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| Registros recuperados: 52 | |
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| Sicre, Ma; Bard, E; Ezat, U; Rostek, F. |
| The C(37)-C(39) alkenones were quantified in suspended particulate matter obtained from the surface waters of the North Atlantic, including the Nordic seas, over a temperature range of 4degrees20 C. U(37)(K') values were linearly correlated to temperature over the entire range covered by our data set, i.e., 420 C (U(37)(K') = 0.027T + 0.036, r(2) = 0.97). The compilation of water column data from the Atlantic, Pacific, and Southern Ocean and Mediterranean Sea suggests that the linear model may not be the best function for fitting U(37)(K') and in situ temperature values. It also shows that suspended matter data from warm waters (T >20degreesC) are still needed to constrain the equation of the global curve. High abundances of C(37: 4) were found in the... |
| Tipo: Text |
Palavras-chave: Alkenones; Paleotemperature; Calibration; Atlantic Ocean; Plankton; Geochemistry; Marine geochemistry; Global change; Biogeochemical processes (4805); Oceanography; Paleoceanography. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33393/31866.pdf |
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| Almeida Júnior,Agenor Bezerra de; Nascimento,Clístenes Williams Araújo do; Biondi,Caroline Miranda; Souza,Adailson Pereira de; Barros,Felipe Martins do Rêgo. |
| ABSTRACT Soil contamination by heavy metals threatens ecosystems and human health. Environmental monitoring bodies need reference values for these contaminants to assess the impacts of anthropogenic activities on soil contamination. Quality reference values (QRVs) reflect the natural concentrations of heavy metals in soils without anthropic interference and must be regionally established. The aim of this study was to determine the natural concentrations and quality reference values for the metals Ag, Ba, Cd, Co, Cu, Cr, Mo, Ni, Pb, Sb and Zn in soils of Paraíba state, Brazil. Soil samples were collected from 94 locations across the state in areas of native vegetation or with minimal anthropic interference. The quality reference values (QRVs) were (mg... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geochemistry; Soil pollution; Micronutrients; Trace elements. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100509 |
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| Cuadra, T. de la; Chalén, X.; Pérez, P.; Macías, P.; Ortega, D.; Ormaza, F.. |
| Las masas de agua encontradas a partir de las variables de estado, indican una contribución muy pobre de Agua Subtropical Superficial (ASTS), mientras que las mayores contribuciones fueron de Agua Tropical Superficial (ATS). Parámetros como la temperatura y la salinidad determinaron un calentamiento del océano, tanto a nivel superficial como subsuperficial, lo cual sería una consecuencia de los procesos de redistribución de calor del océano.Esta dinámica ocasionaría anomalías del orden de los 30 metros para el caso de la profundidad de la termoclima y 2°C para el caso de la TSM. En el plancton se registraron valores mayores a 5000 larvas de peces/10 m2. La menor cantidad (260 larvas/10 m2) se registró hacia el norte del Golfo, observándose al mismo tiempo... |
| Tipo: Journal Contribution |
Palavras-chave: Oceanographic data; Geochemistry; Salinity data; Plankton; Organic matter; Plankton; Organic matter; Geochemistry; Http://aims.fao.org/aos/agrovoc/c_5950; Http://aims.fao.org/aos/agrovoc/c_5387; Http://aims.fao.org/aos/agrovoc/c_24848. |
| Ano: 1994 |
URL: http://hdl.handle.net/1834/3080 |
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| Seo, Inah; Lee, Yuri; Lee, Yong Il; Yoo, Chan Min; Hyeong, Kiseong. |
| This paper investigates paleoceanographic changes at a central equatorial Pacific site (6 degrees 40N, 177 degrees 28W) since the last glacial maximum using planktic foraminifera assemblages, together with the oxygen isotope (O-18) and Mg/Ca compositions of three species (Globigerinoides sacculifer, Pulleniatina obliquiloculata, and Globorotalia tumida) that dwell in the mixed layer, upper thermocline, and lower thermocline, respectively. While the Mg/Ca-derived temperatures of the mixed layer and lower thermocline varied within a narrow range from 18 ka onward, the upper thermocline temperature increased by as much as 3 degrees C during the last deglaciation (18-12 ka) with a simultaneous decrease of O-18. These changes are best explained by an enhanced... |
| Tipo: Text |
Palavras-chave: Planktic foraminifera; Geochemistry; Micropaleontology; Paleoceanography; Intertropical Convergence Zone; Last deglaciation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00496/60721/65271.pdf |
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| Beck, Pierre; Chaussidon, M; Barrat, J.a.; Gillet, Ph.; Bohn, Marcel. |
| Ion-microprobe was used to measure Li abundances and isotopic compositions in pyroxenes from three Martian meteorites belonging to the nakhlite family. The profiles performed across augite crystals from Northwest Africa 817 show a large isotopic zoning from crystal cores (delta Li-7 similar to 0 parts per thousand) to rims (delta Li-7 similar to +20 parts per thousand) while Li abundances are almost constant (similar to 9.2 mu g/g). Unlike NWA 817, the pyroxene studied in the Miller Range 03346 nakhlite shows a zoning in Li abundance, with concentrations increasing from similar to 2.5 mu g/g in the core to similar to 9 mu g/ g in the rim. The augite rim (delta Li-7 = +7 parts per thousand) is slightly enriched in Li-7 with regard to the core (delta Li-7 =... |
| Tipo: Text |
Palavras-chave: Magma; Pyroxene; Lithium; Geochemistry; Mars planet; Isotopic composition. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1955.pdf |
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| Chalk, T. B.; Foster, G. L.; Wilson, P. A.. |
| The origin and carbon content of the deep water mass that fills the North Atlantic Basin, either Antarctic Bottom Water (AABW) or North Atlantic Deep Water (NADW) is suggested to influence the partitioning of CO2 between the ocean and atmosphere on glacial-interglacial timescales. Fluctuations in the strength of Atlantic meridional overturning circulation (AMOC) have also been shown to play a key role in global and regional climate change on timescales from annual to millennial. The North Atlantic is an important and well-studied ocean basin but many proxy records tracing ocean circulation in this region over the last glacial cycle are challenging to interpret. Here we present new B/Ca-[CO32-] and boron isotope-pH data from sites spanning the North... |
| Tipo: Text |
Palavras-chave: Boron; Geochemistry; Palaeoceanography; Carbonate system; Glacial; Atlantic. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00496/60812/64631.pdf |
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| Ziem A. Bidias, Luc Achille; Chazot, Gilles; Moundi, Amidou; Nonnotte, Philippe. |
| We investigated mafic and felsic volcanic rocks from the Bamoun plateau, a magmatic province located north of Mount Cameroon, in the continental part of the Cameroon Volcanic Line (CVL). Basalts and dacites were probably emplaced more than 40 Ma ago, while basanites represent very young volcanic eruptions. Among the basalts, some of them have suffered crustal contamination during their uprise through the continental crust, and their primary trace element and isotopic compositions have been slightly modified. The formation of the dacites was also accompanied by some crustal contamination. Non-contaminated rocks show that the oldest magmas are transitional basalts formed by relatively high degrees of partial melting of a moderately enriched mantle source,... |
| Tipo: Text |
Palavras-chave: Cameroon Volcanic Line; Geochemistry; Mantle source; Crustal contamination; Basalt. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74996/75730.pdf |
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| Auzende, Jean-marie; Boespflug, Xavier; Bougault, Henri; Dosso, Laure; Foucher, Jean-paul; Joron, Jean-louis; Ruellan, Etienne; Sibuet, Jean-claude. |
| Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidenced only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compm·ed to the East Pacific Ridge. The Lau basin displays an intem1ediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in... |
| Tipo: Text |
Palavras-chave: Ouest Pacifique; Bassins arriere arc; Structure; Accretion; Geochimie; West Pacific; Back arc basins; Structure; Accretion; Geochemistry. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00119/23058/20893.pdf |
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| GUIMARÃES,JOSÉ T.F.; SAHOO,PRAFULLA K.; SOUZA-FILHO,PEDRO W.M.; FIGUEIREDO,MARIANA M.J. COSTA DE; REIS,LUIZA S.; SILVA,MARCIO S. DA; RODRIGUES,TARCÍSIO M.. |
| ABSTRACT Down-core changes in sedimentary facies, elemental geochemistry, pollen, spore, δ13C, δ15N and radiocarbon records from a filled lake, named R4, of the Serra Sul dos Carajás were used to study the relationship between the paleomorphological and paleoecological processes and their significance for Holocene paleoclimatology of the southeast Amazonia. The sediment deposition of the R4 lake started around 9500 cal yr BP. Increase of detrital components from 9500 to 7000 cal yr BP suggests high weathering of surrounding catchment rocks and soils, and deposition into the lake basin under mudflows. At that time, montane savanna and forest formation were already established suggesting predominance of wet climate. However, from 7000 to 3000 cal yr BP, a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazon Forest; Canga vegetation; Palynology; Carbon and nitrogen isotopes; Geochemistry. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000400502 |
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| Ben Gharali, A.; Ouakad, M.; Gueddari, M.. |
| L'oued Tinja relie la garaet Ichkeul à la lagune de Bizerte laquelle communique avec la mer Méditerranée par un long goulet. Les eaux de cet oued dépendent à la fois des apports saisonniers des eaux marine et douce et présente de ce fait, des salinités très fluctuantes. L'important réseau hydrographique associé au plan d'eau de l'Ichkeul (avec un bassin versant très important d'environ 2080 km2) est sujet à de nombreux aménagements hydrauliques, notamment la construction de barrages de retenues d'eau douce. Ces derniers sont susceptibles de perturber les caractéristiques hydrologiques, sédimentologiques et géochimiques du système laguno-lacustre (lagune de Bizerte et garaet Ichkeul) et d'entamer par voie de conséquence sa diversité et sa richesse... |
| Tipo: Journal Contribution |
Palavras-chave: Environmental impact; Geochemistry; Hydrology; Quality; Sediment analysis; Species diversity. |
| Ano: 2008 |
URL: http://hdl.handle.net/1834/4270 |
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| Registros recuperados: 52 | |
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