts sedimentary iron cycling and related biogeochemical processes through the reduction of large quantities of iron oxides.
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In-situ geotechnical measurements of surface sediments were carried out along large subaqueous dunes in the Knudedyb tidal inlet channel in the Danish Wadden Sea using a small free-falling penetrometer. Vertical profiles showed a typical stratification pattern with a resolution of ~1 cm depicting a thin surface layer of low sediment strength and a stiffer substratum below (quasi-static bearing capacity equivalent: 1-3 kPa in the top layer, 20-140 kPa in the underlying sediment; thickness of the top layer ca. 5-8 cm). Observed variations in the thickness and strength of the surface layer during a tidal cycle were compared to mean current velocities (measured using an acoustic Doppler current profiler, ADCP), high-resolution bathymetry (based on multibeam echo sounding, MBES) and qualitative estimates of suspended sediment distributions in the water column (estimated from ADCP backscatter intensity). The results revealed an ebb dominance in sediment remobilization, and a general accretion of the bed towards low water. A loose top layer occurred throughout the tidal cycle, likely influenced by bedload transport and small events of suspended sediment resettlement (thickness: 6 +-2 cm). Furthermore, this layer showed a significant increase in thickness (e.g. from 8 cm to 16 cm) related to periods of overall deposition. These findings imply that dynamic penetrometers can conveniently serve to (1) quantify potentially mobile sediments by determining the thickness of a loose sediment surface layer, (2) unravel sediment strength development in potentially mobile sediments and (3) identify sediment accumulation. Such data are an important complement and add a new geotechnical perspective during investigations of sediment remobilization processes in highly dynamic coastal environments.
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Magnetic iron minerals are widespread and indicative sediment constituents in estuarine, coastal and shelf systems. We combine environmental magnetic, sedimentological and numerical methods to identify magnetite-enriched placer-like zones in a complex coastal system and delineate their formation mechanisms. Magnetic susceptibility and remanence measurements on 245 surficial sediment samples collected in and around Tauranga Harbour, the largest barrier-enclosed tidal estuary of New Zealand, reveal several discrete enrichment zones controlled by local hydrodynamic conditions. Active magnetite enrichment takes place in tidal channels, which feed into two coast-parallel nearshore magnetite-enriched belts centered at water depths of 6-10 m and 10-20 m. A close correlation between magnetite content and magnetic grain size was found, where higher susceptibility values are associated within coarser magnetic crystal sizes. Two key mechanisms for magnetite enrichment are identified. First, tide-induced residual currents primarily enable magnetite enrichment within the estuarine channel network. A coast-parallel, fine sand magnetite enrichment belt in water depths of less than 10 m along the barrier island has a strong decrease in magnetite content away from the southern tidal inlet and is apparently related to active coast-parallel transport combined with mobilizing surf zone processes. A second, less pronounced, but more uniform magnetite enrichment belt at 10-20 m water depth is composed of non-mobile, medium-coarse-grained relict sands, which have been reworked during post-glacial sea level transgression. We demonstrate the potential of magnetic methods to reveal and differentiate coastal magnetite enrichment patterns and investigate their formative mechanisms.
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The impact of late glacial changes on the sedimentary record was investigated in two long vibracores, collected from the shelf edge off Mauritania, northwest Africa. Lithology and radiocarbon dates indicate that the sedimentary sequences were mainly controlled by sea-level changes on the shelf. The upper Pleistocene sequence is characterized by deposition in coastal environments, while the Holocene sequence represents deposition in shelf environments. During low sea level, much sediment was supplied to the present outer shelf, and the data imply an average accumulation rate of up to 43.0 cm/1000 yrs during the late Pleistocene, which is substantially higher than the Holocene rate. Shelf sediments were continuously reworked and redistributed on a regional scale during falling and rising sea level. The presence of reworked material results in radiocarbon ages which are too old. The mollusc. Venus striatula, which presently is found north of, but not along, the Mauritanian coast, occurs in the upper Pleistocene sequence, suggesting cooler water conditions in the shelf during late glacial times. This species probably migrated to the south during late glacial times, following the southward extension of the cold Canary Current. Radiocarbon dates of the shells broadly coincide with a lowstand of sea level over this part of the continental shelf.