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Tudurí, Adriana, Leandro Bergamino, Roberto Violante, José Luis Cavallotto, and Felipe García-Rodríguez. "SPATIAL AND TEMPORAL VARIATION IN THE PRESENT AND HISTORICAL SEDIMENTARY ORGANIC MATTER WITHIN THE RÍO DE LA PLATA ESTUARY (SOUTH AMERICA) IN RELATION TO THE SALINITY/TURBIDITY GRADIENT / VARIAÇÃO ESPACIAL E TEMPORAL PRESENTE E HISTÓRICA DA MATÉRIA ORGÂNICA SEDIMENTAR NO ESTUÁRIO DO RÍO DE LA PLATA (AMÉRICA DO SUL) EM RELAÇÃO AO GRADIENTE DE SALINIDADE / TURBIDEZ." Journal of Sedimentary Environments 3, no. 4 (December 23, 2018): 265–79. http://dx.doi.org/10.12957/jse.2018.39152.
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The aim of this study is to examine sedimentary organic matter sources, spatial distribution and temporal variability in a large estuarine system, the Río de la Plata estuary (South America). For this purpose, this work integrates recent and historical carbon and nitrogen isotopes (δ13C, δ15N), total organic carbon, total nitrogen, C/N ratios and sediment grain size analyses along the Río de la Plata estuary. Principal component analysis based on biogeochemical variables and salinity revealed two main biogeochemical contrasting zones, corresponding to the upper and the lower estuary. Such zones are derived from the density gradient observed at the maximum turbidity zone acting as a physical barrier by trapping fine sediments and controlling primary productivity. As a consequence, sedimentary total organic carbon and total nitrogen increase from upper reaches towards lower reaches to attain maximum values under the turbidity gradient due to the presence of fine sediments. On the other hand, C/N ratios display an opposite trend, with higher values in the upper reaches due to a higher influence of continental organic matter. Moreover, Stable Isotope Analysis in R (SIAR) based on δ13C and δ15N reveals that the main organic matter source to the sediment appears to be the continental particulate organic matter and the estimated percentages of terrestrial allochthonous contribution (C3 plants) indicated a decreased contribution towards the lower reaches. The paleoenvironmental analysis shows a change in the sedimentary organic matter composition since 1970 associated to an increased influence of terrestrial organic matter. This trend is related to an increase in the Paraná River flow, which in turn is related to climatic variability (i.e., the polarity change of the Pacific Decadal Oscillation). ResumoO objetivo deste estudo é estimar fontes de matéria orgânica sedimentar, distribuição espacial e variabilidade temporal num grande sistema estuarino, o estuário do Río de la Plata (América do Sul). Este trabalho integra dados atuais e históricos de isótopos de carbono e nitrogênio (δ13C, δ15N), carbono orgânico total, nitrogênio total, relação C/N e granulometria do sedimento ao longo do estuário do Río de la Plata. A análise de componentes principais baseada em variáveis biogeoquímicas e salinidade revelou duas zonas biogeoquímicas contrastantes, correspondentes ao estuário superior e inferior. Tais zonas são definidas por diferenças no gradiente de densidade na zona de turbidez máxima, o qual atua como uma barreira física, causando o aprisionamento de sedimentos finos e influenciando a produtividade primária. Como conseqüência, o carbono orgânico total sedimentar e o nitrogênio total aumentam dos trechos superiores para os trechos inferiores atingindo valores máximos sob o gradiente de turbidez devido à presença de sedimentos finos. Por outro lado, a razão C/N exibe uma tendência oposta, atingindo valores mais elevados no estuário superior devido a uma maior influência da matéria orgânica continental. Os resultados isotópicos de δ13C e δ15N sugerem que a principal fonte de matéria orgânica para o sedimento é a matéria orgânica particulada continental. A contribuição alóctone terrestre (plantas C3) diminui no estuário inferior. A análise paleoambiental mostra uma mudança na composição da matéria orgânica sedimentar a partir de 1970, causada pelo aumento do fornecimento da matéria orgânica terrestre. Essa tendência está relacionada a um aumento no fluxo do Rio Paraná, na sequência de alterações climáticas relacionadas com a mudança de polaridade da Oscilação Decadal do Pacífico.
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Ooi, Jieun Lin, Lee Woen Ean, Bashar S. Mohammed, M. A. Malek, Leong Sing Wong, Chao Wei Tang, and He Qing Chua. "Study on the Properties of Compressed Bricks Using Cameron Highlands Reservoir Sediment as Primary Material." Applied Mechanics and Materials 710 (January 2015): 25–29. http://dx.doi.org/10.4028/www.scientific.net/amm.710.25.
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This research is to investigate the properties of compressed building bricks producedfrom Cameron Highlands reservoir sediment. The particle size distribution of the sediments are graded as silt and sand. The sediments used were as total replacement of the normal soils used in the compressed soil bricks. This paper presents the compilation of experimental brick properties; compressive strength, water absorption, microstructure and heavy metal leachingof the compressed sediment bricks. The experimental results shows that increasing use of reservoir sediments decrease the compressive strength andincrease the water absorption. The heavy metal concentrations of the leachates from the leaching test are all within the regulatory limits. The optimum mix is derives from the compressive strength and the water absorption in which in this research is Mix 4, 70% sedimenta, 20% sedimentb and 10% cement,complying with ASTM C129 – Non Load Bearing Bricks [1].
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Laut, Lazaro, Maria Virgina Alves Martins, Pierre Belart, Maria Lucia Lorini, Iara Clemente, Leandro Nogueira, Anna Juliace, and Luiz Francisco Fontana. "ORGANIC COMPOUNDS AS PROXIES OF THE SEDIMENTARY ENVIRONMENTAL QUALITY OF THE MARICÁ-GUARAPINA LAGOON SYSTEM (SE, BRAZIL)." Journal of Sedimentary Environments 4, no. 2 (June 15, 2019): 159–73. http://dx.doi.org/10.12957/jse.2019.43371.
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Bottom sediment is a natural trap for organic matter and different kinds of pollutants. The accumulation of large amount of organic matter gives rise to the eutrophication of the aquatic ecosystems. The analyses of the quantity and quality of the organic matter (biopolymers) help to determine the trophic status of coastal ecosystems. The Maricá-Guarapina Lagoon System (MGLS) is located in Rio de Janeiro and is composed by four connected lagoons: Maricá, Barra, Padre and Guarapina. It has been suffering impacts due to the intense and uncontrolled property speculation. Based on this problem, this study aimed to characterize the organic matter (OM) amount and quality in sediments and the relation with the impacted areas in this lagoon system. The collected sediment samples were analyzed for geochemical data combined with grain size and physical-chemical environmental parameters of the bottom water. Statistical results evidenced that the sedimentary environment of the MGLS is heterogenous. The organic matter supplied to the MGLS is provided from different sources but the autochthonous contribution (phytoplanktonic productivity and vegetal detritus from the mangrove fringe) prevails. The anthropogenic contribution was more evident in Padre Lagoon, where the sediments had relatively low TOC contents (0.1-0.8%). The MGLS is accumulating mainly aged organic matter. The most impacted zones were found in Guarapina, Barra and Maricá lagoons, in bottoms of fine-grained sediments, with relatively high TOC and labile biopolymeric compounds (proteins, carbohydrates and lipids) contents, which should evolve into an ever-increasing stage of eutrophication. COMPOSTOS ORGÂNICOS USADOS COMO INDICADORES DA QUALIDADE AMBIENTAL SEDIMENTAR DO SISTEMA LAGUNAR MARICÁ-GUARAPINA (SE DO BRASIL)ResumoO sedimento de fundo constitui uma armadilha natural para a matéria orgânica e diferentes tipos de poluentes. O acúmulo de grande quantidade de matéria orgânica dá origem à eutrofização dos ecossistemas aquáticos. Estimativas de quantidade e qualidade da matéria orgânica (biopolímeros) podem ajudar a determinar o estado trófico dos ecossistemas costeiros. O Sistema Lagunar de Maricá-Guarapina (MGLS), localizado no Estado do Rio de Janeiro (SE do Brasil), é composto por quatro lagunas interconectadas: Maricá, Barra, Padre e Guarapina. Este sistema tem sofrido impactos devido à intensa e descontrolada especulação imobiliária. Neste contexto, este estudo teve como objetivo caracterizar a quantidade e qualidade de matéria orgânica (MO) dos sedimentos do MGLS. Foram obtidos dados geoquímicos e confrontados com resultados granulométricos em amostras de sedimentos coletados em 22 estações de amostragem e analisados parâmetros físico-químicos da água. Os resultados estatísticos evidenciaram que o ambiente sedimentar do MGLS é heterogêneo. Este sistema recebe matéria orgânica de diferentes fontes, sendo, porém, prevalecente a contribuição autóctone (produtividade fitoplanctônica e detritos vegetais dos manguezais existentes na região). A contribuição antropogênica de matéria orgânica foi mais evidente na Lagoa do Padre, onde os sedimentos apresentaram teores de COT relativamente baixos (0,1-0,8%). As zonas mais impactadas foram encontradas em fundos de sedimentos finos, com teores relativamente elevados de COT e de compostos biopoliméricos lábeis (proteínas, carboidratos e lipídios), nas lagunas de Guarapina, Barra e Maricá. Os resultados obtidos revelam também que o MGLS está acumulando principalmente matéria orgânica envelhecida e permitem prever que as referidas áreas podem evoluir para um estágio de cada vez maior grau de eutrofização.Palavras-chave: Lagunas Costeiras Tropicais. Biopolímeros. Eutrofização. Dinâmica Sedimentar.
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Rosa, Kátia Kellem da, Rosemary Vieira, and Jefferson Cardia Simões. "Identificação de Mudanças Ambientais Através da Caracterização Sedimentar e Investigação de Processos Glaciogênicos e Paraglaciais no Ambiente Glacial da Geleira Wanda, Ilha Rei George, Antártica (Identification of Environmental Change Through...)." Revista Brasileira de Geografia Física 6, no. 1 (July 17, 2013): 029. http://dx.doi.org/10.26848/rbgf.v6i1.232807.
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Este estudo objetiva identificar as características sedimentares associadas aos depósitos glaciogênicos e sedimentos com modificação por processos não glaciais na área proglacial da geleira Wanda, Ilha Rei George, Antártica. A metodologia foi desenvolvida através de atividades de campo realizadas durante a estação de verão em 2007, 2010 e 2011. Os sedimentos foram analisados para determinar a distribuição granulométrica e características morfoscópicas. Este estudo apresenta resultados de interpretações dos sedimentos coletados na proglacial da geleira Wanda. A análise sedimentar possibilita a distinção de sedimentos glaciogênicos e dos sedimentos modificados por atividade paraglacial, podendo evidenciar mudanças ambientais em decorrência do aumento da temperatura atmosférica superficial e da precipitação líquida. AbstractThis study arms identify sediment characteristics related to glaciogenics deposits and modification with paraglacial processes in Wanda Glacier proglacial area, King George Island, Antarctica. The methodology was developed through field activities performed during summers in 2007, 2010 and 2011. The sediments were analyzed to determine the particle size distribution and morphoscopical characteristics. This study presents results of the samples sediment interpretation in Wanda Glacier proglacial area. The sediment analyses provided the discrimination of the glaciogenicssediments and paraglacial modified sediments, and was evidence for environment changes in the study area due to the increase surface atmospheric temperature and liquid precipitation.
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Pinto, Anita Fernandes Souza, José Carlos Martins Ramalho, Leonardo Borghi, Thiago Gonçalves Carelli, Josiane Branco Plantz, Egberto Pereira, Denise Terroso, et al. "BACKGROUND CONCENTRATIONS OF CHEMICAL ELEMENTS IN SEPETIBA BAY (SE BRAZIL)." Journal of Sedimentary Environments 4, no. 1 (March 25, 2019): 108–23. http://dx.doi.org/10.12957/jse.2019.40992.
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This study intends to evaluate baseline concentrations of chemical elements for unpolluted sediments of Sepetiba Bay (SE Brazil). It analyzes the concentrations of potentially toxic elements (PTE) and other chemical elements (by Inductively Coupled Plasma Mass Spectrometry and Inductively Coupled Plasma Emission Spectrometry) from the upper part of the SP2 drillcore (or 2-SPT-1-RJ; with 50.30 m length), collected on the margins of Sepetiba Bay (at latitude 22° 55'S and longitude 43° 46'W). This core was described and sampled. Textural, mineralogical and geochemical analyses were performed in 17 sediment levels. The sediment layers of interest were selected, considering the period in which they were deposited, before high anthropic influence in the area, and on sediment grain-size. Only the muddy levels were selected, since fine sediments generally tend to have higher elemental concentrations. Foraminiferal occurrence was also analyzed in the selected layers. The results indicate that the studied sediments were deposited in a transitional marine context, after being exposed to multiple sedimentary cycles and weathering. The baseline concentrations, related to natural sediment sources were estimated for As, Cd, Co, Cr, Cu, Ni, Pb, Zn) and P and for other chemical elements. These results are useful in environmental impact assessment not only in the study area, but also for other coastal regions of Rio de Janeiro State. TÍTULO: CONCENTRAÇÕES DE FUNDO DE ELEMENTOS QUÍMICOS NA BAÍA DE SEPETIBA (SE BRASIL) RESUMO:Este estudo pretende avaliar as concentrações de fundo de elementos químicos, em sedimentos não poluídos, na Baía de Sepetiba (Se Brasil). Analisa as concentrações de elementos potencialmente tóxicos (PTE) e outros elementos químicos (por Espectrometria de Massa Plasma Acoplada Indutivamente e Espectrometria de Emissão Plasma Acoplada Indutivamente) da parte superior do testemunho SP2 (ou 2-SPT-1 RJ; com 50,30 m de comprimento), coletado nas margens da Baía de Sepetiba (à latitude 22° 55'S e longitude 43° 46'W). Este testemunho foi descrito e amostrado a cada 5 cm. Análises estruturais, mineralógicas e geoquímicas foram realizadas em 17 níveis de sedimentos. Os níveis de interesse foram selecionados, considerando o período em que foram depositados, antes da alta influência antrópica na área, e no tamanho do grão do sedimento. Apenas os níveis de lama foram selecionados, uma vez que os sedimentos finos tendem geralmente a ter maiores concentrações de elementos quimicos. A ocorrência de foraminíferos foi também analisada nas camadas selecionadas. Os resultados indicam que os sedimentos estudados foram depositados num contexto marinho de transição, após serem expostos a múltiplos ciclos sedimentares e a intemperismo. As concentrações de fundo, relacionadas a fontes naturais de sedimento foram estimadas para As, Cd, Co, Cr, Cu, Ni, Pb, Zn) e P e para outros elementos químicos. Esses resultados são úteis para a avaliação de impacto ambiental, não apenas na área de estudo, mas também em outras regiões costeiras do Estado do Rio de Janeiro. PALAVRAS-CHAVE: Multi-indicadores. Sedimentos. Registros Holocénicos. Litoral. Atlântico Sul.
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Alves Martins, Maria Virgínia, Márcia Andréia Da Silva Nunes, Marcio Inacio Alves, Marco Helenio de Paula Alves Coelho, Wellen Fernanda Louzada Castelo, Lucia Maria Lorini, Denise Terroso, et al. "GEOCHEMICAL NORMALIZERS APPLIED TO THE STUDY OF THE PROVENANCE OF LITHOGENIC MATERIALS DEPOSITED AT THE ENTRANCE OF A COASTAL LAGOON. A CASE STUDY IN AVEIRO LAGOON (PORTUGAL) / NORMALIZADORES GEOQUÍMICOS APLICADOS AO ESTUDO DE PROVENIÊNCIA DE MATERIAIS LITOGÉNICOS DEPOSITADOS NA ENTRADA DE UMA LAGUNA COSTEIRA. UM ESTUDO DE CASO NA LAGUNA DE AVEIRO (PORTUGAL)." Journal of Sedimentary Environments 3, no. 2 (June 9, 2018): 74–92. http://dx.doi.org/10.12957/jse.2018.34815.
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The use of geochemical normalizers has been applied in sedimentological studies in several study contexts, such as pollution, diagenetic and provenance assessment. Selected textural and mineralogical data of 137 surface sediment samples were compared by statistical analyses with geogenic elements concentrations normalized by the Al, Be, Ce, Fe, Fe+Al, Li, Rb and Sc aiming to identify the best normalizer to trace different sources of bottom sediments for the Aveiro Lagoon entrance (NW of Portugal). The study area is heterogenous in terms of hydrodynamics and sedimentary processes.The most commonly applied geochemical normalizer for the sediments elemental concentrations has been the aluminum. However, the statistical analyses evidenced that the best normalizer was the scandium, since Principal Components Analysis results have evidenced that the element/Sc values are largely independent of sediment granulometry and thus have allowed the identification of compositional differences not related to grain size. Statistical analyses have also allowed to discriminate groups of stations that: i) trace the entry and exit of mixed sources sediments of the lagoon due to the action of tidal currents; ii) contain materials provided from the erosion of granitoids present mainly along the Douro River basin, located to the north, and transported southward by coastal drift; iii) encompasse sediments provided from the erosion of the Schist–Greywacke Complex crossed by the Vouga River that drains into the inner central zone of the lagoon and; iv) represent an area of sediment accumulation located near the entrance of Mira Channel, where lithogenic materials, provided by mixed lithologies in addition to organic matter, are being deposited. The results of this work contribute to the knowledge of the sedimentary dynamics of the Aveiro Lagoon, a coastal system which is part of a littoral stretch that is being strongly eroded, due to natural and anthropic causes and should be applicable to other coastal systems with similar characteristics. ResumoO uso de normalizadores geoquímicos tem sido aplicado em estudos sedimentológicos em diversos contextos, como por exemplo, de poluição, avaliação diagenética e de proveniência de sediments. Dados texturais e mineralógicos selecionados de 137 amostras de sedimentos superficiais foram comparados através de análises estatísticas com concentrações de elementos geogênicos normalizadas por Al, Be, Ce, Fe, Fe + Al, Li, Rb e Sc. O estudo visou identificar o melhor normalizador para traçar diferentes fontes de sedimentos de fundo para a entrada da Lagoa de Aveiro (NW de Portugal), uma área heterogênea em termos de processos hidrodinâmicos e sedimentares.O normalizador geoquímico mais comumente aplicado em sedimentos tem sido o alumínio. No entanto, as análises estatísticas evidenciaram que o melhor normalizador foi o escândio, uma vez que os resultados da análise de componentes principal evidenciaram que os valores das razões elemento/Sc são amplamente independentes da granulometria sedimentar e permitiram a identificação de diferenças composicionais não relacionadas com o tamanho do grão. Análises estatísticas também permitiram discriminar grupos de estações que: i) traçam a entrada e saída de fontes mistas de sedimentos da laguna, devido à ação das correntes de maré; ii) contêm materiais provenientes da erosão de granitóides presentes principalmente ao longo da bacia do Rio Douro, localizada a norte, e transportados para sul por deriva litoral; iii) contêm sedimentos provenientes da erosão do Complexo Xisto-grauvaquico atravessado pelo Rio Vouga, que desagua na zona central interna da laguna e; iv) representam uma área de acumulação de sedimentos localizada perto da entrada do Canal Mira, onde materiais litogênicos, fornecidos por litologias diversificadas, além de matéria orgânica, estão sendo depositados.Os resultados deste trabalho contribuem para o conhecimento da dinâmica sedimentar da Laguna de Aveiro, um sistema costeiro que faz parte de um trecho litorâneo fortemente erodido, devido a causas naturais e antrópicas and may be applicable to other coastal systems with similar characteristics.
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Kenney, William F., Claire L. Schelske, and Andrew D. Chapman. "Changes in polyphosphate sedimentation: a response to excessive phosphorus enrichment in a hypereutrophic lake." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 5 (May 1, 2001): 879–87. http://dx.doi.org/10.1139/f01-040.
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Historic changes in lake phosphorus (P) loading are often determined in paleolimnological investigations by assessing stratigraphic changes in sediment total P. Polyphosphate (poly-P) in sediments may provide additional information on historic lake trophic status, because phytoplankton store surplus P intracellularly as poly-P when supplies exceed growth requirements. We hypothesize that phytoplankton (i.e., cyanobacteria and diatoms) with stored poly-P can remain intact and viable for many decades after sedimentation and that sedimented poly-P is not geochemically reactive. We tested our hypotheses with sediment cores from Lake Apopka, Fla., U.S.A., where P loading has increased ~7-fold since the 1920s and phytoplankton biomass is nitrogen limited owing to excessive P enrichment. We show that sedimented poly-P is mobilized by sample drying (i.e., becomes water soluble, geochemically reactive, and bioavailable); that anthropogenic P enrichment is expressed in the sediment record as increasing concentrations of poly-P; and that, consequently, sedimentary poly-P is a sensitive indicator of historic excessive P enrichment. Sedimentary poly-P is not geochemically reactive; thus, it represents biological attenuation that may partially ameliorate the effects of excessive P loading.
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Locat, Jacques, and Serge Leroueil. "Physicochemical and geotechnical characteristics of recent Saguenay Fjord sediments." Canadian Geotechnical Journal 25, no. 2 (May 1, 1988): 382–88. http://dx.doi.org/10.1139/t88-039.
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In the spring of 1985 the first goetechnical reconnaissance of recent Saguenay Fjord sediments took place, in which were recorded the two Saint-Jean-Vianney slides of 1663 and 1971. Cores from the upper part of the fjord were tested onboard the ship and in the laboratory. The mineralogy of the recent sediments is like that of the raised marine deposits of the area, except for the organic content, which is higher. The microstructure of the sediment is quite typical of flocculated marine soils. The freshly sedimented soil, in its sedimentary environment, has gained strength and sensitivity (up to 12) in excess of what is usually expected for such material. It has been concluded that the physicochemical characteristics of the sediment, such as depicted by its initial plasticity (before leaching), are first-order parameters in the source of apparent overconsolidation and structuration. Key words: recent sediments, shear strength, sensitivity, consolidation, structuration, microstructure, landslide, physicochemistry, mineralogy.
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Navas-S., G. R., S. Zea, and N. H. Campos. "FLUJO DE NITRÓGENO Y FÓSFORO EN LA INTERFASE AGUA-SEDIMENTO EN UNA LAGUNA COSTERA TROPICAL (CIÉNAGA GRANDE DE SANTA MARTA, CARIBE COLOMBIANO)." CICIMAR Oceánides 18, no. 2 (December 31, 2003): 45. http://dx.doi.org/10.37543/oceanides.v18i2.5.
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. Para evaluar el papel del sedimento sobre la alta producción primaria de una laguna costera tropical, Ciénaga Grande de Santa Marta (Caribe, Colombia), se midió el flujo de nitrógeno y fósforo (inorgánico disuelto, particulado) en la interfase agua-sedimento. Entre 1996 y 1997 se incubaron núcleos de sedimento en el laboratorio y se ubicaron trampas de partículas en campo, en dos estaciones contrastadas por la influencia de aguas dulces y marinas. Los flujos tuvieron una alta variabilidad espacial y temporal pero no mostraron esquemas claros en su dirección e intensidad en relación con las características de los sedimentos o de la columna de agua de las dos estaciones. Esto evidencia una alta heterogeneidad en la naturaleza y actividad de los organismos responsables de los procesos biogeoquímicos. Los sedimentos liberaron en promedio al agua 1643 μmolNm-2d-1 de amonio y 1.3 μmolNm-2d-1 de nitrito, aportando a la columna el 1.90-3.41 % de lo requerido en la producción. En condiciones óxicas normales, el sedimento actuó como sifón del fósforo, absorbiendo en promedio 178 μmolPm-2d-1 disueltos y recibiendo 36277 μmolPm-2d-1 particulados. Pero el fósforo se mantiene en exceso en la columna, en parte, por liberación desde el sedimento en condiciones anóxicas durante florecimientos microalgales masivos. Flux of nitrogen and phosphorus at the water-sediment boundary in a tropical coastal lagoon (Ciénaga Grande de Santa Marta, Colombian Caribbean) To evaluate the role of the sediment in the high primary production of a tropical coastal lagoon, "Ciénaga Grande de Santa Marta" (Caribbean, Colombia), the flux of nitrogen and phosphorous (dissolved, inorganic, particulate) in the water-sediment boundary was measured. From 1996 to 1997 sediment cores were incubated in the laboratory and sediment traps were deployed in the field, in two sites contrasted by the influence of fresh and marine waters. The fluxes were spatially and temporally highly variable but did not show clear patterns in their direction and intensity in relation to the sediment or water column characteristics at the two sites. This evidences a high heterogeneity in the nature and activity of the organisms responsible of the biogeochemical processes. The sediments liberated to the water on average 1643 μmolNm-2d-1 of ammonium and 1.3 μmolNm-2d-1 of nitrite, offering 1.90-3.41 % of the amount required in production. In normal oxic conditions, the sediment acted as a phosphorous sink, absorbing on average 178 μmolPm-2d-1 dissolved and receiving 36277 μmolPm-2d-1 particulate. But the phosphorous is maintained in excess in the column, in part, due to its liberation from the sediment in anoxic conditions during massive algal blooms.
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Navas-S., G. R., S. Zea, and N. H. Campos. "FLUJO DE NITRÓGENO Y FÓSFORO EN LA INTERFASE AGUA-SEDIMENTO EN UNA LAGUNA COSTERA TROPICAL (CIÉNAGA GRANDE DE SANTA MARTA, CARIBE COLOMBIANO)." CICIMAR Oceánides 18, no. 2 (December 31, 2003): 45. http://dx.doi.org/10.37543/oceanides.v18i2.5.
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. Para evaluar el papel del sedimento sobre la alta producción primaria de una laguna costera tropical, Ciénaga Grande de Santa Marta (Caribe, Colombia), se midió el flujo de nitrógeno y fósforo (inorgánico disuelto, particulado) en la interfase agua-sedimento. Entre 1996 y 1997 se incubaron núcleos de sedimento en el laboratorio y se ubicaron trampas de partículas en campo, en dos estaciones contrastadas por la influencia de aguas dulces y marinas. Los flujos tuvieron una alta variabilidad espacial y temporal pero no mostraron esquemas claros en su dirección e intensidad en relación con las características de los sedimentos o de la columna de agua de las dos estaciones. Esto evidencia una alta heterogeneidad en la naturaleza y actividad de los organismos responsables de los procesos biogeoquímicos. Los sedimentos liberaron en promedio al agua 1643 μmolNm-2d-1 de amonio y 1.3 μmolNm-2d-1 de nitrito, aportando a la columna el 1.90-3.41 % de lo requerido en la producción. En condiciones óxicas normales, el sedimento actuó como sifón del fósforo, absorbiendo en promedio 178 μmolPm-2d-1 disueltos y recibiendo 36277 μmolPm-2d-1 particulados. Pero el fósforo se mantiene en exceso en la columna, en parte, por liberación desde el sedimento en condiciones anóxicas durante florecimientos microalgales masivos. Flux of nitrogen and phosphorus at the water-sediment boundary in a tropical coastal lagoon (Ciénaga Grande de Santa Marta, Colombian Caribbean) To evaluate the role of the sediment in the high primary production of a tropical coastal lagoon, "Ciénaga Grande de Santa Marta" (Caribbean, Colombia), the flux of nitrogen and phosphorous (dissolved, inorganic, particulate) in the water-sediment boundary was measured. From 1996 to 1997 sediment cores were incubated in the laboratory and sediment traps were deployed in the field, in two sites contrasted by the influence of fresh and marine waters. The fluxes were spatially and temporally highly variable but did not show clear patterns in their direction and intensity in relation to the sediment or water column characteristics at the two sites. This evidences a high heterogeneity in the nature and activity of the organisms responsible of the biogeochemical processes. The sediments liberated to the water on average 1643 μmolNm-2d-1 of ammonium and 1.3 μmolNm-2d-1 of nitrite, offering 1.90-3.41 % of the amount required in production. In normal oxic conditions, the sediment acted as a phosphorous sink, absorbing on average 178 μmolPm-2d-1 dissolved and receiving 36277 μmolPm-2d-1 particulate. But the phosphorous is maintained in excess in the column, in part, due to its liberation from the sediment in anoxic conditions during massive algal blooms.
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Sang, Pham Nhu, Nguyen Tien Dung, Phan Thi Thanh Hien, and Vo Thi Cong Chinh. "The degree of chemical weathering in the Ba River basin, South Central Vietnam: Major-element geochemistry investigations of morden river sediments and sedimentary rocks." Journal of Mining and Earth Sciences 61, no. 1 (February 28, 2020): 82–91. http://dx.doi.org/10.46326/jmes.2020.61(1).09.
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Major-element geochemistry of Miocene sedimentary rock and modern river sediment samples in the Ba River basin, South Central Vietnam are utilized to assess the degree of chemical weathering in the Miocene and the present time. Sediment samples were analysed by X-ray fluorescence (XRF) spectrometer show that Miocene sedimentary rocks contain higher SiO2 and K2O, but lower Fe2O3, TiO2, MgO, Na2O, MnO, CaO, P2O5 than modern river sediment. Major-element geochemistry indicates that Miocene sedimentary rocks and modern river sediment are characterized by stronger depliption of Ca, Na and Mg than K and Si during the chemical weathering in this river basin. The similar relative depleption of Na, Ca, Mg, Si and K between modern river sediments and sedimentary rocks indicate not much deffirent the intensity of chemical weathering in the Miocene and the present time. The chemical index of alteration (CIA) alter from 69 to 93 in Miocene sedimentary rocks (average 74) and from 69 to 78 (average 77) in morden river sediments, indicating moderate chemical weathering in the Ba River basin in the Miocene and the present time.
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Edgett, Kenneth S., Steven G. Banham, Kristen A. Bennett, Lauren A. Edgar, Christopher S. Edwards, Alberto G. Fairén, Christopher M. Fedo, et al. "Extraformational sediment recycling on Mars." Geosphere 16, no. 6 (October 6, 2020): 1508–37. http://dx.doi.org/10.1130/ges02244.1.
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Abstract Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth’s geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument–based studies show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration’s Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment.
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Shotbolt, L. A., A. D. Thomas, and S. M. Hutchinson. "The use of reservoir sediments as environmental archives of catchment inputs and atmospheric pollution." Progress in Physical Geography: Earth and Environment 29, no. 3 (September 2005): 337–61. http://dx.doi.org/10.1191/0309133305pp452ra.
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Lakes and reservoirs act as sinks for both catchment and atmospherically derived particulates and so their sediments can provide valuable information on temporal changes in these inputs. While the use of lake sediments as environmental archives is well established, reservoir sediments have less frequently been used as temporal records. Yet, for investigating pollution histories, reservoirs are ostensibly of greater interest: they are generally located close to urban and industrial sources of pollution and accumulate sediment rapidly and over similar time periods to major emissions of pollutants. The lack of interest in reservoir sediments stems from the perception that fluctuating water levels are likely to result in significant sediment disturbance. This perception is sustained, perhaps mistakenly, by a lack of research into reservoir sedimentary systems. There is, therefore, a need to review the available published research on reservoir sedimentation processes and patterns, the relatively few studies that have used reservoir sediments and relevant studies from the lake-sediment literature, and thus critically evaluate the potential and problems of using reservoir sediments as temporal records of pollution. Current understanding of the processes of sedimentation and resulting distributions are reviewed. Some significant differences between sedimentation in lakes and reservoirs are highlighted and the implications for sampling and interpretation of sedimentary records discussed. It is suggested that, at present, a valuable resource is being underutilized and it is demonstrated that, where sediment deposition patterns are taken into account, reservoir sedimentary records can provide important data for reconstructing past atmospheric and catchment pollutant inputs.
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Montety, Laure de, Bernard Long, Gaston Desrosiers, Jean-François Crémer, Jacques Locat, and Georges Stora. "Utilisation de la scanographie pour l'étude des sédiments : influence des paramètres physiques, chimiques et biologiques sur la mesure des intensités tomographiques." Canadian Journal of Earth Sciences 40, no. 7 (July 1, 2003): 937–48. http://dx.doi.org/10.1139/e03-027.
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In July 1996, a flash flood resulted in the input of 9 million m3 of sediment toward the Bay of Ha! Ha!, leading to the elimination, partly or totally, of the benthic fauna of the bay. In this study, the CT scanner has been used in a highly perturbed environment, the Bay of Ha! Ha!, to both assess (i) the relationships between the variations of tomographic intensities and the sedimentologic parameters of the sedimentary column and (ii) to quantify the biogenic structures resulting from the activity of benthic organisms. Compaction, CaCO3 contents, and granulometry of sediments are the most important influences on the variation of tomographic intensities. The scanner allowed the study and quantification, in a non destructive way, of the sediment occupation by biogenic structures and, more particularly, allowed to further assess most of the relative importance of the fine fraction of biogenic structures (0.2501 mm) in the surface sediment layer (05 cm). Sediment occupation by biogenic structures reached maximal values at the upper part of the sedimentary column and decreased with depth. If sedimentary reworking leads to an increase in the sediment porosity, destabilization generated by the activity of organisms is balanced by the consolidation of the wall of the biogenic structures. Bioturbation resulting from the activity of benthic organisms into the sediments has a significant role on the sedimentary structure and biogeochemical processes. It is therefore necessary to quantify the volume of sediments occupied by biogenic structures to assess the activity of benthic organisms in the sedimentary column.
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Szczepańska, Aleksandra, Agata Zaborska, Anna Maciejewska, Karol Kuliński, and Janusz Pempkowiak. "Distribution and origin of organic matter in the Baltic Sea sediments dated with 210Pb and 137Cs." Geochronometria 39, no. 1 (March 1, 2012): 1–9. http://dx.doi.org/10.2478/s13386-011-0058-x.
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Abstract Organic carbon deposited in marine sediments is an important part of the global carbon cycle. The knowledge concerning the role of shelf seas (including the Baltic Sea) in the carbon cycle has increased substantially, however organic carbon accumulation rates in the Baltic sediments still require clarification. This paper describes methods used for assessing organic carbon and nitrogen accumulation rates in six sediment cores collected in the sediment accumulation areas in the Baltic Sea. Mass sediment accumulation rates were based on 210Pb method validated by 137Cs measurements. The organic carbon accumulation rates ranged from 18 to 75 g·C·m−2·yr−1. The C/N ratios and δ13C were used to access sedimentary organic matter provenance. The C/N ratios in the investigated cores vary in the range from 7.4 to 9.6, while δ13C ranged from −24.4‰ to −26.4‰. Results of the terrestrial organic matter contribution in the sedimentary organic matter were calculated basing on δ13C using the end member approach. Large proportion (41–73%) of the sedimentary organic carbon originates on land. The obtained results indicate the Baltic Sea sediments as an important sink for organic carbon. Substantial fraction of the sedimentary load originates on land.
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Trenggono, Mukti, Roy Andreas, Amron Amron, Rizqi Rizaldi Hidayat, Hendrayana Hendrayana, Rr Diah Febri Astuti, and Cristiana Manullang. "An Assessment of Cilacap Coast's Total Carbonate Sediment Content." Jurnal Kelautan Tropis 24, no. 1 (December 12, 2020): 15–24. http://dx.doi.org/10.14710/jkt.v24i1.8849.
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Sediments are particles derived from the dismantling of rocks from the land and pieces of shell and remains of marine organisms that contain organic matter, included carbonate sediment. The total carbonate sediment content was influenced by many factors, such as sediment grain type. This study aimed to determine the carbonate content in sediments and to determine their relationship to the sediment grain characteristic on the Cilacap coast. The sediment's carbonate content used the titration method, while the sediment grain test used a dry filter. Statistical analysis was used to determine the sediment grain characteristic (mean, sorting, skewness, and kurtosis). The results showed that sediments' total carbonate content had a range of 1.93% - 6.23%, with an average of 4.21%. Sediments are dominated by fine sand with very well sorted, very platykurtic, and very fine skewed characteristics. The relationship between sediment grain characteristics and total sediment carbonate content showed a good correlation due to the sorting factor. Other parameters such as mean size and skewness have been shown a low correlation, whereas kurtosis has a shallow relationship with carbonate content.
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Bratek, Alexander, Justus E. E. van Beusekom, Andreas Neumann, Tina Sanders, Jana Friedrich, Kay-Christian Emeis, and Kirstin Dähnke. "Spatial variations in sedimentary N-transformation rates in the North Sea (German Bight)." Biogeosciences 17, no. 10 (May 28, 2020): 2839–51. http://dx.doi.org/10.5194/bg-17-2839-2020.
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Abstract. In this study, we investigate the role of sedimentary N cycling in the southern North Sea. We present a budget of ammonification, nitrification and sedimentary NO3- consumption and denitrification in contrasting sediment types of the German Bight (southern North Sea), including novel net ammonification rates. We incubated sediment cores from four representative locations in the German Bight (permeable, semi-permeable and impermeable sediments) with labeled nitrate and ammonium to calculate benthic fluxes of nitrate and ammonium and gross rates of ammonification and nitrification. Ammonium fluxes generally suggest oxic degradation of organic matter, but elevated fluxes at one sampling site point towards the importance of bioirrigation or short-term accumulation of organic matter. Sedimentary fluxes of dissolved inorganic nitrogen are an important source for primary producers in the water column, supporting ∼7 % to 59 % of the average annual primary production, depending on water depth. We find that ammonification and oxygen penetration depth are the main drivers of sedimentary nitrification, but this nitrification is closely linked to denitrification. One-third of freshly produced nitrate in impermeable sediment and two-thirds in permeable sediment were reduced to N2. The semi-permeable and permeable sediments are responsible for ∼68 % of the total benthic N2 production rates, which, based solely on our data, amounts to ∼1030 t N d−1 in the southern North Sea. Thus, we conclude that semi-permeable and permeable sediments are the main sinks of reactive N, counteracting eutrophication in the southern North Sea (German Bight).
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Bachrach, Ran, and Tapan Mukerji. "The effect of texture and porosity on seismic reflection amplitude in granular sediments: Theory and examples from a high‐resolution shallow seismic experiment." GEOPHYSICS 69, no. 6 (November 2004): 1513–20. http://dx.doi.org/10.1190/1.1836824.
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Sediment properties such as grain shape, sorting, porosity, and the effective stress applied on the grains affect the elastic behavior of granular aggregates and, with it, the propagation of seismic waves. Seismic reflections from boundaries within granular sedimentary packs such as sands carry information about variation in the sediment properties. In this paper we analyze elastic contact mechanics models of granular media to show that within mineralogically uniform, homogeneously saturated sediments, the reflection strength can be theoretically related to variations in texture and porosity. The theoretical formulation indicates that in dry, mineralogically uniform sediments, seismic reflection amplitude depends strongly on changes in textures (such as angularity or sorting). In saturated sediments at low confining pressures, the reflection amplitude is primarily related to changes in porosity. Shallow seismic field data are interpreted quantitatively within the context of the theory. The field seismic data and supportive evidence from a nearby well are consistent with our interpretation of reflections arising from changes in textural properties of the sediment above the water table. This analysis can be used to quantify texture and porosity changes within sedimentary packets from measurements of seismic reflection strength and, thus, spatially map sedimentary properties in aquifers.
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Tu, Luyao, Paul Zander, Sönke Szidat, Ronald Lloren, and Martin Grosjean. "The influences of historic lake trophy and mixing regime changes on long-term phosphorus fraction retention in sediments of deep eutrophic lakes: a case study from Lake Burgäschi, Switzerland." Biogeosciences 17, no. 10 (May 20, 2020): 2715–29. http://dx.doi.org/10.5194/bg-17-2715-2020.
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Abstract. Hypolimnetic anoxia in eutrophic lakes can delay lake recovery to lower trophic states via the release of sediment phosphorus (P) to surface waters on short timescales in shallow lakes. However, the long-term effects of hypolimnetic redox conditions and trophic state on sedimentary P fraction retention in deep lakes are not clear yet. Hypolimnetic withdrawal of P-rich water is predicted to diminish sedimentary P and seasonal P recycling from the lake hypolimnion. Nevertheless, there is a lack of evidence from well-dated sediment cores, in particular from deep lakes, about the long-term impact of hypolimnetic withdrawal on sedimentary P retention. In this study, long-term sedimentary P fraction data since the early 1900s from Lake Burgäschi provide information on benthic P retention under the influence of increasing lake primary productivity (sedimentary green-pigment proxy), variable hypolimnion oxygenation regimes (Fe∕Mn ratio proxy), and hypolimnetic withdrawal since 1977. Results show that before hypolimnetic withdrawal (during the early 1900s to 1977), the redox-sensitive Fe∕Mn-P fraction comprised ∼50 % of total P (TP) in the sediment profile. Meanwhile, long-term retention of total P and labile P fractions in sediments was predominantly affected by past hypolimnetic redox conditions, and P retention increased in sedimentary Fe- and Mn-enriched layers when the sediment-overlaying water was seasonally oxic. However, from 1977 to 2017, due to eutrophication-induced persistent anoxic conditions in the hypolimnion and to hypolimnetic water withdrawal increasing the P export out of the lake, net burial rates of total and labile P fractions decreased considerably in surface sediments. By contrast, refractory Ca–P fraction retention was primarily related to lake primary production. Due to lake restoration since 1977, the Ca–P fraction became the primary P fraction in sediments (representing ∼39 % of total P), indicating a lower P bioavailability of surface sediments. Our study implies that in seasonally stratified eutrophic deep lakes (like Lake Burgäschi), hypolimnetic withdrawal can effectively reduce P retention in sediments and potential for sediment P release (internal P loads). However, after more than 40 years of hypolimnetic syphoning, the lake trophic state has not improved nor has lake productivity decreased. Furthermore, this restoration has not enhanced water column mixing and oxygenation in hypolimnetic waters. The findings of this study are relevant regarding the management of deep eutrophic lakes with mixing regimes typical for temperate zones.
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Nugroho, Septriono Hari, and Purna Sulastya Putra. "DETERMINING TEXTURAL AND GEOCHEMICAL ELEMENT CHARACTERISTICS OF SEAFLOOR SEDIMENT USING MULTIVARIATE ANALYSIS ALONG THE SIMEULUE SUB-BASIN, INDONESIA." Rudarsko-geološko-naftni zbornik 35, no. 4 (2020): 79–92. http://dx.doi.org/10.17794/rgn.2020.4.7.
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The Simeulue sub-basin is situated off north-western Sumatra between the outer arc and the mainlands. The sediment and geochemical element characteristics of basins are the important sedimentology variables to recognize the process of sediment deposition. However, the characteristics of the sediment and the geochemical elements in the Simeulue subbasin have not been well explained. This study aims to investigate the textural and geochemical elements characteristics of marine sediments and the distribution of these two variables to determine the sedimentary facies in the Simeulue sub-basin. Samples were taken from various depths in the sub-basin and collected during the 2017 Expedition of “Widya Nusantara” by using the “Baruna Jaya VIII” Research Vessel. The grain size trend analysis showed that the middle part of the basin was dominated by mud, while the edge of the basin near the island (mainland) was mostly dominated by coarser sediments. A geochemical element analysis was performed on each sample to observe the origin of the sediments. The results of these two analyses were subjected to multivariate statistics. This approach was selected because it is appropriate for determining the sedimentary facies and the depositional environments. Based on the multivariate analysis, the sedimentary facies in the Simeulue sub-basin was divided into five facies with similar sediment characteristics and depositional environments. These facies were deposited in the environment with low to medium energy.
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Ostrofsky, Milton L. "Phosphorus Species in the Surficial Sediments of Lakes of Eastern North America." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 5 (May 1, 1987): 960–66. http://dx.doi.org/10.1139/f87-114.
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Species of phosphorus, total iron, and organic matter were determined from surficial profundal sediments of 66 lakes of eastern North America. The lakes represented a broad range of lake type, from oligotrophic to eutrophic and from soft water to moderately alkaline. The sediment characteristics were less variable than the lake characteristics. Highly significant correlations were found between percent loss on ignition and sedimentary organic phosphorus and between sedimentary iron and NH4Cl-extractable, NaOH-extractable, HCl-extractable, total inorganic, and total phosphorus in the sediments. There was no relationship between spring total phosphorus or alkalinity and any sediment character measured. The results suggest that lakes with high sedimentary iron have disproportionately higher concentrations of NH4Cl and NaOH-extractable phosphorus, two species that are most likely to contribute to internal loading of phosphorus.
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Dias, Gilberto Tavares de Macedo, Luiz Henrique P. Fontana, Cleverson Guizan Silva, Rafael Cuellar de Oliveira e. Silva, Uirá Cavalcanti Oliveira, Leonardo da Silva Lima, José Antônio Baptista Neto, and Estefan Monteiro da Fonseca. "GEOMORPHIC AND SEDIMENTARY IMPACTS ON THE CONTINENTAL SHELFAFTER ACCUMULATED DREDGE DISPOSAL FROM RIO DE JANEIRO HARBOR, BRAZIL." Brazilian Journal of Geophysics 37, no. 4 (December 1, 2019): 515. http://dx.doi.org/10.22564/rbgf.v37i4.2024.
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ABSTRACT.Marine dredging is a subaquatic excavation activity executed around the globe for various purposes by many industries. The negative impacts ofdredged material discharge on benthic ecosystems are diverse. Researches on the results of dredging on estuarine geomorphology and its sedimentary regime areusual. Still, the results of dumping dredged material off the coast, in the Brazilian continental shelf, are not easily found in the literature. The present research evaluatedthe geomorphic disturbance resulted from discharging dredged material from Rio de Janeiro Harbor in the inner Rio de Janeiro continental shelf. Grain size analysisof the dredged and dumped sediments was compared to the inner shelf original seabed sediments. The geomorphological impact was evaluated through bathymetricand high resolution seismic and side scan sonar imagery methods. Obtained data revealed significant geomorphologic changes on the offshore bottom caused by theaccumulation of compacted mud from the dredge site underlying the recent soft mud bottom of the harbor area. Besides the morphological sea bottom disturbance,sediment accumulation, and local grain size characteristics exhibited significant change, potentially impacting the surrounding benthic environment.Keywords: Guanabara Bay, seafloor geomorphology, marine sediments, marine pollution.RESUMO.A dragagem marinha é uma atividade de escavação subaquática executada em todo o mundo por muitas indústrias para diferentes fins. Os impactosnegativos do descarte de material dragado nos ecossistemas bentônicos são diversos. Pesquisas sobre os resultados da dragagem na geomorfologia estuarina e o seuregime sedimentar são frequentes. Ainda assim, os resultados do despejo de material dragado ao longo da costa, na plataforma continental brasileira, não são facilmenteencontrados na literatura. A presente pesquisa avaliou o distúrbio geomórfico resultante do descarte de material dragado do Porto do Rio de Janeiro na plataformacontinental interna do Rio de Janeiro. A granulometria dos sedimentos dragados e descartados foi comparada com os sedimentos originais do fundo marinho naplataforma interna. O impacto geomorfológico foi avaliado através de métodos batimétricos, sísmica de alta resolução e imageamento por sonar de varredura lateral.Os dados obtidos revelaram mudanças geomorfológicas significativas no fundo causadas pelo acúmulo de lama compactada do local dragado, subjacente ao fundode lama mole recente da área do porto. Além do distúrbio morfológico do fundo marinho, o acúmulo de sedimentos e as características locais de tamanho de grãoapresentaram mudança significativa, potencialmente impactando o ambiente bentônico circundante.Palavras-chave: Baía de Guanabara, geomorfologia submarina, sedimentos marinhos, poluição marinha.
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Rutyna, Brendo Benato, Carlos Roberto Soares, Carlos Augusto Wroblewski, and Eduardo Vedor de Paula. "Assoreamento nas baías de Antonina e de Paranaguá – PR: análise integrada das áreas fontes de sedimentação e obras de dragagem." Revista Brasileira de Geografia Física 14, no. 2 (May 25, 2021): 676. http://dx.doi.org/10.26848/rbgf.v14.2.p676-693.
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A segurança à navegação é um fator primordial para garantir aos navios acesso aos portos. Obras de dragagens são necessárias para a manutenção dos canais de navegação diante do processo de assoreamento em regiões estuarinas. Entretanto, o volume, em metros cúbicos dragados, na região portuária do Complexo Estuarino de Paranaguá (CEP), aumentou ao longo do tempo. O presente estudo se restringe aos setores que interessam à navegação e às instalações portuárias, isto é, o eixo E-W do CEP, que abrange os trechos do canal de acesso aos portos paranaenses nas baías de Paranaguá e Antonina. O total de sedimentos realocados entre 1999 e 2018 nos trechos do canal foi da ordem de 42.517.662,79 m³. A manutenção destes setores é extremamente onerosa, uma vez que mais de 4.000.000 m³.a-1 de material sedimentar são retirados atualmente para garantir acessibilidade aos navios. Ao estimar a produção de sedimentos na área de drenagem do CEP, obteve-se o valor anual de 197.017,23 ton. Dessa forma, torna-se necessário desenvolver estratégias para a retenção de sedimentos nas áreas fonte, a fim de garantir a prosperidade das atividades portuárias nos próximos anos. Recomendações à expansão dos portos na região foram apresentadas ao final. Silting in the Bays of Antonina and Paranaguá - PR: Integrated Analysis of Sedimentation Sources and Dragging WorksA B S T R A C TSafety in navigation is a primordial aspect to the ports. Dredging works are necessary for the maintenance of the navigation channels before the process of silting in estuarine regions. However, the volume in cubic meters dredged in the port region of the Paranaguá Estuary Complex (CEP) has increased over time. This study is restricted to sectors that are of interest to navigation and to port installation, in other words, the E-W axis of the CEP that includes the sections of the access channel to the ports of Paraná in the bays of Paranaguá and Antonina. The total of relocated sediments between 1999 and 2018 in the canal segments is of the order of 42.517.662,79 m³. The maintenance of these sectors becomes extremely costly, since more than 4.000.000 m³.a-1 of sedimentary material is removed to guarantee accessibility to the ships. When estimating the sediment production in the CEP drainage area, the annual value of 197,017.23 tons is obtained. Thus, it becomes necessary to develop strategies for retaining sediments in the source areas, in order to guarantee the prosperity of port activities in the coming years. Recommendations for expanding ports in the region were presented at the end.Keywords: Hydrographic Units. Sedimentary Dynamics. Sedimentary Disposal. Port Environmental Management.
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Ding, Zhong Jun, Bao Hua Liu, Wei Gao, and Xiang Mei Meng. "Analysis of Resistivity Characteristics of Sediments in Northwestern of South Yellow Sea." Applied Mechanics and Materials 568-570 (June 2014): 8–11. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.8.
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The resistivity characteristics of sediments are important to analyze marine sedimental environment and material source. A kind of penetration multiple parameter micro-probe which is designed to measure the resistivity of sediment sample in the northwestern of South Yellow Sea. In this paper, shelf sediment resistivity property off northwest of the South Yellow Sea is studied by analyzing the influence factors and relations, for providing valuable information to the marine sedimental environment around this area.
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Brydie, J. R., and D. A. Polya. "Metal dispersion in sediments and waters of the River Conwy draining the Llanrwst Mining Field, North Wales." Mineralogical Magazine 67, no. 2 (April 2003): 289–304. http://dx.doi.org/10.1180/0026461036720100.
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The dispersion and sediment-water partitioning of Pb and Zn have been studied in the Conwy River, North Wales. Analysis included major and trace element water chemistry and concentrations of sediment-hosted Pb and Zn. In situ solution pH, Eh, temperature and conductivity were also measured. Sediments were characterized via SEM, XRD, nitric acid leaching and sequential chemical extraction to quantify metal distribution and sediment phase associations. Dissolved and sediment-bound Pb and Zn within river and estuary waters and sediments have been used to calculate whole sediment- and phase-specific apparent partition coefficients.Weathering of galena and sphalerite, associated with the Llanrwst Mining Field, provide point sources of elevated dissolved and sedimentary Pb and Zn in the upper catchment. Dissolved Pb is actively adsorbed onto sedimentary surface coatings of Fe-Mn (hydr)oxides and organics whilst Fe-Mn (hydr)oxides, organics and carbonates were the main hosts for Zn. Systematic changes in metal sorption are evident between the estuary and the upper catchment, with organic matter becoming progressively more important upstream. This change is ascribed to the sorptive properties of sedimentary organic material. Solution pH, [Cl] and aqueous metal speciation are the dominant solution controls on metal partitioning. Laboratory sorption experiments parallel Pb sorption behaviour in the natural system.
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Liu, Yuanhong, Corey D. Wallace, Yaoquan Zhou, Reza Ershadnia, Faranak Behzadi, Dipankar Dwivedi, Lianqing Xue, and Mohamad Reza Soltanian. "Influence of Streambed Heterogeneity on Hyporheic Flow and Sorptive Solute Transport." Water 12, no. 6 (May 28, 2020): 1547. http://dx.doi.org/10.3390/w12061547.
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The subsurface region where river water and groundwater actively mix (the hyporheic zone) plays an important role in conservative and reactive solute transport along rivers. Deposits of high-conductivity (K) sediments along rivers can strongly control hyporheic processes by channeling flow along preferential flow paths wherever they intersect the channel boundary. Our goal is to understand how sediment heterogeneity influences conservative and sorptive solute transport within hyporheic zones containing high- and low-K sediment facies types. The sedimentary architecture of high-K facies is modeled using commonly observed characteristics (e.g., volume proportion and mean length), and their spatial connectivity is quantified to evaluate its effect on hyporheic mixing dynamics. Numerical simulations incorporate physical and chemical heterogeneity by representing spatial variability in both K and in the sediment sorption distribution coefficient ( K d ). Sediment heterogeneity significantly enhances hyporheic exchange and skews solute breakthrough behavior, while in homogeneous sediments, interfacial flux and solute transport are instead controlled by geomorphology and local-scale riverbed topographies. The hyporheic zone is compressed in sediments with high sorptive capacity, which limits solute interactions to only a small portion of the sedimentary architecture and thus increases retention. Our results have practical implications for groundwater quality, including remediation strategies for contaminants of emerging concern.
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Shaiek, Moez, Noureddine Zaaboub, Deniz Ayas, Maria Virgínia Alves Martins, and Mohamed Salah Romdhane. "CRABS AS BIOINDICATORS OF TRACE ELEMENT ACCUMULATION IN MEDITERRANEAN LAGOON (BIZERTE LAGOON, TUNISIA) / CARANGUEJOS USADOS COMO BIOINDICADORES DE ACUMULAÇÃO DE METAIS NUMA LAGUNA MEDITERRÂNEA (LAGUNA DE BIZERTE, TUNÍSIA)." Journal of Sedimentary Environments 3, no. 1 (February 25, 2018): 1–11. http://dx.doi.org/10.12957/jse.2018.32950.
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Nine crab species samples, males and females, were collected after homogeneously prospection of sediment surface of Bizerte Lagoon. Crabs were caught by dip net from Bizerte Lagoon during spring 2012. Concentrations of metals (Zn, As, Cd, Cr, Cu, Fe, Ni, Pb and Zn) were evaluated in the carapace and muscle tissue of crabs and in surface sediment samples. Concentrations of metals accumulated in the benthic crabs tissues were compared to the reactive metals content that constitute the bioavailable fraction of the sediments. Total organic carbon and carbonate contents were also determined, since they are principal requirements associated with crab development.Results of this work indicate that, in the study area, the metals that reach the highest concentrations in the sediments-water interface are by decreasing order Zn, Cr and Pb. The reactive concentrations of these metals are also the highest. However, the trace elements that are being accumulated in the carapace and muscle of crabs are mainly As and Cu.Continental waters flowing into the Bizerte Lagoon are the main source and the principal cause of the enrichment of trace elements in sediment. Results highlight that the reactive concentrations of metals in sediments were the principal cause of their bioaccumulation in the crabs tissues.The important results of this work highlight that cabs can be very useful on studies of monitoring and evaluation of environmental quality in addition to data obtained from the sediment as they also give information about the bioaccumulation of metals through the oceanic food webs. ResumoNove amostras de espécies de caranguejos, machos e fêmeas, foram coletadas na superfície do sedimento da Laguna de Bizerte. Os caranguejos foram capturados com uma rede na Laguna de Bizerte, na primavera de 2012. Foram avaliadas nas carapaças e no tecido muscular dos caranguejos e em amostras de sedimentos superficiais, concentrações de metais (Zn, As, Cd, Cr, Cu, Fe, Ni, Pb e Zn). As concentrações de metais acumuladas nos tecidos de caranguejos bênticos foram comparadas com o teor de metais reativos que constituem a fração biodisponível dos sedimentos. Os teores totais de carbono orgânico e carbonato também foram determinados, uma vez que são requisitos principais associados ao desenvolvimento dos caranguejos.Os resultados deste trabalho indicam que, na área de estudo, os metais que atingem as maiores concentrações na interface sedimentos-água são, por ordem decrescente, Zn, Cr e Pb. As concentrações reativas desses metais também são as mais elevadas. No entanto, os metais que estão sendo acumulados nas carapaças e nos músculos dos caranguejos são principalmente As e Cu. As águas continentais que desembocam na Laguna Bizerte são a principal fonte e a principal causa do enriquecimento de metais nos sedimentos. Os resultados sugerem que as concentrações reativas de metais nos sedimentos foram a principal causa de sua bioacumulação nos tecidos dos caranguejos.Os resultados deste trabalho revelam que para além dos dados sedimentológicos, os caranguejos podem ser muito úteis em estudos de monitoramento e avaliação da qualidade ambiental, pois fornecem informações sobre a bioacumulação de metais através das cadeias alimentares oceânicas.
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Hindshaw, Ruth S., Nicholas J. Tosca, Alexander M. Piotrowski, and Edward T. Tipper. "Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)." Earth Surface Dynamics 6, no. 1 (March 5, 2018): 141–61. http://dx.doi.org/10.5194/esurf-6-141-2018.
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Abstract. The identification of sediment sources to the ocean is a prerequisite to using marine sediment cores to extract information on past climate and ocean circulation. Sr and Nd isotopes are classical tools with which to trace source provenance. Despite considerable interest in the Arctic Ocean, the circum-Arctic source regions are poorly characterised in terms of their Sr and Nd isotopic compositions. In this study we present Sr and Nd isotope data from the Paleogene Central Basin sediments of Svalbard, including the first published data of stream suspended sediments from Svalbard. The stream suspended sediments exhibit considerable isotopic variation (εNd = −20.6 to −13.4; 87Sr ∕ 86Sr = 0.73421 to 0.74704) which can be related to the depositional history of the sedimentary formations from which they are derived. In combination with analysis of the clay mineralogy of catchment rocks and sediments, we suggest that the Central Basin sedimentary rocks were derived from two sources. One source is Proterozoic sediments derived from Greenlandic basement rocks which are rich in illite and have high 87Sr ∕ 86Sr and low εNd values. The second source is Carboniferous to Jurassic sediments derived from Siberian basalts which are rich in smectite and have low 87Sr ∕ 86Sr and high εNd values. Due to a change in depositional conditions throughout the Paleogene (from deep sea to continental) the relative proportions of these two sources vary in the Central Basin formations. The modern stream suspended sediment isotopic composition is then controlled by modern processes, in particular glaciation, which determines the present-day exposure of the formations and therefore the relative contribution of each formation to the stream suspended sediment load. This study demonstrates that the Nd isotopic composition of stream suspended sediments exhibits seasonal variation, which likely mirrors longer-term hydrological changes, with implications for source provenance studies based on fixed end-members through time.
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Brenner, H., U. Braeckman, M. Le Guitton, and F. J. R. Meysman. "The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea." Biogeosciences 13, no. 3 (February 12, 2016): 841–63. http://dx.doi.org/10.5194/bg-13-841-2016.
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Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.
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Gilbert, Robert, Eugene W. Domack, and David Tewksbury. "Sediment Content in Antarctic Iceberg Fragments Sufficient to Sink the Ice." Géographie physique et Quaternaire 58, no. 1 (June 26, 2006): 147–49. http://dx.doi.org/10.7202/013115ar.
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Abstract Iceberg fragments recovered from the sea floor near Swift Glacier, Antarctica, contained sufficient sediment to sink the ice. Sediment concentrations in the samples would have caused them to settle at 0.13 to 0.35 m/s through the water column. Impact with the sea floor would significantly turbate soft sediments. Unlike sediment dumped from icebergs, the stratigraphy of the frozen sediments created by glacial processes may be preserved in the marine sedimentary record after melting of the ice. Negatively buoyant berg fragments may be common in polar regions, and when driven by currents may scour the sea floor up and down slopes unlike floating ice.
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Adikaram, Madurya, Amarasooriya Pitawala, Hiroaki Ishiga, Daham Jayawardana, and Carla M. Eichler. "An Ecological Risk Assessment of Sediments in a Developing Environment—Batticaloa Lagoon, Sri Lanka." Journal of Marine Science and Engineering 9, no. 1 (January 13, 2021): 73. http://dx.doi.org/10.3390/jmse9010073.
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The land-sea interface is considered as a threatening environment due to anthropogenic development activities. Unplanned developments can cause effects on important ecosystems, water and human health as well. In this study, the influence of rapid regional development on the accumulation of trace elements to the sediments of an important ecosystem, Batticaloa lagoon, Sri Lanka was examined. Surface sediment pollution status and ecological risk was compared with that of the recent sedimentary history of about 1 m depth. Sediment core samples were collected and analyzed for grain size, organic matter and carbonate contents and trace elements (As, Pb, Zn, Cu, Ni and Cr) by the X-Ray Fluorescence (XRF) technique. The chemical results of core samples and recently published data of surface sediments of the same project were evaluated by pollution load index (PLI), potential ecological risk index (PERI) and sediment quality guidelines (SQG). Except for Cr, all other elements in cores show lower concentrations than the SQGs confirming the high Cr contents as recorded in the most of other Sri Lankan sediments. The sediment cores indicate an unpolluted, low ecological risk sedimentary history for all core sampling locations, whereas most of the surface sediments of the lagoon are less polluted with low potential ecological risk. Present anthropogenic practices and illiteracy of this rapid developing region can damage the green environment and hence environmental management planning is suggested for a sustainable future.
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Kļaviņš, Māris, Ilga Kokorīte, Valērijs Rodinovs, and Maruta Jankevica. "Past human impact and pollutant loading reconstruction in Lake Engure as a tool for lake basin management." Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. 68, no. 1-2 (April 1, 2014): 31–37. http://dx.doi.org/10.2478/prolas-2014-0003.
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Abstract Environmental pollution of lakes and rivers is considered as one of the most important environmental problems. Analysis of nutrient and trace element accumulation in sedimentary phases of lakes can reflect the overall regional pollution level, and the observed accumulation patterns of pollutants in sediment profiles can be used to reconstruct the history of anthropogenic impacts. As pollutants in sediments are associated with other substances, it is important not only to study total concentrations of pollutants, but also their speciation forms. The aim of this study was to describe phosphorus (including speciation forms) and trace element concentrations in sediment profiles of Lake Engure and to evaluate human impact on organic matter accumulation and properties in lake sediments. The concentrations of the studied elements in sediments of Lake Engure are at background levels, which is clearly evident when compared with metal concentrations in lake sediments in West European countries. The analysis of element concentration changes in sedimentary profiles provided information about trends in recent accumulation (within the last 100 years) and on the balance between natural and human-induced accumulation processes. Analysis of nutrient concentrations in sediments aided in identifying background values as targets for lake management activities.
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Novak, Ana, Andrej Šmuc, Sašo Poglajen, Bogomir Celarc, and Marko Vrabec. "Sound Velocity in a Thin Shallowly Submerged Terrestrial-Marine Quaternary Succession (Northern Adriatic Sea)." Water 12, no. 2 (February 18, 2020): 560. http://dx.doi.org/10.3390/w12020560.
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Estimating sound velocity in seabed sediment of shallow near-shore areas submerged after the Last Glacial Maximum is often difficult due to the heterogeneous sedimentary composition resulting from sea-level changes affecting the sedimentary environments. The complex sedimentary architecture and heterogeneity greatly impact lateral and horizontal velocity variations. Existing sound velocity studies are mainly focused on the surficial parts of the seabed sediments, whereas the deeper and often more heterogeneous sections are usually neglected. We present an example of a submerged alluvial plain in the northern Adriatic where we were able to investigate the entire Quaternary sedimentary succession from the seafloor down to the sediment base on the bedrock. We used an extensive dataset of vintage borehole litho-sedimentological descriptions covering the entire thickness of the Quaternary sedimentary succession. We correlated the dataset with sub-bottom sonar profiles in order to determine the average sound velocities through various sediment types. The sound velocities of clay-dominated successions average around 1530 m/s, while the values of silt-dominated successions extend between 1550 and 1590 m/s. The maximum sound velocity of approximately 1730 m/s was determined at a location containing sandy sediment, while the minimum sound velocity of approximately 1250 m/s was calculated for gas-charged sediments. We show that, in shallow areas with thin Quaternary successions, the main factor influencing average sound velocity is the predominant sediment type (i.e. grain size), whereas the overburden influence is negligible. Where present in the sedimentary column, gas substantially reduces sound velocity. Our work provides a reference for sound velocities in submerged, thin (less than 20 m thick), terrestrial-marine Quaternary successions located in shallow (a few tens of meters deep) near-shore settings, which represent a large part of the present-day coastal environments.
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Tudhope, Alexander W., and Terence P. Scoffin. "Processes of sedimentation in Gollum Channel, Porcupine Seabight: submersible observations and sediment analyses." Transactions of the Royal Society of Edinburgh: Earth Sciences 86, no. 1 (1995): 49–55. http://dx.doi.org/10.1017/s0263593300002157.
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AbstractManned submersible dives were conducted in the submarine canyon channel system of Porcupine Seabight, NE Atlantic Ocean. Visual observations were made, and sediment samples collected and analysed to elucidate the nature of the sedimentary regime. In the upper part of the canyon (480-940 m water depth) sediments consisted of a mixture of terrigenous quartz rich silts and sands, skeletal carbonate of benthonic and planktonic origin and minor clay minerals and authigenic dolomite. There were localised Lophelia pertusa coral thickets on both the flanks and floor of the canyon. Sedimentary structures and physical measurements revealed there to be active transport of sediments in the canyon down to a depth of at least 940 m, effected by (?tidal) reversing currents and bioturbation. In these parts of the canyon, deposits around glacial dropstones and coral thickets indicate that there has been a maximum of 0-1 m of net sediment accumulation since the last glacial period. At 3000 m water depth, in the channel system, the sediments were fine calcareous ooze with a drape (up to 0-3 m thick) of flocculant phytoplankton detritus. At these depths, there was no evidence for present-day sediment resuspension by currents.
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Anggraini, Rifka Rimbi, Yenny Risjani, and Uun Yanuhar. "Distribution of Bottom Sediment in Lekok Water, Pasuruan Regency, East Java." Research Journal of Life Science 7, no. 3 (December 1, 2020): 168–75. http://dx.doi.org/10.21776/ub.rjls.2020.007.03.7.
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Lekok water is one of the open waters. This will greatly affect the sedimentation process in Lekok water. The purpose of this study is to examine the distribution of bottom sediments in Lekok Water, Pasuruan Regency. The study was conducted in October-November 2019 using ekman grab at 9 site points. Sediment samples were obtained then analyzed in the laboratory to determine the grain size, as well as statistical calculations to analyze the distribution of the sediment. Based on the results of the study note that sediments distributed in Lekok Water are generally dominated by three types of sediments namely: sandy loam, loam and silt loam. Sorting values are in a well-sorted to the moderately well-sorted condition where the sediment conditions are well sorted. The skewness value is skewed positively where the value indicates a positive skewed sedimentary condition. The value of kurtosis is in the leptokurtic condition where the sediment from station 1 to station 9 is homogeneous.
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Tomkins, Jessica D., Scott F. Lamoureux, Dermot Antoniades, and Warwick F. Vincent. "Sedimentology of perennial ice-covered, meromictic Lake A, Ellesmere Island, at the northern extreme of CanadaPolar Continental Shelf Program Contribution 00109." Canadian Journal of Earth Sciences 46, no. 2 (February 2009): 83–100. http://dx.doi.org/10.1139/e09-008.
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The sedimentology of coastal, meromictic Lake A, Ellesmere Island (83°00′N, 75°30′W), was investigated to understand the linkages between the extreme lake environment and its sedimentary features. Four facies were identified within the sedimentary record that represent stages of the lake’s development from a marine embayment to a meromictic lake. Despite low ecosystem productivity, both clastic and biogenic materials contribute substantially, and highly seasonal sedimentation, pervasive ice cover, and anoxia in the saline bottom water (monimolimnion) act to preserve annual sedimentary units (varves) within the upper part of the sedimentary record. Sediment texture is predominantly silt and clay, but the irregular presence of sand indicates past episodes of higher energy stream discharge to the lake. Oxygen incursions into the chemocline likely cause bacteria mortality and provide elemental sulphur for iron sulphides that are deposited in the sediments. Millimetre-scale sedimentary pellets are also a conspicuous feature in the sediments and are interpreted to result from littoral sediment transport by ice-rafting. Many of Lake A’s notable sedimentary features are also evident in other High Arctic meromictic lakes, particularly those on the northern coast of Ellesmere Island. These similarities and the important biogenic component identified in Lake A suggest that processes in these sedimentary environments are more complex than previously thought.
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Hurley, James P., and David E. Armstrong. "Pigment Preservation in Lake Sediments: A Comparison of Sedimentary Environments in Trout Lake, Wisconsin." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 3 (March 1, 1991): 472–86. http://dx.doi.org/10.1139/f91-061.
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Fluxes and concentrations of a phorbins and major algal carotenoids were quantified in sediment trap material and sediment cores from two basins of Trout Lake, Wisconsin (TrDH and TrAB). The basins were chosen to contrast the influence of oxygen content at the sediment–water interface (TrDH, oxic and TrAB, reducing), sediment accumulation rate, and focusing. Pigment diagenesis occurred in both basins, but transformations and destruction were more extensive in TrDH. Although untransformed chlorophyll a was the major phorbin deposited at the sediment surface of both basins (51–64 mol%), pigment destruction, coupled with transition to pheophytin, accounted for substantial losses, especially in oxic TrDH sediments. Fucoxanthin, peridinin, and diadinoxanthin, despite representing > 70% of the deposited carotenoid flux, were substantially degraded or transformed in both basins. However, preservation was relatively high for secondary carotenoids, such as diatoxanthin and β-carotene, and for a major cryptomonad pigment, alloxanthin. Residual profiles in sediments show that pigment sedimentation from the epilimnion and accumulation in the permanent sediments are not directly related and that diagenesis must be considered in interpreting sedimentary pigments.
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Clark, M. W., and D. M. McConchie. "Development of acid sulfate soil in sub-aerially disposed dredge spoil at Fisherman Islands, Brisbane, Australia." Soil Research 42, no. 6 (2004): 553. http://dx.doi.org/10.1071/sr03072.
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During disposal of Brisbane River estuary dredge sediments into the reclamation paddocks at Fisherman Islands, a size separation of the fine (<63 µm) pyrite-rich silts and clays from the coarser (>63 µm) pyrite-poor sands and gravels occurs. The sand and gravel fractions contain most of the shell material and, therefore, most of the acid-neutralising capacity. In the most recently reclaimed paddock this size separation is of little consequence because sediments remain well buffered and acid produced from sulfides contained in the oxidising estuarine sediments is readily neutralised by the large volume of seawater and fine-grained carbonate minerals. However, as more sediment is added to the paddock, sediments become anoxic and sulfate reduction within the sedimentary pile occurs. This reduction rapidly produces pyrite and black monosulfides, consequently the pyrite content and degree of pyritisation and sulfidisation (DOP, DOS) of the sediment increase. Sulfide production rapidly removes sulfate from sediment pore waters and the process quickly becomes sulfate-limited because the fine-grained sediment texture restricts sediment permeability and therefore sulfate replenishment. Consequently, a clear relationship between DOP and DOS is observed for the reclamation paddock sediments. However, pre-existing mud-flat, and older unbunded dredge spoil sediments from the 1960s and 1970s, have no clear relationship between DOP and DOS values because they contain fewer fines and the production of pyrite was not limited by sulfate availability, but was constrained by other geochemical factors (e.g. redox potential, organic matter, or iron availability). Because of the increasing pyrite content of the paddock sediments as they age, the carbonate-buffering capacity provided by the sediment is readily exceeded, and the sediments become potentially acid sulfate. Should these sediments subsequently be disturbed and allowed to oxidise, the surrounding environment could be subject to large quantities of metal-rich acidic waters.
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Kharismalatri, Hefryan Sukma, Yoshiharu Ishikawa, Takashi Gomi, Roy C. Sidle, and Katsushige Shiraki. "Evaluating Factors for Controlling Sediment Connectivity of Landslide Materials: A Flume Experiment." Water 11, no. 1 (December 21, 2018): 17. http://dx.doi.org/10.3390/w11010017.
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Connectivity of landslide sediment to and within fluvial systems is a key factor affecting the extent of mobilization of hillslope material. In particular, the formation of landslide dams and the transformation into landslide-induced debris flows represent “end members” of landslide sediment mobility. To quantify sediment connectivity, we developed a two-segment flume representing tributary inflow and the main channel. Mobility of sediment was examined by combinations of various topographic factors, such as tributary inflow angle (0 to 90° in 30° increments) and main channel gradient (10° and 15°), as well as water content of sediment (0 to 100% in 20% increments). We also examined differences of mobility among sediments derived from various lithologies (sand and shale, pyroclastic sediment, weathered granite, and weathered sedimentary rock). Mobility of sediment differed, depending on the water content of sediment, particularly less than saturation or greater than saturation. When all types of unsaturated landslide sediments entered the channel at inflow angles of 60° and 90°, substantial deposition occurred, suggesting the formation of landslide dams. At low inflow angles (0° and 30°) in a steep channel (15°), >50% of landslide sediment was transported downstream, indicating the occurrence of a debris flow. The amount of sediment deposited at the junction angle was greater for pyroclastic sediment followed by weathered granite, weathered sedimentary rock, and finally, sand and shale. Our connectivity index suggests that a threshold exists between landslide dam formation and debris flow occurrence associated with topographic conditions, water content, and types of sediment.
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Marinho, Rogério Ribeiro, Antonio Fábio Sabbá Guimarães Vieira, and Feliciano De Souza Maciel. "Análise Montante-Jusante da Granulometria dos Sedimentos de Fundo e Suspenso do Rio Negro e Tributários (Bacia Amazônica, Brasil)." Revista Brasileira de Geografia Física 14, no. 2 (April 14, 2021): 997. http://dx.doi.org/10.26848/rbgf.v14.2.p997-1008.
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O conhecimento das características físicas de sedimentos transportados por grandes sistemas fluviais possui significativa importância para o entendimento de processos geomorfológicos e hidrológicos. O nível de conhecimento dos grandes sistemas fluviais da Amazônia e sua relação com o transporte de sedimentos ainda é limitado, resultando em lacunas de conhecimento sobre a dinâmica da paisagem nesta complexa região. Este trabalho teve como objetivo avaliar a distribuição espacial da granulometria de sedimentos de fundo e suspenso do Rio Negro e tributários. Realizou-se análise da distribuição do tamanho dos sedimentos em seções amostrais localizadas no alto, médio e baixo curso do Rio Negro. Os resultados da análise granulométrica da carga de fundo indicam a predominância de sedimentos com tamanho variando de 0,25 a 1,0 mm (principalmente areia fina, areia média e areia grossa) enquanto no baixo curso as amostram oscilaram de areia fina a partículas lamosas (< 0,50 mm). No Rio Negro os sedimentos suspensos são compostos principalmente de partículas finas de silte (90% menor que 80 µm) com diâmetro mediano (D50) de 25 µm. As características granulométricas apresentadas neste trabalho fornecem subsídios para o entendimento de processos hidrodinâmicos de transporte e deposição dos sedimentos de fundo e suspenso neste gigante sistema fluvial. Upstream-downstream Granulometry Analysis of bed and suspended sediments in the Negro River Basin (Amazon Basin, Brazil)A B S T R A C TThe knowledge of the physical characteristics of sediments transported by large river systems has significant importance for the understanding of geomorphological and hydrological processes. The level of knowledge of the large rivers of the Amazon basin and their relationship with sediment transport is limited, resulting in gaps about the dynamics of the landscape in this complex region. This article analyzes the spatial distribution of granulometry of bed and suspended sediments in the Negro River and tributaries. An analysis of the sediment size distribution was carried out in sample sections located in the upper, middle and lower reaches of the Negro River. The results of the granulometric analysis of the bed load indicate the predominance of sediments with sizes ranging from 0.25 to 1.0 mm (mainly fine sand, medium sand and coarse sand) while in the low course they showed oscillated from fine sand to muddy particles (<0.50 mm). In the Negro River basin the suspended sediments are composed mainly of fine silt particles (90% less than 80 µm) with a median diameter (D50) of 25 µm. The granulometric characteristics presented in this work provide subsidies for the understanding of hydrodynamic processes of transport and deposition of bed and suspended sediments in this huge fluvial system.Keywords: sediment transport, Amazon floodplain, multichannel river, anabranching
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Burone, Leticia, Paula Franco-Fraguas, Michel Michaelovitch de Mahiques, Nuria Lahuerta, Jorge Rey Diaz de Rada, Matilde Rodríguez, Marcia Caruso Bícego, Yamandú Marín, Mónica Gómez-Erache, and Leonardo Ortega. "THE IMPRINT OF THE GEOLOGICAL INHERITANCE AND PRESENT DYNAMICS ON URUGUAYAN INNER SHELF SEDIMENTS (SOUTH-WESTERN ATLANTIC)." Journal of Sedimentary Environments 4, no. 4 (December 1, 2019): 403–20. http://dx.doi.org/10.12957/jse.2019.47021.
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The Uruguayan continental shelf is characterised by a unique hydrographic system, composed of the Río de la Plata buoyant plume (RdlP-BP), and by water masses of contrasting thermohaline characteristics. Below the RdlP-BP the southward-flowing Subtropical Shelf Water and the northward-flowing Subantarctic Shelf Water converge at the Subtropical Shelf Front, which is the shelf extension of the Brazil-Malvinas Confluence. Three main sedimentary environments can be described associated with; I) “Atlantic coastal sands” (i.e. onshore from the palaeovalley); II) the SW-NE running “RdlP palaeovalley” and; III) “Relict sands” (i.e., offshore of the RdlP palaeovalley). Three exposed sedimentary units (U1 to U3) identified from acoustic profiles and sediment cores (sedimentary characteristics of stratigraphic units) almost entirely restricted to the palaeovalley. The transect here studied intersects these three environments contributing thus with the description of the morphological setting and sedimentary coverture. Physical and geochemical data were integrated and used to characterise the sedimentary facies previously described in the inner shelf and to understand environmental control on the development of these facies.Sediments from U1 show the terrestrial imprint of the RdlP and drier regional conditions, while sediments that characterised U3 indicate a sandy facies (quartz and bioclasts: whole and fragmented shells and polychaetes tubes) corresponding to an ancient coast. This last (with approximately 11 m height), is probably related to sea-level stabilization, between 20 and 25 m occurring during the Upper Pleistocene and Holocene for the South-Western Atlantic. The sediment from U3 reflects the colder and drier conditions prevailing in the region during the formation of this facies (13.7 and 9.7 cal ka BP). Eroded sediments (e.g., from U3; ancient coast) are deposited inside the palaeovalley and on the onshore region (between the palaeovalley and coastal sands). Also, U1 extends from the palaeovalley covering the onshore region. The outcrop of warmer oceanic shelf waters was probably a consequence of the geomorphology of the palaeovalley (edge of the palaeovalley) and related to the still fall presence of waters typical of the austral warm season when higher advection of Brazil Current occurs over the shelf. In this regard, the mound-like feature should induce bottom water to rise, operating as a ramp. Productivity proxies (Si/Ti, Ba/Ti, Ca/Ti and P/Ti) present the highest values in these stations (S16-S18), reflecting the imprint of the upwelling in the sediment.The information reported in this work is particularly important to better understand sedimentological dynamics in the Uruguayan inner shelf and the Southwestern Atlantic region. It is also important for elaborating more precise paleoenvironmental and palaeoceanographic reconstructions. ResumoA plataforma continental uruguaia é caracterizada por um sistema hidrográfico único, composto pela pluma túrbida do Rio de la Plata (RdlP-BP) e por massas de água com características termohalinas contrastantes. Abaixo da RdlP-BP, a água subtropical da plataforma que flui para sul e a água subantártica da plataforma que flui para norte convergem para a frente subtropical da plataforma, a qual é a extensão da Confluência Brasil-Malvinas.Três principais ambientes sedimentares podem ser descritos associados: I) a "areias costeiras atlânticas" (com ocorrência em direção a terra a partir do “Paleovale do RdlP”); II) o “Paleovale do RdlP” com direção SW-NE e; III) a "Areias relíquia" (para offshore do “Paleovale do RdlP”). Três unidades sedimentares estratigráficas expostas (U1 a U3) identificadas a partir de perfis acústicos e testemunhos de sedimentos quase que totalmente restritas ao paleovale. Dados físicos e geoquímicos foram integrados e utilizados para caracterizar as fácies sedimentares encontradas na plataforma continental interna e para entender o controle ambiental sobre o desenvolvimento dessas fácies.Os sedimentos da unidade U1 representam o registo terrestre da RdlP e condições regionais mais secas, enquanto os sedimentos que caracterizam a unidade U3 indicam fácies arenosas (quartzo e bioclastos: conchas inteiras e fragmentadas e tubos de poliquetas) correspondente a uma costa antiga. Este último (com aproximadamente 11 m de altura) está provavelmente relacionado à estabilização do nível do mar, entre 20 e 25 m durante o Pleistoceno Superior e o Holoceno, no Atlântico Sudoeste. O sedimento da unidade U3 reflete as condições mais frias e secas da região durante a formação desta fácies (entre 13,7 e 9,7 cal ka BP). Sedimentos erodidos (por exemplo, de U3; costa antiga) são depositados dentro do paleovale e na região onshore (entre o paleovale e as areias costeiras). Além disso, a unidade U1 estende-se do paleovale até ao continente.O afloramento de águas oceânicas mais quentes, foi provavelmente uma consequência da geomorfologia do paleovale e está relacionado à presença de águas típicas da estação quente austral, quando ocorre maior advecção da corrente do Brasil na plataforma. A estrutura semelhante a um monte deve induzir a subida da água no fundo, operando como uma rampa. Os proxies de produtividade (Si/Ti, Ba/Ti, Ca/Ti e P/Ti) apresentam os maiores valores nessas estações (S16-S18), refletindo a impressão da ressurgência no sedimento.As informações obtidas através deste trabalho são particularmente importantes para melhor compreender a dinâmica sedimentar na plataforma interna uruguaia e na região do sudoeste do Atlântico. Também é importante para elaborar reconstituições paleoambientais e paleoceanográficas mais precisas. Palavras-chave: Dinâmica sedimentar. Dinâmica hidrográfica. Estuário do Rio de la Prata. Atlântico sudoeste. Plataforma continental interna.
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Wang, Chengtao, Min Chen, Hongshuai Qi, Wichien Intasen, and Apichai Kanchanapant. "Grain-Size Distribution of Surface Sediments in the Chanthaburi Coast, Thailand and Implications for the Sedimentary Dynamic Environment." Journal of Marine Science and Engineering 8, no. 4 (April 2, 2020): 242. http://dx.doi.org/10.3390/jmse8040242.
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This paper analyzes the grain-size distribution of surface sediments of the Chanthaburi coast of Thailand to investigate the sedimentary environment and its evolution to better use and protect the coast. The Flemming triangle method, the grade-standard deviation method, and the Gao–Collins grain-size trend analysis method (GSTA model) were used to study the dynamic sedimentary environment of the area and provide preliminary identification of source materials. There are seven types of surface sediments on this coast, with grain sizes (φ) generally consisting of sand and silt. Sorting is generally poor, and becomes gradually poorer with distance offshore. Skewness is generally positive. The study area is mainly composed of sand and silt, indicating that the hydrodynamics are strong. The results of grade-standard deviation analysis indicate that sediment grain size b (3.25–4.5φ) is a sensitive indicator of environmental change. This sediment type exhibits a relatively complex transport trend, mainly characterized by northwestward and northeastward transport from sea to land. Sediments at the mouth of the Chanthaburi Estuary and the Welu River fluctuate under the influence of tidal currents. Based on the results of grade-standard deviation analysis and grain-size trend analysis, the study area was divided into three provinces, representing different sedimentary environments and material sources. Compared with tidal-controlled estuaries in the temperate regions of eastern China, the two tropical estuaries examined in this study exhibited smaller suspended sediment loads, runoff amounts, and tidal ranges. However, hydrodynamic conditions were generally stronger. The main reasons for the similarities and differences in the transport trends of sediments in these estuaries were differences in hydrodynamic conditions and the specifics of regional topography.
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Nwosu, Ebuka Canisius, Patricia Roeser, Sizhong Yang, Lars Ganzert, Olaf Dellwig, Sylvia Pinkerneil, Achim Brauer, Elke Dittmann, Dirk Wagner, and Susanne Liebner. "From Water into Sediment—Tracing Freshwater Cyanobacteria via DNA Analyses." Microorganisms 9, no. 8 (August 21, 2021): 1778. http://dx.doi.org/10.3390/microorganisms9081778.
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Sedimentary ancient DNA-based studies have been used to probe centuries of climate and environmental changes and how they affected cyanobacterial assemblages in temperate lakes. Due to cyanobacteria containing potential bloom-forming and toxin-producing taxa, their approximate reconstruction from sediments is crucial, especially in lakes lacking long-term monitoring data. To extend the resolution of sediment record interpretation, we used high-throughput sequencing, amplicon sequence variant (ASV) analysis, and quantitative PCR to compare pelagic cyanobacterial composition to that in sediment traps (collected monthly) and surface sediments in Lake Tiefer See. Cyanobacterial composition, species richness, and evenness was not significantly different among the pelagic depths, sediment traps and surface sediments (p > 0.05), indicating that the cyanobacteria in the sediments reflected the cyanobacterial assemblage in the water column. However, total cyanobacterial abundances (qPCR) decreased from the metalimnion down the water column. The aggregate-forming (Aphanizomenon) and colony-forming taxa (Snowella) showed pronounced sedimentation. In contrast, Planktothrix was only very poorly represented in sediment traps (meta- and hypolimnion) and surface sediments, despite its highest relative abundance at the thermocline (10 m water depth) during periods of lake stratification (May–October). We conclude that this skewed representation in taxonomic abundances reflects taphonomic processes, which should be considered in future DNA-based paleolimnological investigations.
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Vieira, Rosemary, Humberto Marotta, Kátia Kellem da Rosa, Ricardo Jaña, Carolina Lorenz Simões, Enoil De Souza Júnior, Fabrício Ferreira, et al. "Análisis Sedimentológico y geomorfológico de áreas lacustres en la Península Fildes, Isla Rey Jorge, Antártica Marítima." Investigaciones Geográficas, no. 49 (July 29, 2015): 3. http://dx.doi.org/10.5354/0719-5370.2015.37511.
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Geomorphological features and sedimentary characteristics are analized from five sets of shallow sediment cores collected in lakes in the Fildes Peninsula, King George Island. The geomorphology of the area was observed and sediments samples were obtained at field activities during the XXXI Brazilian Antarctic Operation (March-April/2013). Biogeochemical characteristics, physical parameters, mineralogical composition, particle size distribution, macroscopic characteristics of the sediments and satellite images were analized. Preliminary results indicate climatic and environmental changes in north-south transect of the peninsula. The mineralogical composition is associated with geological structure of the area, where basaltic rocks predominate. The particle size variation reflects different sediment source environments. Macroscopic analysis and mineralogical composition variation reflect the action of weathering along the peninsula. The sediments also have potential mineralization and subsequent release of greenhouse gases. A preliminary map of the classification of the lakes is presented. In addition, it was identified that wetland sediment presents methane production rates (CH4) about 40 times larger and more sensitive to the effect of global warming compared to lake sediment. Subpolar aquatic ecosystems sediments from Maritime Antarctica can be a preferential site for the effects of climate variability.
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CURTIS, MICHAEL L., and TEAL R. RILEY. "Mobilization of fluidized sediment during sill emplacement, western Dronning Maud Land, East Antarctica." Antarctic Science 15, no. 3 (September 2003): 393–98. http://dx.doi.org/10.1017/s0954102003001408.
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Large mafic sills in the Ahlmannryggen region of western Dronning Maud Land were intruded into partially lithified sediments of the mid-Proterozoic Ritscherflya Supergroup. Clastic sedimentary dykes intruding the thick mafic sills have been identified, and show evidence for fluidization of the partially lithified sediments. Previous work had demonstrated in situ fluidization and localized anatectic melting. This study demonstrates mobilization of the fluidized sediments, with penetration at least 50 m into the fractured, intruding sill. Physical features within the clastic dykes (e.g. sediment balls, flame structures) suggest that the sediments were largely unconsolidated, or at most only partially lithified. The presence of a thin zone of anatectic melt along the dyke—sill contact suggests that the mafic sill was still hot (c. 700°C) at the time of sedimentary dyke injection.
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Kanbar, Hussein Jaafar, Thai Tran Le, Fredrik Olajos, Göran Englund, and Michael Holmboe. "Tracking mineral and geochemical characteristics of Holocene lake sediments: the case of Hotagen, west-central Sweden." Journal of Soils and Sediments 21, no. 9 (July 26, 2021): 3150–68. http://dx.doi.org/10.1007/s11368-021-03012-y.
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Abstract Purpose Intact lake sediments reflect the development of terrestrial ecosystems. This development can be understood by decoding mineral and geochemical information of sedimentary archives. Therefore, we characterized a Holocene lake sediment core and revealed bulk to micro-scale variations via a combination of geochemical techniques and statistical methods. Methods A 2.3 m sediment core was collected from Hotagen, a lake in west-central Sweden; a sediment sample was collected every 5 cm. A part of each sediment sample was kept untreated (named bulk) and another part was size-fractionated into < 4, 4–16, 16–64, and > 64 µm subsamples. Characterization was then made with respect to grain size distribution (GSD), physico-chemical parameters, geochemical properties, organic composition, and mineralogy. The sediments were investigated at bulk, micro-, and elemental scales using powder X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM–EDX). Results The deepest sediment was identified as glacial till dating back to the Late Pleistocene. The bulk sediments showed a clear distinction between 0–195 cm (unit 1, U1) and 200–225 cm (unit 2, U2) depths. Quartz and feldspar minerals decreased and organic matter and clay minerals increased from the till towards the lower limit of U1. The development in the sedimentary properties marked the transformation of the terrestrial ecosystem from glacier-covered land to vegetated areas. This development was also well reflected by the appearance of X-ray amorphous materials and the formation of distinct organo-mineral aggregates; chlorite was the predominant clay mineral in these aggregates. The geochemical variation between U2 and U1 sediments was further established by resolving the DRIFT spectral components through multivariate curve resolution alternating least square (MCR-ALS). The U1 sediments settled over a period of ~ 7500 years and showed comparable mineral, geochemical, and organic composition. However, the size-fractionated sediments, mainly < 4 µm, showed diverse mineral and geochemical composition. Indeed, these sediments were distinct by containing relatively higher amounts of X-ray amorphous materials and clay minerals, the latter had variable Na, Mg, and K contents. Conclusion The combined use of geochemical and statistical approaches used in this study followed the mineral and geochemical development of sediments that had settled during the Late Pleistocene and Early Holocene Epochs. Finally, the U2 sediments marked the terrestrial ecosystem development that occurred during the late glaciation, deglaciation, and post-glaciation periods. Graphical abstract
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Kamiludin, Udaya, and Yudi Darlan. "KARAKTERISTIK PASIR DI PANTAI DAN LEPAS PANTAI BINUANGEUN, LEBAK-BANTEN." JURNAL GEOLOGI KELAUTAN 11, no. 2 (February 16, 2016): 79. http://dx.doi.org/10.32693/jgk.11.2.2013.235.
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Pasir merupakan sesuatu penomena yang menarik karena padanya tersimpan misteri bagaimana partikel itu terendapkan sesuai dengan lingkungannya, apakah merupakan pasir pada lingkungan marin, pantai atau sungai. Untuk mengetahui lingkungan pengendapan tersebut maka dilakukan identifikasi karakteristik pasirnya. Metoda penelitan meliputi pengambilan contoh, analisis besar butir, klasifikasi nomenklatur sedimen dan parameter statistik. Klasifikasi nomenklatur sedimen pada endapan sedimen permukaan dasar laut, gisik pasir, tanggul gisik dan endapan sungai aktif didapat pasir sebanyak, masing masing 19, 35, 15 dan 3 percontoh. Ke empat jenis endapan mempunyai ukuran butir rata-rata (mean) relatif seragam, yaitu pasir halus (2 Φ - 3 Φ). Begitu juga ukuran pasirnya berupa pasir halus dengan kurva distribusi persen berat fluktuatif. Perbedaan terlihat pada ukuran pasir sedimen permukaan dasar laut dan sedimen sungai aktif, selain pasir halus hadir pula pasir menengah (1 Φ - 2 Φ). Klasifikasi lingkungan pasir memperlihatkan bahwa ke empat endapan mempunyai kesesuaian lingkungan pengendapan disertai adanya muatan partikel yang mengkasar dan menghalus dengan bentuk kurtosis leptokurtik dan platikurtik monomodal. Sumber batuan asal sedimen diduga berasal dari hasil abrasi batugamping terumbu yang tersingkap di pantai bagian tengah daerah penelitian dan pengerjaan ulang batuan gunungapi dan batuan sedimen asal volkanik yang umum tersingkap di utara daerah penelitian.
Kata Kunci : Sedimen permukaan dasar laut, gisik pasir, tanggul gisik, sedimen sungai aktif, lingkungan pengendapan pasir, sumber batuan.
Sand sediment is something interesting phenomenon because the sand is stored in the mystery of how the sand particles sedimented according to the deposition environment, what is the sand that was deposited in marine, beach or river environment. The identification of sand sediment characteristic is used for the determination of depositional environment. Study methods include sediment sampling, grain size analysis of sediment, sediment nomenclature classification and computing the statistical parameters. Sediment nomenclature classification results on the seafloor surface sediment, sand beach sediment, berm sediment and active stream sediment derived as much sand sediment types, respectively 19, 35, 15 and 3 samples. The four types of sediment deposition that has mean is relatively uniform, which falls on the fine sand (Φ 2 - Φ 3). While the size of sand fall in the fine sand with fluctuating weight percent distribution curve. The difference was in the size of the sand on the sea floor sediments and active stream sediments, in addition to fine sand also present medium sand (Φ1 - Φ2). Sand environment classification showed that all four types of the sediments have suitability depositional environment be accompanied excess coarse and fine particles with curved kurtosis leptokurtic and platykurtic monomodal. Source rocks of the sediments probably derived from the abrasion of coralreef limestone exposed in the central coast of study area and rework volcanic rocks and sedimentary rocks of volcanic origin are commonly exposed in the northern of study area.
Key words: Seafloor surface sediment, sand beach, berm, active stream sediment, sand depositional environment, source rocks.
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Larsen, T., L. T. Bach, R. Salvatteci, Y. V. Wang, N. Andersen, M. Ventura, and M. D. McCarthy. "Assessing the potential of amino acid <sup>13</sup>C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis." Biogeosciences 12, no. 16 (August 21, 2015): 4979–92. http://dx.doi.org/10.5194/bg-12-4979-2015.
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Abstract. Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. It is uncertain whether archaea may have contributed to sedimentary δ13CAA patterns we observe, and controlled culturing studies will be needed to investigate whether δ13CAA patterns can differentiate bacterial from archeal sources. Further research efforts are also needed to understand how closely δ13CAA patterns derived from hydrolyzable amino acids represent total sedimentary proteineincous material, and more broadly sedimentary organic nitrogen. Overall, however, both our culturing and sediment studies suggest that δ13CAA patterns in sediments will represent a novel proxy for understanding both primary production sources, and the direct bacterial role in the ultimate preservation of sedimentary organic matter.
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Billy, Petrick, Jane M. Mamuaja, Royke M. Rampengan, Medy Ompi, Esry T. Opa, and Joppy Mudeng. "Foraminifera On The Beach Of Malalayang Dua." JURNAL ILMIAH PLATAX 6, no. 2 (July 31, 2018): 114. http://dx.doi.org/10.35800/jip.6.2.2018.20660.
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Beach as one on the landform that reflects the work of hydro-oceanographic factors, generally in the form of loose sedimentary material. Loose sediment is a collection of organic and inorganic particles that accumulate widely and are irregular in shape. One example of organism in marine waters that contributes to the availability of organic particles in the beach landform is foraminifera. Foraminifera is a single-celled organism that has the ability to form shells from substances of CaCO3 which originate from itself or from the surrounding environment. This study was aimed to classify physical sediments on the Malalayang Dua beach according to the points of sediment sampling, and see how the composition of foraminifera in the beach area and analyze the presence of foraminifera in relation to the granulometry of beach sediments. From the result of the study, it is found that the composition of grain size of sediment on the beach of Malalayang Dua is different, in stasion 1A, 1B, 2A, and 2B the sediment were mostly composed by fine grains while in station 3A and 3B were of coarse-grained sediment. A number of a species of foraminifera (dead test) was found in the study, and the number of tests was highes in fine sediments compared to coarse sediment.Keywords : Beach Landform, Malalayang Dua Coast, Foraminifera ABSTRAKGisik sebagai salah satu bentuklahan yang merefleksikan kerja faktor-faktor hidro-oseanografi, umumnya berwujud material sedimen lepas. Sedimen lepas adalah kumpulan partikel organik dan anorganik yang terakumulasi secara luas dan bentuknya tidak beraturan. Salah satu organisme di perairan laut yang berkontribusi terhadap ketersediaan partikel organik di gisik adalah foraminifera. Foraminifera merupakan organisme bersel tunggal yang mempunyai kemampuan membentuk cangkang dari zat-zat CaCO3yang berasal dari dirinya sendiri atau dari lingkungan sekitarnya. Penelitian ini bertujuan untuk mengelompokkan sedimen gisik di pantai Malalayang Dua menurut titik-titik pengambilan sampel sedimen, dan melihat bagaimana komposisi foraminifera di kawasan gisik serta menganalisis keberadaan foraminifera dalam kaitannya dengan granulometri sedimen gisik. Dari hasil penelitian komposisi ukuran butir sedimen pada lahan gisik di pantai Malalayang Dua berbeda menurut stasiun yang ditetapkan, di ruang pantai ke arah Timur yaitu stasiun 1A, 1B, 2A, 2B komposisi sedimennya berukuran halus, sedangkan di ruang pantai ke arah Barat yaitu stasiun 3A dan 3B komposisi sedimennya berukuran kasar, komposisi sedimen di setiap stasiun gisik litoral dan sublitoral menampilkan adanya perbedaan tingkat kekasaran partikel sedimen. Dari hasil penelitian ditemukan 9 cangkang foraminifera. Pada komposisi sedimen gisik yang berukuran halus ditemukan jumlah cangkang foraminifera yang lebih banyak dibandingkan dengan gisik yang komposisi sedimen berukuran kasar.Kata kunci : Lahan Gisik, Pantai Malalalayang Dua, Foraminifera
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Versteegh, Gerard J. M., Andrea Koschinsky, Thomas Kuhn, Inken Preuss, and Sabine Kasten. "Geochemical consequences of oxygen diffusion from the oceanic crust into overlying sediments and its significance for biogeochemical cycles based on sediments of the northeast Pacific." Biogeosciences 18, no. 17 (September 13, 2021): 4965–84. http://dx.doi.org/10.5194/bg-18-4965-2021.
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Abstract. Exchange of dissolved substances at the sediment–water interface provides an important link between the short-term and long-term geochemical cycles in the ocean. A second, as yet poorly understood sediment–water exchange is supported by low-temperature circulation of seawater through the oceanic basement underneath the sediments. From the basement, upwards diffusing oxygen and other dissolved species modify the sediment, whereas reaction products diffuse from the sediment down into the basement where they are transported by the basement fluid and released to the ocean. Here, we investigate the impact of this “second” route with respect to transport, release and consumption of oxygen, nitrate, manganese, nickel and cobalt on the basis of sediment cores retrieved from the Clarion Clipperton Zone (CCZ) in the equatorial Pacific Ocean. We show that in this abyssal ocean region characterised by low organic carbon burial and sedimentation rates vast areas exist where the downward- and upward-directed diffusive fluxes of oxygen meet so that the sediments are oxic throughout. This is especially the case where sediments are thin or in the proximity of faults. Oxygen diffusing upward from the basaltic crust into the sediment contributes to the degradation of sedimentary organic matter. Where the sediments are entirely oxic, nitrate produced in the upper sediment by nitrification is lost both by upward diffusion into the bottom water and by downward diffusion into the fluids circulating within the basement. Where the oxygen profiles do not meet, they are separated by a suboxic sediment interval characterised by Mn2+ in the porewater. Where porewater Mn2+ in the suboxic zones remains low, nitrate consumption is low and the sediment continues to deliver nitrate to the ocean bottom waters and basement fluid. We observe that at elevated porewater manganese concentrations, nitrate consumption exceeds production and nitrate diffuses from the basement fluid into the sediment. Within the suboxic zone, not only manganese but also cobalt and nickel are released into the porewater by reduction of Mn oxides, diffusing towards the oxic–suboxic fronts above and below where they precipitate, effectively removing these metals from the suboxic zone and concentrating them at the two oxic–suboxic redox boundaries. We show that not only do diffusive fluxes in the top part of deep-sea sediments modify the geochemical composition over time but also diffusive fluxes of dissolved constituents from the basement into the bottom layers of the sediment. Hence, the palaeoceanographic interpretation of sedimentary layers should carefully consider such deep secondary modifications in order to prevent the misinterpretation of primary signatures.