Spelling suggestions: "subject:"rate earth elements (REE)"" "subject:"race earth elements (REE)""
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Rare earth element bioaccumulation and anomalies in organisms of northeastern Nunavik (Quebec, Canada)Marginson, Holly 07 1900 (has links)
Comme la demande mondiale des éléments de terres rares (ETR) ne cesse d'augmenter, de
nouveaux projets d'exploration ont été lancés dans de nombreux pays, incluant au Canada. Le
présent projet découle d'un programme communautaire environnemental issu d'une
collaboration entre des chercheurs et la communauté inuite de Kangiqsualujjuaq suite à la
proposition d’un projet minier d'ETR au Nunavik. Pour répondre aux études limitées sur la
distribution des ETR dans les environnements non pertubés, cette étude rapporte les niveaux
actuellement observés des sédiments, des lichens et de multiples espèces animales provenant
d'écosystèmes terrestres, d’eau douce et du milieu marin du subarctique de l’est du Canada. Les
résultats suggèrent que toutes les matrices ont la capacité d'accumuler les ETR, bien qu'une
dilution trophique soit notée. De plus, l’analyse des tissus d’espèces alimentaires traditionnelles
a démontré que le foie des vertébrés avait des concentrations d'ETR plus élevées que le muscle
et le gras, tandis que les tissus osseux et rénaux présentaient généralement des concentrations
intermédiaires. En outre, les tendances observées pendant l'analyse des anomalies du cérium
sensibles aux transformations d’oxydoréduction ont suggéré que ces anomalies peuvent servir de
biomarqueur dans l’exposition aux ETR et leur transformation biologique. Dans l'ensemble, cette
étude présente une bioaccumulation et un fractionnement d’ETR spécifiques aux espèces et aux
tissus, ce qui justifie des recherches plus approfondies afin de comprendre les facteurs de
contrôle du comportement d’ETR au sein des espèces animales. Ces résultats peuvent également
servir à établir des lignes directrices nationales d’ETR, et servir de référence dans les futures
études de biosurveillance. / A gradual increase in the release of rare earth elements (REE) to the environment has been
reported, as well as a continuous rise in their global demand. New REE exploration projects have
been initiated in multiple countries, including within Canada where REE deposits are frequently
located in northern regions. This project stems from a community-based environmental program
between researchers and the Inuit community of Kangiqsualujjuaq in the context of a prospective
REE mine in Nunavik. To address the limited review of REE distribution in natural environments,
the present study reports the current REE values for sediments, lichens, and multiple animal
species from terrestrial, freshwater and marine ecosystems of the eastern Canadian subarctic.
Results suggest that all matrices have the capacity to accumulate REE, though a biodilution across
taxonomic groups is noted. Also, a study of animal tissue samples from country food species
demonstrated that liver tissues have significantly higher concentrations of REE than the muscle
and blubber, with bone and kidney tissues typically presenting intermediate concentrations.
Further, the analysis of redox-sensitive cerium anomalies supported the presence of tissue-specific
mechanisms that suggest these anomalies may serve as a biomarker in REE exposure and
biological transformation. Overall, this study presents a species- and tissue- specific
bioaccumulation and fractionation of REE that warrants further investigation to better
understand the controlling factors of REE processing within animal species. The results may
additionally serve in the establishment of national REE guidelines for environmental health and
human consumption, and act as a reference in future biomonitoring studies.
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Prvková analýza plochých zobrazovacích zařízení pro urban mining / Elemental analysis of the flat display devices for urban miningŠtípek, Radek January 2016 (has links)
aaaaaRare earth elements (Sc, Y and group 15 lanthanides) and their compounds currently have significant practical use in metallurgy, glass industry, as highly active catalysts for the production of so-called. NiMH batteries, alloys for the manufacture of permanent magnets and e.g. moderators rods in the nuclear energy, but above all they have an irreplaceable role in modern electronics for phosphors TV screens, CRT earlier today, PDP and LCD monitors and displays, tablets, mobile phones etc., which give them a high-quality picture and sound. Unlike most base and precious metals are concentrated in the conquerable ore deposits, occur in the form of compounds as part of mixed minerals in the rarely economically exploitable concentrations, a mining and processing is costly and negative impacts on the environment, paradoxically towards the title but their overall content in the crust is relatively high, the average concentration in the range of about 150 to 220 ppm. The main world producer of REE, China, in 2010, significantly reduced exports by 40 %, making prices of some REE increased up to 1500 % during the month. Demand for REE is growing, so often talks about the recycling of valuable materials back into production, as called. "Urban mining", ie "urban mining", thereby reducing the amount of...
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Geochemie Porifera-reicher Mud Mounds und Mikrobialithe des Mittel- und Oberdevons (Westaustralien, Nordfrankreich) / Geochemistry of Porifera-rich mud mounds and microbialites of the Middle and Upper Devonian (Western Australia, Northern France)Hühne, Cathrin 07 November 2005 (has links)
No description available.
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