Search results for "Geochemistry"

Performance Study of Twisted Darrieus Hydrokinetic Turbine With Novel Blade Design

2021

Abstract Twisted Darrieus water turbine is receiving growing attention for small-scale hydropower generation. Accordingly, the need for raised water energy conversion incentivizes researchers to focus on the blade shape optimization of twisted Darrieus turbine. In view of this, experimental analysis has been performed to appraise the efficiency of a spiral Darrieus water rotor in the present work. To better the performance parameters of the studied water rotor with twisted blades, three novel blade shapes, namely U-shaped blade, V-shaped blade, and W-shaped blade, have been numerically tested using a computational fluid dynamics three-dimensional numerical model. The maximum power coefficie…

Nitrogen isotopes in tooth enamel record diet and trophic level enrichment: results from a controlled feeding experiment

2021

Nitrogen isotope ratios (δ15N) are a well-established tool for investigating the dietary and trophic behavior of animals in terrestrial and marine food webs. To date, δ15N values in fossils have primarily been measured in collagen extracted from bone or dentin, which is susceptible to degradation and rarely preserved in deep time (>100,000 years). In contrast, tooth enamel organic matter is protected from diagenetic alteration by the mineral structure of hydroxyapatite and thus is often preserved over geological time. However, due to the low nitrogen content (<0.01 %) of enamel, the measurement of its nitrogen isotopic composition has been prevented by the analytical limit…

Carbon isotope stratigraphy, magnetostratigraphy, and 40Ar/39Ar age of the Cretaceous South Atlantic coast, Namibe Basin, Angola

2014

This publication results from Projecto PaleoAngola, an international cooperative research effort among the contributing authors and their institutions, funded by the National Geographic Society, the Petroleum Research Fund of the American Chemical Society, Sonangol E.P., Esso Angola, Fundacao Vida of Angola, LS Films, Maersk, Damco, Safmarine, ISEM at SMU, The Royal Dutch Embassy in Luanda, TAP Airlines, Royal Dutch Airlines, The Saurus Institute, and the Perot Museum of Nature and Science. JS was additionally funded by Yale University and the Alfred Kordelin Foundation. We dedicate this contribution to the late Kalunga Lima, our friend and colleague in Projecto PaleoAngola. We thank Margar…

One-dimensional compression and consolidation of shales

2016

This paper presents a comprehensive methodology for analysing the compression and consolidation behaviour of shales. An apparatus was designed to perform oedometric high-pressure tests by applying a maximum vertical total stress of 100 MPa and simultaneously controlling the pore water pressure of the specimen. An analytical method was formulated to analyse the shale consolidation behaviour, which allows information to be gathered on the coefficient of consolidation, stiffness, poroelastic properties, secondary compression and permeability of the tested material as a function of the applied stress conditions. Results obtained on Opalinus Clay shale using the developed methodology are present…

Nouveaux biohorizons et propositions pour le découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France

2008

International audience; Un nouveau découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France est proposé. Il tient compte des renouvellements fauniques, des données séquentielles ainsi que des données historiques. Il est enrichi de quatre biohorizons nouveaux. Le Barrémien supérieur comporte à présent les trois biozones (anciennement six) à Vandenheckei, Sartousiana et Giraudi. La première contient les trois sous-zones à Uhligi, dont le statut est discuté, Sayni et Barremense, ainsi que les deux nouveaux biohorizons à Marchandi et Breistrofferi (sommet de la Sous-Zone à Barremense). La Biozone à Sartousiana admet les sous-zones à Limentinus, Provincialis et Feraudianus. …

Preface: Environmental benefits of biochar

2014

J. Paz-Ferreiro1, A. Mendez6, A. M. Tarquis3,4, A. Cerda5, and G. Gasco2 1School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne 3001, VIC, Melbourne, Australia 2Departamento de Produccion Agraria, E.T.S.I. Agronomos, Universidad Politecnica de Madrid, Ciudad Universitaria, 28004 Madrid, Spain 3CEIGRAM, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain 4Departamento de Matematica Aplicada, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain 5Soil Erosion and Degradation Research Group, Department of Geography, University of Valencia, C/Blasco Ibanez 10, 46010 Valencia, Spain 6Departamento de Ingen…

Water-extractable organic matter linked to soil physico-chemistry and microbiology at the regional scale

2015

10 pages; International audience; A better understanding of the links between dissolved organic matter and biogeochemical processes in soil could help in evaluating global soil dynamics. To assess the effects of land cover and parental material on soil biogeochemistry, we studied 120 soil samples collected from various ecosystems in Burgundy, France. The potential solubility and aromaticity of dissolved organic matter was characterised by pressurised hot-water extraction of organic carbon (PH-WEOC). Soil physico-chemical characteristics (pH, texture, soil carbon and nitrogen) were measured, as was the δ13C signature both in soils and in PH-WEOC. We also determined bacterial and fungal abund…

2020

Strontium isotopes in biogenic apatite, especially enamel, are widely employed to determine provenance and track migration in palaeontology and archaeology. Body tissues record the 87Sr/86Sr of bioavailable Sr of ingested food and water. To identify non-local individuals, knowledge of the 87Sr/86Sr of a non-migratory population is required. However, varying factors such as tissue turnover rates, feeding selectivity, Sr content, digestibility of food, and the ingestion of mineral dust can influence body tissue 87Sr/86Sr. To evaluate the Sr contribution of diet and water to mammalian hard tissues 87Sr/86Sr, controlled feeding studies are necessary. Here we present 87Sr/86Sr from controlled fe…

Dynamic Triggering of Mud Volcano Eruptions During the 2016–2017 Central Italy Seismic Sequence

2017

©2017. American Geophysical Union. All Rights Reserved. On 24 August 2016 a seismic event (Mw6.0) was the first of the long Central Italy sequence (ongoing at the end of 2017) of medium-to-high magnitude earthquakes, with nine Mw≥5 up to October 2017, and with about 74.000 seismic events registered after 1 year. The largest was the Mw6.5 30 October 2016 event near Norcia. After the major seismic events, 17 mud volcanoes erupted around Monteleone di Fermo village (Marche region). Mud volcano eruptions generally occurred a few hours to a few days after the main earthquakes, suggesting a seismic triggering. We analyzed the peak ground velocities and dynamic stresses during the three largest ea…

Non-invasive Geophysical Surveys in Search of the Roman Temple of Augustus Under the Cathedral of Tarragona (Catalonia, Spain): A Case Study

2018

An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious…