Littérature scientifique sur le sujet « Sediment core sample »
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Articles de revues sur le sujet "Sediment core sample"
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Nelson, Michelle, Tammy Rittenour, and Harriet Cornachione. "Sampling Methods for Luminescence Dating of Subsurface Deposits from Cores." Methods and Protocols 2, no. 4 (2019): 88. http://dx.doi.org/10.3390/mps2040088.
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Study of subsurface deposits often requires coring or drilling to obtain samples for sedimentologic and geochemical analysis. Geochronology is a critical piece of information for stratigraphic correlation and rate calculations. Increasingly, luminescence dating is applied to sediment cores to obtain depositional ages. This paper provides examples and discussion of guidelines for sampling sediment core for luminescence dating. Preferred protocols are dependent on the extraction method, sedimentology, core integrity, and storage conditions. The methods discussed include subsampling of sediment in opaque core-liners, cores without liners, previously open (split) cores, bucket auger samples, and cuttings, under red lighting conditions. Two important factors for luminescence sampling of sediment core relate to the integrity of the natural luminescence signal and the representation of the dose rate environment. The equivalent dose sample should remain light-safe such that the burial dose is not reset (zeroed) by light exposure. The sediment sampled for dose rate analyses must accurately represent all units within at least 15 cm above and below the equivalent dose sample. Where lithologic changes occur, units should be sampled individually for dose rate determination. Sediment core extraction methods vary from portable, hand-operated devices to large truck- or vessel-mounted drill rigs. We provide recommendations for luminescence sampling approaches from subsurface coring technologies and downhole samplers that span shallow to deep sample depths.
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Andrews, John T., Eugene W. Domack, Wendy L. Cunningham, et al. "Problems and Possible Solutions Concerning Radiocarbon Dating of Surface Marine Sediments, Ross Sea, Antarctica." Quaternary Research 52, no. 2 (1999): 206–16. http://dx.doi.org/10.1006/qres.1999.2047.
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Radiocarbon accelerator mass spectrometric (AMS) dates on the acid-insoluble fraction from 38 core tops from the western Ross Sea, Antarctica, are used to address these questions: (1) What are the apparent ages of sediments at or close to the present sediment/water interface? (2) Is there a statistically significant pattern to the spatial distribution of core top ages? and (3) Is there a “correction factor” that can be applied to these age determinations to obtain the best possible Holocene (downcore) chronologies? Ages of core top sediments range from 2000 to 21,000 14C yr B.P. Some “old” core top dates are from piston cores and probably represent the loss of sediment during the coring process, but some core top samples >6000 14C yr B.P. may represent little or no Holocene deposition. Four possible sources of variability in dates ≤6000 14C yr B.P. (n = 28) are associated with (1) different sample preparation methods, (2) different sediment recovery systems, (3) different geographic regions, and (4) within-sample lateral age variability. Statistical analysis on an a posteriori design indicates that geographic area is the major cause of variability; there is a difference in mean surface sediment age of nearly 2000 yr between sites in the western Ross Sea and sites east of Ross Bank in south-central Ross Sea. The systematic variability in surface age between areas may be attributed to: (a) variable sediment accumulation rates (SAR) (surface age is inversely related to SAR), (b) differences in the percentage of reworked (dead) carbon between each area, and/or (c) differences in the CO2 exchange between the ocean and the atmosphere.
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Chen, Jie, Ping Liu, Dandan Sun, Dan Zhang, Bingdi Miao, and Jing Chen. "Riverine Sediment Geochemistry as Provenance Fingerprints along the Eastern Coast of China: Constraint, Approach, and Application." Minerals 10, no. 1 (2019): 29. http://dx.doi.org/10.3390/min10010029.
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Sediment geochemistry is affected by sediment granularity and chemical partition, which may greatly influence the accuracy of sediment source identification. In this study, we analyzed Ca, Co, Zr, V, Cr, Ti, Sc, Th, and Al in the sediments of major rivers and a Holocene core along the eastern coast of China to reveal the constraints on sediment geochemistry related to granularity and chemical partition and to try and identify the sources of the sediments present in the core. The results reveal that the element concentrations have a significant positive correlation with Al concentration in all these riverine sediments. There are significant differences in the element contents of the bulk sample and the residual sediment leached with acid, including in their ratios. The ratios of Cr/Th–Sc/Th, which is often used for provenance discrimination, reveal that uncertainty of provenance discrimination will increase if the impact of sediment granularity and chemical phase on the index system is not considered. We applied this geochemical approach for provenance on a Holocene core of the East China Sea using Cr/Th–Al, Sc/Th–Al, Ti/Zr–Al, and Cr/Th–Sc/Th with the same granularity as the residue sediments. Based on this approach, we identified the core sediments to have had a large component derived from the western Taiwanese rivers since the mid-Holocene. This study sheds light on the sediment geochemistry used to identify the provenance of marginal seas with multiple rivers entering them.
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Winantris, Winantris, and Lia Jurnaliah. "Pollen and Foraminifera Approaches to Identify Sediment Sources In The River Mouth Mahakam East Kalimantan." Journal of Geoscience, Engineering, Environment, and Technology 2, no. 4 (2017): 242. http://dx.doi.org/10.24273/jgeet.2017.2.4.689.
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The central role of Mahakam River in the construction of Mahakam Delta is to supply sediment from terrestrial to the river mouth. The river upstream comes from Mount Camaru and the downstream part terminate at Makasar Strait. The surrounding area of the river is overgrown by wet tropical flora that produces pollen. The existence pollen in river sediments as an indicator that sediment came from terrestrial, and foraminifera as an indicator that sediment came from marine. The ratio changes of pollen to foraminifera show that there were differences of sediment source supply. The study was conducted at the river mouth. A shallow core, 200 cm depth, composed of sand and mud and sandy mud, from it taken vertically 11 samples to be analyzed pollen and foraminifera. Sample preparation was using standard methods acetolysis. Meanwhile, sample preparation of foraminifera using Hydrogen Peroxide method. Pollen found at all samples, but foraminifera only found in 8 samples. The data indicating that sedimentation process in the mouth of a river not only gets sediment supplies from terrestrial but also from marine. The quantity of pollen and foraminifera varies vertically. The frequency of pollen much higher than foraminifera that indicates of source sediments dominance came from terrestrial which carried by Mahakam river current. Sonneratia caseolaris pollen continuously found in all samples. Stictogongylus vandiemensis is species foraminifera the most common that followed by Ramulina confossa, both of them come from the sea particularly from the shallow sea.
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Weisbrod, Barbara, Susanna A. Wood, Konstanze Steiner, et al. "Is a Central Sediment Sample Sufficient? Exploring Spatial and Temporal Microbial Diversity in a Small Lake." Toxins 12, no. 9 (2020): 580. http://dx.doi.org/10.3390/toxins12090580.
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(1) Background: Paleolimnological studies use sediment cores to explore long-term changes in lake ecology, including occurrences of harmful cyanobacterial blooms. Most studies are based on single cores, assuming this is representative of the whole lake, but data on small-scale spatial variability of microbial communities in lake sediment are scarce. (2) Methods: Surface sediments (top 0.5 cm) from 12 sites (n = 36) and two sediment cores were collected in Lake Rotorua (New Zealand). Bacterial community (16S rRNA metabarcoding), Microcystis specific 16S rRNA, microcystin synthetase gene E (mcyE) and microcystins (MCs) were assessed. Radionuclide measurements (210Pb, 137Cs) were used to date sediments. (3) Results: Bacterial community, based on relative abundances, differed significantly between surface sediment sites (p < 0.001) but the majority of bacterial amplicon sequence variants (88.8%) were shared. Despite intense MC producing Microcystis blooms in the past, no Microcystis specific 16S rRNA, mcyE and MCs were found in surface sediments but occurred deeper in sediment cores (approximately 1950′s). 210Pb measurements showed a disturbed profile, similar to patterns previously observed, as a result of earthquakes. (4) Conclusions: A single sediment core can capture dominant microbial communities. Toxin producing Microcystis blooms are a recent phenomenon in Lake Rotorua. We posit that the absence of Microcystis from the surface sediments is a consequence of the Kaikoura earthquake two years prior to our sampling.
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Pearman, John, Georgia Thomson-Laing, Jamie Howarth, et al. "Environmental DNA variability in lake sediment cores." ARPHA Conference Abstracts 4 (March 4, 2021): e65128. https://doi.org/10.3897/aca.4.e65128.
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Lake sediments are natural archives that accumulate information about biological communities and their surrounding catchments. Paleolimnology has traditionally focussed on identifying fossilized organisms to reconstruct past environments. In the last decade, the application of molecular methodologies has increased in paleolimnological studies, but further studies investigating factors such as sample heterogeneity and DNA degradation are required. Here we investigated bacterial community heterogeneity (16S rRNA metabarcoding) within depth slices. Sediment cores were collected from three lakes with differing sediment compositions. Samples were collected from a variety of depths (1-cm width) which represent a period of time of approximately 1,200 years. Triplicate samples were collected from each slice and bacterial 16S rRNA metabarcoding was undertaken on each sample. Rarefaction curves showed that except for the deepest (oldest) slices, the combination of three replicate samples were insufficient to characterise the entire bacterial diversity. However, shared Amplicon Sequence Variants (ASVs) accounted for the majority of the reads in each slice (max. shared proportional read abundance 96%, 86%, 65% in the three lakes). Within slice similarity was higher than between slice similarity. No general trend was observed in variability among replicates with depth amongst the lakes. In one core. there was a higher community dissimilarity in older sediment, which may be due to laminae not being horizontal. These results highlight the fact that microbial communities can be differentiated with depth however it is critical to interpret these results in the context of the stratigraphic data of the core.
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Voskuhl, Lisa, Hannah Möhlen, Christian Schlautmann, et al. "Microbial activities along a 20 million-year-old pristine oil reservoir." ARPHA Conference Abstracts 6 (October 13, 2023): e108098. https://doi.org/10.3897/aca.6.e108098.
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Studies on oil reservoir microbiology typically take samples from producing reservoirs and sample fluids that have been pumped to the surface. This comes with problems since producing oil reservoirs are affected by production processes leading to changes in environmental conditions and the natural microbiome. Hence, pumped samples do not display an unaltered picture of the spatial distribution and composition of the microorganisms in the reservoir.We took 13 samples from a freshly drilled sediment core of a pristine, heavily biodegraded oil reservoir in the North Sea. Core samples originated from above, within, and below the reservoir.16S rRNA gene amplicon sequencing of the microbiome revealed distinct differences between sediments and formation water, indicating that studies on microbiomes from formation water alone are not necessarily representative for the microbial processes in an oil reservoir. Fluorescence microscopy showed that microorganisms live in small microcolonies on the sediment surface. CT-scanning with image analysis visualized the water phase distribution inside the reservoir sediments and clearly indicated water-filled voids that might be habitable for microorganisms, enlarging the surface for potential biodegradation. Employing microcosm experiments and reverse isotope labelling, we were able to determine the first degradation rates measured from cores above, within, and below a reservoir ranging from no activity up to 1 mM CO<sub>2</sub>/(g<sub>sediment</sub> x year)<sub>, </sub>Results indicate significant degradation potential from autochthonous microorganisms in the reservoir above the water-contact-zone.Evading the general issues of produced oil samples for studying microbiomes results in a more realistic picture of an oil reservoir unaffected by production artefacts.
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Sveinbjörnsdóttir, Árný E., Jan Heinemeier, Peter Kristensen, Niels Rud, Áslaug Geirsdóttir, and Jórunn Harđardóttir. "14C AMS Dating of Icelandic Lake Sediments." Radiocarbon 40, no. 2 (1997): 865–72. http://dx.doi.org/10.1017/s003382220001883x.
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We report an age-depth profile for the sediments of the Lake Hesrvatn, southern Iceland, based on 14C analyses of the organic fraction of bulk sediment samples, molluscs and foraminifera. Our age-depth curve is supported by the occurrence of the well-dated Vedde ash in the lowermost part of the sediments. Comparison of foraminifera dates with the age of the Vedde ash indicates a reservoir age of ca. 400 yr. The results suggest that the sediments at Hestvatn accumulated in a marine environment until ca. 8700 bp and thereafter in freshwater.Owing to the lack of terrestrial macrofossils and the low concentration of molluscs and foraminifera, we were forced to attempt to date most of the core with the organic fraction of the bulk sediment samples. We found, however, that this fraction is not homogeneous in density or 14C age. We believe that during sample pretreatment we managed to isolate a light organic fraction, which closely represents the true age of the sediment, whereas the denser fraction yields ages that are too high. This age diversity may to some extent be explained by the large drainage area of the lake, from which plant remains of different ages may have been washed into the lake.
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Keigwin, L. D., та A. R. Gagnon. "Comparison of Large and Ultra-Small Δ14C Measurements in Core Top Benthic Foraminifera from the Okhotsk Sea". Radiocarbon 57, № 1 (2015): 123–28. http://dx.doi.org/10.2458/azu_rc.57.18153.
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The radiocarbon activity of benthic foraminifera was investigated in surface sediments from a high deposition rate location at a depth of 1000 m in the Okhotsk Sea. Sediments were preserved and stained with Rose Bengal to identify foraminifera that contain cytoplasm. The benthic fauna at this site is dominated by large specimens of Uvigerina peregrina, and bulk samples (∼150 individuals) of stained and unstained specimens were dated. The stained sample was about 240 14C yr younger than the unstained, and the presence of bomb 14C is inferred by comparison to water column data in the nearby open North Pacific. Using new methods, multiple measurements were also made on samples of three stained and unstained individuals (as small as 7 μg C). Results are consistent with those from the bulk samples. This suggests that similar ultra-small measurements could be made at other locations to reveal the age distribution of individuals in a sediment sample in order to assess the extent of bioturbation and the presence of bomb 14C contamination.
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Andrews, John T., Wendy J. Roth, and Anne E. Jennings. "Grain size and mineral variability of glacial marine sediments." Journal of Sedimentary Research 93, no. 1 (2023): 37–49. http://dx.doi.org/10.2110/jsr.2022.044.
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ABSTRACT Glacial marine sediment deposition varies both spatially and temporally, but nearly all studies evaluate down-core (∼ time) variations in sediment variables with little consideration for across core variability, or even the consistency of a data set over distance scales of 1 to 1000 m. Grain size and quantitative X-ray diffraction (qXRD) methods require only ≤ 1 g of sediment and thus analyses assume that the identification of coarse sand (i.e., ice-rafted debris) and sediment mineral composition are representative of the depth intervals. This assumption was tested for grain size and mineral weight % on core MD99-2317, off East Greenland. Samples were taken from two sections of the core that had contrasting coarse-sand content. A total of fourteen samples were taken consisting of seven (vertical) and two (horizontal) samples, with five replicates per sample for qXRD analyses and ∼ 10 to 20 replicates for grain size. They had an average dry weight of 10.5 ± 0.5 g and are compared with two previous sets of sediment samples that averaged 54.1 ± 18.9 g and 20.77 ± 5.8 g dry weight. The results indicated some significant differences between the pairs of samples for grain-size parameters (mean sortable silt, and median grain size) but little difference in the estimates of mineral weight percentages. Out of 84 paired mineral and grain-size comparisons only 17 were significantly different at p = &lt; 0.05 in the post-hoc Scheffe test, all of which were linked to grain-size attributes.
Thèses sur le sujet "Sediment core sample"
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Reboul, Guillaume. "Metabarcoding and metagenomic approaches to decipher microbial communities in suboxic environments Microbial eukaryotes in the suboxic chemosyn- thetic ecosystem of Movile Cave, Romania Hyper- diverse archaea near life limits at the polyextreme geothermal Dallol area Performance of the melting seawater-ice elution method on the metabarcoding characterization of benthic protist communities Core microbial communities of lacustrine microbialites sampled along an alkalinity gradient Environmental drivers of plankton protist communities along latitudinal and vertical gradients in the oldest and deepest freshwater lake Ancient Adaptive Lateral Gene Transfers in the Symbiotic Opalina-Blastocystis Stramenopile Lineage Marine signature taxa and microbial community stability along latitudinal and vertical gradients in sediments of the deepest freshwater lake." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL041.
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L’écologie microbienne concerne l’étude des microorganismes et de leurs interactions biotiques et abiotiques dans un écosystème donné. Ces vingt dernières années, l’avancement des techniques moléculaires pour analyser la diversité microbienne et, notamment, les nouvelles technologies de séquençages (NGS) ont permis de surmonter les limitations associées aux approches traditionnelles basées sur la culture et la microscopie. Ces approches moléculaires ont conduit à une accumulation des données de diversité microbienne et de potentiel métabolique dans des communautés microbiennes des écosystèmes variés.Cependant, ces efforts ont été principalement appliqués sur des environnements facilement accessibles ou liés à l’humain, comme le plancton (marin principalement) et la flore intestinale. Néanmoins, ceci a conduit à une très forte augmentation de données environnementales et au développement de la bioinformatique par le biais de nombreux outils. Parmi les environnements délaissés des études, les environnements faibles en oxygène sont probablement également porteurs de nouveautés phylogénique ou métaboliques.Afin de palier à cela, nous avons choisi d’explorer deux environnements suboxiques relativement peu étudiés : la cave Movile (Roumanie) et les sédiments du lac Baikal (Sibérie, Russie). Notre but étant de montrer les diversités phylogénétiques et fonctionnelles des microbes de ces biotopes.Pour cela, j’ai d'abord développé un pipeline d’analyse de données métabarcoding (petite sous-unités ribosomique). Ensuite, j’ai appliqué cet outil sur des données de métabarcoding de protistes provenant d’échantillons d’eau et de tapis microbiens de la cave de Movile, un écosystème chemosynthétique pratiquement fermé. Nous avons montré que la diversité des protistes de la cave s’étendait à quasiment tous les grands groupes eucaryotes et provenait à la fois d’origine d’eaux douces et marines. De plus, la plupart ont été affiliées à des groupes d’organismes typiquement anaérobies, ce qui est concordant avec les paramètres abiotiques de la cave. Écologiquement, ces protistes sont des prédateurs mais aussi vraisemblablement des partenaires symbiotiques avec des espèces procaryotes de la cave.Dans une deuxième étude, j’ai eu l’opportunité d’appliquer ce pipeline de métabarcoding sur des données procaryotes et eucaryotes provenant des couches superficielles des sédiments du lac d’eau douce Baikal. Comme attendu, les communautés microbiennes dans ces sédiments sont particulièrement diverses et relativement enrichis en archées. Nous avons aussi pu mettre en évidence des lignées que l’on pensait exclusivement marines dans ces sédiments. Ces lignées sont probablement planctoniques mais s’accumulent au fond par sédimentation. Enfin, les échantillons ont été prélevés dans le but de tester les influences de la profondeur, du bassin et de la latitude sur les communautés. Aucune d’elles ne s’est révélée significative.Dans une troisième étude, j'ai utilisé une approche métagénomique afin de révéler les acteurs écologiquement majeurs dans les sédiments, leurs rôles et de reconstruire leurs génomes. Cela nous a permis notamment de mettre en évidence le rôle primordial des Thaumarchaeota dans le cycle de l’azote et la production primaire de molécules de carbone. Les chloroflexi et les protéobacteries ont aussi un rôle important dans la surface des sédiments du lac Baikal. Ce travail de thèse participe à la connaissance globale de la diversité microbienne sur la planète en mettant en lumière des environnements peu étudiés. De plus, l’étude de la surface des sédiments du lac Baikal apporte de nouvelles données sur le sujet de la transition eau douces/eau marines des microbes. Enfin, la métagénomique a permis de révéler le cycle des nutriments et les microorganismes y participant dans ces échantillons de sédiment. En résumé, ce travail vient mettre en lumière l’écologie microbienne d’écosystèmes suboxiques, notamment la surface des sédiments du lac Baikal<br>Microbial ecology is the science of micro-organisms and their biotic and abiotic interactions in a given ecosystem. As technology has advanced, molecular techniques have been widely used to overcome the limitations of classical approaches such as culturing and microscopy. Indeed, the development of Next Generation Sequencing (NGS) technologies in the past twenty years has largely helped to unravel the phylogenetic diversity and functional potential of microbial communities across ecosystems.Nonetheless, most of the environments studied through these techniques concentrated on relatively easily accessible, tractable and host-related ecosystems such as plankton (especially in marine ecosystems), soils and gut microbiomes. This has contributed to the rapid accumulation of a wealth of environmental diversity and metagenomic data along with advances in bioinformatics leading to the development of myriads of tools. Oxygen-depleted environments and especially their microbial eukaryote components are less studied and may lead to future phylogenetic and metabolic discoveries.In order to address this, we conducted analyses on two poorly studied suboxic ecosystems: Movile Cave (Romania) and lake Baikal sediments (Siberia, Russia). In this task, we aimed at unveiling the taxonomic and functional diversity of microorganims in these environments.To do so, I first evaluated the available bioinformatics tools and implemented a bioinformatics pipeline for 16S/18S rRNA gene-based metabarcoding analysis, making reasoned methodological choices. Then, as a case study, I carried out metabarcoding analyses of the water and floating microbial mats found in Movile Cave in order to investigate its protist diversity. Our study showed that Movile Cave, a sealed off chemosynthetic ecosystem, harbored a substantial protist diversity with species spanning most of the major eukaryotic super groups. The majority if these protists were related to species of freshwater and marine origins. Most of them were putatively anaerobic, in line with the cave environment, and suggesting that in addition to their predatory role, they might participate in prokaryote-protist symbioses.In a second study, I applied my metabarcoding pipeline to explore unique and relatively unexplored environment of Lake Baikal sediments. I first applied a metabarcoding approach using 16S and 18S rRNA genes to describe prokaryotic as well as protist diversity. Overall, the communities within these ecosystems were very diverse and enriched in ammonia-oxidizing Thaumarchaeota. We also identified several typical marine taxa which are likely planktonic but accumulate in sediments. Finally, our sampling plan allowed us to test whether differences across depth, basin or latitude affected microbial community structure. Our results showed that the composition of sediment microbial communities remained relatively stable across the samples regardless of depth or latitude.In a third study, we applied metagenomics to study the metabolic potential of communities associated to Baikal sediments and to reconstruct metagenome-assembled genomes (MAGs) of dominant organisms. This revealed the considerable ecological importance of Thaumarchaeota lineages in lake Baikal sediments, which were found to be the major autotrophic phyla and also very implicated in the nitrogen cycle. Chloroflexi and Proteobacteria-related species also appeared ecologically important.This PhD thesis reveals the taxonomic diversity of poorly studied suboxic ecosystems and therefore contributes to our knowledge of microbial diversity on Earth. Additionally, the analyses of surface sediment samples in lake Baikal adds new light on freshwater-marine transitions. The metagenomic analyses reported here allowed us to postulate a model of nutrient cycle carried out by microorganismsin these sediments. Overall, this work sheds light on the microbial ecology of oxygen-depleted environments, and most notably lake Baikal surface sediments
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Boscardin, Adriane G. "Development of miniature full flow and model pipeline probes for testing of box core samples of surficial seabed sediments." 2013. https://scholarworks.umass.edu/dissertations/AAI3588996.
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The box corer is a relatively new tool used in the geotechnical community for collection of soft seabed sediments. Miniature full flow and model pipeline probes were developed as tools to characterize and obtain soil parameters of soft seabed sediments collected in the box core for design of offshore pipelines and analysis of shallow debris flows. Probes specifically developed for this study include the miniature t-bar, ball, motorized vane (MV), and toroid. The t-bar, ball, and MV were developed to measure intact and remolded undrained shear strengths (su and sur). The t-bar and ball can obtain continuous strength profiles and measure sur at discrete depths in the box corer while the MV measures su and s ur at discrete depths. The toroid is a form of model pipeline testing which was developed to investigate pipe-soil interaction during axial pipeline movement. Vertical loading and displacement rates can be selected for the toroid to mimic axial pipeline displacement for a variety of pipe weights. A load frame for both miniature penetrometer and toroid testing was developed for testing directly on box core samples offshore. This research presents results from offshore and laboratory testing of the box core and recommended testing procedures for full flow and toroid probes on box core samples.
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Kawamura, Taro, Michika Ohtake, Yasuhide Sakamoto, et al. "EXPERIMENTAL STUDY OF ENHANCED GAS RECOVERY FROM GAS HYDRATE BEARING SEDIMENTS BY INHIBITOR AND STEAM INJECTION METHODS." 2008. http://hdl.handle.net/2429/1401.
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The inhibitor and steam injection methods have been examined using a laboratory-prepared methane hydrate bearing sediment. New experimental apparatuses have been designed and constructed. In the case of inhibitor injection, the measurement of gas production vs. time suggested that the inhibitor increased dissociation rate. Core temperature decreased upon the inhibitor injection, in contrast to that in the case of pure water injection. The observed pressure differentials between the inlet and outlet of the core sample suggest that the inhibitor effectively prevented the hydrate reformation within the dissociating core sample. In the case of steam injection coupled with depressurization, it can be seen that the effect of steam (or hot water) injection was clear in the later stage of dissociation, compared with that in the case of depressurization alone. The inner (core) temperature change indicates that the coupling of depressurization and steam injection induces MH dissociation from upstream and downstream to the center of the sample. However, it starts from an upstream region and continues downstream steadily in the case of steam (hot water) injection alone.
Livres sur le sujet "Sediment core sample"
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Cahill, Richard A. Assessment of sediment quality in Peoria Lake: Results from the chemical analysis of sediment core samples collected in 1998, 1999, and 2000. Illinois State Geological Survey, 2001.
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Pope, R. J. Analysis of benthic macroinvertebrate samples from St. Marys River sediment cores, 1987: Report. The Branch, 1990.
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Center, National Geophysical Data. Marine geological data: Index to marine geological samples, "The Core curators' file". The Center, 1986.
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Poore, Richard Z. Stable isotope data and AMS ¹⁴C dates from Arctic Ocean Section 1994 surface sediment transect and box core samples from the Mendeleyev Ridge area. U.S. Dept. of the Interior, U.S. Geological Survey, 1999.
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E, Church S., and Geological Survey (U.S.), eds. Analytical results for 42 fluvial tailings cores and 7 stream sediment samples from High Ore Creek, northern Jefferson County, Montana. U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
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Geological Survey (U.S.), ed. STABLE ISOTOPE DATA AND AMS 14C DATES FROM ARCTIC OCEAN SECTION 1994 SURFACE SEDIMENT TRANSECT AND BOX CORE SAMPLES FROM THE MENDELEYEV RIDG. s.n., 2000.
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E, Church S., Finney Christopher J, and Geological Survey (U.S.), eds. Analytical results for 35 mine-waste tailings cores and six bed-sediment samples, and an estimate of the volume of contaminated material at Buckeye Meadow on upper Basin Creek, northern Jefferson County, Montana. U.S. Dept. of the Interior, U.S. Geological Survey, 1999.
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Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001. U.S. Geological Survey, 2004.
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STABLE ISOTOPE DATA AND AMS 14C DATES FROM ARCTIC OCEAN SECTION 1994 SURFACE SEDIMENT TRANSECT AND BOX CORE SAMPLES FROM THE MENDELEYEV RIDG. s.n., 2000.
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Norrgård, Stefan. Changes in Precipitation Over West Africa During Recent Centuries. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.536.
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Water, not temperature, governs life in West Africa, and the region is both temporally and spatially greatly affected by rainfall variability. Recent rainfall anomalies, for example, have greatly reduced crop productivity in the Sahel area. Rainfall indices from recent centuries show that multidecadal droughts reoccur and, furthermore, that interannual rainfall variations are high in West Africa. Current knowledge of historical rainfall patterns is, however, fairly limited. A detailed rainfall chronology of West Africa is currently only available from the beginning of the 19th century. For the 18th century and earlier, the records are still sporadic, and an interannual rainfall chronology has so far only been obtained for parts of the Guinea Coast. Thus, there is a need to extend the rainfall record to fully understand past precipitation changes in West Africa.The main challenge when investigating historical rainfall variability in West Africa is the scarcity of detailed and continuous data. Readily available meteorological data barely covers the last century, whereas in Europe and the United States for example, the data sometimes extend back two or more centuries. Data availability strongly correlates with the historical development of West Africa. The strong oral traditions that prevailed in the pre-literate societies meant that only some of the region’s history was recorded in writing before the arrival of the Europeans in the 16th century. From the 19th century onwards, there are, therefore, three types of documents available, and they are closely linked to the colonization of West Africa. These are: official records started by the colonial governments continuing to modern day; regular reporting stations started by the colonial powers; and finally, temporary nongovernmental observations of various kinds. For earlier periods, the researcher depends on noninstrumental observations found in letters, reports, or travel journals made by European slave traders, adventurers, and explorers. Spatially, these documents are confined to the coastal areas, as Europeans seldom ventured inland before the mid-1800s. Thus, the inland regions are generally poorly represented. Arabic chronicles from the Sahel provide the only source of information, but as historical documents, they include several spatiotemporal uncertainties. Climate researchers often complement historical data with proxy-data from nature’s own archives. However, the West African environment is restrictive. Reliable proxy-data, such as tree-rings, cannot be exploited effectively. Tropical trees have different growth patterns than trees in temperate regions and do not generate growth rings in the same manner. Sediment cores from Lake Bosumtwi in Ghana have provided, so far, the best centennial overview when it comes to understanding precipitation patterns during recent centuries. These reveal that there have been considerable changes in historical rainfall patterns—West Africa may have been even drier than it is today.
Chapitres de livres sur le sujet "Sediment core sample"
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Kawamura, Kiichiro, Kazumasa Oguri, Mutsuo Inoue, Kan-Hsi Hsiung, Taishi Kudaka, and Ken Takai. "Ongoing Persistent Slope Failures at the Toe of a Giant Submarine Slide in the Ryukyu Trench that Generated the AD 1771 Meiwa Tsunami." In Progress in Landslide Research and Technology, Volume 1 Issue 2, 2022. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-18471-0_5.
Texte intégralRésumé :
AbstractThis study investigates sedimentation processes and associated submarine sliding on the floor of the Ryukyu Trench. Three dive surveys were conducted using the manned submersible Shinkai 6500 (hereafter 6K) in the trench. The AD 1771 Meiwa tsunami was generated by a giant submarine slide on the landward trench slope in this region. Dive survey site 6K#1469 was located on a mouth of the submarine canyon in the forearc basin. Dive survey site 6K#1468 was located on the uppermost part of the submarine slide, where steps and fissures were observed. Dive survey site 6K#1467 was located at the toe of the submarine slide, which is covered by a muddy sediment layer. Core sample 6K#1467 measured 36.3 cm long and comprised muddy sediments interlayered with silt and/or sand laminations. The paleocurrent direction of the laminated sediments is mostly from north to south, indicating that they were not transported along with the trench but were from the landward slope, probably via repeated small submarine slides. The sedimentation rate for sample 6K#1467 was estimated at 2.42 mm/year using a depth profile of 210Pbex concentration within 10 cm deep and a date for the sediment of ~ 50 year ago. Based on the sedimentation rate and the number of laminae, the typical recurrence interval of the silt/sand layers is calculated to be ~ 6 year. We interpret these results as indicating that repeated small submarine slides have occurred persistently (recurrence interval of ~ 6 year) at the toe of the investigated giant submarine slide in the Ryukyu Trench over the last 50 year.
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Weltje, G. J., M. R. Bloemsma, R. Tjallingii, D. Heslop, U. Röhl, and Ian W. Croudace. "Prediction of Geochemical Composition from XRF Core Scanner Data: A New Multivariate Approach Including Automatic Selection of Calibration Samples and Quantification of Uncertainties." In Micro-XRF Studies of Sediment Cores. Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-9849-5_21.
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Murat, Anne, Emmanuel Poizot, Gwendoline Grégoire, et al. "The dynamics of silica sediment at the ECUSED site in the Baie de Seine based on the COVA methodology: (1) glauconite traced by arsenic." In ASF Publications. Association des Sédimentologistes Français, 2025. https://doi.org/10.70665/ghzd8391.
Texte intégralRésumé :
The English Channel, and specifically the Baie de Seine, is one of the maritime areas hosting the most human activities in Europe. The ECUSED project focuses on the cumulative impact of marine aggregate extraction activities (“Granulats Marins du Havre” concession) and dumping of dredged sediment by the Normand harbours (“Grands Ports Maritimes”) for the maintenance of navigation channels (MACHU site), which are concentrated at the outlet of the Seine estuary. To achieve this goal, we used an innovative methodology (ELCOVA) on 114 surface sediments samples according to a regular grid of 2 stations per km². Samples were separated by sieving into 16 particle size fractions and elemental geochemical analyses were carried out on the separated granulometric fractions using X-ray fluorescence spectrometry. The present work focuses on identifying the movements of the various grain sizes naturally present at the site. The mineral considered is glauconite, an alumino-silicate, traced in the elemental analysis by arsenic. The study zone reveals a complex history in terms of granulometry, geography and time. We identify two sources of material, underwater erosion, river input, transports on the seabed and in suspension and a dynamic equilibrium sedimentary state. An essential point of the results obtained is that each granulometric fraction has its own history. Grains belonging to the same sediment sample do not come from the same sources, have not been transported in the same direction, and have not been deposited at the same time under the same energy conditions. It is possible to find grains of the same size and mineralogy from different sources in the same surface sample. This directly challenges the view of sedimentologists on sedimentation.
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Gaines, Susan M., Geoffrey Eglinton, and Jürgen Rullkötter. "Deep Sea Mud: Biomarker Clues to Ancient Climates." In Echoes of Life. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195176193.003.0011.
Texte intégralRésumé :
Though the concept of the biomarker emerged from attempts to infer the provenance of petroleum and the incidence of life on the young earth—for all the successes and disappointments of the early studies on Precambrian rocks, lunar dust, and oil shales—it was in the sediments of the deep sea that biomarkers really came into their own. The Deep Sea Drilling Project (DSDP) was initiated in the 1960s by a consortium of American oceanographic research institutions, but institutions in Russia, the United Kingdom, France, and Germany were quick to sign on. In what began as an effort to understand the makeup and dynamics of the earth’s crust and mantle, the DSDP’s special research ship traveled the world’s oceans, drilling thousands of meters into the seafloor to retrieve sediment cores that soon became coveted objects of study for geologists, oceanographers, biologists, paleontologists, and geochemists around the world. When Geoff’s group started analyzing the DSDP sediments in the early 1970s, most of the organic chemists involved with the program were from the oil industry and formed part of the drill ship’s safety program, monitoring the cores as they were brought on deck to ensure that dangerous accumulations of gas or liquid hydrocarbons weren’t being penetrated. But Geoff saw the DSDP as the perfect opportunity to wean his Bristol lab of its dependence on NASA’s Apollo program—a chance to bring his full attention back to Earth and its still largely unexplored realm of fossil molecules. The British Natural Environment Research Council had earmarked a large pot of funding for work on the cores, which would be unencumbered by the narrow commercial goals and secrecy that surrounded the limited offerings from oil-company bore holes. Geoff’s budding Organic Geochemistry Unit would be aligned with a multidisciplinary community of scientists who were all studying the same cores, working cooperatively, and publishing freely. And, unlike the lunar samples, ocean sediments were rife with interesting organic compounds, including many entirely unforeseen structures. Most of the cores consisted of sediments that had been laid down and buried sequentially without ever being subjected to the tectonic turmoil of stretching and subsidence, and the overlying kilometers of cold water had kept their temperatures relatively low.
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Yamashita S., Moriwaki T., Hachikubo A., et al. "Strength change of seabed soils due to the vaporization of dissolved gas in the pore water." In Deformation Characteristics of Geomaterials. IOS Press, 2011. https://doi.org/10.3233/978-1-60750-822-9-905.
Texte intégralRésumé :
In this study, to evaluate the effect of the vaporization of dissolved gas in the pore water on the strength properties of sea-bottom shallow sediments obtained from deep seabed, core samplings were conducted in offshore Sakhalin Island, Sea of Okhotsk shallow gas hydrate province. Some kinds of on-board tests such as vane shear and cone penetration tests and physical properties tests such as water content, grain size distribution, specific gravity, plasticity tests were performed for the samples. These test results were compared to the concentration of dissolved gas in the pore water of the samples.
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Dal Molin, Franck, Paul Blowers, Daniel Brady, et al. "Determination of Blue Carbon sequestration rates in the UK North Sea using lead-210 and complementary fingerprinting tools." In Environmental Radiochemical Analysis VII. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781837670758-00069.
Texte intégralRésumé :
The fallout of lead-210 (210Pb), present naturally in the atmosphere from the decay of radon gas, is a source of information that is commonly utilised to estimate time-trends of relatively recent environmental changes, variations and pressures recorded in aquatic sediment cores. Over the last four decades, this geochronological tool has been utilised in diverse environmental research applications. Currently in the United Kingdom (UK), there is a particular growing demand from marine scientists interested in further understanding the sequestration rates of natural sources of organic carbon, also known as Blue Carbon (BC), that help mitigate the effect of climate change. Between 2021 and 2022, several surveys were undertaken in different coastal and offshore regions of the UK North Sea. These presented an opportunity to test different sample preparative and analytical approaches for measuring 210Pb and radium-226 (226Ra) in marine sediments, review the most important challenges and limitations when applying this geochronological tool in this marine region and investigate the best fingerprinting options available that could help validate results obtained from 210Pb-based modelling.
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"Laboratory Measurements on Core-scale Sediment and Hydrate Samples to Predict Reservoir Behavior." In Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards. American Association of Petroleum Geologists, 2009. http://dx.doi.org/10.1306/13201173m893364.
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Bera, Samir. "Pollen-Spore Transport Into Antarctica and Possible Past Climatic Oscillations." In Geoscientific Investigations From the Indian Antarctic Program. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-4078-0.ch004.
Texte intégralRésumé :
During XIX-XX Indian Antarctic Expedition (IAE), two sediment cores were collected. The occurrence of the exotic pollen taxa like Larix, Ulmus, grasses, few herbs, local moss spores, and other cryptogams prove the activity of the palaeowind, which in turn caused transportation microbiota from a long distance. The study of pollen-spores accumulation in polar air (deduced from slide exposures from 40° S) to Antarctic mainland studied for two years (2000 and 2001) as well as surface deposits (45 moss tuft, 15 lichen samples, 10 frozen soils, 10 moraine matrix) is well corroborated with lake sediment study. Ten bulk ice samples from the Antarctic ice cap (5 litres of ice melt) from Schirmacher Oasis were studied to recover trapped palynodebris to understand the depositional pattern of various microbiota in the Antarctic ice sheet.
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Gray, John S., and Michael Elliott. "Introduction." In Ecology of Marine Sediments. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198569015.003.0004.
Texte intégralRésumé :
As the oceans cover 70% of the earth’s surface, marine sediments constitute the second largest habitat on earth, after the ocean water column, and yet we still know more about the dark side of the moon than about the biota of this vast habitat. The primary aim of this book is to give an overview of the biota of marine sediments from an ecological perspective—we will talk of the benthos, literally the plants and animals at the bottom of the sea, but we will also use the term to include those organisms living on the intertidal sediments, the sands and muds of the shore. Given that most of that area is below the zone where light penetrates, the photic zone, the area is dominated by the animals and so we will concentrate on this component. Many of the early studies of marine sediments were taxonomic, describing new species. One of the pioneers was Carl von Linnaeus (1707–1778), the great Swedish biologist who developed the Linnaean classification system for organisms that is still used today (but under threat from some molecular biologists who argue that the Linnaean system is outdated and propose a new system called Phylocode). Linnaeus described hundreds of marine species, many of which come from marine sediments. The British marine biologist Edward Forbes was a pioneer who invented the dredge to sample marine animals that lived below the tidemarks. Forbes showed that there were fewer species as the sampled depth increased and believed that the great pressures at depths meant that no animals would be found deeper than 600 m. This was disproved by Michael Sars who in 1869 used a dredge to sample the benthos at 600 m depth off the Lofoten islands in Norway. Sars found 335 species and in fact was the first to show that the deep sea (off the continental shelf) had high numbers of species. Following these pioneering studies, one of the earliest systematic studies of marine sediments was the HMS Challenger expedition of 1872–1876, the first global expedition. The reports of the expedition were extensive but were mostly descriptive, relating to taxonomy and general natural history.
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"Chapter XV. Analyses of Cores and Sediment Samples from the Ancient Lagoon." In The Roman Port and Fishery of Cosa. Princeton University Press, 2017. http://dx.doi.org/10.1515/9781400886685-025.
Texte intégralActes de conférences sur le sujet "Sediment core sample"
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Escudero, José A., Juan A. Ramírez-Macías, Julio C. Correa, and David Rozo. "Experimental Study of Push Coring Forces During Sediment Extraction Using a Robot Manipulator." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61933.
Texte intégralRésumé :
This work addresses the experimental study of the forces exerted during the extraction of sediment samples using push corers. The study aims to measure push and pull forces under different deployment conditions for corer speed and coring depth using sand, sandy silt and silt as sediment. To guarantee a repeatable automated process, a KUKA KR6 robot manipulator was used to extract the sample. The forces were measured using a bidirectional S-type load cell. The required data is extracted from the robot’s internal variables log and from the load cell’s data acquisition system. The raw data is processed to develop simplified models for the forces using linear regression which are further analyzed and tested. Finally, the results obtained are discussed in the context of core sampling and practical conclusions are drawn from the experiments.
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Charnaux, P., I. A. Perez, C. A. B. Silveira, and V. P. C. Braga. "Geotechnical Site Investigation Over 3500 Meters Depth." In Offshore Technology Conference. OTC, 2024. http://dx.doi.org/10.4043/35269-ms.
Texte intégralRésumé :
Abstract This paper aims to present a survey executed in 3000 meters depth, to support the design of subsea structures in exploration blocks located in Sergipe/Alagoas basin, Brazil, with geotechnical work made over 3500 meters depth, using a Piston Corer for sampling and a gravity CPT for testing. The vessel used for this project was R/V Seward Johnson, a Research/Survey vessel. The Piston Corer used for the survey, to work in depths above 3000 meters, was configured with a core head weighing 1,500 kg, with a maximum length of the sampling tube of 12 m and a 3.5 meters free fall. The samples were recovered in a 102 mm inner diameter plastic PVC (liner) coating within the 112 mm outer diameter steel tube. In addition to being stationary, the Piston Corer have a piston immobilizer, that protects the sample from disruptive forces during pull-out. The gravity CPT that was used in this campaign was coupled on Piston Corer structure, to function in the pressure of deep water. For this Project, gCPT tests was conducted to verify the soil resistance and Piston Corer samples collected, to analyze tactile-visual Classification, determination of moisture content, determination of apparent specific weight, evaluation of the content of Calcium carbonate (CaCO3) and determination of Undrained Shear Strength (Su) by pocket penetometer test, torvane test and laboratory mini vane test. Through the piston core sampling and tactile visual classification, it was possible to define the soil content in the area, consisted of normally consolidated clays. This geotechnical survey has few locations to make a more accurate assessment of what may have occurred geologically in this area. Despite few evidence, analyzing the Piston Core samples onshore, along with gCPT results, the layers of deposition of the sediment were identified, with the general soil composition of the area being described as light brown clayed SILT with fine sand and shell fragments in the superficial sediments and dark gray silty CLAY with fine sand in the deeper sediments. The data produced from this campaign shows the possibility of geotechnical studies in areas of deep water, over 3500 meters depth, with reliable results. In order to work in a deep area, there were some alterations needed in the equipment, such as assembling the CPT in Piston Corer structure, and using a Piston immobilizer on the piston corer sampler. The improved equipment provided good quality data of the region.
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Inoue, Tomoya, Hiroyuki Osawa, Hiroshi Yoshida, et al. "Sea Trial Results of ROV “ABISMO” for Deep Sea Inspection and Sampling." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57347.
Texte intégralRésumé :
JAMSTEC (Japan Agency for Marine-Earth Science and Technology) has been developing the deep sea ROV ABISMO (Automatic Bottom Inspection and Sampling Mobile) having the capability to dive to the deepest sea. The purposes of ABISMO are to inspect on the seabed in the deep sea and to obtain sediment samples from there. ABISMO consists of a launcher and a vehicle which is launched from the launcher and surveys on the seabed to determine the place for sampling. Core sampling system, which is exchangeable with a gravity piston type or a grab type, is equipped in the launcher. The both of the launcher and the vehicle have cameras to observe. One of the features of ABISMO is that the vehicle has crawlers in addition to thrusters in order to advance mobility. ABISMO is operated with the support ship KAIREI and dived by means of its onboard equipment including a primary cable. We conducted sea trials in January and September 2007 at the areas with the water depths up to 1,300m in Sagami Bay as primary function tests. And we conducted the third sea trial at Izu-Ogasawara trench in December 2007 and made the successful results of diving to the depths up to 9707 m and obtaining a sediment sample from the seabed in 9760 m water depth. This paper describes the features and the outline of ABISMO as well as the sea trial results.
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Katsui, Tokihiro, Tomoya Inoue, Kenta Izutani, Yuhi Nagaishi, Chang-Kyu Rheem, and Miki Y. Matsuo. "Considerations on Numerical Procedure for Stick-Slip Analysis of Drill String." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62158.
Texte intégralRésumé :
Stick-slip is one of the typical phenomenon which is observed in offshore drilling and considered as a critical problem for the drilling operation. The stick-slip makes a large fluctuation of drill bit rotation, even though the top of the drill pipe is rotating at a steady velocity and sometimes causes the damage of the drill bit. Additionally, it leads a crushing of the sediment layer which is a big problem especially for the scientific drilling [1][2][3]. The main purpose of the scientific drilling is to correct high quality core samples of sediment layers under the seabed. However, once the stick-slip occurs, it makes difficult to recover a high-quality sediment layer core sample. Therefore, it is necessary to detect the occurrence of stick-slip and its fundamental characteristics such as oscillation periods and amplitudes by simulation with the aid of surface drilling data, which can be monitored during the drilling operation to mitigate or prevent stick-slip. It would be advantageous to identify the characteristics of the stick-slip from the surface drilling data. The past study [4][5][6] investigated a numerical method to analyze the stick-slip by solving the NDDE (Neutral Delay Differential Equation) which is derived from torsional vibration equation. A small-scale model experiment was conducted in a water tank to observe the stick-slip phenomenon, and the result from the analytical model is evaluated with that obtained from the experiments. In this study, the numerical model is applied for the stick-slip analysis not only of the drill pipe model but also the actual drill pipe in operation. The solutions of the NDDE is depend on not the initial value but the initial history of the solution, because NDDE contains a delayed function term. Especially, the initial history settings have much effect on the numerical solution of NDDE in case of the actual drill pipe. Additionally, to solve the NDDE for stick-slip analysis, we must set some model parameters concerned with the frictional torque on drill bit. The present study investigated the effects of the initial history and the model parameters settings on numerical solutions in detail and presented an procedure to determine the appropriate settings of the initial history and the model parameters by reference to the measured top drive torque.
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Al-Shamary, Noora. "Assessment of Organic and Inorganic Pollutants along the Qatari Coast." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0036.
Texte intégralRésumé :
Qatar sits in the middle of the world’s most important hydrocarbon producing areas where significant regional refining activity and shipping traffic take place. In addition to significant local coastline, development prominently along the eastern coast, has taken place over recent decades. Protecting Qatar’s marine ecosystems from the adverse effects of environmental contaminants is a core component of the Environmental Development pillar within the National Vision 2030. However, a limited number of studies have investigated contaminant concentrations in the coastal environment of Qatar. The accumulation of contaminants in aquatic environments can affect coastal and marine ecosystems, and cause adverse effect on marine organisms and human health. This study aims to determine contamination in Qatar’s coastal environment by measuring organic and inorganic contaminants, along with physiochemical parameters, at four sites located on the contrasting east and west coast of the country. The Pearl Oyster Pinctada radiata, which is considered an iconic organism in Qatar, was used to determine a baseline of contaminants in an aquatic organism. Surface seawater, surface sediment and oysters were collected four times over two years in different seasons from the four sites. In-situ parameters (temperature, pH, and salinity), and abiotic parameters (TOC and grain sizes) were measured for seawater and sediment. Organic (TPHs, PAHs) and inorganic contaminants (trace metals including: Cd, Cu, Cr, Ni, Pb and Zn, T-Hg) were measured in all samples. Overall, Al Wakra (higher in boat traffic and fueling activities) on the east coast reported the highest levels of contaminants. High PAHs were observed in oyster tissues, while high Pb was noted in seawater and high Zn was observed in sediment and oyster. Benzo (a) pyrene was the highest compound detected in oyster. However, high TPHs were also noted in oyster tissues from Simaisma. At Al Khor, also on the east coast, high level of TPHs were recorded in seawater, while high PAHs and TOC observed in surface sediment, which had a relatively higher clay and silt content than other sites. Umm Bab (with a desalination plant near the coast), the sole sample site on the west coast, showed the highest level of TOC in seawater and sediment, highest Ni in seawater and highest total mercury in oyster. Our results, in general, report lower levels in seawater and sediment compared to other studies in the region and more widely; however, in oysters most of the contaminants are higher when compared to international guideline values. These higher levels indicate the potential for these filter-feeding organisms to absorb contaminants into their tissues from the environment that surrounds them. Additionally, bioaccumulation can occur. This study provides background information for further investigation to understand the presence and distribution of organic and inorganic contaminants in Qatar’s rapidly changing coastal environment. It indicates the usefulness of applying a holistic view to environmental monitoring including the use of biomonitoring.
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Kuo, Matthew Y.-H., and Malcolm D. Bolton. "Faecal Pellets in Deep Marine Soft Clay Crusts: Implications for Hot-Oil Pipeline Design." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49399.
Texte intégralRésumé :
In recent years, the presence of crusts within near surface sediments found in deep water locations off the west coast of Angola has been of interest to hot-oil pipeline designers. The origin for these crusts is considered to be of biological origin, based on the observation of thousands of faecal pellets in natural crust core samples. This paper presents the results of laboratory tests undertaken on natural and faecal pellet-only samples. These tests investigate the role faecal pellets play in modifying the gemechanical behaviour of clayey sediments. It is found that faecal pellets are able to significantly alter both the strength and the average grain-size of natural sediments, and therefore, influence the permeability and stiffness. Hot-oil pipelines self-embed into and subsequent shear on crusts containing faecal pellets. Being able to predict the time required for installed pipelines to consolidate the underlying sediment and thus, how soon after pipe-laying, the interface strength will develop is of great interest to pipeline designers. It is concluded from wet-sieving samples before and after oedometer tests, that the process of pipe laying is unlikely to destroy pellets. They will therefore, be a major constituent of the sediment subject to soil-pipeline shearing behaviour during axial pipe-walking and lateral buckling. Based on the presented results, a discussion highlighting the key implications for pipeline design is therefore provided.
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Komai, Yukio, Yukio Komai, Mana Sakata, et al. "RELEASE OF NUTRIENTS FROM BOTTOM SEDIMENTS IN OSAKA BAY, JAPAN IN 2015." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b937eec5797.84530079.
Texte intégralRésumé :
Osaka Bay is the most polluted enclosed sea area, in which is located the eastern part of the Seto Inland Sea, Japan. There are four kinds of sources on loadings of nutrients to Osaka Bay, which are land including rivers and industrial effluents beside coast, ocean sea water, release from bottom sediment to sea water, and wet and dry deposition from air. The pollutant loadings inflowing from the land to Osaka Bay have been cut by various policies since 1970’s. The concentrations of nutrients in the inner part of Osaka Bay have showed an obvious decreasing tendency. However, the water quality in offshore sea has not satisfied the environmental standard on nutrients. We investigated the amount of nutrients released from bottom sediments. The core samples were taken at two stations in the inner part of Osaka Bay once a month from February to November, 2015. The core incubation experiment in laboratory was conducted for 24 hours according to Tada et.al. The concentrations of ammonium nitrogen (NH4-N) and phosphate phosphorus (PO4-P) were measured by an automatic analyzer. The flux showed similar range with the values investigated in 1986. The results suggested that the flux of nutrients from bottom sediments in the inner part of Osaka Bay has not decreased during summer season at least since 1985. Therefore, the contribution of release from bottom sediment on the nutrients budget would relatively become larger in inner part of Osaka Bay.
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Komai, Yukio, Yukio Komai, Mana Sakata, et al. "RELEASE OF NUTRIENTS FROM BOTTOM SEDIMENTS IN OSAKA BAY, JAPAN IN 2015." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b43154dd828.
Texte intégralRésumé :
Osaka Bay is the most polluted enclosed sea area, in which is located the eastern part of the Seto Inland Sea, Japan. There are four kinds of sources on loadings of nutrients to Osaka Bay, which are land including rivers and industrial effluents beside coast, ocean sea water, release from bottom sediment to sea water, and wet and dry deposition from air. The pollutant loadings inflowing from the land to Osaka Bay have been cut by various policies since 1970’s. The concentrations of nutrients in the inner part of Osaka Bay have showed an obvious decreasing tendency. However, the water quality in offshore sea has not satisfied the environmental standard on nutrients. We investigated the amount of nutrients released from bottom sediments. The core samples were taken at two stations in the inner part of Osaka Bay once a month from February to November, 2015. The core incubation experiment in laboratory was conducted for 24 hours according to Tada et.al. The concentrations of ammonium nitrogen (NH4-N) and phosphate phosphorus (PO4-P) were measured by an automatic analyzer. The flux showed similar range with the values investigated in 1986. The results suggested that the flux of nutrients from bottom sediments in the inner part of Osaka Bay has not decreased during summer season at least since 1985. Therefore, the contribution of release from bottom sediment on the nutrients budget would relatively become larger in inner part of Osaka Bay.
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Inoue, Tomoya, Tokihiro Katsui, Kohtaro Ujiie, and Junya Ishiwata. "Utilization of Surface Drilling Data for Estimation of Sediment Properties in Scientific Drilling of Tohoku Earthquake Zone." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41750.
Texte intégralRésumé :
Japan Agency for Marine-Earth Science and Technology (JAMSTEC) operates the scientific deep-sea drilling vessel Chikyu, which undertook the drilling project under Japan Trench Fast Drilling Program (JFAST) to determine the mechanism of the catastrophic Tohoku Earthquake and the resulting huge tsunami. As targeted drilling sites were located about 1,000 m below the seafloor, at water depths of 7,000 m, JFAST was a challenging deep riserless drilling. Drilling operation can also provide information on the properties of the drilling layer. This is important as a main aim of the scientific drilling is to obtain core samples from sediment layers under the seabed for evaluating sediment properties. Even a rough estimate of sediment properties could potentially provide an important notice for conducting coring operations. Thus, we attempted to estimate properties of sediment layers using surface drilling data, such as drilling torque acquired from JFAST, and compare with properties of the core samples. As shear stress of sediment is a key parameter, it was estimated from surface drilling data. It was then compared with shear stress data determined from laboratory tests using core samples, and data from temperature sensors set in borehole.
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Cardona, Alejandro, Athma R. Bhandari, and Peter B. Flemings. "Geomechanical Properties of Hydrate-Bearing Sediments from the Gulf of Mexico - Viscoplastic Behavior." In 58th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2024. http://dx.doi.org/10.56952/arma-2024-0779.
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ABSTRACT: The geomechanical behavior of hydrate-bearing sandy silts controls in-situ stresses and compression upon hydrate dissociation. Here, we measure the uniaxial strain compression of natural hydrate-bearing (pressure cores) and hydrate-free reconstituted samples from Green Canyon 955 - deepwater Gulf of Mexico. We document these hydrate-bearing sandy silts behave viscoplastically. Under constant strain rate compression under uniaxial strain conditions, sandy-silts with hydrate are stiffer but have a larger uniaxial lateral stress ratio (K0) than equivalent non-hydrate-bearing sediments. When we pause the compression, the stress ratio increases towards K0 = 1.0 in the hydrate sample, whereas the K0 remains constant for the hydrate-free sample. We develop a model to link these experimental observations quantitatively. Our model assumes that the hydrate phase and the sediment skeleton share any applied external load. Model results show the hydrate phase bears a more significant fraction of the applied load because the hydrate is less compressible than the sediment skeleton. The viscoplastic behavior of hydrate-bearing sediments will impact gas production and in situ stresses. For example, viscous deformation away from the production zone affects water flow, affecting gas and water flow rates closer to the well. Furthermore, the time dependency of the stress ratio may affect hydraulic fracturing strategies in these reservoirs as the rate of pressurization may impact stress evolution on the wellbore. 1. INTRODUCTION Gas hydrates are crystalline solids with guest molecules trapped within water lattices (Sloan and Koh 2007). In natural environments, methane is the most common guest molecule. These compounds are stable at high pressure and low temperature, which delimits their geological distribution to permafrost and submarine settings (Boswell and Collett 2011). Methane hydrates are envisioned as a new energy resource and an active component in the carbon cycle. Silt- and sand-rich marine environments commonly host high concentrations of hydrates. Coarse-grained deposits in Green Canyon 955 (GC 955) - Gulf of Mexico (Flemings et al. 2020; Meazell et al. 2020), Krishna-Godavari Basin offshore India (Collett et al. 2019), and in the eastern Nankai Trough in offshore Japan (Komatsu et al. 2015) contain hydrate saturations exceeding 80%.
Rapports d'organisations sur le sujet "Sediment core sample"
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Brooks, G. R. Thickness record of varves from glacial Ojibway Lake recovered in sediment cores from Frederick House Lake, northeastern Ontario. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329275.
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The thicknesses of 384 rhythmic couplets were measured along a composite sequence of glacial Lake Ojibway glaciolacustrine deposits recovered in two sediment cores from Frederick House Lake, Ontario. The visual comparison of distinctive couplets in the CT-scan radiographs of the Frederick House core samples to photographs of core samples from Reid Lake show a match of ±1 varve number from v1656-v1902, and ±5 varve numbers between v1903-v2010, relative to the regional numbering of the Timiskaming varve series. There are two interpretations for the post-v2010 couplets that fall within the Connaught varve sequence of the regional series. In the first, the interpreted numbering spans from v2066-v2115, which produces a gap of 55 missing varves equivalent to v2011-v2065, and corresponds to the original interpretation of the Connaught varve numbering. The second spans v2011a-v2060a, and represents alternative (a) numbering for the same varves. Varve thickness data are listed in spreadsheet files (.xlsx and .csv formats), and CT-Scan radiograph images of core samples are laid out on a mosaic poster showing the interpreted varve numbering and between-core sample correlations of the varve couplets.
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Friske, P. W. B., and M. W. McCurdy. Results of a detailed infill lake-sediment survey in the Snow Lake area: evaluation and comparison of grab sample and short core data. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1996. http://dx.doi.org/10.4095/207590.
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Knight, R. D., and H. A. J. Russell. Quantifying the invisible: pXRF analyses of three boreholes, British Columbia and Ontario. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331176.
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Portable X-ray fluorescence (pXRF) technology collects geochemical data at a fraction of the cost of traditional laboratory methods. Although the pXRF spectrometer provides concentrations for 41 elements, only a subset of these elements meet the criteria for definitive, quantitative, and qualitative data. However, high-quality pXRF data obtained by correct application of analytical protocols, can provide robust insight to stratigraphy and sediment characteristics that are often not observed by, for example, visual core logging, grain size analysis, and geophysical logging. We present examples of geochemical results obtained from pXRF analysis of drill core samples from three boreholes located in Canada, that demonstrate: 1) Definitive stratigraphic boundaries observed in geochemical changes obtained from 380 analyses collected over 150 m of core, which intersects three Ordovician sedimentary formations and Precambrian granite. These boundaries could not be reconciled by traditional visual core logging methods. 2) Significant elemental concentration changes observed in 120 samples collected in each of two ~120 m deep boreholes located in a confined paleo-glacial foreland basin. The collected geochemical data provide insight to sediment provenance and stratigraphic relationships that were previously unknown. 3) Abrupt changes in the geochemical signature in a subset of 135 samples collected from a 151 m deep borehole intersecting Quaternary glacial derived till, sands, and ahomogeneous silt and clay succession. These data provide a platform for discussion on ice sheet dynamics, changes in depositional setting, and changes in provenance. Results from each of these studies highlights previously unknown (invisible) geological information revealed through geochemical analyses. A significant benefit of using pXRF technology is refining sampling strategies in near real time and the ability to increase sample density at geochemical boundaries with little increase in analysis time or budget. The data also provide an opportunity to establish a chemostratigraphic framework that complements other stratigraphic correlation techniques, including geophysical methods. Overall, data collected with pXRF technology provide new insights into topics such as spatial correlations, facies changes, provenance changes, and depositional environment changes.
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Bridges, Todd, Sandra Newell, Alan Kennedy, et al. Long-term stability and efficacy of historic activated carbon (AC) deployments at diverse freshwater and marine remediation sites. Engineer Research and Development Center (U.S.), 2020. http://dx.doi.org/10.21079/11681/38781.
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A number of sites around the United States have used activated carbon (AC) amendments to remedy contaminated sediments. Variation in site-specific characteristics likely influences the long-term fate and efficacy of AC treatment. The long-term effectiveness of an AC amendment to sediment is largely unknown, as the field performance has not been monitored for more than three years. As a consequence, the focus of this research effort was to evaluate AC’s long-term (6–10 yr) performance. These assessments were performed at two pilot-scale demonstration sites, Grasse River, Massena, New York and Canal Creek, Aberdeen Proving Ground (APG), Aberdeen, Maryland, representing two distinct physical environments. Sediment core samples were collected after 6 and 10 years of remedy implementation at APG and Grasse River, respectively. Core samples were collected and sectioned to determine the current vertical distribution and persistence of AC in the field. The concentration profile of polychlorinated biphenyls (PCBs) in sediment pore water with depth was measured using passive sampling. Sediment samples from the untreated and AC-treated zones were also assessed for bioaccumulation in benthic organisms. The data collected enabled comparison of AC distribution, PCB concentrations, and bioaccumulation measured over the short- and long-term (months to years).
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Løvschal, Mette, and Havananda Ombashi. Palynological Sampling in Western Jutland 2021-22: Anthea Work Package #2. Det Kgl. Bibliotek, 2023. http://dx.doi.org/10.7146/aulsps-e.478.
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A palynological sampling programme was carried out in three areas of Western Jutland in 2021-22. Our goal was to collect new sediment samples from archaeological excavations and peat deposits to reconstruct patterns in past heathland use and development. The location of the case areas was determined by the potential of the sites for combination with existing palynological data (Solsø Hede) and/or archaeological data (the Vejen area). At Solsø Hede, a pollen core was obtained near Solsø. At Vejen, two separate sediment collections took place. To the north of Vejen, in Gammelby Mose, peat sediments were collected. To the south of Vejen, at Kongehøj, 15 samples were collected from a Bronze Age house floor plan. The sampling programme formed part of the research project called ANTHEA (Løvschal 2021), which focuses on the deep history of anthropogenic heathlands. The project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 853356).
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Serne, R. Jeffrey, Bruce N. Bjornstad, Herbert T. Schaef, et al. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples. Office of Scientific and Technical Information (OSTI), 2002. http://dx.doi.org/10.2172/15001166.
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Serne, R. Jeffrey, Bruce N. Bjornstad, Herbert T. Schaef, et al. Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples. Office of Scientific and Technical Information (OSTI), 2008. http://dx.doi.org/10.2172/938580.
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Fourqurean, James, Johannes Krause, Juan González-Corredor, Tom Frankovich, and Justin Campbell. Caricas Partner's Practical Field and Laboratory Guide. Florida International University, 2024. http://dx.doi.org/10.25148/merc_fac.2024.32.
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This field and laboratory guide describes the field and laboratory methods used to characterize blue carbon in seagrass meadows. It was developed for the Caribbean Carbon Accounting in Seagrass project and describes the protocols and methods used by the network. In brief, at each project site, seagrass abundance, species composition, canopy height, and sediment type were assessed at sixteen 0.25 m2 quadrats placed at random locations within the site. Eight 20 cm diameter cores were taken to assess seagrass biomass, shoot density, and to provide the material for assessing seagrass carbon and nutrient content. All seagrasses within each of the eight cores were separated by species and tissue type, washed and scraped to remove epiphytes, then dried and weighed. A piston core of uncompressed soils was retrieved, to a depth of 1 m or until refusal. Cores were subsampled at 5 cm depth intervals using small subcorers. All subcores were weighed wet to permit the calculation of porosity and soil dry bulk density. Seagrass tissue and sediment samples were oven-dried at 60°C, and dry weight recorded. Finally, samples were analyzed in the laboratory for determination of Loss on Ignition, total carbon content, inorganic carbon content, organic carbon content, and carbon and nitrogen content as well as stable isotope ratios. The resulting data allow for the estimation of seagrass organic carbon stocks as well as nutrient and carbonate stocks in biomass and sediment, their relationship with environmental covariates, and the contribution of seagrass material to carbon stocks.
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Kneafsey, Timothy J., Yongkoo Seol, George J. Moridis, Liviu Tomutsa, and Barry M. Freifeld. Laboratory measurements on core-scale sediment/hydrate samples topredice reservoir behavior. Office of Scientific and Technical Information (OSTI), 2005. http://dx.doi.org/10.2172/929088.
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Sommer, Stefan, and Andrew W. Dale. Field-experiment to determine the short-term impact of bottom trawling on the benthic ecosystem in the German coastal Baltic Sea - Cruise No. AL616, 18.07. – 09.08.2024, Kiel (Germany) – Kiel (Germany), MGF-OSTSEE-2024. GEOMAR Helmholtz Centre for Ocean Research Kiel, 2025. https://doi.org/10.3289/cr_al616.
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Within the BMBF funded second phase of the DAM project „Ausschluss mobiler grund-berührender Fischerei (MGF) in marinen Schutzgebieten der Ostsee – Phase II (MGF-Ostsee-II)“ an experimental field study has been conducted to determine the effects of bottom trawling on the benthic ecosystem of the German coastal Baltic Sea. An area characterized with low fishing activity was selected in the Mecklenburger Bight ca. 5 km north of the town Kühlungsborn based on geo-acoustic and sedimentological criteria. In a part of this area referred to as High Impact area, high intensity trawling was simulated by performing several trawls, whereas in the neighboring control area the sediments were undisturbed. Both areas were repeatedly investigated over a period of 3 weeks using biogeochemical sediment analyses, in situ benthic flux measurements and visual seafloor inspection to determine the response and changes of the benthic ecosystem to the trawling impact. Further biogeochemical analyses were conducted in sediment push cores taken by divers from specific sediment features of trawl mark tracks. In addition, physico-chemical investigations were carried out of the suspended particle plume generated during trawling as well as seafloor imaging to decipher the degree of disturbance and redistribution of sediments possibly affecting benthic communities. A total of 97 stations were sampled, including 38 MUC casts, 18 XOFOS surveys, 10 BIGO, 6 DSR and 7 CTD/water sampling rosette deployments. (Alkor-Berichte AL616)