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| Registros recuperados: 52 | |
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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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| 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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| Barbieri,Diogo Mazza; Marques Júnior,José; Siqueira,Diego Silva; Teixeira,Daniel De Bortoli; Panosso,Alan Rodrigo; Pereira,Gener Tadeu; La Scala Junior,Newton. |
| Improvements in working conditions, sustainable production, and competitiveness have led to substantial changes in sugarcane harvesting systems. Such changes have altered a number of soil properties, including iron oxides and organic matter, as well as some chemical properties, such as the maximum P adsorption capacity of the soil. The aim of this study was to characterize the relationship between iron oxides and the quality of organic matter in sugarcane harvesting systems. For that purpose, two 1 ha plots in mechanically and manually harvested fields were used to obtain soil samples from the 0.00-0.25 m soil layer at 126 different points. The mineralogical, chemical, and physical results were subjected to descriptive statistical analyses, such as the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Degree of humification; Geochemistry; Soil management; Sustainable agriculture. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832014000400010 |
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| Beaumais, Aurelien; Bertrand, Herve; Chazot, Gilles; Dosso, Laure; Robin, Claude. |
| Gaua Island (also called Santa Maria), from the central part of the Vanuatu arc, consists of a large volcano marked by a caldera that hosts the active Mount Garet summit cone. In this paper, a geochemical study including Sr, Nd, Pb and Hf isotopic compositions of 25 lavas emitted since 1.8 Ma is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed (Mount Garet) the caldera forming event. All lavas show an island arc signature with enrichment in LILE and depletion in HFSE. Post-caldera lavas define a medium-K calc-alkaline trend, whereas lavas from the former main cone have high-K calc-alkaline compositions. Compared to the pre-caldera volcanic suite, the Mount Garet lavas have... |
| Tipo: Text |
Palavras-chave: Gaua; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00319/43052/42557.pdf |
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| Beaumais, Aurelien; Chazot, Gilles; Dosso, Laure; Bertrand, Herve. |
| Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc... |
| Tipo: Text |
Palavras-chave: Lopevi; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00167/27801/26223.pdf |
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| Beck, Pierre; Barrat, J; Chaussidon, M; Gillet, P; Bohn, Marcel. |
| Lithium abundances and isotopic compositions were measured by ion microprobe in individual grains of pyroxene, and in a few maskelynites and Ca-phosphates grains, from the Martian meteorite Northwest Africa 480 (NWA 480). In pyroxenes Li abundances are nearly constant from core to rim with concentrations ranging between 3 and 4 mug/g. In contrast, a significant isotopic zoning is observed with delta(7)Li values increasing within single crystals from similar to -17parts per thousand in the core to similar to +10parts per thousand in the rim, most of the variability being observed in the core. Plagioclase (now maskelynite) and phosphate crystals, which co-crystallized with the pyroxene rims, display similar delta(7) Li values. Because of the incompatible... |
| Tipo: Text |
Palavras-chave: Mars planet; Magma; Pyroxene; Isotopic composition; Lithium; Geochemistry. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-735.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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| 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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| Carrera Villacrés, David Vinicio. |
| El desarrollo geológico de la Sierra Madre Oriental y la Plataforma Valles-San Luis, estados de Querétaro y San Luis Potosí en donde se localiza la cuenca evaporítica de Río Verde-Matehuala, formó una diversidad salina de aguas y suelos. La salinidad causa baja fertilidad y deterioro en los campos agrícolas, solamente el manantial de Media Luna riega aproximadamente 5000 ha, lo que hace relevante su estudio. Los objetivos de este trabajo fueron conocer la salinidad cuantitativa y cualitativa tanto en aguas como en suelos, además, determinar la vía evolutiva que toman las aguas en la meteorización por evaporación de las mismas como un ejemplo del calentamiento global y, relacionar los efectos de la salinidad de las aguas y suelos sobre los cultivos. La... |
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Palavras-chave: Geoquímica; Evolución de las aguas; Calentamiento global; Sodicidad; Geochemistry; Water evolution; Global warming; Sodicity; Doctorado; Hidrociencias. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/476 |
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| Carrera Villacrés, David Vinicio. |
| El desarrollo geológico de la Sierra Madre Oriental y la Plataforma Valles-San Luis, estados de Querétaro y San Luis Potosí en donde se localiza la cuenca evaporítica de Río Verde-Matehuala, formó una diversidad salina de aguas y suelos. La salinidad causa baja fertilidad y deterioro en los campos agrícolas, solamente el manantial de Media Luna riega aproximadamente 5000 ha, lo que hace relevante su estudio. Los objetivos de este trabajo fueron conocer la salinidad cuantitativa y cualitativa tanto en aguas como en suelos, además, determinar la vía evolutiva que toman las aguas en la meteorización por evaporación de las mismas como un ejemplo del calentamiento global y, relacionar los efectos de la salinidad de las aguas y suelos sobre los cultivos. La... |
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Palavras-chave: Geoquímica; Evolución de las aguas; Calentamiento global; Sodicidad; Geochemistry; Water evolution; Global warming; Sodicity; Doctorado; Hidrociencias. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/476 |
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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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| Crosta, X; Shemesh, A. |
| [1] Oceanic nutrient cycling in the Southern Ocean is supposed to have an important impact on glacial-interglacial atmospheric CO(2) changes and global climate. In order to characterize such nutrient cycling over the last two climatic cycles we investigated carbon and nitrogen isotopic ratios of diatom-bound organic matter (delta(13)C(diat) and delta(15)N(diat)- respectively) in two cores retrieved form the Atlantic and Indian sectors of the Antarctic Ocean. The two cores show the same isotopic patterns. The delta(13)C(diat) values are depleted during glacial periods and enriched during interglacial periods, indicating lower productivity during cold times. The delta(15)N(diat) values are enriched during glacial periods and depleted during interglacial... |
| Tipo: Text |
Palavras-chave: Southern Ocean; Paleoceanography; Geochemistry; Diatoms. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33402/31859.pdf |
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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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| Faust, Johan C.; Tessin, Allyson; Fisher, Ben J.; Zindorf, Mark Sebastian; Papadaki, Sonia; Hendry, Katharine R.; Doyle, Katherine A.; März, Christian. |
| Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that... |
| Tipo: Text |
Palavras-chave: Carbon cycle; Geochemistry. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00675/78755/80923.pdf |
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| Registros recuperados: 52 | |
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