Dissertations / Theses: 'Marie Clay'

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Judd, Mariane, and n/a. "The efficacy of a reading recovery program or an extra lesson program in comparison to no intervention for children having difficulty reading in their second year at school." University of Canberra. Professional & Community Education, 1996. http://erl.canberra.edu.au./public/adt-AUC20060803.131535.

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The purpose of the study was to investigate the efficacy of a 'Reading Recovery' or an 'Extra Lesson' program in comparison to no intervention for children having difficulty reading in their second year at school. 'Reading Recovery' is an intervention program developed by Marie Clay to assist children who are showing signs of having difficulty learning to read after the first year at school. 'Reading Recovery' uses a whole language approach. The assumption is that given a second chance in a 1:1 structured learning environment, with a trained Reading Recovery teacher, the child will learn to read at an age appropriate level. The 'Extra Lesson' intervention is based on the paradigm of Rudolf Steiner's concept of education, which is a holistic developmental approach. The assumption is that there is a relationship between learning and development in the first seven years of the child's life. The 'Extra Lesson' assessment tests for and identifies developmental difficulties within the first seven years of the child's life and skills testing clarifies if the child has any significant learning difficulty. The 'Extra Lesson' intervention is a 1:1 program, based on a holistic developmental perspective of Rudolf Steiner, to work with the child's difficulties. The efficacy of both interventions was evaluated by using a case study design with embedded forms of analysis and a pre-test post-test non equivalent control group quasi-experimental design to measure the changes in the children's reading skills, processing speed, short term auditory memory and awareness of body geography. Follow up tests were administered 10 months after the post-tests. Case studies have been used to present the data collated for individual subjects and graphs were used for the analysis of group data. All the subjects showed an improvement in reading skills from the pre to the post-test. At follow up all the subjects tested continued to show an improvement in reading skills. Both interventions were shown to affect the subjects reading skills. A comparison of groups showed a slight measurable difference between the 'Reading Recovery', 'Extra Lesson' and Control group, with the 'Extra Lesson' showing a slightly larger improvement in sight word recognition. The treatment and Control groups' Writing Vocabulary increased from the pre to the post-test. The 'Reading Recovery' and Control groups' Writing Vocabulary decreased and the Extra Lesson group continued to improve at follow up. All the groups showed an improvement in short term auditory memory at the post-test and the Control and 'Extra lesson' groups continued to increase slightly at follow up and the 'Reading Recovery' group remained relatively constant. All the groups had relatively constant scores on Processing Speed from the pre to the post- test and at follow up. Neither intervention showed a measurable effect on Processing Speed. All the groups showed an improvement in graphical representation of body geography at the post-test and at follow up. The 'Extra Lesson' group showed the largest improvement at the post-test and long-term. The 'Extra Lesson' intervention had a positive and measurable effect on graphical representation of body geography after the intervention and long-term.

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Taha, Ahmed M. "Interface Shear Behavior of Sensitive Marine Clays --Leda Clay." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28768.

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Leda clay, which is a type of sensitive marine clay in Canada, is a hazardous soil that could undergo sudden collapse and flow upon wetting and remolding. This type of soil causes many landslide disasters and foundation damage. The existence of Leda clay at or near the proximities of developed cities makes it challenging for infrastructure expansion, and therefore, challenging for geotechnical engineers. At the location where this sensitive marine clay exists, many foundation designers have adopted the use of deep foundations, such as pile foundations to support heavy structures. The shear behavior and strength parameters at the interface between the (friction) pile and soil are key design parameters. A sufficient knowledge of these interface shear behaviors and strength parameters is also essential for the safe and cost-effective design of several other geotechnical structures (e.g., retaining walls, reinforced soils, and buried structures). However, no studies have yet been implemented on the interface shear behavior between Leda clay and structural material. There is therefore, a need to generate more knowledge about the interface shear behavior of Leda clay. This thesis deals with an experimental study of the shear behavior at the interface between Leda clay and structural material, such as steel and concrete. The effects of several factors, such as surface roughness of the construction material, Leda clay's overconsolidation ratio (OCR), saturation degree, density, and salt content on interface shear behavior are also investigated. Laboratory tests have been carried out by using an automatic direct shear machine connected to a linear variable differential transformer (LVDT), loading cell and a data logging system. The results of the interface shear tests show that under consolidated drained (CD) and saturated conditions, the interface friction angle increases with an increase in the clay's OCR. The results also indicate that increasing the salinity of Leda clay's pore water enhances its frictional resistance at the interface. Furthermore, the results reveal that Leda clay with a higher dry density shows higher interface shear resistance. On the other hand, the results also show that the interface shear resistance decreases as the degree of saturation of the Leda clay increases.

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So, Tze-chung, and 蘇子頌. "Engineering behaviour of Hong Kong marine clay during vacuum preloading." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41634147.

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So, Tze-chung. "Engineering behaviour of Hong Kong marine clay during vacuum preloading." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41634147.

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Panikom, Nattawadee. "Climate Change Impact on Rainfall-Induced Landslides in Ottawa Sensitive Marine Clays." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41041.

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The City of Ottawa is situated in an area known as the Champlain Sea, 17,000 years before present (BP) the entire area was covered with sea water. This area deposited marine clays which are known to be highly sensitive. The City of Ottawa needs to expand land use to allow for the expansion of infrastructure and housing to support its growth. This study is intended to assist the City of Ottawa’s geotechnical engineers in their decision-making by identifying future sensitive areas prone to landslides due to rainfall based on future climate model data. The project incorporates rainfall intensities from downscaled climate model data in the Transient Rainfall Infiltration and Grid-based Regional Slope-Stability (TRIGRS) model to investigate areas sensitive to landslides, then within a GIS platform, the future landslide susceptibility maps were created based on Factor of Safety (FS) values showing the areas prone to landslides. The data input for the model includes climate model data, topography, hydrogeology, geology and geophysical data obtained from a previous study. These data were prepared using ArcGIS software and converted into ascii format for TRIGRS model. The model was calibrated using historical rainfall intensities and validated by comparing to historical landslide areas. Sensitivity analysis were performed to ranges of geotechnical properties found within sensitive marine clays in the area to find the values best to create the ideal scenario, normal scenario and worst-case model scenario for the prediction. Rainfall intensities from projected climate data Intensities Duration Frequency (IDF) of 10 years and 50 years returning period and rainfall intensities of 12 hr, 24 hr, and 48 hr were selected for the model. Results from simulations find the projected climate rainfall intensity do not have impact or has minimal impact to slope stability in sensitive marine clay areas in Ottawa directly. However, higher rainfall runoff is expected from projected rainfall RCP8.5 than the RCP4.5. The infiltration rate remains constant throughout each simulation, which is the same value as the hydraulic conductivity. The time when the slope becomes unstable varies depending on initial water levels. Results from the ideal and normal scenario show no areas prone to slope failure after 48 hours of rainfall duration. However, the factor of safety decreases as the rainfall duration increases and is expected to decrease with longer rainfall durations. The worst-case scenario shows some areas prone to slope failure (FS < 1) with 2% probability of slope failure at 48 hours of rainfall duration. The distribution of these unstable areas are located along the Ottawa River, Rideau River, Carp River, Mississippi River and valleys along their tributaries, the majority of the area prone to slope instability from rainfall are in the east part of the City of Ottawa. While there are many uncertainties and limitations which contribute to the model results, this study is useful to engineers and planners in initial implementation of mitigation strategies to mitigate the damages and cost from landslides events. The susceptibility maps can also assist in decision making for planners in developing into these areas.

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Nader, Athir. "Engineering Characteristics of Sensitive Marine Clays - Examples of Clays in Eastern Canada." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30670.

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Sensitive marine clay in Ottawa is a challenging soil for geotechnical engineers. This type of clay behaves differently than other soils in Canada or other parts of the world. They also have different engineering characteristic values in comparison to other clays. Cone penetration testing in sensitive marine clays is also different from that carried out in other soils. The misestimation of engineering characteristics from cone penetration testing can result. Temperature effects have been suspected as the reason for negative readings and erroneous estimations of engineering characteristics from cone penetration testing. Furthermore, the applicability of correlations between cone penetration test (CPT) results and engineering characteristics is ambiguous. Moreover, it is important that geotechnical engineers who need to work with these clays have background information on their engineering characteristics. This thesis provides comprehensive information on the engineering characteristics and behaviour of sensitive marine clays in Ottawa. This information will give key information to geotechnical engineers who are working with these clays on their behaviour. For the purpose of this research, fifteen sites in the Ottawa area are taken into consideration. These sites included alternative technical data from cone and standard penetration tests, undisturbed samples, field vanes, and shear wave velocity measurements. Laboratory testing carried out for these sites has resulted in acquiring engineering parameters of the marine clay, such as preconsolidation pressure, overconsolidation ratio, compression and recompression indexes, secondary compression index, coefficient of consolidation, hydraulic conductivity, clay fraction, porewater chemistry, specific gravity, plasticity, moisture content, unit weight, void ratio, and porosity. This thesis also discusses other characteristics of sensitive marine clays in Ottawa, such as their activity, sensitivity, structure, interface shear behaviour, and origin and sedimentation. Furthermore, for the purpose of increasing local experience with the use of cone and ball penetrometers in sensitive marine clays in Ottawa, three types of penetrometer tips are used in the Canadian Geotechnical Research Site No. 1 located in south-west Ottawa: 36 mm cone tip, and 40 mm and 113 mm ball tips. The differences in their response in sensitive marine clays will be discussed. The temperature effects on the penetrometer equipment are also studied. The differences in the effect of temperature on these tips are discussed. Correlations between the penetrometer results and engineering characteristics of Ottawa's clays are verified. The applicability of correlations between the testing results and engineering characteristics of sensitive marine clays in Ottawa is also presented in this thesis. Two correlations from the Canadian Foundation Engineering Manual are examined. One of these correlations is between the N60 values from standard penetration testing and undrained shear strength. The other correlation is between the shear wave velocity measurement and site class. Temperature corrections are suggested and discussed for penetrometer equipment according to laboratory calibrations. The significance of the effects due to radical temperature changes in Canada and Ottawa is discussed. Some of the main findings from this research are as follows. • The Canadian Foundation Engineering Manual presents a correlation between standard penetration tests (SPTs) and the undrained shear strength of soils. This relationship may not be applicable to sensitive marine clays in Ottawa. • Another correlation between the site class, shear wave velocity, and undrained shear strength is presented by this same manual which may not be applicable to sensitive marine clays in Ottawa. • The rotation rate for field vane testing as recommended by ASTM D2573 is slow for sensitive marine clays in Ottawa. • Correction factors applied to undrained shear strength from laboratory vane tests may not result in comparable values with the undrained shear strength obtained by using field vane tests. • Loading schemes in consolidation or oedometer testing may affect the quality of the targeted results. • Temperature corrections should be applied to penetrometer recordings to compensate for the drift in the results of these recordings due to temperature changes. • The secondary compression index to compression index ratio presented in the literature may not be the value obtained from this research.

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Sam, Wa Ngai. "Numerical modeling of embankment on soft marine clay stabilized by vertical drains." Thesis, University of Macau, 2003. http://umaclib3.umac.mo/record=b1445106.

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Arulrajah, Atputharajah. "Field measurements and back-analysis of marine clay geotechnical characteristics under reclamation fills." Curtin University of Technology, Department of Civil Engineering, 2005. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16008.

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Due to the scarcity of land at coastal regions around the world, land reclamation is commonly carried out for the future expansion of various infrastructure facilities. Marine clay is present at the coastal regions of Southeast Asia. Land reclamation on this highly compressible soil foundation often requires the use of soil improvement works to eliminate significant future settlements from occurring. The combination of prefabricated vertical drains with preloading is one of the most widely used ground improvement methods in land reclamation projects. The best means available for field measurement and back-analysis of the marine clay geotechnical characteristics under reclamation fills is by carrying out extensive field instrumentation and in-situ tests. In-situ testing of marine clay was carried out at a test site. In-situ penetration testing was used to analyse the degree of consolidation, the improved shear strengths, overconsolidation ratio and the effective stress of marine clay prior to reclamation as well as after surcharge loading. In-situ dissipation testing was used to determine the coefficient of consolidation due to horizontal flow and horizontal hydraulic conductivity of the marine clay prior to reclamation as well as after surcharge loading. The in-situ penetration and dissipation tests were carried out by means of the field vane shear, piezocone, dilatometer, self-boring pressuremeter and BAT permeameter. Field instrumentation methods, assessment and hack-analysis of marine clay behaviour under reclamation fills forms the crux of this research.
The factors that affect the field instrumentation assessment of marine clays treated with prefabricated vertical drains, forms an integral part of this research study. Settlement gauges and piezometers were used to monitor the performance of the vertical drains and to assess the degree of consolidation of the improved soil at two case study sites. The field settlement data were back-analysed by the Asaoka and Hyperbolic methods to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement and piezometer monitoring data also enabled the coefficient of consolidation due to horizontal flow to be closely estimated. Finite element modeling of marine clay and prefabricated vertical drains was carried out and compared with the field surface settlement results at the two case study sites.

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王偉洪 and Wai-hung Wong. "A study of constitutive models on engineering properties of Hong Kong marine clay." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31214745.

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Wong, Wai-hung. "A study of constitutive models on engineering properties of Hong Kong marine clay /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18650399.

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Vaughan, Andrew P. "Mechanisms of enrichment and diagenesis of uranium in organic-rich shales of the Kimmeridge Clay Formation." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244734.

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Ho, Sao Man. "Numerical modeling of consolidation of marine clay under vacuum preloading incorporating prefabricated vertical drains." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2182937.

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Castillo, M., M. Castillo, K. Hernández, J. Rodriguez, and C. Eyzaguirre. "Low Permeability Concrete for Buildings Located in Marine Atmosphere Zone using Clay Brick Powder." Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/651761.

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The concrete is not one hundred percent impermeable since the water that remains inside it causes its corrosion, in the case of reinforced concrete, exposed in an area of marine atmosphere, the sea salt mostly present in large particles of the marine spray, produce the reduction of the alkalinity of the concrete causing a rapid corrosion of the steel. There are buildings built in this marine area that have been designed without durability criteria, in which the use of pozzolanic materials is considered, for example, to fill the pores of the cement matrix and thus guarantee its impermeability. In the present study, the effect of clay brick powder (PLA) as a replacement for cement in concrete manufacturing is addressed, evaluating different characteristics of its components. The results indicate that pozzolanic activity and compressive strength increase, slump, voids content and the coefficient of permeability to water decreases.

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Shi, Xuan Tao. "Experimental investigation on the consolidation and very small-strian stiffness properties of Macau marine clay." Thesis, University of Macau, 2008. http://umaclib3.umac.mo/record=b1783628.

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Al-Umar, Mohammad. "GIS Based Assessment of Climate-induced Landslide Susceptibility of Sensitive Marine Clays in the Ottawa Region, Canada." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37218.

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Landslides are relatively frequent in Ottawa due to the presence of sensitive marine clays (Leda clay or Champlain Sea clay), and the presence of natural or climatic triggers such as rainfall or snowmelt. A geographic information system (GIS) based modeling tool has been developed to assess and predict climate (rainfall and snowmelt)-induced landslides in the sensitive marine clays of the Ottawa region. The Transient Rainfall Infiltration and Grid-based Regional Slope-Stability (TRIGRS) model is used in a GIS framework to investigate the influence of rainfall and snowmelt on shallow landslides through the Ottawa region, with respect to time and location. First, the GIS and TRIGRS models are combined to assess landslide susceptibility with respect to rainfall. The GIS-TRIGRS approach requires topographic, geologic, hydrologic, and geotechnical information of the study area. In addition to this technical information (input data), rainfall intensity data for different durations (5 minutes, and 6, 12, 18, and 24 hours), and historical data of the regional landslides is required. This data is used to verify the locations of predicted landslide-susceptible areas with respect to historical landslide maps in the area. The generated results from the GIS-TRIGRS model were verified by comparing the predicted and historical locations of shallow landslides induced by rainfall throughout the Ottawa region. The comparison results showed a high correlation between the predicted areas of landslides and the previously reported landslides. In addition, the results also indicated that not all previous landslides in Leda clays were triggered by rainfall. The second application of the developed GIS-TRIGRS approach was used to assess and predict snowmelt-induced landslides in areas of sensitive marine clay in the Ottawa region. Similar to the first analysis, the approach requires the following input data: topographic, geologic, hydrologic, geotechnical, snowmelt intensity data for various periods (6–48 hours, 3–15 days, 25 days, and 30 days), This approach also requires data indicating the location of historical landslides in the study area. Using this data, we examine both the timing and location of shallow landslides due to snowmelt in a GIS-based framework. The developed model was validated by comparing the predicted landslide-susceptible areas to historical landslide maps in the study area. A high correlation between predicted and historical landslide location trends was obtained, confirming that the developed GIS-TRIGRS model can predict the snowmelt-induced landslide susceptibility in the sensitive marine clays relatively well. The model results reinforced the conclusion that areas with high slopes and sensitive marine clays were more prone to snowmelt-induced landslides. Finally, in a Geographic Information System (GIS) the landslide occurrence susceptibility in the Ottawa area was modeled. Results of such models are presented as maps showing landslide susceptibility in Champlain Sea clays (Leda clays) in the Ottawa area due to both rainfall and snowmelt. Various input data was collected and entered into a GIS and TRIGRS model. The main categories of such inputs are climate, topography, geology, hydrology, and geotechnical data. The rainfall and snowmelt intensity data was extracted for 24 to 48 hour periods from Environment and Climate Change Canada historical climate records. Thereafter, the factor of safety was calculated in order to determine the stability of slopes across the study area. The model assesses the effects of rainfall and snowmelt on landslide occurrence, and based on the calculated factor of safety at each pixel of the study area, the model calculates the landslide susceptibility. The results presented in this thesis will provide a geotechnical basis for making appropriate engineering decisions during slope management and land use planning in the Ottawa region.

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Sousa, Joana. "Study of broodstock conditioning and determination of markers of gamete quality in the european clam Ruditapes decussatus." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0034/document.

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La palourde grise européenne, Ruditapes decussatus est un coquillage d’importance socio-économique en Europe du Sud. Sa production est basée sur le recrutement naturel, qui est sujet à de fortes fluctuations annuelles. Au Portugal, les principales zones de production de cette espèce sont les lagunes de Ria de Aveiro et Ria Formosa. Ces populations présentent des réponses différentes à l'induction de la ponte, résultat d’intérêt dans un contexte d'amélioration de la production aquacole. L'objectif de cette thèse était d'améliorer les connaissances sur la reproduction de R. decussatus en utilisant des approches génomiques et cellulaires avec pour principales applications : le conditionnement de géniteurs et la qualité des gamètes.Le cycle de reproduction de ces populations a été caractérisé par histologie pour le développement gonadique, l’aire gonadique et le diamètre de l’ovocyte. À l'exception de la dynamique de la gamétogénèse, aucune différence significative n’a été identifiée entre populations. Grâce à un effort de séquençage (Illumina) de banque d’ADNc de différents tissus/stades pour enrichir en transcrits liés à la reproduction, une puce à ADN (oligoarray) représentant 51 678 contigs a été produite et utilisée afin de caractériser les bases transcriptomiques de la reproduction de R. decussatus. Des gènes différentiellement exprimés et la voie “N-Glycan biosynthesis”, impliquées dans l'interaction spermatozoïde – ovocyte, ont été soulignés, ce qui suggère que la reconnaissance entre gamètes puisse expliquer en partie les différences de succès d'induction de ponte entre ces populations. De plus, le transcriptome d’ovocytes collectés chez 15 femelles a été analysé par puce à ADN avec pour objectif d'identifier des potentiels marqueurs de la qualité des ovocytes. Des gènes codant pour des protéines chaperonnes, dont certains caractérisés comme des ARNm maternels essentiels pour le développement précoce, sont apparus différentiellement exprimés entre ovocytes de bonne et mauvaise qualité établie sur le taux de larves D obtenu. La présente étude fournit de nouvelles informations génomiques précieuses pour la compréhension de la reproduction de cette espèce et liste des gènes candidats codant la protéine disulforide isomerase (PDI), des calmodulines et la caspase 8 comme points de départ possibles pour des études fonctionnelles. Leur implication dans les phases importantes de la reproduction comme l’interaction spermatozoïde-ovocyte, la protection de l'ovocyte, la régulation du calcium et l'apoptose ont font des marqueurs potentiels de la qualité ovocytaire de cette espèce
The European clam, Ruditapes decussatus is considered a high value seafood product in Southern Europe. Its production is almost based on natural recruitment, which is subject to annual fluctuations. In Portugal, two of the main production areas of this species are Ria de Aveiro and Ria Formosa Lagoons. These populations were characterized by different responses to spawning induction, which is of great interest in a context of improvement of aquaculture. The purpose of this thesis was to improve the cellular and genomic knowledge on the reproduction of R. decussatus with major applications: broodstock conditioning and gamete quality.The reproductive cycle of the two populations was histologically characterized by comparing the gonadal development, gonadal area and oocyte diameter. With the exception of the dynamics of gonadal development, which may originate in the environment, no differences concerning gametogenesis were found. cDNA libraries of oocytes, larvae and gonads were sequenced on Illumina platform, to enrich resources in reproductive Expressed Sequence Tags, and a custom oligoarray representing 51,678 assembled contigs was then designed. To characterize the transcriptomic bases of reproduction, microarray analyses were performed in four gonadal maturation stages of the two populations. Differentially expressed probes and the “N-Glycan biosynthesis” pathway, potentially involved in sperm-egg interaction, were identified, suggesting that gamete recognition can explain part of the differences in terms of spawning induction success between populations.Moreover, microarray analyses were also performed in oocytes, with the objective of identifying potential markers of oocyte quality in this species. Genes coding for chaperone proteins demonstrated to be important markers of oocyte quality, with some of them being maternal mRNAs essential for early development.The present study provides new highly valuable genomic information for the understanding of reproduction of R. decussatus and emphasizes some candidate genes like protein disulforide isomerase (PDI), Calmodulin family and caspase 8 as possible starting points for further functional studies

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Rahman, Shaily. "Cosmogenic Silicon-32 reveals extensive authigenic clay formation in deltaic systems and constrains the marine silica budget." Thesis, State University of New York at Stony Brook, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10140185.

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Cosmogenic ³²Si (t_1/2 ∼ 140 yrs) was used in a novel way to constrain the quantity of reactive Si storage and early diagenetic reactions of Si in the highly mobile deltaic sediments along the coast of French Guiana, representative of deposits along the ~1600 km Amazon–Guianas coastline downdrift of the Amazon delta. A sequential leach was developed to extract and purify SiO₂ from different operational pools in large samples of surface sediments (0–10cm). This methodology, a hot 1% Na₂CO₃ leach followed by a hot 4M NaOH leach, was adapted from the existing leaches widely used to estimate biogenic silica (bSi) content in marine sediments, and ultimately to constrain the global oceanic Si budget. ³²Si activity was determined in each pool via its daughter product ³²P. Results from several sites in coastal mudbanks near Kourou and Sinnamary indicate no detectable ³²Si activity in the bSi fraction, whereas ³²Si was detected in the Si-NaOH fraction after removal of bSi. The lack of detectable activity in the 1% Na₂CO₃ leach and its detection in the NaOH fraction (0.4–2.5 dpm) indicate that the method widely used to determine bSi content recovers only a minor fraction of the originally deposited reactive bSi in these deposits. The results are consistent with rapid alteration of biogenic silica and clay authigenesis or reverse weathering. They also demonstrate that the current estimate of biogenic silica storage in tropical deltaic sediments is significantly underestimated. Assuming an initial diatom specific activity range of ∼5–40 dpm/kg SiO₂, the ³²Si activity in the NaOH fraction corresponds to a reactive Si storage of ∼150–18,000 µmol Si/g sediment. This magnitude is more consistent with estimates of reactive Si (ΣSi_hr) storage in the Amazon delta based on modified operational leach techniques that target poorly crystalline clays and with diagenetic modeling of pore water K⁺, F⁻, and Si(OH)₄, though these modified leaches also appear to underestimate the amount of reactive Si stored along this system. To directly confirm whether these modified operational extractions underestimate reactive Si storage, a sequential extraction methodology was also developed to first isolate ³²Si activity in the ΣSi_hr fraction (0.1N HCl followed by 1% Na₂CO₃) and then extract any remaining ³²Si from the residual fraction using 4M NaOH.

Sediment from 2 stations in the Gulf of Papua, Papua New Guinea, 1 station in the northern Gulf of Mexico near the Southwest Pass, and 1 station in Long Island Sound (Smithtown Bay) were also extracted for ³²Si in the bSi fraction as well as the residual fraction after removal of bSi. Bulk ³²Si activities in the residual fractions in the Gulf of Papua (0.5–0.7 dpm/kg sediment) were used to extrapolate Si storage in the outer topset and forset of the clinoform delta.

³²Si activity was detected in the both the bSi (0.21 ± 0.04 dpm/kg sediment) and the residual fraction (0.44 ± 0.08 dpm/kg sediment) from the site in the Gulf of Mexico. A Si burial rate using the ³²Si activity in the bSi fraction (assuming an activity of 15dpm/kg in starting Si materials) of 0.004Tmol/y was calculated over approximately 5000 km2 of the delta, whereas the burial rate calculated using the Si content in this same fraction from a classic bSi leach, was ∼0.006Tmol/y. Adding the Si burial rate using the ³²Si activity in the residual fraction (0.008Tmol/y) yielded a total storage per year of 0.012Tmol Si, ∼10% of the total Si inputs (dissolved and amorphous Si) from the Mississippi-Atchafalaya river system. ³²Si activity was also detected in the residual fraction (0.53 ± 0.08 dpm/kg sediment) after removal of ΣSi_hr and using this activity yielded similar calculated rates of Si burial (∼0.01 Tmol/y).

In Smithtown Bay, Long Island Sound, ³²Si activity was also detected in both the bSi (0.15 ± 0.05 dpm/kg sediment) and the residual (0.4 ± 0.2 dpm/kg sediment) fractions from the site in Smithtown Bay, Long Island Sound, yielding a total Si storage estimate (assuming an activity of 15 dpm/kg in starting Si materials) of 1.6 × 10⁻³ Tmol/y over the entire Sound, comparable to estimates of Si storage calculated using the Si content in the classic bSi (1.1 × 10⁻³ Tmol/y) and the classic ΣSi_hr (2.2 × 10⁻³ Tmol/y) leaches. It appears that reverse weathering is an important sink of Si in these deposits and that classic bSi or ΣSi_hr leaches can underestimate Si storage in these system by two to four-fold. (Abstract shortened by UMI.)

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Brylawski, Bryce J. "Cultural eutrophication and the clam Macoma balthica: Evidence for trophic disruption and effects on blue crabs." W&M ScholarWorks, 2009. https://scholarworks.wm.edu/etd/1539616585.

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Cultural eutrophication (CE) is the allochthonous input introduction of a quantity of matter, such as sediments, organic material, or nutrients, into a water body over the pre-anthropogenic (natural) levels. In most coastal estuaries CE has come to refer primarily to an increase in the concentration of phyto-nutrients. CE has been identified as the cause of very graphic phenomena such as hypoxia and fish kills. In this work I examine the potential for CE to alter the composition of the primary producer community and potentially alter or disrupt the benthic food web, using Macoma balthica as an indicator species. A series of surveys and experiments identified that clams in areas with greater than average nutrient concentrations had lower health, slower growth, and greater non-predatory mortality than clams in less eutrophic areas. Primary production, as estimated from chlorophyll a concentration, was greater at higher nutrient locations while the health and growth of clams was lower. The phytoplankton community in the more eutrophic areas had a lower proportion of diatoms relative to dinoflagellates. A biochemical analysis of clam tissue indicated that the clams from the less nutrient rich sites had a greater proportion of Eicosapentaenoic acid (EPA) relative to other fatty acids. Diatoms are rich in EPA compared to dinoflagellates. Thus, we hypothesize that CE induced shifts from diatom based production toward dinoflagellates may be limiting trophic transfer due to a lack of EPA. Using a series of models we were able to predict that trophic disruption could significantly reduce the scope for growth of the blue crab, Callenecties sapidus . Thus it is possible that the CE induced changes to primary producer community could disrupt the food web creating a trophic bottleneck.

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19

Parks, L. F. "A study of Kuwait marine clay and its suitability for production of synthetic aggregate and other building materials." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370679.

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20

Sengco, Mario Rhuel. "The aggregation of clay minerals and marine microalgal cells : physicochemical theory and implications for controlling harmful algal blooms." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/29050.

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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Biology, and the Woods Hole Oceanographic Institution), 2001.
Includes bibliographical references.
In recent years, the use of clay minerals has emerged as one of the most promising strategies for directly controlling harmful algal blooms (HABs). Its principle is based on the mutual aggregation of algal cells and mineral particles, leading to the formation of large flocs that rapidly settle to the ocean floor. This work investigated the effectiveness of various domestic clays against a number of bloom-forming species from the United States. Twenty-five clays were tested against the dinoflagellate, Karenia brevis (formerly Gymnodinium breve), and the chrysophyte, Aureococcus anophagefferens. In general, the highest removal efficiencies (RE>90% at 0.25 g l-1 of clay) against K brevis were found using montmorillonite, bentonite and phosphatic clays (i.e. a product of phosphate mining containing large amounts of montmorillonite). The RE of phosphatic clays remained high (>80%) even at 0.03 g l-1. Kaolinite and zeolite were mostly ineffective against K brevis. Removal with clay exceeded those for alum, polyaluminum chloride (PAC) and several other polymeric flocculants by a factor of two. However, the combination of phosphatic clay and PAC (at 5 mg l-1) decreased the amount of clay needed to maintain 80% RE by one order of magnitude. Cell viability and recovery remained high when clay loading stayed below 0.03 g l-1 with or without resuspension of the sediment. However, cell mortality approached 100% with 0.50 g l-1 even with daily resuspension. Between 0.10 and 0.25 g l-1, K brevis survival and recovery depended on the interplay of clay loading, the frequency of resuspension, and duration of contact prior to the first resuspension event.
(cont.) For A. anophagefferens, the RE did not exceed 40% for any clay at 0.25 g l-1 even in combination with coagulants and flocculants. The highest removal was achieved by thoroughly mixing the clay slurry (e.g. phosphatic clay) into the cell culture. The RE by phosphatic clay varied significantly in a survey consisting of 17 different species from five algal classes. Moreover, the removal trends varied substantially with increasing cell concentration. For example, cell removal increased with increasing clay loading and cell concentration for K. brevis. However, RE dropped below 70% when cell concentration was <1000 cell ml-1 for clay loadings up to 0.50 g l-1. This suggested that a critical number of organisms should be present for clays to remain effective. Similarly, enhanced removal with increasing cell concentration was also found in Akashiwo sanguinea (formerly Gymnodinium sanguineum), Heterosigma akashiwo and Heterocapsa triquetra. In the six remaining species, RE initially increased then decreased, or RE remained constant as more cells were treated. The removal pattern among the species at comparable cell numbers did not correlate with the cross-sectional area (R2=0.23), swimming speed (R2=0.04), or a type of cell covering (i.e. theca, silica frustule) ...
by Mario Rhuel Sengco.
Ph.D.

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21

Armitage, Thomas M. "A bioeconomic model of the middle Atlantic surf clam (Spisula solidissima) fishery." W&M ScholarWorks, 1985. https://scholarworks.wm.edu/etd/1539616551.

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A bioeconomic simulation model of the middle Atlantic surf clam (Spisula solidissima) fishery has been developed from a survey of biological and econometric relationships. While identifying the biological input parameters available in the literature, the economic submodel of the fishery has been developed with price and landings time series data, and with data obtained through the use of survey questionnaires and interviews with surf clam fishermen and processors. Alternative management scenarios in the fishery have been evaluated from industry costs in both the harvesting and processing sectors and analysis of the demand for raw product confronting surf clam fishermen. Multiple regression analysis of time series data indicates that surf clam ex-vessel prices may be negatively related to surf clam landings whereas hard clam prices are positively related to ex-vessel ocean quahog prices and ex-vessel oyster prices. The strength of this relationship confirms the status of ocean quahogs as very close substitutes for surf clams. The results of case studies using the model suggest that the Mid-Atlantic Fishery Management Council has followed a prudent course of action in managing the surf clam fishery. The model also projects that, (1) larger yield quotas may be possible in the immediate future without jeopardizing surf clam population stability, (2) overcapitalization in the fishery appears to remain a problem, and (3) the economic outlook for the operators of small vessels remains relatively bleak.

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22

Woods, Helen. "An Examination of Potential Conflict between SAV and Hard Clam Aquaculture in the Lower Chesapeake Bay." W&M ScholarWorks, 2001. http://web.vims.edu/library/Theses/Woods01.pdf.

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23

Hao, Gang. "Laboratory study of shear wave velocity and very small stain modulus of Macao marine clay under anisotropic stress condition." Thesis, University of Macau, 2008. http://umaclib3.umac.mo/record=b1783644.

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24

Houben, Maria Engelina [Verfasser]. "In situ characteriation of the microstructure and porosity of Opalinus Clay (Mont Terri Rock Laboratory, Switzerland) / Maria Engelina Houben." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1038680247/34.

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25

Montafia, Alberto. "Influence of Physical Properties of Marine Clays on Electric Resistivity and Basic Geotechnical Parameters." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23295.

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Adding resistivity measurements to classical cone penetration tests (CPTU) provides further information useful for stratigraphy interpretation. Resistivity CPTUs (R-CPTU) have already been used for quick clay mapping, but there are still uncertainties related to the interval of resistivity values corresponding to quick clays and to whether resistivity is able to give information on geotechnical parameters that can then be utilized in engineering design. The results of four R-CPTU soundings, carried out in sites characterized by leached clays with different properties in eastern and central Norway, were complemented with their corresponding laboratory data in order to get an improved definition of the range of values associated to each soil type. Chemical analyses of the pore water and salinity measurements were also undertaken as to improve the understanding of the physical phenomena that regulate and determine soil?s bulk resistivity. It was observed that the role of salinity becomes less important in this process as salt content itself reaches very low values, and below a certain threshold concentration it appears as if the contribution of salinity is almost negligible. As long as the feedback that resistivity gives in distinguishing sensitive clay from quick clay is cencerned, it appeared as if the differences in mechanical properties of the two soil types were not evident enough to reflect into different R-CPTU measurements. More successful results were achieved when soil types with more dissimilar characteristics were considered. The diffusion of R-CPTU in geotechnical investigation practice in Norway is still limited, but it is gaining in popularity due to the very little additional effort required to acquire this information. The potentiality of R-CPTU will be better exploited once that more data from sites with leached, unleached and eventually also non-marine clays will be collected.

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26

Cha, Mei-wah. "The ecology of tapes philippinarum (Bivalvia: Veneridae) in Starfish Bay, Hong Kong, and its potential as a biological indicator of coastal pollution /." [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13762370.

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27

PINHEIRO, GIORGIANA FREITAS. "EXPERIMENTAL STUDY OF THE EFFECTS OF LEACHING ON THE BEHAVIOR OF BRAZILIAN SOFT MARINE CLAYS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1253@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
As modificações ambientais ocorridas após a formação de um depósito sedimentar podem modificar suas características geotécnicas. No caso de sedimentos marinhos, a lixiviação dos sais, foi essencial para o desenvolvimento de solos altamente sensitivos em depósitos litorâneos de vários países. O presente trabalho tem por objetivo avaliar as implicações da lixiviação no comportamento geotécnico de sedimentos marinhos típicos do litoral brasileiro. Para tanto foram realizados ensaios de laboratório em amostras de solo procedentes da baía de Sepetiba (Rio de Janeiro) e da Enseada do Cabrito (Bahia). O programa experimental proposto envolveu a caracterização geotécnica e mineralógica dos solos, lixiviação das amostras estudadas em câmaras triaxiais, ensaios mecânicos, análises químicas e do arranjo dos grãos das amostras em estado natural e lixiviadas. Os ensaios e análises realizados foram executados nos laboratórios de Geotecnia, Metalurgia e Ciência dos Materiais e Química da PUC-Rio, e no Laboratório de Química de Solos do CNPS/ EMBRAPA-Rio. As análises dos resultados foi comparativa do comportamento geotécnico apresentado pelos solos antes e após a lixiviação, em particular quanto a sensitividade.
The environmental changes that occur after the development of a sedimentary deposit may change your geotechnical characteristics. In the case of marine sediments, the leaching of pore salts is essential for the development of very sensitivity soils in shore deposits in some countries. This work aimed at evaluating the implication of leaching the behaviour of geotechnical marine sediments, typical from Brazilian littoral. Tests were carried out in samples obtained from Sepetiba´s Bay (Rio de Janeiro) and Cabrito´s Inlet (Bahia). The experimental program covered the geotehcnical and mineralogical characterisation of soils, leaching of soil samples, mechanics tests, chemical analyses and fabric of samples in nature and leaching states. The testing and analyses were made Geotechnical, Metallurgical and Chemistry laboratories at PUC-Rio and in Chemistry at Soil laboratory of CNPS/EMBRAPA-Rio. The Analysis of results were made by a comparison of the behaviour of soils after and before there leaching, in special about the sensitivity.
Las modificaciones ambientales ocurridas después la formación de un depósito de sedimentos pueden modificar sus características geotécnicas. En el caso de sedimentos marinos, la lixiviación de sal fue esencial para el desarrollo de suelos altamente sensitivos en depósitos litoráneos de varios países. El presente trabajo tiene por objetivo evaluar las implicaciones de la lixiviación en el comportamiento geotécnico de sedimentos marinos típicos del litoral brasilero. Con este objetivo, fueron realizados ensayos de laboratorio en muestras de suelo procedentes de la bahía de Sepetiba (Rio de Janeiro) y de la Ensenada del Cabrito (Bahia). El programa experimental propuesto envuelve la caracterización geotécnica y mineralógica de los suelos, lixiviación de las muestras estudiadas en cámaras triaxiales, ensayos mecánicos, análisis Químicas y del arreglo de los granos de las muestras en estado natural y lixiviadas. Los ensayos y análisis realizados fueron ejecutados en los laboratórios de Geotecnía, Metalurgía y Ciencia de los Materiales y Química de la PUC-Rio, y en el Laboratório de Química de Suelos del CNPS/ EMBRAPA-Rio. El análisis de los resultados compara el comportamiento geotécnico presentado por los suelos antes y después de la lixiviación, en particular en cuanto la sensitividad.

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28

Mathieu, Anne. "Analyse synoptique de la couche limite atmosphérique marine pendant la campagne sémaphore." Paris 6, 2000. http://www.theses.fr/2000PA066315.

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29

Lana, Celaya María Aránzazu. "Marine aerosols, their precursors and their influence on clouds over the global ocean." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/83367.

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Marine aerosols have a large potential to influence the Earth¿s climate through their effects on cloud properties. The CLAW hypothesis goes further, and suggests that marine aerosols formed by the sulphur cycle of the ocean and the atmosphere act as a mechanism for regulating the Earth's climate. This effect is produced through the influence of plankton emissions of sulphur compounds on cloud formation. Phytoplankton produces dimethylsulphide (DMS), a highly volatile sulphur compound. Once in the atmosphere, DMS is oxidized and becomes the main source of natural atmospheric sulphates. These sulphates act as condensation nuclei, particles that are essential for the formation of clouds. Those marine particles in the atmosphere play an important role in the Earth's radiation budget. Indirectly they produce a greater amount of cloud droplets. Higher cloud condensation nuclei imply smaller cloud droplets. The efficiency of smaller droplets in reflecting incident solar radiation is greater, resulting in an increase in cloud albedo, producing a cooling effect on the Earth's surface. To properly study the marine aerosols we need accurate knowledge of the global seawater distribution of the aerosol precursors. Our work focused on the ocean-to-atmosphere emissions of DMS and other biogenic gases that can have an impact on cloud microphysics. During the thesis we updated the monthly global DMS climatology taking advantage of the three-fold increased size and better resolved distribution of the observations available in the DMS database. The emerging patterns found with the previous versions of the database and climatology were explored with the updated version. The statistical relationships between the seasonalities of DMS concentrations and solar radiation doses and chlorophyll a concentrations were here re-examined. Analyses of nine years of satellite data suggested that there is a natural inverse correlation between the spatial cover of low marine clouds and the cloud droplet size, which is related to the presence of small aerosols. This coupled seasonality pushes cloud albedo to contribute higher negative radiative forcing in summer and lower in winter. This relation is disrupted in the marine atmosphere regions heavily impacted by anthropogenic aerosols. Consequently, the potential influence the aerosol precursors have on marine clouds was next analysed over unpolluted and polluted ocean, separately. The 9 years of global satellite data and ocean climatologies were used to derive parameterizations of the production fluxes of secondary aerosols formed by oxidation of DMS and other biogenic organic volatiles. Further, the emission fluxes of biogenic primary organic and sea salt aerosols ejected by wind action on sea surface were also globally studied. Series of weekly estimates of these fluxes were correlated to series of cloud droplet effective radius. The outcome of the statistical analyses indicated that sulphur and organic secondary aerosols might be important in seeding cloud nucleation and droplet activation over mid and high latitude unpolluted oceanic regions. Conversely, primary aerosols (organic and sea salt) showed that, despite contributing to large shares of the marine aerosol mass, they do not seem to be major drivers of the variability of cloud microphysics. Our results provide partial support for the feasibility of the CLAW hypothesis at the seasonal scale. Despite that DMS has drawn much of the attention on the links between marine biota and climate regulation, the implication of other biogenic precursors on cloud formation provides and suggests a wider scope on the formulation of such hypothesis.
Los aerosoles marinos tienen un gran potencial para influir en el clima de la Tierra a través de sus efectos en las propiedades de las nubes. La hipótesis de CLAW va más allá y sugiere que los aerosoles marinos formados por el ciclo del azufre en océanos y atmósfera actúan como un mecanismo para la regulación del clima de la Tierra. Este efecto se produce a través de la influencia de las emisiones de plancton de compuestos de azufre en la formación de nubes. El fitoplancton produce sulfuro de dimetilo (DMS), un compuesto de azufre altamente volátil. Una vez en la atmósfera, el DMS se oxida y se convierte en la principal fuente de sulfatos naturales atmosféricos. Estos sulfatos actúan como núcleos de condensación, partículas esenciales para la formación de nubes. Estas partículas presentes en la atmósfera marina juegan un papel importante en el ciclo radiativo de la Tierra. Indirectamente, producen una mayor cantidad de gotas de las nubes. Mayor número de núcleos de condensación en las nubes implica gotas de nubes más pequeñas. La eficacia de las pequeñas gotas en reflejar la radiación solar incidente es mayor, lo que resulta en un aumento del albedo de las nubes, produciendo un efecto de enfriamiento en la superficie de la Tierra. Para estudiar adecuadamente los aerosoles marinos necesitamos tener un correcto conocimiento de la distribución oceánica global de los precursores de aerosoles. Nuestro trabajo se ha centrado en las emisiones del océano a la atmósfera de DMS y otros gases biogénicos que puede tener un impacto en la microfísica de nubes. Durante la tesis se ha actualizado la climatología mensual global de DMS, aprovechando el aumento en tres veces del número de observaciones y una mejor distribución global de las mismas, en la base de datos de DMS. Los patrones emergentes encontrados con las versiones anteriores de la base de datos y de la climatología se han re-evaluado con la versión actualizada. Las relaciones estadísticas encontradas entre la evolución temporal de las concentraciones de DMS y las dosis de radiación solar y concentraciones de clorofila han sido re-examinadas. Los análisis de nueve años de datos de satélite sugieren que existe una correlación inversa entre la cubierta espacial de nubes marinas bajas y el tamaño de las gotas de nubes, relacionado con la presencia de aerosoles pequeños. Esta estacionalidad acoplada conduce al albedo de las nubes a contribuir a un forzamiento radiativo negativo superior en verano, y más bajo en invierno. Esta relación se interrumpe en las regiones de la atmósfera marina con un alto impacto de los aerosoles antropogénicos. En consecuencia, la posible influencia de los precursores de aerosoles marinos en las nubes se ha analizado en una atmósfera marina limpia y contaminada, por separado. Los 9 años de datos satelitales globales y climatologías oceánicas se han utilizado para derivar las parametrizaciones de los flujos de producción de aerosoles secundarios, formados por la oxidación de DMS, y otros compuestos volátiles orgánicos biogénicos. Además, los flujos de emisiones biogénicas de aerosoles primarios orgánicos y aerosoles de sal marina expulsados por acción del viento sobre la superficie del mar se ha estudiado también a nivel global. Las series semanales de las estimaciones de estos flujos se han correlacionado con las series temporales de los radios de las gotas de nubes. El resultado de los análisis estadísticos ha indicado que el azufre orgánico y otros aerosoles secundarios pueden ser importantes en la nucleación y la activación de sus gotas sobre las regiones oceánicas no contaminadas en latitudes medias y altas. Por el contrario, aerosoles primarios (orgánico y la sal del mar) han mostrado que, a pesar de que contribuyen a una gran proporción de la masa de aerosol marino, no parecen ser los principales motores de la variabilidad de la microfísica de nubes. Nuestros resultados proporcionan un apoyo parcial a la viabilidad de la hipótesis de CLAW a escala estacional. A pesar de que el DMS ha llamado mucho la atención sobre los vínculos entre la biota marina y la regulación del clima, la implicación de otros precursores biogénicos en la formación de nubes ofrece y sugiere un mayor alcance en la formulación de esta hipótesis.

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30

Holtzapffel, Thierry. "Minéraux argileux lattes : les smectites du domaine atlantique." Angers, 1986. http://www.theses.fr/1986ANGE0006.

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Les smectites des sédiments atlantiques du jurassique supérieur à l'actuel ; on distingue des particules floconneuses mixtes et lattées. Les premières, d'origine détritique probable, n'ont subi aucune modification post-sédimentaire ; les dernières résultent du réajustement diagenétique précoce des premières. L'intensité de ce réajustement, qui a lieu à bilans chimique et minéralogique pratiquement constants, a été quantifiée puis comparée à de nombreux paramètres sédimentaires. Trois facteurs importants : microperméabilité initiale du sédiment, temps de contact entre particules et fluides interstitiels et la composition de ces fluides.

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31

Picariello, Adriana. "The Effects of Climate Change on the Population Ecology of the Atlantic Surf Clam, Spisula solidissima, in the Middle Atlantic Bight." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539617848.

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32

Wooldridge, L. J. "Understanding the processes governing the origin of clay coated sand grains and sediment heterogeneity in petroleum reservoirs : insights from a modern marginal marine system." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3021138/.

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33

Junttila, J. (Juho). "Clay minerals in response to Mid-Pliocene glacial history and climate in the polar regions (ODP, Site 1165, Prydz Bay, Antarctica and Site 911, Yermak Plateau, Arctic Ocean)." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514283680.

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Abstract This thesis examines the Mid-Pliocene climatic extreme ca. three million years ago (Ma) which was the latest longtime warm period. It is an important topic because the climate back then was warmer compared with the present. The bipolar regions are studied because they represent the largest areas that control the global climate. This study is based on clay mineral research that may significantly improve our knowledge of the Mid-Pliocene climate when combined with other palaeoenvironmental data. The paleoclimatological objectives of this study were: 1) to investigate how clay minerals reflect the Mid-Pliocene Global Warmth event, 2) to study ice sheet development at high latitudes, especially in East-Antarctica, and the history of ice rafting and sea ice, especially in the Arctic Ocean. This thesis deals with the clay mineral distribution and compositional analysis of the Pliocene-aged marine sediment sequences provided by the Ocean Drilling Program (ODP). The first studied site, Site 1165, is located at the continental rise of Prydz Bay, East Antarctica, and the second studied site, Site 911, is located at the Yermak Plateau, north of Svalbard, in the Arctic Ocean. The Pliocene smectite clay minerals at Site 1165 were mainly derived from Antarctic continental sources and transported to the site primarly by bottom currents related to warm events during the last 5 Ma. The evidence obtained in this study shows that the East Antarctic ice sheet may have been a dynamic ice sheet during the past 5 Ma, especially during the Mid-Pliocene. The results from the Mid-Pliocene possibly suggest a general warming trend. Based on the composition of the heavy minerals and clay minerals, at Site 911, the Pliocene smectite clay minerals were mainly transported within sea ice by the Siberian branch of the Transpolar Drift. The results indicate a warming trend at approximately 3 Ma after which they indicate a shift back to glacial conditions. Based on this study, the Mid-Pliocene Global Warmth can be observed in both the Arctic and Antarctic regions.

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34

Kuschner, Michael A. "A Model of Carrying Capacity and Ecosystem Impacts in a Large-Scale, Bivalve-Dominated Agro-Ecosystem: Hard Clam Aquaculture in Cherrystone Inlet, VA." W&M ScholarWorks, 2015. https://scholarworks.wm.edu/etd/1539617960.

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With the recent growth of the hard clam aquaculture industry, sites of intensive aquaculture have emerged as large-scale agro-ecosystems where the success of aquaculture production is dynamically linked to ecosystem function. Large scale clam aquaculture operations are associated with a range of potential positive and negative feedbacks related to nutrient dynamics, water and sediment quality, proliferation of macroalgae, and carrying capacity. Quantitative modeling tools are needed to support system-level planning related to site selection, scale of operations, production capacity and ecosystem function. The purpose of this study was to develop a model for Cherrystone Inlet, VA, where one-third (1.9 km2) of the sub-tidal bottom area is held as 37 separate, private shellfish leases with an estimated 100-150 million cultured clams. A reduced complexity estuarine ecosystem model was coupled with a hard clam energetics and growth model and a watershed loading model. The linked models facilitate ecosystem-based management and enable regional spatial planning in a full ecosystem context, through coupled simulations of aquaculture activities, land use changes, nutrient loading, climate change, and estuarine response. Modeled output for hard clam growth and water column chlorophyll-o, dissolved oxygen, and dissolved inorganic nitrogen and phosphorous reproduced in situ data. Simulations with increasing clam numbers up to 500 million resulted in diminishing returns in terms of reduced growth rates, increased time to harvestable size, and reduced harvestable biomass, confirming observations by Cherrystone farmers of reduced clam growth rates above 200 million cultured clams. Modeled hard clam production capacity decreased in the absence of benthic microalgal resuspension (6%) and without the input of external production from the Chesapeake Bay (41%), and increased in simulations with increased water column chlorophyll-o (11%) and the removal of predator exclusion nets (13%). Simulations to optimize siting indicated that the highest hard clam growth rates occurred up-estuary. Model simulations with changes in land use and climate indicated that clam growth is most sensitive to increasing temperature, with rates decreasing by 37% when temperatures were increased by 5°C, while changes in land use, sea level rise and salinity did not result in large changes in hard clam production. At the system scale hard clam aquaculture was predicted to account for 14% of total nitrogen inputs to the water column between sediment recycling of clam feces (13%) and direct clam excretion (1%). The Cherrystone ecosystem model fills a critical gap on the Eastern Shore of Virginia and in similar coastal systems, providing resource managers with the most current available science in a decision-support framework to promote effective regional spatial planning and sustainability of hard clam operations and the surrounding coastal ecosystems.

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Delano, Kristen Adams. "Metapopulation Dynamics, Habitat Quality, and Spatial Scale: Variation in Reproductive Output of the Baltic Clam, Macoma balthica, in Shallow Systems of the Chesapeake Bay." W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539617825.

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36

Cha, Mei-wah, and 車美華. "The ecology of tapes philippinarum (Bivalvia: Veneridae) in Starfish Bay, Hong Kong, and its potential as a biological indicator of coastalpollution." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31233442.

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37

Roden, John. "Determining the physiological and behavioral aspects of salinity tolerance in the Asian clam, Corbicula fluminea." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/honors/443.

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The Asian clam, Corbicula fluminea, is an invasive bivalve species that now occurs through most of the lower 48 United States. While a significant degree of salinity tolerance has been observed in C. fluminea, owing to its estuarine lineage, the physiological and behavioral responses to changes in salinity by these organisms are not completely understood. It was hypothesized that Corbicula would initially avoid elevated salinity levels (>1 g/L) behaviorally through valve closure, but would eventually have to open to dispel anaerobic waste products and deal with the salinity. To explore this, Corbicula were collected and put through a series of experiments at salinity exposures of 0, 2.5, and 5.0 g/L, with tissue water content and hemolymph osmolality being measured. After an initial 96-hour exposure, it was observed that the percent tissue water content of clams in 2.5 g/L and 5.0 g/L water dropped 3.29% and 4.18%, respectively, below that of the control groups in 0 g/L. After a 24-hour time-course experiment, this change in tissue water was found to largely occur within the first eight hours of exposure for the 2.5 g/L and 5.0 g/L groups. It was also noted that the hemolymph osmolality of both the 2.5 g/L and 5.0 g/L groups rose to approximately 78 mOsm/kg and 148 mOsm/kg, respectively, matching the osmolality of their exposure water in roughly the same time span and indicating that little behavioral avoidance of the elevated salinity was occurring. The osmolality of the control group did not match the osmolality of the 0 g/L water at 0.5 mOsm/kg, but was held at a constant level around 50 mOsm/kg. In a later experiment measuring the same variables for clams in 10.0 g/L, it was found that the tissue water and osmolality did not begin to change significantly until after 12 hours, indicating behavioral avoidance at this salinity level. A context study was also conducted comparing oxygen consumption and percent tissue water between various salinities in a light and dark exposure to determine if ambient light influenced siphoning of the clams and exposure to the salt. In this experiment, it was observed that clams held in salinities of 5.0 g/L for 24 hours consumed roughly 1.90 mg O2/L/g/h, whereas clams held in the control only consumed roughly 0.73 mg O2/L/g/h. These findings suggest that Corbicula osmoregulate in freshwater but osmoconform at salinities of 2.5 g/L and 5.0 g/L. The data from the context study also suggests that this conformation comes at a significant metabolic cost. Furthermore, and in contrast to the results of some previous studies, a significant level of behavioral avoidance of elevated salinity does not appear to commence until the clams are at a salinity above 5 g/L.

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McDaniel, Eileen M. Peterson Charles Henry. "The effectiveness of rotating marine protected areas MPAs in fisheries management a case study of the NC hard clam fishery /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1788.

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.
Title from electronic title page (viewed Sep. 16, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Curriculum in Ecology." Discipline: Ecology; Department/School: Ecology.

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Udgata, Devi Bhagabati Prasad. "DEPOSITIONAL AND STRATIGRAPHIC SIGNIFICANCE OF MARINE, GREEN-CLAY, MINERAL FACIES IN THE LOWER-MIDDLE MISSISSIPPIAN BORDEN AND FORT PAYNE FORMATIONS, WESTERN APPALACHIAN AND EASTERN ILLINOIS BASINS, KENTUCKY." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/808.

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Detailed study of strata associated with the glauconite-rich Floyds Knob Bed in the western Appalachian and eastern Illinois basins have corroborated previous interpretations that the unit is a widespread, largely synchronous marker horizon. However, in some areas there are multiple glauconite beds; in others a distinct bed is lacking, but the glauconite is dispersed throughout many beds, forming an interval rather than a distinct bed. In Kentucky and adjacent states, the Floyds Knob interval, in upper parts of the Lower-Middle Mississippian Borden-Grainger delta sequence and in lower parts of the Fort Payne carbonate sequence, was deposited at the end of loading-type relaxation during a flexural cycle in the Neoacadian (final) tectophase of the Acadian Orogeny. Tectonic influence, combined with a major late Osagean sea-level lowstand, created conditions that generated sediment starvation and shallower seas across widespread parts of the western Appalachian and eastern Illinois basins. In the absence of major sediment influx, glauconite was deposited uniformly across many major depositional settings, ranging from delta-platform to basinal environments. Especially important, however, is the newly reported occurrence of the Floyds Knob interval in basinal Fort Payne environments from south-central Kentucky, where it is represented by a thick, pelletal, glauconite-rich horizon that separates clastics at the base of the Fort. Payne Formation from carbonates at top. The study also provides the first-ever radiometric dating of the Floyds Knob glauconites, which suggests a late Osagean origin. These results support the existing biostratigraphic studies that point to a late Osagean origin for the Floyds Knob interval.

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Aita, Rômulo Augusto Aragones. "VARIAÇÃO ESPACIAL DA ARGILA NUMA TOPOSEQUÊNCIA EM UM SEGMENTO DE VERTENTE NO DISTRITO DE PAINS - SANTA MARIA, RS." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/9471.

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This research puts forward as its central subject an inquiry into the existence of an underground lateral flow capable of carrying particles that leads to morfogenetical implications. Regarding the pertinence to this analysis of a survey by Werlang et al. (2014), this project builds on the conclusions reached by the application of the pedological cover structural analysis in a toposequence. From these outcomes, as well as due to the significant finding of a notorious low hydraulic conductivity of the underground horizons proven in trials, it was possible identify a lateral flow predominantly on the eluvial horizon. In an area next to that the mentioned study took place, we selected a hillslope to proceed a preliminary topographic survey to define the hillslope geomorphic nature and set up the geomorphic breaking points of this hillslope. Subsequently, this allowed to conduct the soil sounding along the toposequence of eleven points in these geomorphic breaking points, determining depth and thickness of the present horizons and collecting samples for laboratory analysis. Similarly, the morphological description of the probed profiles was performed. After this stage of field works, a new topographic survey was conducted designed to locate, within the mentioned area, the probing points aiming at obtaining a profile of the hillslope topossequence segment data. This procedure allowed to obtain a bidimensional analysis of the pedological cover and enabled to develop several substantial inferences. Taking into account the results of this analysis, we proceed to characterize, both in field and laboratory, the present litology condition in the area on the Santa Maria Formation. The samples obtained in field allowed to accomplish the granulometrical characterization, and next, tabulate these data. In this way, the discussion could identify gradients of concentration from different granulometrical grades, which were then used to define a dynamics based on surface and underground flows supporting a wide discussion engaged thereof. The presence of positive gradients, albeit tenuous, in the clay fraction down the slope, afforded to infer the existence of a subsurface flow with transport and further accumulation of material on top of the B horizon of profiles located at lower levels. Accordingly, this allowed to testify the validity of purpose of this study, noting however the presence of two distinct litologies from the Santa Maria Formation whose permeability has shown that the dynamics of the hillslope is highly complex insomuch as inserted in the landscape as a whole.
O presente estudo propõe a investigação da existência de um fluxo lateral subsuperficial carreador de partículas com implicações morfogenéticas. Considerando a pertinência para nossa análise de um trabalho de Werlang et al. (2014), este projeto toma como base as conclusões obtidas com a aplicação da análise estrutural da cobertura pedológica em uma topossequência. A partir dessas considerações, bem como da significativa constatação de uma notória baixa condutividade hidráulica dos horizontes subsuperficiais comprovada em ensaios, foi possível identificar um fluxo lateral predominante no horizonte E ao longo da topossequência. Em uma área próxima a do estudo mencionado, foi selecionado um segmento de vertente a partir do qual se procedeu ao levantamento topográfico preliminar e definiu-se os pontos de ruptura geomórfica deste segmento de vertente. Subsequentemente, foram realizadas sondagens ao longo da topossequência nos pontos destas rupturas geomórficas, determinando profundidade e espessura dos horizontes presentes e coletando amostras para análise laboratorial. Foi realizada também a descrição morfológica dos perfis sondados. Finalizada esta etapa dos trabalhos de campo, efetuou-se um novo levantamento destinado a situar, dentro da área referida, os pontos de sondagem visando possibilitar a obtenção de um perfil da topossequência do segmento de vertente. O procedimento permitiu uma análise bidimensional da cobertura pedológica que subsidiou inferências significativas. Contabilizando os resultados dessa análise, foi caracterizada em campo e em laboratório a situação das litologias presentes na área relativa à Formação Santa Maria. Com as amostras resultantes deste procedimento foi possível realizar a análise granulométrica, sendo a seguir tabulados e discutidos os dados obtidos. Foi possível então identificar gradientes de concentrações das diferentes classes granulométricas, que foram utilizados para definir uma dinâmica de fluxos em superfície e subsuperfície subsidiando as discussões. A presença de gradientes positivos, ainda que tênues, na fração argila no sentido do declive da vertente, possibilitou inferir a existência de um fluxo subsuperficial com carreamento e acúmulo de materiais no topo do horizonte B dos perfis situados em cotas inferiores. Isso permitiu constatar a validade do propósito deste estudo, observando que a presença de duas litologias de permeabilidade distintas tenha demonstrado que a dinâmica de uma vertente é invariavelmente complexa, visto que inserida no todo da paisagem e contemplando mais de um fator determinante.

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Yun, SeongKyu. "Development of the numerical procedure to describe multi-dimensional behavior of the alternating Pleistocene foundations." Kyoto University, 2020. http://hdl.handle.net/2433/245842.

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Silva, Natália Alvarenga da. "Biodegradação dos pesticidas clorpirifós, metil paration e profenofós por fungos de origem marinha." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-30072013-091823/.

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Neste trabalho, foi realizada uma triagem com os fungos marinhos Aspergillus sydowii CBMAI 934, Aspergillus sydowii CBMAI 935, Aspergillus sydowii 1241, Penicillium decaturense CBMAI 1234, Penicillium raistrickii CBMAI 931, Penicillium raistrickii CBMAI 1235 e Trichoderma sp. CBMAI 932 com o objetivo de avaliar o potencial enzimático destes micro-organismos frente à biodegradação dos pesticidas organofosforados clorpirifós, metil paration e profenofós. Os fungos selecionados para as reações em meio líquido de malte 2%, que melhor adaptaram-se na presença do pesticida clorpirifós, foram as cepas de A. sydowii CBMAI 935 e Trichoderma sp. CBMAI 932, na presença de metil paration foram A. sydowii CBMAI 935 e P. decaturense CBMAI 1234 e na presença de profenofós foram os fungos A. sydowii CBMAI 935 e P. raistrickii CBMAI 931. Foram realizadas curvas analíticas com o objetivo de estimar a extensão da biodegradação dos pesticidas clorpirifós, metil paration, profenofós, e seus respectivos produtos de hidrólise, os derivados fenólicos 3,5,6-tricloro-2-piridinol, 4-nitrofenol e 4-bromo-2-clorofenol, respectivamente. As reações de biodegradação em meio líquido de malte 2% foram avaliadas com 10, 20 e 30 dias de reação com concentração inicial dos pesticidas organofosforados de 50 ppm. O pesticida, profenofós, apresentou uma biodegradação completa com o fungo P.raistrickii CBMAI 931 com 30 dias de reação, e 70% com o fungo A. sydowii CBMAI 935, para o mesmo período. Os fungos também apresentaram potencial para a degradação (ou conjugação) do metabólito, 4-bromo-2-clorofenol. Na presença dos fungos A. sydowii CBMAI 935 e Trichoderma sp. CBMAI 932, clorpirifós apresentou a menor degradação entre os pesticidas avaliados, com uma taxa de degradação de 63 e 72%, respectivamente, em 30 dias de reação. Os fungos selecionados não foram capazes de promover uma degradação apreciável do 3,5,6-tricloro-2-piridinol. Na presença dos fungos A. sydowii CBMAI 935 e P. decaturense CBMAI 1234, o metil paration apresentou uma degradação de 100% em 20 dias de reação. O 4-nitrofenol apresentou degradação (ou conjugação) de aproximadamente 50 e 40% na presença dos fungos A. sydowii CBMAI 935 e P. decaturense CBMAI 1234, respectivamente. Finalmente, os estudos apresentados comprovam a eficiência dos fungos de ambiente marinhos na biodegradação de pesticidas organofosforados.
In this work was performed a screening with the marine fungi Aspergillus sydowii CBMAI 934, Aspergillus sydowii CBMAI 935, Aspergillus sydowii 1241, Penicillium decaturense CBMAI 1234, Penicillium raistrickii CBMAI 931, Penicillium raistrickii CBMAI 1235 e Trichoderma sp. CBMAI 932 to evaluate the enzymatic potential of these microorganisms in the presence of organophosphate pesticides chlorpyrifos, methyl parathion and profenofos. The selected fungi for the reactions in liquid medium of malt 2%, which demonstrated better adaptation in presence of the pesticide chlorpyrifos, were the strains of A.sydowii CBMAI 935 and Trichoderma sp. CBMAI 932, in the presence of methyl parathion were A.sydowii CBMAI 935 and P. decaturense CBMAI 1234 and, in presence of profenofos were the fungi A. sydowii CBMAI 935 and P. raistrickii CBMAI 931. Analytical curves were performed in order to estimate the extent of biodegradation of the pesticide chlorpyrifos, methyl parathion, profenofos, and their hydrolysis products, 3,5,6-trichloro-2-pyridinol, 4-nitrophenol, 4-bromo 2-chlorophenol, respectively. Biodegradation reactions in liquid medium of malt 2% were evaluated with 10, 20 and 30 days with an initial concentration of 50 ppm of organophosphate pesticides. Profenofos, presented a complete biodegradation (100%) with the fungus P.raistrickii CBMAI 931, in 30 days of reaction, and 70% of biodegradation in the presence of the fungus A. sydowii CBMAI 935, at the same period. The fungi also showed a potential for degradation (or conjugation) of 4-bromo-2-chlorophenol. In the presence of the fungus A. sydowii CBMAI 935 and Trichoderma sp. CBMAI 932, chlorpyrifos exhibited the lowest degradation among the evaluated pesticides, presenting a degradation rate of 63 and 72%, respectively, at 30 days of reaction. The selected fungi were not capable of promoting an appreciable degradation of 3,5,6-trichloro-2-pyridinol. In the presence of A. sydowii CBMAI 935 and P. decaturense CBMAI 1234, methyl parathion showed a degradation of 100%, at 20 days of reaction. The 4-nitrophenol showed a degradation (or conjugation) of approximately 50 and 40% in the presence of the fungus A. sydowii CBMAI 935 and P. decaturense CBMAI 1234, respectively. Finally, the presented studies demonstrated the efficiency of the marine fungi in biodegradation of organophosphate pesticides.

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Marquardt, Alexandria R. "PISMO CLAMS (Tivela stultorum) IN CALIFORINA: POPULATION STATUS, HABITAT ASSOCIATIONS, REPRODUCTION, AND GROWTH." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2172.

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Marine shellfish play a vital role in intertidal ecosystems and coastal communities, but many of these fisheries are small-scale and lack the necessary monitoring to ensure long-term sustainability. Effective management often requires information on key demographic parameters, such as population status, reproduction and growth. Pismo clams (Tivela stultorum) are a culturally important and iconic species in California, which supported a thriving commercial and recreational fishery throughout much of the 1900’s. However, Pismo clam populations have declined statewide in recent decades and are attributed to human harvest and predation by California sea otters (Enhydra lutris); However, no studies have examined their populations, population drivers, or life history for at least 40 years. Managers require updated and expanded information on populations, habitat associations, reproduction and growth rates to effectively manage, regulate, and recover Pismo clam in California. In Chapter 1, we investigated current Pismo clam population levels in California and examined the role of abiotic and biotic factors as correlates of clam abundance. We quantified Pismo clam presence, density and biomass at 38 sites in California during 2018 and 2019. Our results indicate that while human population density does not appear to drive clam populations, median sediment grain size is an important predictor for Pismo clams on open coast beaches. As median grain size increases, the probability of clam presence, density, and biomass decreases, suggesting that the composition of beach habitat is a critical factor regulating Pismo clam populations. Additionally, clam density and biomass are significantly higher on beaches north of Point Conception compared to beaches south. This suggests that Pismo clam population declines are more complicated than conventional wisdom suggests. Overall, Pismo clam densities are lower and size structures are shifted towards smaller sizes than historical accounts. This study is the most comprehensive set of population surveys to date and identifies key factors associated with Pismo clam abundance, which may be used to inform management and guide restoration and recovery of this once iconic species. In Chapter 2, we examined life history characteristics of Pismo clams in California. Specifically, we investigated the annual reproductive cycle of Pismo clams in California, pairing multiple metrics within a single study to describe the sex ratio, gonad development stages, body condition index, and length at sexual maturity. Further, we examine age-length relationships across California to provide estimates of age structure and growth rate, which will better inform recovery timelines for the recreational fishery in California. Our results indicate that the sex ratio is 1:1, peak spawning occurred in late summer, and clams can spawn in their first year (<20 >mm). Cycles of body condition were influenced primarily by mean monthly sea surface temperature, but mean monthly chlorophyll-a concentration, photoperiod, clam size, and year were also important. Body condition was significantly correlated with the proportion of clams in the Ripe stage. Thus, body condition has the potential to be a rapid, inexpensive proxy for monitoring reproduction in Pismo clams, potentially providing useful information about changes in reproductive patterns. Finally, examination of age-length relationships for Pismo clams suggest that clams may require over 13 years to reach a legally harvestable size (114 mm across most of California). The estimated age at legal size is substantially older than historical estimates, which suggested that Pismo clams could reach legally harvestable size in as few as 6 years. Collectively, this work represents a significant advance in our knowledge of the biology and ecology of this iconic and culturally important species. Furthermore, it provides vital information on the current population status, reproduction, and growth rates to inform management, regulation, and potential recovery of Pismo clams in California.

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CAPELLE, THIERRY. "Penetration libre dans les sediments marins : etude du comportement dynamique et rheologique d'une argile reconstituee." Toulouse 3, 1988. http://www.theses.fr/1988TOU30045.

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Etude de la penetration libre dans les sediments marins afin d'en evaluer les capacites de resistance au cisaillement ou pour determiner des profondeurs d'enfouissement maximales. Les phenomenes limitant l'enfouissement sont du a la portance et au frottement. On determine les proprietes rheologiques et dynamique de l'argile a partir d'une serie de tirs de projectiles effectues en fosse d'essais. L'etude du decelerogramme d'essai distingue les phases ou le comportement du sol au contact du penetreur varie depuis l'hydrodynamique jusqu'a la visco-plasticite

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45

Aldana, Carlos. "Etude des propriétés de transfert de la zone non saturée : application auxcalcaires aquitaniens de l’aquifère de Beauce." Thesis, Orléans, 2019. http://www.theses.fr/2019ORLE2010.

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L’aquifère calcaire de Beauce a été étudié au cours des dernières décennies. Cependant, la plupart des études ont concerné les tous premiers mètres de la zone non saturée (ZNS) (0 à 3 mètres) et/ou la zone saturée de l’aquifère. Les processus d’écoulement, à travers la ZNS, largement stratifiée, ne sont pas bien compris. De nombreux auteurs ont souligné son hétérogénéité, aussi bien latérale que verticale, avec des lithologies assez variables. L’accès à toute la ZNS reste un enjeu majeur, dont les principales difficultés sont techniques et économiques. L’objectif général de ce travail de recherche est de contribuer à une meilleure compréhension des mécanismes de transfert de l’eau au sein de la ZNS des calcaires aquitaniens de l’aquifère de Beauce. Cette ZNS va de la surface du sol jusqu’à une profondeur d’une vingtaine de mètres. Au droit du site d’étude retenu (lieu‐dit « les Hôtels »), la nappe s’établissait à 18,3 m en mars 2017. L’échantillonnage de la zone d’étude a été réalisé via une campagne de carottage au terrain. Trois sondages carottés d’une profondeur de 20 m ont permis de recueillir suffisamment d’échantillons intacts pour pouvoir réaliser un certain nombre de caractérisations physiques, physicochimiques, minéralogiques et hydriques. Pour l’étude des propriétés de transfert de ces échantillons, un dispositif expérimental de type triaxial a été conçu pour la mesure des propriétés hydriques avec la méthode multi‐step de débit d’extraction. Les caractéristiques de rétention en eau ont été comparées à celles mesurées par la méthode de la presse de Richards, et complétées par des mesures dans la gamme de pF 3‐6, réalisées à l’aide du dispositif WP4C. La conductivité hydraulique à saturation des facies sableux et sablo‐marneux sont les plus élevées parmi les faciès de la ZNS à exception des certains échantillons de roches micro‐fissurées. Les valeurs plus faibles ont été observées pour le sol limonoargileux et pour les faciès de marne. La rétention en eau la plus élevée est celle mesurée pour les sols. Les valeurs les plus faibles correspondent à la roche. Les faciès de roche calcaire se désaturent très rapidement lorsque le potentiel matriciel diminue, ce qui engendre une diminution brutale de la conductivité hydraulique. Nos résultats montrent que les premiers mètres de la ZNS représentent une zone où l’écoulement (vertical) vers la nappe est relativement lent, mais, à partir d’environ 7 mètres de profondeur, le transport de l’eau est beaucoup plus rapide étant donné la présence de fissures et fractures
The Beauce limestone aquifer has been studied in recent decades. However, most of the studies concerned the very first meters of the unsaturated zone (VZ) (0 to 3 meters) and / or the saturated zone of the aquifer. The flow processes, through the widely stratified VZ are not well understood. Many authors have emphasized its heterogeneity, both lateral and vertical, with quite variable lithologies. Access to the entire VZ remains a major issue, whose main difficulties are technical and economic. The goal is to contribute to a better understanding of the mechanisms of water transfer within the VZ of the lime Beauce aquifer. This VZ goes from the surface of the ground to a depth of about twenty meters. In the area of interest (lieu‐dit “les Hôtels"), the water table was found at 18.3 m depth in march 2017. Sampling of the unsaturated zone was carried out via a coring campaign. Three wells were cored from surface up to a depth of around 20 m. Sampling of the VZ allowed to perform physical, physicochemical, mineralogical and hydraulic characterizations of the unsaturated material. To study the transfer properties of these samples, a triaxial system was set up to measure hydraulic properties using the multistep outflow method. The water retention curves were compared to those measured by the temp cell method (Richards method), and supported by measurements in the pF 3‐6 range, performed using the WP4C device. The saturated hydraulic conductivity values of sandy and sandy‐marly samples were the larges among all unconsolidated materials of the vadose zone of the aquifer. Rock samples having micro‐fissures and fractures showed the largest values of saturated hydraulic conductivity. Lower values were observed for loamy clay soil and for marl samples. The highest water retention is that measured for soils. The lowest values correspond to the rock. Rocks samples drain very rapidly when the matrix potential decreases, which causes a sudden decrease in the hydraulic conductivity. Our results show that the first meters of VZ represent an area where the (vertical) flow towards the aquifer is relatively slow, but, from about 7 meters deep, water transport is much faster due to the presence of cracks and also due

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Godrant, Aurélie. "The role of superoxide in iron acquisition by marine phytoplankton." Brest, 2009. http://www.theses.fr/2009BRES2061.

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Le rôle clef du fer dans le cycle biogéochimique du carbone et de l’azote dans l’océan a été mis en évidence au cours de la dernière décennie. Une des découvertes majeures récentes en océanographie biologique est la limitation de la croissance du phytoplancton par la disponibilité en fer dans au moins 40% de l’océan mondial. Or, la chimie de cet élément dans l’océan est particulièrement complexe et la forme sous laquelle il est disponible pour le phytoplancton reste encore mal connue. Plusieurs mécanismes sont utilisés par le phytoplancton marin pour améliorer la solubilité du fer en eau de mer et parvenir à absorber les quantités suffisantes en fer nécessaires à leur survie. Un de ces mécanismes implique la production de radicaux superoxyde en milieu extracellulaire, ce qui accroît la bio-disponibilité du fer en eau de mer en réduisant la forme Fe(III) sous forme Fe(II), plus bio-disponible aux cellules de phytoplancton. Les objectifs principaux de ce travail étaient de i) développer une méthode appropriée pour détecter la production de superoxyde en milieu extracellular par n’importe quelle cellule de phytoplancton marin, et ii) examiner la relation entre la production extracellulaire de superoxyde et l’absorption du fer par la cyanobactérie Trichodesmium erythraeum IMS101. Une méthode de détection du superoxyde a été développée, qui utilise du red-CLA ou du MCLA, deux sondes chimiluminescentes spécifiques à la détection du superoxyde, qui ont donné des résultats fiables, même sur de très faibles quantités d’échantillons. En effet, comparée aux autres méthodes employées, la détection de la production du superoxyde par microplaques permet de réduire le volume d’échantillon par 10, et de réduire le temps d’analyse de tréplicats d’un échantillon, d’un blanc et de trois standards à 10 minutes. De plus, cette méthode présente une large gamme de travail avec une limite de détection de 0,076 pmol/s, ce qui lui confère un grand avantage pour le travail sur le phytoplancton marin. Les taux de production de superoxyde en milieu extracellulaire par la cyanobatérie Trichodesmium erythraeum ont été mesurés en condition de laboratoire et allaient de 0,93 à 16,21 pmol/trichome/h. La limitation en fer des cellules de Trichodesmium résultat en une augmentation de ce taux de production, qui a été multiplié par un facteur 2,9 entre les cellules non limitées et les cellules limitées en fer. Il a aussi été montré que la production de superoxyde suivait un rythme diurne avec une forte augmentation du taux de production en milieu du cycle « jour», spécialement marqué pour les cultures maintenues en milieu pauvre en fer. Les taux de production extracellulaire de superoxyde et d’absorption du fer par Trichodesmium ont été mesurés simultanément sur des cultures pré-limitées ou non limitées en fer. Les taux d’absorption étaient 10 fois plus élevés pour les cultures non limitées, sauf lorsqu’un composé réducteur (acide ascorbique) était ajouté. Dans ce cas, les taux d’absorption des deux cultures étaient similaires. De plus, les deux cultures ont montré une plus grande aptitude à absorber le fer lié à des ligands faibles comme le citrate. Dans l’ensemble, les résultats ont montré une relation entre la production de superoxyde et l’absorption de fer par Trichodesmium, mais aucune influence directe entre ces deux processus n’a pu être démontrée. La méthode de détection du superoxyde par microplaque a été utilisée lors de campagnes sur la Grande Barrière de corail en Australie. L’analyse de deux blooms de Trichodesmium a montré de forts taux de production de superoxyde, en cohérence avec les analyses effectuées au laboratoire. De plus, l’utilisation de cette méthode (entre autres) a permis de démontrer une accumulation d’espèces Fe(II) en concentrations biologiquement significatives, quand la concentration en superoxyde dans l’eau de mer était inférieure à 1 nM. Par contre, lorsque cette concentration se trouvait supérieure à 1nM, la plupart des espèces réduites (Fe(II)) étaient réoxidées, ce qui résultait en un fort taux de production de peroxyde d’hydrogène du à la dismutation du superoxyde. Dans l’ensemble, cette étude a permis le développement d’une méthode de détection de la production de superoxyde par le phytoplancton marin en milieu extracellulaire qui peut être utilisée au laboratoire ou en conditions d’étude sur le terrain. Nous avons aussi démontré que les cellules de Trichodesmium erythraeum IMS101 produisent de grandes quantités de superoxyde, en particulier lorsqu’elles sont limitées en fer. L’étude des taux d’absorption du fer par ces même cellules a démontré une forte relation entre ce processus et la production de superoxyde par les cellules: ces résultats sont en accord avec l’hypothèse que le modèle d’absorption du fer par le phytoplancton marin «Fe’» serait fortement influencé par ce type d’organisme capable de modifier l’équilibre redox du milieu présent à la surface des cellules
It is hypothesised that, under iron limitation, phytoplankton cells develop biochemical mechanisms to increase their iron uptake efficiency with one of these mechanisms involving the production of superoxide in the extracellular environment that increases the bioavailability of iron in seawater by reducing Fe(III) to the more soluble Fe(II). The main objectives of this work were 1) to develop an appropriate method to detect extracellular production of superoxide by marine phytoplankton, and 2) to examine the relationship between extracellular production of superoxide and iron acquisition by Trichodesmium erythraeum. A method to measure superoxyde production is described using red-CLA and MCLA probes, yielding considerable improvement for analysis compared to other available methods. Extracellular superoxide production and iron uptake rates were measured simultaneously on iron replete and iron deplete Trichodesmium erythraeum IMS 101 laboratory cultures : iron starvation leads to a 2. 9-fold increase in superoxide production rate and 10-fold decrease in the iron uptake rate (except when a reducing compound was added) compared to iron replete cultures. Extracellular superoxide production shows a pronounced circadian rythm in iron deplete cultures, but less so in iron replete cultures. Overall, no direct impact of extracellular superoxide production by Trichodesmium is observed, but both processes are shown to be related. Both iron deplete and iron replete cultures demonstrate greater ability to uptake iron bound to weaker iron-binding ligands such as citrate. Application of the method to field studies in the Great Barrier Reef lagoon showed an accumulation of biologically significant concentrations of reduced trace metals including Fe(II) when the concentration of superoxide was lower than 1 nM. When the concentration of superoxide was higher than 1 nM, most of the reduced species were oxidised resulting in high rates of hudrogen peroxide production rates, consistent with laboratory studies. Overall, this thesis permitted the development of a method to detect superoxide production rates by marine phytoplankton cells that could be used routinely in field studies. The observations are in accord with the conclusion that fit the ongoing hypothesis that the extablished Fe' uptake model for phytoplankton would be strongly influenced by such organisms that are able to modify the redox equilibrium of the solution at their cells surface

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Ngombi-Pemba, Lauriss-Paule. "Géochimie et minéralogie des formations argileuses (2.2 - 2.0 Ga) du bassin de Franceville au Gabon : fluctuations de l'oxygène atmosphérique, chimie des océans et diagenèse au Paléoprotérozoïque." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2259.

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Le bassin Francevillien d'âge Paléoprotérozoïque (2.2–2.0 Ga) du Gabon, est bien connu grâce à ses réacteur nucléaires, et pour avoir fourni l'évidence des plus ancienns macrofossiles complexes et organisés. Les sédiments Francevilliens renferment également des minéraux interstratifiés riches en smectite, supposés absents dans des sédiments aussi anciens. Cependant, peu de données existent sur l’état d’oxygénation de l’atmosphère et de l’hydrosphère lors du dépôt de ces roches. Afin d’évaluer les conditions redox de la colonne d’eau lors du dépôt, une étude biogéochimique des éléments sensibles au redox (C, S, Fe, métaux traces, et terres rares) a été effectuée, à l’échelle de la série. Une étude minéralogique des argiles a également été abordée afin de vérifier l’éventuelle relation entre la signature minéralogique des argiles observée, et les conditions redox de dépôt. Les données géochimiques obteunues montrent que lors du dépôt de formations FB et FC, les eaux étaient globalement oxygénées, excepté lors de la sédimentation ferrifère et manganésifère. Celle-ci s’est effectuée sous une colonne d’eau profonde anoxique, lors d’une période de haut niveau marin. En revanche, les black shales de la partie supérieure de la série (FD) se sont déposés dans des conditions euxinques. Ces conditions euxiniques sont reflétées par l’enrichissement en métaux traces, le shift à des valeurs très négatives de δ13Corg et les valeurs de δ98Mo. La série Francevillienne fournit une fenêtre de temps exceptionnelle qui enregistre l’état redox des océans et les fluctuations de l’oxygène atmosphérique durant et immédiatement après le Lomagundi Event, par conséquent, après le GOE. Les analyses
The Paleoproterozoic Francevillian series (2.2–2.0 Ga) of Gabon is well known for its natural nuclear reactor and for having provided evidence of the earliest large colonial macrofossils. These ancient rocks also contain unexpected smectite-rich mixed layers minerals. However, few data are available yet on the oxygenation state of the atmosphere and ocans during the deposition of the Francevillian sediments. In order to investigate the nature of marine water-column chemistry, samples representing the entire section (FB, FC, and FD formations) were subjected to multielement (C, S, Fe, trace metals, and REE) biogeochemical study. In addition, to assess the impact of atmospheric and oceanic paleoredox conditions on clay minerals, a clay minralogical study was performed. Geochemical data show deep water oxic conditions during deposition of FB and FC formations in agreement with the Lomagundi Event (LE). Nevertheless the interlayered Mn and Fe deposits occured in ferruginous anoxic conditions reflecting sea-level changes. The FD black shales reflect euxinic conditions. These conditions, are indicated by trace metals enrichment, negative shift of δ13Corg values and δ98Mo. The Francevillian series show direct geochemical evidence for the state of atmospheric and ocean oxygenation both during and after the LE. These data confirm a significant decrease in the oxygenation of ocean water in the aftermath of the LE and the Great Oxidation Event (GOE). The mineralogical results reveal that the clay mineralogical signature observed in the basin, is not the consequence of the atmospheric oxygen fluctuations. The survival of smectitic minerals is strictly dependent on diagenetic transfo

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Joussain, Ronan. "Histoire de l’érosion de l’Himalaya durant le dernier cycle climatique : approches sédimentologiques, minéralogiques et géochimiques des sédiments de la partie proximale de l’éventail sous-marin profond du Bengale." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS433.

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L’objectif de cette étude est de reconstruire le régime de l’érosion des chaînes himalayennes, et de relier ces paramètres aux variations climatiques globales et à l’intensité de la mousson. Dans ce travail, Les sédiments de 3 carottes prélevées dans la baie du Bengale pendant la mission MONOPOL ont fait l’objet d’analyses minéralogiques (XRD et granulométrie) et géochimiques (majeurs, traces, la composition isotopique du Nd et du Sr). La mise en âge des carottes, est basée sur les enregistrements de δ¹⁸O de foraminifères planctoniques (G. ruber), et des datations au ¹⁴C (AMS). Ces 3 enregistrements sédimentaires couvrent les derniers 180 ka. L'approche multi-traceur menée sur ces carottes, nous donne des informations essentielles sur les sources, afin de reconstruire les changements au cours du temps des sédiments transportés vers la partie proximale du cône sous-marin du Bengale, et de mieux comprendre ses liens potentiels avec les changements climatiques (mousson indienne et/ou des changements au niveau de la mer). Les résultats de cette étude, donnent également des clefs sur les processus d'altération chimique et de la dynamique du transport des sédiments au cours du temps. En outre, une étude à haute résolution, sur un site localisé sur la levée du chenal actif du cône sous-marin fournit des informations sur les changements dans le degré d'altération et la dynamique de transport des sédiments du système himalayen au cours de l'Holocène. Ainsi, il est possible de quantifier l'impact de la mousson d’été sur la sédimentation au niveau de la levée durant cette période climatique. Les résultats de cette étude ont été utilisés pour estimer les changements dans les sources sédimentaires (plaine Indo-Gangétique vs haute-chaine) et retracer l'altération chimique du matériel détritique au sein du bassin versant du système fluviatile du Ganges-Brahmapoutre
The aim of this study is to reconstruct the erosional history of the Himalayan ranges, in order to connect these parameters to global climatic events and variations in the intensity of the monsoon. In this work, sediments from 3 marine cores collected in the Bay of Bengal, during the MONOPOL cruise were analyzed using mineralogical (XRD and grain-size) and geochemical (major, trace, Nd and Sr isotopic composition) methods. Chronological framework of studied cores were based on δ¹⁸O from planktonic foraminifera (G. ruber), and ¹⁴C ages dating (AMS). These cores cover the last 180 kyr. The multi-proxy approach conducted on these cores, gives us critical information about the source, to reconstruct the temporal variability of sediment export to the proximal northeastern Bengal Fan and its potential links to climatic changes (Indian monsoon and/or sea-level changes). Results also give insights on the chemical weathering processes and the dynamic of transport of the sediments through time as well. Moreover, a high-resolution study, on a site located on the active middle fan channel levee of the fan provides information on changes in the weathering pattern and the dynamic of transport of sediments from the Himalayan system during the Holocene. Thus, it is possible to quantify the impact effect of summer monsoon rainfall during that time interval. These results have been used to assess changes in the sedimentary sources (Indo-Gangetic plain vs highlands) and document the chemical weathering states of the detrital material within the Ganges-Brahmaputra river basin catchment

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Chen, Quan. "Signatures détritiques des changements paléoenvironnementaux du Quaternaire récent dans le bassin nord de la mer de Chine du Sud." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS492/document.

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Le but de cette thèse est de reconstruire l’évolution environnementale de la région nord de la mer de Chine du Sud au cours du Quaternaire récent. L'objectif est d'identifier des traceurs des interactions continent-océan, de la mousson est-asiatique et de la circulation océanique. Pour cela, des analyses des minéralogies argileuse et magnétique, de la composition en éléments majeurs, et la taille des grains ont été effectuées sur les sédiments de carotte MD12-3432 couvrant les derniers 400 ka avec un taux de sédimentation variant entre 4.5 et 24 cm/ka. Nous avons tout d'abord amélioré les calibrations de la composition en éléments majeurs obtenue par XRF core-scanning. En effet, celles-ci ne corrigeaient pas des variations de teneur en eau interstitielle observées la séquence sédimentaire étudiée. Nous avons donc proposé une correction polynomiale quadratique qui convertit maintenant correctement les données XRF core-scanning en concentrations précises d’éléments majeurs. La composition en élément majeurs, les minéralogies argileuse et magnétique, et la granulométrie indiquent que les changements climatiques à basse latitude influencent les diverses fractions terrigènes de différentes manières. Considérant d’abord les éléments majeurs et les argiles, nous observons que les rapports smectite/(illite+chlorite) et K₂O/Al₂O₃ présentent tous deux des cyclicités orbitales. Le rapport K₂O/Al₂O₃ qui reflète la contribution relative des apports de Taiwan par dénudation, augmente pendant les interglaciaires quand la mousson d’été asiatique est forte. Le rapport smectite/(illite+chlorite) présente des cyclicités également liées à l’excentricité et à la précession en phase avec les changements d’insolation de l’hémisphère nord en été. Connaissant les régions sources de ces argiles, nous suggérons que l’apport en smectite est étroitement lié à l'intensité de l’altération chimique et à la dénudation fluvial induite par les fortes précipitations de mousson, tandis que l’apport d’illite/chlorite depuis Taiwan répond principalement à la dénudation. Le rapport smectite/(illite+chlorite) reflète ainsi principalement l'intensité de l’altération chimique contemporaine (rapide) et donc l’intensité de la mousson d'été asiatique. Les résultats obtenus confirment que la mousson d'été asiatique est renforcée pendant les périodes interglaciaires et quand l'insolation d'été boréal est forte. Les propriétés magnétiques sédimentaires offrent des informations complémentaires sur les changements environnementaux passés dans cette région. La fraction magnétique de la carotte MD12-3432 est composée de magnétites, sulfures de fer et hématite. Des augmentations de teneur en hématite et des diminutions de la granulométrie sédimentaire sont observées aux minima de précession. Ces évènements qui ont lieu pendant les périodes arides pourraient illustrer des apports éoliens depuis le nord de la Chine, liés à des changements d'intensité et/ou de route des vents, probablement aussi liés à l’intensification de la mousson d'hiver. Outre les changements climatiques de basse latitude, le climat global et l'activité tectonique influencent aussi les apports terrigènes dans cette région. Les augmentations à long terme de la teneur en pyrrhotite par rapport à la magnétite et à l’hématite, de la teneur de illite/chlorite indiquent une contribution croissante de sédiment fine d'origine Taiwanaise au cours des derniers 400 ka. Ceci est très probablement lié à l’intensification de l'orogenèse taïwanais. A l'échelle glaciaire-interglaciaire, les variations synchrones des compositions argileuse et magnétique, de la taille des grains sédimentaires et magnétiques, et des taux de sédimentation sont attribuées aux changements de niveau marin. En effet, les bas niveaux marins pendant les périodes glaciaires exposent l’immense plateau continental et permettent à la Rivière des Perles de livrer au site du sédiment terrigène en plus grande quantité et plus grossier
The aim of this study is to reconstruct late Quaternary environmental changes in the northern South China Sea by applying multi-disciplinary proxies of land-sea interaction, East Asian monsoon, and oceanic circulation. Investigations of clay and magnetic mineralogy, major element composition, and grain size were performed on marine sediment Core MD12-3432 retrieved from the continental slope of the northern South China Sea. The core covers the last 400 ka with a sedimentation rate varying between 4.5 and 24 cm/ka. We examined the accuracy of existing calibration methods on major element composition obtained by XRF core-scanning, because downcore variations in interstitial water content should strongly affect scanned element contents. We proposed a quadratic polynomial correction to account for this effect and implemented it in the calibration methods. Data from Core MD12-3432 show that the improved calibration process now correctly converts XRF core-scanning data into major element concentrations. Our results on high-resolution major element composition, clay and magnetic mineralogy, and grain size data indicate that low-latitude climate changes influence various terrigenous fractions in different ways. In bulk sediment, K₂O/Al₂O₃ ratio mainly reflects the relative contribution of detrital supply from Taiwan, and its variation exhibits eccentricity cycles. The ratio increases during interglacials, showing that strong precipitation and denudation are induced by enhanced East Asian summer monsoon. In clay fractions, smectite/(illite+chlorite) ratio presents both eccentricity and precession periodicities, in phase with the northern hemisphere summer insolation changes and therefore with the East Asian summer monsoon evolution. Based on the knowledge of sediment provenances, these results suggest that high smectite/(illite+chlorite) ratios illustrate contemporaneous chemical weathering intensity in Luzon. It supports the understanding that East Asian summer monsoon is enhanced during interglacial periods and when the boreal summer insolation is strong. Therefore, these two ratios are appropriate sedimentary tracers for East Asian summer monsoon evolution in the South China Sea. The magnetic fraction yields complementary information about environmental changes in the South China Sea. The magnetic mineral assemblage of Core MD12-3432 is mainly composed of magnetite, sulphide, and hematite, and the relative contributions of all these magnetic mineral contents change with time. Variations on precessional band related to the low latitude East Asian monsoon are observed in magnetic properties and grain size values. High magnetic inputs with high hematite proportion, which is part of fine-grain sediment, are observed during the precession minima. These events occurring during arid periods may illustrate enhanced eolian inputs caused by changes in intensity and/or winds pathway of winds, probably related to enhanced winter monsoon. Besides the low-latitude climate changes, global climate and tectonic activity also influence the terrigenous composition at the studied site at different timescales. A long-term increase in pyrrhotite content with respect to magnetite and hematite and in illite/chlorite contents indicates an increasing contribution of fine grained sediments from Taiwan. This is most likely related to the intensification of Taiwanese orogeny over the last 400 ka. On glacial-interglacial scale, coeval increases observed in sedimentation rate, magnetite/pyrrhotite content, kaolinite content, and grain size during glacial periods are attributed to sea-level changes. Low sea-level during glacial periods exposes the vast shelf and allows the Pearl River to deliver more and coarser terrigenous sediments to our site

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Dunoyer, Hugues. "Expérimentation en laboratoire et in-situ d'un procédé de stabilisation des remblais ferroviaires argilo-marneux : les colonnes de sol traité à la chaux éteinte et au ciment." Paris, ENMP, 1986. http://www.theses.fr/1986ENMP0011.

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Pour la prévention de l'instabilité des talus de remblais argileux du réseau sncf, mise au point d'un nouveau procédé de stabilisation: les colonnes de sol traitées à la chaux et au ciment fabriquées dans le talus même du remblai. Essais en laboratoire et en place de l'efficacité et de la faisabilité de ce procédé (matériau de remblai traité à 8% de chaux de boran, 10% de ciment cpj45 et un mélange de 5% de chaux et 10% de ciment). Etude de la rupture de ces éprouvettes cylindriques de matériau traité. Comparaison du comportement d'éprouvettes conservées a 60**(o)c en étuve humide et de celles conservées a 20**(o)c en atmosphère ambiante. Recherche des évolutions texturale et minéralogique du matériau traité. Interpretation des essais au bleu de methylène des produits de réaction a l'intérieur des mélanges. Controle effectue sur le terrain sur un plat d'essai pour étudier la faisabilité du procédé. Standardisation de la méthodologie d'étude

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Dissertations / Theses on the topic 'Marie Clay'

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