Search results for " REE"

Zirconium and hafnium fractionation and distribution of Rare Earth Elements in neutral–alkaline waters: Case study of Lake Van hydrothermal system, T…

2021

International audience; We investigated the distribution of Zr, Hf, and rare earth elements (REE) as the sum of lanthanides plus Y in the hydrothermal system in the Lake Van area of south-eastern Turkey. This system is characterised by water with variable pH in alkaline conditions resulting from hydrothermal CO2 upraise and neoformation of calcite minerals in near equilibrium with the interacting waters. Zr, Hf, and REE determinations were carried out for aqueous phases and suspended solids in lake water and surrounding thermal springs. We found that dissolved Hf is partitioned relative to Zr during calcite formation and that such fractionation is a function of the Ca2+ activity in warm wat…

A Triassic carbonate platform edge in the Sciacca zone: implications for the accretion of the Maghrebian chain in southwestern Sicily

2008

Probing the Multiple Structures of Vaterite through Combined Computational and Experimental Raman Spectroscopy.

2014

First-principles Raman spectra have been computed for several new vaterite structural models that have been recently proposed, and compared with spectra recorded on a set of biogenic, geological and synthetic samples. This set includes new measurements collected on Herdamania momus spicules (Great Barrier Reef, Queensland, Australia), which are known to have purity and crystallinity that are higher than for other biogenic samples. Overall, due to the close structural connection between the various models, the computed Raman spectra are found to be broadly similar. However, the spectra obtained for the two most stable models (monoclinic C2 and trigonal P3221, corresponding to two different p…

Calcification is not the Achilles' heel of cold-water corals in an acidifying ocean

2015

Ocean acidification is thought to be a major threat to coral reefs: laboratory evidence and CO2 seep research has shown adverse effects on many coral species, although a few are resilient. There are concerns that cold-water corals are even more vulnerable as they live in areas where aragonite saturation (?ara) is lower than in the tropics and is falling rapidly due to CO2 emissions. Here, we provide laboratory evidence that net (gross calcification minus dissolution) and gross calcification rates of three common cold-water corals, Caryophyllia smithii, Dendrophyllia cornigera, and Desmophyllum dianthus, are not affected by pCO2 levels expected for 2100 (pCO2 1058 ?atm, ?ara 1.29), and nor a…

Mediterranean bioconstructions along the Italian coast

2018

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of prima…

Mediterranean rocky reefs in the Anthropocene: Present status and future concerns

2021

Global change is striking harder and faster in the Mediterranean Sea than elsewhere, where high levels of human pressure and proneness to climate change interact in modifying the structure and disrupting regulative mechanisms of marine ecosystems. Rocky reefs are particularly exposed to such environmental changes with ongoing trends of degradation being impressive. Due to the variety of habitat types and associated marine biodiversity, rocky reefs are critical for the functioning of marine ecosystems, and their decline could profoundly affect the provision of essential goods and services which human populations in coastal areas rely upon. Here, we provide an up-to-date overview of the statu…

Estudio Hidrogeoquimico De Las Áreas Termales Del Complejo Volcánico Copahue-Caviahue

2016

Hydrogeochemical study on Thermal areas of the Copahue-Caviahue Volcanic Complex The hydrothermal system hosted in the Copahue- Caviahue Volcanic Complex consists of different geothermal areas around the Copahue volcano, whose last eruptive cycle started on December 22 of 2012. This work presents new data from the samplings of November 2012 and march 2013 in Las Maquinas, Las Maquinitas, villa de Copahue and Chancho-Có areas. These acid-sulfate and steam heated waters, presented changes in their SO4-2 concentrations, especially in Las Maquinas and Las Maquinitas areas. Meanwhile, SO4-2/Cl- ratios presented a strong decrease in the samples from November 2012, regarding the samples from 2013.…

Interpretation of epicardial mapping by means of computer simulations: Applications to calcium, lidocaine and to BRL 34915

1992

The aim of this work was to compare experimental investigations on effects of lidocaine, calcium and, BRL 34915 on reentries to simulated data obtained by use of a model of propagation based on the Huygens' construction method already described in previous works. Calcium and lidocaine effects are investigated on anisotropic conduction conditions. In both cases, reduction in conduction velocities are observed. In lidocaine case, a refractory area is located along the longitudinal axis. In agreement with experimental electrical mapping, the simulations show that the stabilization of reentrant excitation is mainly due to the existence of this refractory area around which the reentrant circuit …

Performance of a Pilot-Scale Constructed Wetland and Medium-Term Effects of Treated Wastewater Irrigation of Arundo donax L. on Soil and Plant Parame…

2021

On marginal lands in the Mediterranean basin, giant reed (Arundo donax L.) represents one of the most interesting perennial crops due to high levels of biomass production. Considering periodic water shortage during the summer months in this area, the reuse of treated wastewater (TWW) would seem to be a good opportunity for the growth of the species. The aim of this study was to assess the medium-term effects of irrigation using freshwater (FW) and TWW on soil characteristics and growth in giant reed plants. TWW was obtained from a pilot-scale horizontal subsurface flow constructed wetland system (HSSF CWs) with a total surface area of 100 m2. A split-plot design for a two-factor experiment …

De los cruces entre el cine y la literatura: Osvaldo Soriano y la desmitificación del Olimpo hollywoodense

2014

Resumen : Este articulo se propone investigar la recuperacion del discurso cinematografico operada por el escritor argentino Osvaldo Soriano. El autor retoma personajes arquetipicos, esquemas narrativos y convenciones descriptivas de los principales generos cinematograficos hollywoodenses y las adapta al contexto cultural argentino. En particular se analizara la relacion que se establece entre la novela Cuarteles de invierno y el genero western. Se trata de una rescritura parodica en la que Soriano, desmitificando los valores tradicionalmente asociados al genero, transmite un punto de vista critico sobre el presente historico. Palabras Clave :Soriano, desmitificacion, cine, western, reescri…