Consulta: subjectFacets:"Biogeochemistry"
Registros recuperados: 68
Data/hora: 09/06/2024 01:15:37

Balance de carbono y tasa de descomposición de mantillo y horizontes de fermentación de suelos forestales.
Provedor de dados: 32
Autores: Barrales Brito, Edgar.
El mantillo y horizontes de fermentación (CF) es un reservorio dinámico de carbono (C) en suelos forestales. Las metodologías que cuantifican la emisión de CO2 por la descomposición son escasas y requieren periodos largos de medición. Se requieren métodos para poder generar información de la emisión de CO2 de éstas capas orgánicas en tiempos cortos de medición. Los objetivos fueron: generar un protocolo para la medición de la emisión de CO2 por la descomposición de mantillo y CF con un respirómetro manométrico (OxiTop ®). Medir los reservorios de C de mantillo y CF de bosques con diferentes condiciones. Medir la emisión de CO2 del mantillo y CF y las tasas de descomposición con un respirómetro. Analizar las características químicas de los mantillos y...
Palavras-chave: Biogeoquímica; Emisión de CO2; Respirometría; Materia orgánica; Bosques; Biogeochemistry; CO2 emissions; Respirometry; Organic matter; Forest; Edafología; Maestría.
Ano: 2013
URL: http://hdl.handle.net/10521/2096

Природный радионуклид 210Pb в донных отложениях Севастопольской бухты (Черное море)
Provedor de dados: 13
Autores: Лазоренко, Г. Е.
Представлены первые результаты определения концентраций природного радионуклида 210Рb в донных от-ложениях Севастопольской бухты (Черное море). Их величины варьировали от 6.1 до 38.7 Бкּкг-1 сухой мас-сы вещества, при этом самые высокие из них были определены в образцах, отобранных внутри бухты Юж-ная, в местах выхода из нее и из бухты Килен. Характер распределения 210Рb в донных отложениях Севасто-польской бухты свидетельствует о приуроченности его высоких концентраций к местам стоянок морских судов и сброса неочищенных сточных и ливневых вод. Предлагается использовать 210Рb в качестве одного из индикаторов распределения подобного типа загрязнения в донных отложениях бухт, относительно закрытых от открытой части моря.
Tipo: Journal Contribution
Palavras-chave: Природный радионуклид; 210Рb; Донные отложения; Загрязнение; Севастопольская бухта; Индикатор; Городские сточные воды; Natural radionuclide; 210Рb; Bottom sediments; Pollution; Sevastopol Bay; Indicator; City waste water; Bio-inert systems; Biogeochemistry; Living space; The Biosphere Indicators Pollution Pollution http://aims.fao.org/aos/agrovoc/c_6077.
Ano: 2003
URL: http://repository.ibss.org.ua/dspace/handle/99011/40

Соотношение геоморфологических и биологических характеристик водных биокосных систем
Provedor de dados: 13
Autores: Хайлов, К. М.; Александров, Б. Г.; Юрченко, Ю. Ю.
С точки зрения биогеохимии, в терминах биокосных систем (объектов, совмещающих в себе косное Гео и живое Био) рассматривается большая совокупность традиционных экологических объектов (водоемы мор-ского и континентального типа и разного размера) и синэкологических объектов (пологи высших и низших водных растений). В размерных рядах названных объектов рассмотрены соотношения геометрического объ-ема обитаемого пространств (V), живой массы (W) организмов в нем, а также соотношения V и объемной концентрации живого вещества (Cw=W/V). Показана возможность унифицированного численного описания названных соотношений в диапазоне V от 10-20 до 1020 м3.
Tipo: Journal Contribution
Palavras-chave: Биокосные системы; Биогеохимия; Обитаемое пространство; Биосфера; Bio-inert systems; Biogeochemistry; Living space; The Biosphere Biogeochemistry.
Ano: 2003
URL: http://repository.ibss.org.ua/dspace/handle/99011/47

Composição isotópica de carbono e nitrogênio em solos e plantas de uma mata de galeria: efeito do gradiente topográfico.
Provedor de dados: 14
Autores: PARRON, L. M.; BUSTAMANTE, M. M. da C.; CAMARGO, P. B. de.
RESUMO: Estudos de composição isotópica de carbono e nitrogênio em solos e folhas são importantes para identificar diferenças nos processos de ciclagem biogeoquímica em ecossistemas. Nesse estudo foram determinadas as composições isitópicas de C e N em solos e folhas de 15 espécies lenhosas de uma Mata de Galeria no Distrito Federal, de acordo com o gradiente topográfico. O experimento foi realizado entre abril de 2001 e agosto de 2002; numa área de 100x100m , próxima à cabeceira da Mata de Galeria do Córrego Pitoco, na Reserva Ecológica do IBGE. Três transectos foram estabelecidos, paralelos ao córrego e separados a cada 45m, representando as comunidades: úmida (margem do córrego), intermediária e seca (borda da mata). Os valores de composição isotópica...
Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)
Palavras-chave: Biogeoquímica; Ciclagem de nutriente; Savana; Nutrient cyclong.; Cerrado; Floresta Tropical.; Biogeochemistry; Savannas; Tropical forests.
Ano: 2004
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/569212

Produção e composição química da serrapilheira em um gradiente topográfico em mata de galeria no bioma cerrado.
Provedor de dados: 14
Autores: PARRON, L. M.; BUSTAMANTE, M. M. da C.; PRADO, C. L. C.
RESUMO: Em função do gradiente de umidade na topografia do terreno e de diferenças entre estações seca e chuvosa, o presente trabalho teve como objetivos quantificar a produção anual e a disponibilidade de nutrientes (N, P, K, Ca, Mg E S) na serapilheira e estimar a eficiência do uso de nutrientes em uma Mata de Galeria. O experimento foi estabelecido numa área de 100 x 100 m da Mata de Galeria do Córrego Pitoco, na Reserva Ecológica do IBGE, DF (15°56'41"S e 47°56'07"W). Como delineamento experimental, foram estabelecidas três linhas de amostragem paralelas ao córrego, distantes 45 m entre si, denominadas, respectivamente, comunidades úmida (na margem do córrego), intermediárias e seca (adjacentes a uma área de Cerrado Típico). A produção de serapilheira...
Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)
Palavras-chave: Biogeoquímica; Ciclagem de nutriente; Eficiência de nutriente; Savana; Productivity; Nutrient cycling; Litterfall; Nutrient efficiency.; Disponibilidade de Nutriente; Floresta Tropical; Produtividade.; Biogeochemistry; Tropical forests.; Savannas.
Ano: 2004
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/569203

Intercomparison of dissolved iron isotope profiles from re-occupation of three GEOTRACES stations in the Atlantic Ocean
Provedor de dados: 5
Autores: Conway, T. M.; John, S. G.; Lacan, F.
Intercomparison of trace metal data is a key aspect of the International GEOTRACES program, allowing data from multiple laboratories and countries to be combined to produce high-resolution datasets for the oceans. The use of crossover stations by the GEOTRACES program provides the opportunity both for comparison of analytical techniques and assessment of temporal variability in the cycling of trace metals such as iron (Fe). Here, we present the first comparison of dissolved Fe stable isotope ratio (δ56Fe; relative to IRMM-014) profiles in the oceans, from re-occupations of three locations in the Atlantic Ocean; (1) the Bermuda Atlantic Time Series Station (31.75°N 64.17°W) during the U.S. GEOTRACES IC1 cruise (June 2008) and the U.S. GEOTRACES GA03 cruise...
Tipo: Text
Palavras-chave: Trace metals; GEOTRACES; Biogeochemistry; Intercomparison.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00332/44330/43932.pdf

The Biogeochemistry of Electroactive Humic Substances and Its Connection to Iron Chemistry in the North East Atlantic and the Western Mediterranean Sea
Provedor de dados: 5
Autores: Dulaquais, Gabriel; Waeles, Mathieu; Gerringa, Loes J. A.; Middag, Rob; Rijkenberg, Micha J. A.; Riso, Ricardo.
We present the zonal distribution of electroactive humic-like substances (eHS) along a section from Offshore Portugal in the North East Atlantic to the Sicily Channel in the Mediterranean Sea. The concentrations were normalized to Suwannee River Fulvic Acid and ranged from 11g/L to 81g/L. The vertical distributions were typical of those previously reported for dissolved organic carbon in the Mediterranean Sea. High eHS concentrations were measured in surface water and concentrations decreased with depth before increasing again toward benthic maxima measured at some stations. We estimate that eHS represented a relatively small fraction of the natural organic matter in the Mediterranean Sea (2-5%) but considering their important role in the complexation and...
Tipo: Text
Palavras-chave: Humic substances; Iron; Mediterranean Sea; Biogeochemistry; GEOTRACES.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00616/72781/72218.pdf

Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary
Provedor de dados: 5
Autores: Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jerome; Van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine.
Rare earth element (REE) concentrations and neodymium isotopic composition (epsilon Nd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (&lt; 0.45 mu m), colloidal and particulate REE and eNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while epsilon Nd values are shifted from the dissolved Nd river endmember (- 8.9) to values typical of...
Tipo: Text
Palavras-chave: Earth sciences; Biogeochemistry; Oceanography.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00298/40952/40046.pdf

North Atlantic Western Boundary Currents Are Intense Dissolved Organic Carbon Streams
Provedor de dados: 5
Autores: Fontela, Marcos; Pérez, Fiz F; Mercier, Herle; Lherminier, Pascale.
In the North Atlantic, there are two main western boundary currents related to the Atlantic Meridional Overturning Circulation (AMOC): the Gulf Stream flowing northward and the Deep Western Boundary Current (DWBC) flowing southward. Here we analyze data from the OVIDE section (GO-SHIP A25 Portugal-Greenland 40–60°N) that crosses the DWBC and the northward extension of the Gulf Stream, the North Atlantic Current. We show that North Atlantic western boundary currents play a key role in the transport of dissolved organic matter, specifically dissolved organic carbon (DOC). Revisited transports and budgets of DOC with new available data identify the eastern Subpolar North Atlantic (eSPNA) as an important source of locally produced organic matter for the North...
Tipo: Text
Palavras-chave: Dissolved organic carbon; North Atlantic; Carbon budget; Carbon dioxide; Biogeochemistry; Atlantic Meridional Overturning Circulation.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00661/77268/78702.pdf

In-Situ Variability of DOM in Relation with Biogeochemical and Physical Parameters in December 2017 in Laucala Bay (Fiji Islands) after a Strong Rain Event
Provedor de dados: 5
Autores: Koliyavu, Timoci; Martias, Chloe; Singh, Awnesh; Mounier, Stéphane; Gérard, Philippe; Dupouy, Cecile.
Heavy rain events alter the biogeochemical outflows, affects water quality and ecosystem health within the coastal waters of small Pacific Islands. We characterized snapshots of the optical fingerprints of dissolved organic matter (DOM) sources together with the select nutrients, biogeochemical and physical variables for 10 stations in December 2017 in Laucala Bay, Fiji Islands. DOM absorption coefficients and fluorescence components were determined via spectrofluorometry and Parallel Factor Analysis identifying four components: Type M, two terrestrial (humic, fulvic) components, and a protein component linked to marine biological activity. Associations of DOM together with climate variables and the other tested variables were determined via principal...
Tipo: Text
Palavras-chave: DOM absorption; Fluorescence; Biogeochemistry; PARAFAC; EEM spectra; Autochthonous; Allochthonous; Chlorophyll; CDOM; FDOM.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00682/79372/81889.pdf

Hydrological and biogeochemical dynamics of the minor and trace elements in the St. Lawrence River
Provedor de dados: 5
Autores: Rondeau, B; Cossa, Daniel; Gagnon, P; Pham, T; Surette, C.
Surface water samples from the St. Lawrence River were collected in order to study the processes controlling minor and trace elements concentrations (Al, Fe, Mn, Cd, Co, Cu, Ni and Zn), and to construct mass balances allowing estimates of the relative importance of their natural and anthropogenic sources. The two major water inputs, the upper St. Lawrence River, which drains waters originating from the Lake Ontario, and the Ottawa River were collected fortnightly over 18 months. In addition, other tributaries were sampled during the spring floods. The output was monitored near Quebec City at the river mouth weekly between 1995 and 1999. Dissolved metal concentrations in the upper St. Lawrence River carbonated waters were lower than in the acidic waters of...
Tipo: Text
Palavras-chave: St. Lawrence; Mass balance; River; Biogeochemistry; Trace element.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-1357.pdf

Changing Biogeochemistry of the Southern Ocean and Its Ecosystem Implications
Provedor de dados: 5
Autores: Henley, Sian F.; Cavan, Emma L.; Fawcett, Sarah E.; Kerr, Rodrigo; Monteiro, Thiago; Sherrell, Robert M.; Bowie, Andrew R.; Boyd, Philip W.; Barnes, David K. A.; Schloss, Irene R.; Marshall, Tanya; Flynn, Raquel; Smith, Shantelle.
The Southern Ocean plays a critical role in regulating global climate as a major sink for atmospheric carbon dioxide (CO2), and in global ocean biogeochemistry by supplying nutrients to the global thermocline, thereby influencing global primary production and carbon export. Biogeochemical processes within the Southern Ocean regulate regional primary production and biological carbon uptake, primarily through iron supply, and support ecosystem functioning over a range of spatial and temporal scales. Here, we assimilate existing knowledge and present new data to examine the biogeochemical cycles of iron, carbon and major nutrients, their key drivers and their responses to, and roles in, contemporary climate and environmental change. Projected increases in...
Tipo: Text
Palavras-chave: Southern Ocean; Biogeochemistry; Primary production; Iron; Nutrients; Carbon; Ecosystem; Ocean acidification.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00676/78831/81113.pdf

Projected Effects of Climate-Induced Changes in Hydrodynamics on the Biogeochemistry of the Mediterranean Sea Under the RCP 8.5 Regional Climate Scenario
Provedor de dados: 5
Autores: Pagès, Rémi; Baklouti, Melika; Barrier, Nicolas; Ayache, Mohamed; Sevault, Florence; Somot, Samuel; Moutin, Thierry.
The Mediterranean region has been shown to be particularly exposed to climate change, with observed trends that are more pronounced than the global tendency. In forecast studies based on a RCP 8.5 scenario, there seems to be a consensus that, along with an increase in temperature and salinity over the next century, a reduction in the intensity of deep-water formation and a shallowing of the mixed layer [especially in the North-Western Mediterranean Sea (MS)] are expected. By contrast, only a few studies have investigated the effects of climate change on the biogeochemistry of the MS using a 3D physical/biogeochemical model. In this study, our aim was to explore the impact of the variations in hydrodynamic forcing induced by climate change on the...
Tipo: Text
Palavras-chave: Mediterranean Sea; Coupled hydrodynamic-biogeochemical model; RCP scenario; Biogeochemistry; Climate change.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00659/77073/78385.pdf

Decadal biogeochemical changes in the subtropical Indian Ocean associated with Subantarctic Mode Water
Provedor de dados: 5
Autores: Alvarez, M.; Tanhua, T.; Brix, H.; Lo Monaco, C.; Metzl, N.; Mcdonagh, E. L.; Bryden, H. L.
Within the Subantarctic Mode Water (SAMW) density level, we study temporal changes in salinity, nutrients, oxygen and TTD (Transit Time Distribution) ages in the western (W) and eastern (E) subtropical gyre of the Indian Ocean (IO) from 1987 to 2002. Additionally, changes in Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC) are evaluated between 1995 and 2002. The mechanisms behind the detected changes are discussed along with the results from a hindcast model run (Community Climate System Model). The increasing salinity and decreasing oxygen trends from 1960 to 1987 reversed from 1987 to 2002 along the gyre. In the W-IO a decreasing trend in TTD ages points to a faster delivery of SAMW, thus less biogenic matter remineralization, explaining the...
Tipo: Text
Palavras-chave: Indian Ocean; Subantarctic Mode Water; Biogeochemistry.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00253/36400/34942.pdf

Five critical questions of scale for the coastal zone
Provedor de dados: 5
Autores: Swaney, D. P.; Humborg, C.; Emeis, K.; Kannen, A.; Silvert, W.; Tett, P.; Pastres, R.; Solidoro, C.; Yamamuro, M.; Henocque, Yves; Nicholls, R.
Social and ecological systems around the world are becoming increasingly globalized. From the standpoint of understanding coastal ecosystem behavior, system boundaries are not sufficient to define causes of change. A flutter in the stock market in Tokyo or Hong Kong can affect salmon producers in Norway or farmers in Togo. The globalization of opportunistic species and the disempowerment of people trying to manage their own affairs on a local scale seem to coincide with the globalization of trade. Human-accelerated environmental change, including climate change, can exacerbate this sense of disenfranchisement. The structure and functioning of coastal ecosystems have been developed over thousands of years subject to environmental forces and constraints...
Tipo: Text
Palavras-chave: Scale; Coastal management; Governance; Fishery management; Regime shift; Biogeochemistry.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00073/18437/16086.pdf

Estimates of carbon flow through bacteriplankton in the S. Benguela upwelling region based on 3H-thymidine incorporation and predator-free incubations.
Provedor de dados: 5
Autores: Lucas, M; Painting, S; Muir, D.
Spatial and temporal estimates of bacterial numbers, biomass, activity and production were measured in the S. Benguela upwelling system during the course of a phytoplankton bloom. Bacterial numbers and biomass were highest in the euphotic zone and correlated closely with particulate carbon in the water column rather than with chlorophyll a concentrations. 3H-Thymidine incorporation gave good estimates of production. Differential utilisation of photosynthetic exudates and detrital POC by bacterioplankton during the course of a bloom might account for the varying significance ascribed to exudates and POC as a source of carbon for bacterial production.
Tipo: Text
Palavras-chave: Ecological associations; Algal blooms; Biomass; Microorganisms; Carbon cycle; Bacteria; Nannoplankton; Upwelling; Biogeochemistry.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-985.pdf

Bio-Argo quality control manual for the Chlorophyll-A concentration
Provedor de dados: 5
Autores: Schmechtig, Catherine; Claustre, Herve; Poteau, Antoine; D'Ortenzio, Fabrizio.
This document is the bio-Argo quality control manual for Chlorophyll A concentration. It describes the method used in real-time to apply quality control flags to Chlorophyll A concentration calculated from specific sensors mounted on Argo profiling floats.
Tipo: Text
Palavras-chave: Argo; Physical oceanography; In-situ marine data; Profiling floats; Chlorophyll; Operational oceanography; Biogeochemistry.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00243/35385/60181.pdf

Transferts d'acides amines dans un systeme eau-sediment: Etude preliminaire en milieu experimental
Provedor de dados: 5
Autores: Hermin, M; Daumas, R; Drogue, N.
The bacterial activity of the superficial sediment layer was evaluated by incorporation super(14)C-labelled amino-acids mixed an hydrolysate of chlorella cells. Estimation of super(14)C-CO sub(2) super(14)C and super(14)C-A.A. by H.P.L.C. give some informations on the utilization of free dissolved. A.A. and on the transport of labelled compounds from water to sediment. The adsorption mechanism of A.A. on the mineral particles draw to the sediment a larger part of A.A. in the first period; but 28% of this adsorbed A.A. were discharged by an acid treatment. A part of super(14)C-A.A. was incorporated in unhydrolysable organic matter. Di-COOH A.A. are more resistant to bacterial degradation than the other A.A., but arginine is completely metabolized in ten...
Tipo: Text
Palavras-chave: Biogeochemistry; Bacteria; Chromatographic techniques; Metabolism; Amino acids; Sediment water exchanges.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-945.pdf

Le mercure en milieu marin. Biogéochimie et écotoxicologie
Provedor de dados: 5
Autores: Cossa, Daniel; Thibaud, Yves; Roméo, Michèle; Gnassia-barelli, Mauricette.
This report synthesizes the knowledge on the biogeochemical cycle, bioconcentration processes and ecotoxicity of mercury in the marine environment. Man induced changes on the mercury cycle, especially along the French coasts are reviewed. Concentration levels, mechanisms and fluxes between geochemical reservoirs are assessed. Emphasis is given on sublethal effects and toxicity mechanisms. Quality standards used in European Community countries are listed. Conclusions and recommendations for environmental management and research are given.
Tipo: Text
Palavras-chave: Mercure; Biogéochimie; Contamination; Écotoxicologie; Mercury; Biogeochemistry; Contamination; Ecotoxicology.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00332/44319/43890.pdf

Evaluation of the heterotrophic activity in waters by microanalytical methods.
Provedor de dados: 5
Autores: Bertoni, R.
The radiochemical methods proposed for evaluating heterotrophic activity in waters have been severely criticized in recent years because they are not considered to be sufficiently realistic. Thus, the possibility of directly measuring the heterotrophic consumption of naturally occurring Organic Carbon (OC) in fresh water samples incubated under controlled conditions has been evaluated. The analytical performances of two OC analyzers utilizable for this purpose are discussed here, and some examples of the results obtained by the direct measurement of OC consumption are presented. The consumption rates thus measured ranged from 11.6 to 50.2 mu gC/ 1.h. Although the technique discussed here is less sensitive than radiochemical methods, the few assumptions...
Tipo: Text
Palavras-chave: Biogeochemistry; Microbiology; Carbon cycle; Organic carbon; Water; Heterotrophic organisms; Analytical techniques.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-950.pdf

Future change in ocean productivity: Is the Arctic the new Atlantic?
Provedor de dados: 5
Autores: Yool, A.; Popova, E. E.; Coward, A. C.
One of the most characteristic features in ocean productivity is the North Atlantic spring bloom. Responding to seasonal increases in irradiance and stratification, surface phytopopulations rise significantly, a pattern that visibly tracks poleward into summer. While blooms also occur in the Arctic Ocean, they are constrained by the sea-ice and strong vertical stratification that characterize this region. However, Arctic sea-ice is currently declining, and forecasts suggest this may lead to completely ice-free summers by the mid-21st century. Such change may open the Arctic up to Atlantic-style spring blooms, and do so at the same time as Atlantic productivity is threatened by climate change-driven ocean stratification. Here we use low and high-resolution...
Tipo: Text
Palavras-chave: Marine; Ocean; Biogeochemistry; Arctic; Atlantic; Future.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00332/44367/43972.pdf

The Tropical Atlantic Observing System
Provedor de dados: 5
Autores: Foltz, G. R.; Brandt, P.; Richter, I.; Rodríguez-fonseca, B.; Hernandez, F.; Dengler, M.; Rodrigues, R. R.; Schmidt, J. O.; Yu, L.; Lefevre, N.; Da Cunha, L. Cotrim; Mcphaden, M. J.; Araujo, M.; Karstensen, J.; Hahn, J.; Martín-rey, M.; Patricola, C. M.; Poli, P.; Zuidema, P.; Hummels, R.; Perez, Rc; Hatje, V.; Lübbecke, J. F.; Polo, I.; Lumpkin, R.; Bourlès, Bernard; Asuquo, F. E.; Lehodey, P.; Conchon, A.; Chang, P.; Dandin, P.; Schmid, C.; Sutton, A.; Giordani, H.; Xue, Y.; Illig, S.; Losada, T.; Grodsky, S. A.; Gasparin, F.; Lee, T.; Mohino, E.; Nobre, P.; Wanninkhof, R.; Keenlyside, N.; Garcon, V.; Sánchez-gómez, E.; Nnamchi, H. C.; Drévillon, M.; Storto, A.; Remy, E.; Lazar, A.; Speich, S.; Goes, M.; Dorrington, T.; Johns, W. E.; Moum, J. N.; Robinson, C.; Perruche, Coralie; De Souza, R. B.; Gaye, A. T.; López-parages, J.; Monerie, P.-a.; Castellanos, P.; Benson, N. U.; Hounkonnou, M. N.; Duhá, J. Trotte; Laxenaire, R.; Reul, Nicolas.
The tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southern and northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world’s largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time...
Tipo: Text
Palavras-chave: Tropical Atlantic Ocean; Observing system; Weather; Climate; Hurricanes; Biogeochemistry; Ecosystems; Coupled model bias.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00494/60612/64096.pdf

Changes in rivers inputs during the last decades significantly impacted the biogeochemistry of the eastern Mediterranean basin: a modelling study
Provedor de dados: 5
Autores: Pagès, R.; Baklouti, M.; Barrier, Nicolas; Richon, C.; Dutay, J.-c.; Moutin, T.
The Mediterranean Sea (MS) is a semi-enclosed sea characterized by a zonal west-east gradient of oligotrophy, where microbial growth is controlled by phosphate availability in most situations. External inputs of nutrients including Gibraltar inputs, river inputs and atmospheric deposition are therefore of major importance for the biogeochemistry of the MS. This has long been considered to be driven mainly by nutrient exchanges at Gibraltar. However, recent studies indicate that river inputs signi cantly a ect nutrients concentrations in the Mediterranean Sea, although their resulting impact on its biogeochemistry remains poorly understood. In this study, our aim was to make good this lack by addressing the large-scale and long-term impact of variations in...
Tipo: Text
Palavras-chave: Mediterranean Sea; River inputs; Coupled physical-biogeochemical model; Flexible stoichiometry model; Biogeochemistry; Nutrient.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00599/71118/69420.pdf

Relations between bacterial extracellular enzyme activities and heterotrophic substrate uptake in a brackishwater environment.
Provedor de dados: 5
Autores: Hoppe, H.
Extracellular enzymes mediate the decomposition of polymeric organic compounds in natural waters. In many cases these enzymes comprise a component linked to the bacterial fraction of the aquatic community and react in close association with these cells. An annual survey of microbial activities in a brackish water fjord exhibited an excellent correlation between V sub(m) of proteases (ability to split the substrate analogue methylumbelliferyl-leucine) and V sub(m) as well as T sub(R) for leucine uptake by microorganisms. Hydrolysis rates (H sub(R)) for the decomposition of naturally occurring competitive substrate analogues of the model substrates (methylumbelliferyl-(MUF)-leucine, MUF- alpha -D-glucose, MUF-N-acetyl-glucosamine, MUF-phosphate) drastically...
Tipo: Text
Palavras-chave: Biogeochemistry; Fjords; Bacteria; Brackishwater environment; Seasonal variations; Dissolved organic matter; Interspecific relationships; Hydrolysis; Enzymes.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-952.pdf

Metabolism of cyanobacteria in anaerobic marine sediments.
Provedor de dados: 5
Autores: Stal, L; Krumbein, W.
Two cyanobacteria isolated from marine microbial mats metabolized endogenous carbon reserves anaerobically in the dark. Microcoleus chthonoplastes reduced elemental sulfur to sulfide and Oscillatoria sp. additionally produced lactate in the absence of elemental sulfur. Under nitrogen fixing conditions, however, no sulfur reduction occurs. Lactate fermentation appeared to be the mechanism of anaerobic carbon degradation under these conditions. With a nitrogenase-reducible substrate, e.g. acetylene, added, lactate fermentation as well as sulfur reduction stops in cultures of Oscillatoria containing nitrogenase. In this case only ethylene production was observed. These cyanobacteria seem to possess the capability to carry out anaerobic dark metabolism...
Tipo: Text
Palavras-chave: Oscillatoria; Microcoleus chthonoplastes; Cyanophyta; Metabolism; Chemical cycles; Algae; Anoxic sediments; Anaerobic respiration; Algal mats; Biogeochemistry; Fermentation; Sulfur; Nitrogen fixation; Nitrogen cycle.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-974.pdf

A laboratory model system for analysing microbial interactions occurring in anoxic estuarine sediments.
Provedor de dados: 5
Autores: Herbert, R; Keith, S.
Defined mixed populations of Clostridium butyricum, Desulfovibrio desulfuricans and Chromatium vinosum co-existed for long periods when grown in a single stage chemostat with glucose as sole carbon source. The nature and availability of the inorganic nitrogen source exerted a major effect on carbon flow in the experimental system. The data show that both the C. butyricum and D. desulfuricans isolates can utilise NO sub(3) as an e super(-)acceptor with an increase in cell yield. Under these growth conditions the free S super(2-) levels were lower resulting in more stable mixed populations. In addition the data show that the C. butyricum produces more oxidised fermentation end-products (acetate) when NO sub(3) super(-) was available and more reduced products...
Tipo: Text
Palavras-chave: Chromatium vinosum; Desulfovibrio desulfuricans; Clostridium butyricum; Biogeochemistry; Models; Bacteria; Detritus; Mineralization; Anoxic sediments; Estuarine sedimentation; Analytical techniques; Carbon cycle; Interspecific relationships; Microbiology.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-947.pdf

Models of relations between bacteria and plankton, and regeneration processes in marine planktonic ecosystem.
Provedor de dados: 5
Autores: Martin, Y; Lelong, P; Cauchi, B.
In order to study bacteria-plankton relationships, experimental and mathematical models were used to stimulate biological processes implicated in plankton ecosystems and to analyze community relationships. The model components are phytoplankton, zooplankton, autotrophic and heterotrophic bacteria, ciliates, nutrients, organic matter and phytoplankton antibiotics. This study shows the importance of some factors affecting bacteria communities dynamics and the bacterial activity in mineralization process. Bacterial populations seem to be controlled essentially by the concentration and chemical composition of organic substrates. Antibiosis and predation show a lesser importance on changes in bacteria communities.
Tipo: Text
Palavras-chave: Biogeochemistry; Bacteria; Microorganisms; Mathematical models; Mineralization; Ecosystems; Plankton; Ecological associations.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-982.pdf

Dynamique du carbone et des nutriments dans la zone côtière Baie de l’Aiguillon-Pertuis Breton et influence des apports terrestres du bassin versant du Marais poitevin
Provedor de dados: 5
Autores: Lannuzel, Reva.
Coastal zones represent key systems in biogeochemical cycle couplings between continents, oceans and the atmosphere transporting considerable amounts of matter, energy and nutrients (C, N, P et Si) from land to sea. Despite its relatively modest surface area (7 % of the global ocean surface), this zone accounts for 14–30 % of all oceanic primary production. The present study deals with nutrients and carbon dynamics during a full hydrologic cycle in 2017 over the terrestrial-aquatic continuum formed by the Poitevin Marsh-Aiguillon Bay- Breton Sound to better understand terrestrial export influence on the coastal zone. Carbon and nutrient concentrations were sampled twice a month over heterogeneous sites (estuaries, channels and coastal sites) to integrate...
Tipo: Text
Palavras-chave: Zone côtière; Biogéochimie; Carbone; Nutriments; Chlorophylle a; Limitation potentielle et réelle; Dynamique.; Coastal zone; Biogeochemistry; Carbon; Nutrients; Chlorophyll a; Real and potential limitation; Spatio-temporal dynamic.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00445/55647/57299.pdf

L'étain et les organoétains en milieu marin. Biogéochimie et écotoxicologie.
Provedor de dados: 5
Autores: Alzieu, Claude.
This report synthesizes the knowledge on the biogeochemical cycle, bioconcentration processes and ecotoxicity of tin and organotins in the marine environment. Concentrations levels, biomethylation mechanisms and exchanges between sediments and water are assessed. Emphasis is given on tributyltin sublethal effects, toxicity mechanisms and no effect levels for the most sensitive organisms. Regulations on the use of organotins as antifoulants in paints are examined. Conclusions and recommendations for environmental management and research are given.
Tipo: Text
Palavras-chave: Étain; Biogéochimie; Contamination; Écotoxicologie.; Tin; Biogeochemistry; Contamination; Ecotoxicology.
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00332/44314/43883.pdf

Le plomb en milieu marin. Biogeochimie et ecotoxicologie
Provedor de dados: 5
Autores: Cossa, Daniel; Elbaz-poulichet, Françoise; Gnassia-barelli, Mauricette; Romeo, Michèle.
This report synthesises the knowledge on the biogeochemical cycle, bioconcentration processes and ecotoxicity of lead in the marine environment. Man induced changes on the lead cycle, especially along the French coasts are reviewed. Concentration levels, mechanisms and fluxes between geochemical reservoirs are assessed. Emphasis is given on sublethal effects and toxicity mechanisms. Quality standards used in European Community countries are listed. Conclusions and recommendations for environmental management and research are given.
Tipo: Text
Palavras-chave: Ecotoxicology; Contamination; Biogeochemistry; Lead; Ecotoxicologie; Contamination; Biogeochimie; Plomb.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/1993/rapport-1449.pdf

A data assimilating model for estimating Southern Ocean biogeochemistry
Provedor de dados: 5
Autores: Verdy, A.; Mazloff, M. R.
A Biogeochemical Southern Ocean State Estimate (B-SOSE) is introduced that includes carbon and oxygen fields as well as nutrient cycles. The state estimate is constrained with observations while maintaining closed budgets and obeying dynamical and thermodynamic balances. Observations from profiling floats, shipboard data, underway measurements, and satellites are used for assimilation. The years 2008-2012 are chosen due to the relative abundance of oxygen observations from Argo floats during this time. The skill of the state estimate at fitting the data is assessed. The agreement is best for fields that are constrained with the most observations, such as surface pCO(2) in Drake Passage (44% of the variance captured) and oxygen profiles (over 60% of the...
Tipo: Text
Palavras-chave: Southern Ocean; State estimation; Biogeochemistry.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00662/77394/78995.pdf

Microbial hydrogen production potential in shallow oceanic nepheloid layers.
Provedor de dados: 5
Autores: Schwarz, J; Loeblich, L; Schropp, S.
Seawater samples taken from shallow suspended particle maxima (20-57m) at or near the base of the surface mixed layer in various oceanic areas were tested for their potential to produce hydrogen (H sub(2)) gas. Results suggest that hydrogen can be bacterially produced through a fermentative process in microanaerobic niches within particulate matter. The organisms responsible for this process are ubiquitous within the temperate and tropical waters sampled. Enumeration of potential H sub(2)-producing bacteria using fluorescent antibody techniques yielded a maximum at the base of the surface mixed layer, the same depth where the greatest H sub(2) gas production potential was observed. Hydrogen-producing bacteria comprised up to 15% of the total bacterial...
Tipo: Text
Palavras-chave: Suspended particulate matter; Sea water; Gases; Biogeochemistry; Biogenic material; Hydrogen; Anaerobic bacteria; Nepheloid layer; Fermentation.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-962.pdf

Contrasting biogeochemical cycles of cobalt in the surface western Atlantic Ocean
Provedor de dados: 5
Autores: Dulaquais, Gabriel; Boye, Marie; Middag, Rob; Owens, Stephanis; Puigcorbe, Viena; Buesseler, Ken; Masque, Pere; De Baar, Hein J. W.; Carton, Xavier.
Dissolved cobalt (DCo; &lt;0.2 µm; 14 to 93 pM) and the apparent particulate cobalt (PCo; &gt;0.2 µm; &lt;1 to 15 pM) were determined in the upper water column (&lt;1000 m) of the western Atlantic Ocean along the GEOTRACES-A02 section (64°N to 50°S). The lowest DCo concentrations, typical of a nutrient-type distribution were observed in surface waters of the subtropical domains. Strong linear relationships between DCo and phosphate (P) as well as meridional gradients of decreasing DCo from high latitudes were characterized and both linked to the Co biological requirement. External sources such as the Amazon and the atmospheric deposition were found to contribute significantly (&gt;10%) to the DCo stock of the mixed layer in the equatorial and north...
Tipo: Text
Palavras-chave: Cobalt; Biogeochemistry; Atlantic Ocean; Chemical Oceanography; GEOTRACES.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00241/35222/33732.pdf

Relations milieu-ressources : impact de la conchyliculture sur un environnement lagunaire méditerranéen (Thau)
Provedor de dados: 5
Autores: Deslous-paoli, Jean-marc; Souchu, Philippe; Mazouni, N; Juge, Claude; Dagault, Francoise.
Shellfish farming leaves its mark on the environment in which it has developed, and the men who depend upon it. These changes have altogether balanced the lagoon cycle and have caused disastrous episodic events. Increased water c1arity caused by the uptake of particulate material by shellfish farming allows seagrass to grow in deeper areas of the lagoon (down to five metres). Shellfish farming nutrient transformations increase ecosystem productivity, even if the filtration pressure keeps phytoplankton biomass at a low leveI. Storage of phosphorus and nitrogen in animal tissue limits eutrophication in this ecosystem. Transfer of oysters from growout facilities increases animal and vegetal specific diversity. The presence of large amounts of shellfish allows...
Tipo: Text
Palavras-chave: Lagune; Conchyliculture; Biogéochimie; Benthos; Eutrophie; Lagoon; Shellfish farming; Biogeochemistry; Benthos; Eutrophication.
Ano: 1998
URL: https://archimer.ifremer.fr/doc/00039/15032/12365.pdf

Interrelations entre des communautes mixtes de bacteries anaerobies isolees de sediments marins
Provedor de dados: 5
Autores: Marty, D.
The mineralization of cellulose was examined in mono and cocultures of marine anaerobic bacteria (cellulolytic bacteria, fermentative non-cellulolytic bacteria and methane-producing bacteria). These studies displayed interactions between these groups of microorganisms: inhibition relationships (inhibition of methanogens during active growth of fermentative bacteria) and syntrophic relationships (growth of fermentative non-cellulolytic bacteria depended on metabolites produced by cellulolytic bacteria; increased in rate of cellulose hydrolysis in presence of fermentative non-cellulolytic bacteria; interspecies H sub(2) transfer reaction between fermentative bacteria and methane-producing bacteria).
Tipo: Text
Palavras-chave: Biogeochemistry; Sedimentation; Sediments; Fermentation; Mineralization; Cellulose; Methanogenesis; Interspecific relationships; Anaerobic bacteria.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-948.pdf

Lagune de Salses-Leucate. II.- Contamination bactériologique et approche physico-chimique
Provedor de dados: 5
Autores: Ladagnous, Helene; Le Bec, Claude.
En complément de l'analyse bibliographique (vol. 1), une étude de la contamination bactériologique et une approche de la qualité physico-chimique des eaux de la lagune ont été menées. Réalisées aux mois de mai et juin 1996, ces études ont pour objectif d'aborder de façon prospective, la totalité de l'étang. Des secteurs contaminés bactériologiquement ont pu être mis en évidence dans la partie sud de la lagune, sans que les sources soient clairement localisées. De même, pour la partie nord, les taches de contamination mises en évidence lors de précédentes études sont confirmées dans la zone des parcs conchylicoles. Les analyses de sels nutritifs montrent l'importance des résurgences karstiques dans les apports de nutriments, sans que le facteur limitant de...
Tipo: Text
Palavras-chave: Lagune; Méditerranée; Leucate; Salses; Physico-chimie; Biogéochimie; Pollution; Bactériologie; Résurgence; Karst.; Lagoon; Mediterranean; Leucate; Salses; Physico-chemistry; Biogeochemistry; Pollution; Bacteriology; Resurgence-spring; Karst.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00073/18423/15966.pdf

Ship-Based Contributions to Global Ocean, Weather, and Climate Observing Systems
Provedor de dados: 5
Autores: Smith, Shawn R.; Alory, Gaël; Andersson, Axel; Asher, William; Baker, Alex; Berry, David I.; Drushka, Kyla; Figurskey, Darin; Freeman, Eric; Holthus, Paul; Jickells, Tim; Kleta, Henry; Kent, Elizabeth C.; Kolodziejczyk, Nicolas; Kramp, Martin; Loh, Zoe; Poli, Paul; Schuster, Ute; Steventon, Emma; Swart, Sebastiaan; Tarasova, Oksana; Petit De La Villeon, Loic; Vinogradova-shiffer, Nadya.
The role ships play in atmospheric, oceanic, and biogeochemical observations is described with a focus on measurements made near the ocean surface. Ships include merchant and research vessels; cruise liners and ferries; fishing vessels; coast guard, military, and other government-operated ships; yachts; and a growing fleet of automated surface vessels. The present capabilities of ships to measure essential climate/ocean variables and the requirements from a broad community to address operational, commercial, and scientific needs are described. The authors provide a vision to expand observations needed from ships to understand and forecast the exchanges across the ocean–atmosphere interface. The vision addresses (1) recruiting vessels to improve both...
Tipo: Text
Palavras-chave: Ships; Observations; Meteorology; Physical oceanography; Biogeochemistry; Data management; Climatology.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00509/62042/66191.pdf

Metabolism of CO and CH sub(4) by nitrifiers and the determination of the nitrification rate.
Provedor de dados: 5
Autores: Morita, R; Jones, R.
The nitrifying bacteria were found to survive 24 weeks in the absence of ammonium without decreasing their number of cell size. Because H sub(2), CO, and CH sub(4) are present in the marine environment, these substrates were investigated as a possible source of the energy of maintenance for the nitrifying bacteria. super(14)CO and super(14)CH sub(4) were found to be oxidized by the nitrifiers. N-serve was found to inhibit the oxidation of CO. Using the nitrifiers' ability to oxide CO, a method for the determination of the nitrification rate was developed. The ability of nitrifiers to oxidize CO may play a significant role in the cycling of CO sub(2) in the marine environment. Whether CO and CH sub(4) oxidation play a role in the survival of nitrifiers in...
Tipo: Text
Palavras-chave: Methane; Carbon dioxide; Survival; Bacteria; Nitrification; Nitrogen cycle; Oxidation; Carbon cycle; Biogeochemistry; Metabolism.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-975.pdf

Les polychlorobiphényles (PCB) en milieu marin : biogéochimie et écotoxicologie
Provedor de dados: 5
Autores: Marchand, Michel; Abarnou, Alain; Marcaillou-le Baut, Claire.
This report synthesizes the knowledge on the behaviour, bioconcentration processes and ecotoxicity ofPCB in the marine environment. Contamination levels of the French coasts are examined. Concentration levels, mechanisms andfluxes between geochemicai reservoirs are assessed. Emphasis is given on subiethai effects and toxicity mechanisms. Quality standards used in European Community countries are listed. Conclusions and recommendations for environmentai management and research are given.
Tipo: Text
Palavras-chave: PCB; Biogéochimie; Contamination; Écotoxicologie; PCBs; Biogeochemistry; Contamination; Ecotoxicology.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00148/25954/24045.pdf

Nutrient scarcity strengthens soil fauna control over leaf litter decomposition in tropical rainforests
Provedor de dados: 5
Autores: Peguero, Guille; Sardans, Jordi; Asensio, Dolores; Fernández-martínez, Marcos; Gargallo-garriga, Albert; Grau, Oriol; Llusià, Joan; Margalef, Olga; Márquez, Laura; Ogaya, Romà; Urbina, Ifigenia; Courtois, Elodie A.; Stahl, Clément; Van Langenhove, Leandro; Verryckt, Lore T.; Richter, Andreas; Janssens, Ivan A.; Peñuelas, Josep.
Soil fauna is a key control of the decomposition rate of leaf litter, yet its interactions with litter quality and the soil environment remain elusive. We conducted a litter decomposition experiment across different topographic levels within the landscape replicated in two rainforest sites providing natural gradients in soil fertility to test the hypothesis that low nutrient availability in litter and soil increases the strength of fauna control over litter decomposition. We crossed these data with a large dataset of 44 variables characterizing the biotic and abiotic microenvironment of each sampling point and found that microbe-driven carbon (C) and nitrogen (N) losses from leaf litter were 10.1 and 17.9% lower, respectively, in the nutrient-poorest site,...
Tipo: Text
Palavras-chave: Biogeochemistry; Extracellular enzyme activity; Litter decomposition; Nutrients; Soil fauna.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00513/62424/69469.pdf

BGC Argo quality control manual for particles backscattering
Provedor de dados: 5
Autores: Schmechtig, Catherine; Boss, Emmanuel; Briggs, Nathan; Claustre, Herve; Dall'Olmo, Giorgio; Poteau, Antoine.
This document is the BGC-Argo quality control manual for particles backscattering. It describes the method used in real-time to apply quality control flags to particles backscattering calculated from specific sensors mounted on Argo profiling floats.
Tipo: Text
Palavras-chave: Argo; Physical oceanography; In-situ marine data; Profiling floats; Bbp; Operational oceanography; Biogeochemistry.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00491/60262/63668.pdf

Small phytoplankton contribute greatly to CO2-fixation after the diatom bloom in the Southern Ocean
Provedor de dados: 5
Autores: Irion, Solène; Christaki, Urania; Berthelot, Hugo; L’helguen, Stéphane; Jardillier, Ludwig.
Phytoplankton is composed of a broad-sized spectrum of phylogenetically diverse microorganisms. Assessing CO2-fixation intra- and inter-group variability is crucial in understanding how the carbon pump functions, as each group of phytoplankton may be characterized by diverse efficiencies in carbon fixation and export to the deep ocean. We measured the CO2-fixation of different groups of phytoplankton at the single-cell level around the naturally iron-fertilized Kerguelen plateau (Southern Ocean), known for intense diatoms blooms suspected to enhance CO2 sequestration. After the bloom, small cells (&lt;20 µm) composed of phylogenetically distant taxa (prymnesiophytes, prasinophytes, and small diatoms) were growing faster (0.37 ± 0.13 and 0.22 ± 0.09...
Tipo: Text
Palavras-chave: Biogeochemistry; Microbial ecology; Stable isotope analysis.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00684/79595/82286.pdf

Variability in benthic oxygen fluxes during the winter-spring transition in coastal sediments: an estimation by in situ micro-electrodes and laboratory mini-electrodes
Provedor de dados: 5
Autores: Lansard, B; Rabouille, C; Massias, D.
Two expeditions were achieved at the winter-spring transition in the Golfe de Fos (Mediterranean Sea) at a site situated at 21 m depth. An in situ autonomous oxygen profiler and laboratory oxygen mini-electrodes were used to measure the oxygen distribution in the sediments and calculate the diffusive oxygen fluxes. Clearer waters during the second expedition promoted a rapid shift from a net heterotrophic environment to a photosynthesis-dominated sediment. The diffusive exchange fluxes of oxygen through the sediment-water interface varied from an average consumption of 5.3 mmol m(-2) d(-1) (February) to a net production of 12 mmol m(-2) d(-1) (March). At both periods, a large spatial heterogeneity was recorded by the different electrodes, with a larger...
Tipo: Text
Palavras-chave: Oxygène; Micro-électrodes in situ; Biogéochimie; Cycle du carbone; Sédiment côtier; Oxygen; In situ micro-electrodes; Biogeochemistry; Carbon cycle; Coastal sediment.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00322/43272/43003.pdf

Dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) sea surface distributions simulated from a global three-dimensional ocean carbon cycle model
Provedor de dados: 5
Autores: Aumont, Olivier; Belviso, Sauveur; Monfray, Patrick.
[1] A global model for surface dimethylsulfide (DMS) and particulate dimethylsulfoniopropionate (DMSP) (pDMS) distributions is presented. The main goals of this work were to be able to predict the regional distribution of the air-sea fluxes of DMS and to predict eventually their future evolution with climate change. Diagnostic relationships have been established from data sets obtained during the ALBATROSS and EUMELI cruises carried out in the Atlantic Ocean. These equations nonlinearly relate DMS and pDMSP concentrations to chlorophyll concentrations and to the trophic status of surface waters. This model has been embedded in the global ocean carbon cycle model Institut Pierre et Simon Laplace-Ocean Carbon Cycle Model version 2 (ISPL-OCCM2), a simple...
Tipo: Text
Palavras-chave: Ocean; Biogeochemistry; Ecosystem modeling; DMS; Global.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33448/31824.pdf

Geochemistry of an endorheic thalassohaline ecosystem: the Dziani Dzaha crater lake (Mayotte Archipelago, Indian Ocean)
Provedor de dados: 5
Autores: Sarazin, Gérard; Jezequel, Didier; Leboulanger, Christophe; Fouilland, Eric; Le Floc'H, Emilie; Bouvy, Marc; Gerard, Emmanuelle; Agogué, Hélène; Bernard, Cédric; Hugoni, Mylène; Grossi, Vincent; Trousselier, Marc; Ader, Magali.
Dziani Dzaha is a maar the age of which is close to 4000 years. While its water is thought to have originated from seawater it is now considered as an extreme environment due to its hypersaline and alkaline characteristics. Those extreme features have led to the simplification of the trophic network. Cyanobacteria account for up to 95% of the photosynthetic biomass. The main biogeochemical processes, i.e. photosynthesis, bacterial sulfate reduction and methanogenesis could explain the current water composition. As far as we know, this ecosystem could be unique on Earth, extending the nature and chemical limits of aquatic inland ecosystems
Tipo: Text
Palavras-chave: Thalassohaline lake; Endorheic ecosystem; Cyanobacteria; Methane emission; Biogeochemistry; Mayotte.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00667/77948/80128.pdf

Nitrate respiration and nitrification in estuarine sediments.
Provedor de dados: 5
Autores: Herbert, R.
Seasonal data and depth profiles using super(15)N-labelled NO sub(3)u- show that denitrification (77-90% of NO sub(3)u- respired) rather than NO sub(3)u- dissimilation to NH sub(4)u+ was the principal route of nitrate reduction in Kingoodie Bay sediments. Populations of both groups of NO sub(3)u- reducing bacteria were highest in the 0-20 mm horizon in those sediments where highest rates of NO sub(3)u- respiration were recorded (28.56 mu g N.d super(-1) dry wt. sediment super(-1)). Autotrophic nitrification rates shared a marked seasonality with highest rates (0.92 mu g N.d super(-1).g dry wt. sediment super(-1)) occurring during the summer. Maximum populations of autotrophic nitrifying bacteria were also found in the 0-20 mm sediment horizon and these...
Tipo: Text
Palavras-chave: Seasonal variations; Bacteria; Estuaries; Sediment chemistry; Biogeochemistry; Ammonia; Nitrates; Nitrogen cycle.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-971.pdf

Advancing Observation of Ocean Biogeochemistry, Biology, and Ecosystems With Cost-Effective in situ Sensing Technologies
Provedor de dados: 5
Autores: Wang, Zhaohui Aleck; Moustahfid, Hassan; Mueller, Amy V.; Michel, Anna Pm; Mowlem, Matthew; Glazer, Brian T.; Mooney, T. Aran; Michaels, William; Mcquillan, Jonathan S.; Robidart, Julie C.; Churchill, James; Sourisseau, Marc; Daniel, Anne; Schaap, Allison; Monk, Sam; Friedman, Kim; Brehmer, Patrice.
Advancing our understanding of ocean biogeochemistry, biology, and ecosystems relies on the ability to make observations both in the ocean and at the critical boundaries between the ocean and other earth systems at relevant spatial and temporal scales. After decades of advancement in ocean observing technologies, one of the key remaining challenges is how to cost-effectively make measurements at the increased resolution necessary for illuminating complex system processes and rapidly evolving changes. In recent years, biogeochemical in situ sensors have been emerging that are threefold or more lower in cost than established technologies; the cost reduction for many biological in situ sensors has also been significant, although the absolute costs are still...
Tipo: Text
Palavras-chave: In situ; Sensor; OceanObs; Ocean technology; EOVs; Biogeochemistry; Biology; Cost effective.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00514/62567/66921.pdf

Biogeochemical markers of organic matter along the Wight-Cherbourg transect (central English Channel)
Provedor de dados: 5
Autores: Ismaili, Mm; Serve, L; Gadel, F; Lafite, R; Texier, H.
Three cruises on the Wight-Cherbourg transect were undertaken during the FluxManche II Programme in order to study the origin, nature and behaviour of organic matter inputs to the waters of the English Channel. Suspended particulate material (SPM) collected from surface and deep waters at each station was analysed at elemental level for Particulate Organic Carbon and Particulate Organic Nitrogen (POC, PON), at molecular level for main classes of organic compounds using Pyrolysis-Gas Chromatography coupled with Mass Spectrometry (Py-GC-MS) and for phenolic compounds, particularly lignin-derived phenols, using High Performance Liquid Chromatography (HPLC). The SPM content increases from the French (south) to the English coast (north) with the lowest values...
Tipo: Text
Palavras-chave: Matière particulaire en suspension; Composés organiques; Marqueurs phénoliques; Biogéochimie; Manche; Suspended particulate matter; Organic compounds; Phenolic markers; Biogeochemistry; English Channel.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00325/43603/43922.pdf

Concentrations and fractionation of carbon, iron, sulfur, nitrogen and phosphorus in mangrove sediments along an intertidal gradient (semi-arid climate, New Caledonia)
Provedor de dados: 5
Autores: Deborde, Jonathan; Marchand, Cyril; Molnar, Nathalie; Della Patrona, Luc; Meziane, Tarik.
In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ increase in: (i) water content; (ii) TOC; (iii) mangrove-derived OM; II/ and decrease in: (i) salinity; (ii) redox; (iii) pH; (iv) solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and...
Tipo: Text
Palavras-chave: Mangrove; Zonation; Biogeochemistry; New Caledonia.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00251/36252/34802.pdf

Regionalisation of the Mediterranean basin, a MERMEX synthesis
Provedor de dados: 5
Autores: Ayata, Sakina-dorothee; Irisson, Jean-olivier; Aubert, Anais; Berline, Leo; Dutay, Jean-claude; Mayot, Nicolas; Nieblas, Anne-elise; D'Ortenzio, Fabrizio; Palmieri, Julien; Reygondeau, Gabriel; Rossi, Vincent; Guieu, Cecile.
Regionalisation aims at delimiting provinces within which physical conditions, chemical properties, and biological communities are reasonably homogeneous. This article proposes a synthesis of the many recent regionalisations of the open-sea regions of the Mediterranean Sea. The nine studies considered here defined regions based on different, and sometimes complementary, criteria: dynamics of surface chlorophyll concentration, ocean currents, three-dimensional hydrological and biogeochemical properties, or the distribution of organisms. Although they identified different numbers and patterns of homogeneous regions, their compilation in the epipelagic zone identifies nine consensus frontiers, eleven consensus regions with relatively homogeneous conditions,...
Tipo: Text
Palavras-chave: Mediterranean Sea; Regionalisation; Biogeochemistry; Circulation; Mesoscale features; Epipelagic ocean; Management; Spatial planning.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00405/51673/52221.pdf

Two-dimensional ammonium distribution in sediment pore waters using a new colorimetric diffusive equilibration in thin-film technique
Provedor de dados: 5
Autores: Metzger, Edouard; Barbe, Anthony; Cesbron, Florian; Thibault De Chanvalon, Aubin; Jauffrais, Thierry; Jézéquel, Didier; Mouret, Aurélia.
This study presents a new gel based technique to describe the pore water ammonium distribution through the sediment-water interface in two dimensions at a millimeter scale. The technique is an adaptation of the classical colorimetric method based on the Berthelot's reaction. After the thin film of the gel probe was equilibrated by diffusion either in standard solutions or in pore waters, a colorimetric reagent gel was set on the gel probe, allowing development of the characteristic green color. A flatbed scanner and subsequent densitometry image analysis allowed to determine the concentration distribution of ammonium. The gel probe was tested in the laboratory for two media, deionized water and seawater, within the range 0–3000 μM in NH4+. Detection limit...
Tipo: Text
Palavras-chave: Biogeochemistry; High-resolution; Porewater; DET; Densitometry.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00474/58557/61112.pdf

Evolution of bacterial communities precipitating carbonate, in Mediterranean lagoons water and sediment: Study on experimental conditions.
Provedor de dados: 5
Autores: Castanier, S; Maurin, A; Bianchi, A.
To determine if carbonate precipitation is an active or passive bacterial phenomena, factorial analysis has been realized with 880 strains isolated from different samples of sea water and muds kept in various conditions of incubation. Results show the existence of a strong anti-correlation between carbonate precipitation and amino-acid ammonification. Carbonate precipitation is not a passive phenomena linked with amino-acid ammonification.
Tipo: Text
Palavras-chave: MED; Biogeochemistry; Mathematical analysis; Water analysis; Sediments; Amino acids; Bacteria; Coastal lagoons; Chemical precipitation; Calcium carbonates.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-956.pdf

Heat, volume and chemical fluxes from submarine venting: A synthesis of results from the Rainbow hydrothermal field, 36 degrees N MAR
Provedor de dados: 5
Autores: German, C. R.; Thurnherr, A. M.; Knoery, Joel; Charlou, Jean-luc; Jean-baptiste, P.; Edmonds, H. N.
High-temperature hydrothermal activity occurs in all ocean basins and along ridge crests of all spreading rates. While it has long been recognized that the fluxes associated with such venting are large, precise quantification of their impact on ocean biogeochemistry has proved elusive Here, we report a comprehensive study of heat, fluid and chemical fluxes from a single submarine hydrothermal field. To achieve this, we have exploited the integrating nature of the non-buoyant plume dispersing above the Rainbow hydrothermal field, a long-lived and tectonically hosted high-temperature vent site on the Mid-Atlantic Ridge. Our calculations yield heat and volume fluxes for high-temperature fluids exiting the seafloor of similar to 0.5 GW and 450 Ls(-1), together...
Tipo: Text
Palavras-chave: Hydrothermal fluxes; Biogeochemistry; Rainbow vent-field.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00003/11423/8040.pdf

Surface ocean-lower atmosphere study: Scientific synthesis and contribution to Earth system science
Provedor de dados: 5
Autores: Breviere, Emilie H. G.; Bakker, Dorothee C. E.; Bange, Hermann W.; Bates, Timothy S.; Bell, Thomas G.; Boyd, Philip W.; Duce, Robert A.; Garcon, Veronique; Johnson, Martin T.; Law, Cliff S.; Marandino, Christa A.; Olsen, Are; Quack, Birgit; Quinn, Patricia K.; Sabine, Christopher L.; Saltzman, Eric S.
The domain of the surface ocean and lower atmosphere is a complex, highly dynamic component of the Earth system. Better understanding of the physics and biogeochemistry of the air-sea interface and the processes that control the exchange of mass and energy across that boundary define the scope of the Surface Ocean-Lower Atmosphere Study (SOLAS) project. The scientific questions driving SOLAS research, as laid out in the SOLAS Science Plan and Implementation Strategy for the period 2004-2014, are highly challenging, inherently multidisciplinary and broad. During that decade, SOLAS has significantly advanced our knowledge. Discoveries related to the physics of exchange, global trace gas budgets and atmospheric chemistry, the CLAW hypothesis (named after its...
Tipo: Text
Palavras-chave: Ocean; Atmosphere; Processes; Biogeochemistry; Flux; Climate.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00293/40405/38964.pdf

Preparing the New Phase of Argo: Scientific Achievements of the NAOS Project
Provedor de dados: 5
Autores: Le Traon, Pierre-yves; D'Ortenzio, Fabrizio; Babin, Marcel; Leymarie, Edouard; Marec, Claudie; Pouliquen, Sylvie; Thierry, Virginie; Cabanes, Cecile; Claustre, Hervé; Desbruyeres, Damien; Lacour, Leo; Lagunas, Jose-luis; Maze, Guillaume; Mercier, Herle; Penkerc'H, Christophe; Poffa, Noe; Poteau, Antoine; Prieur, Louis; Racape, Virginie; Randelhoff, Achim; Rehm, Eric; Schmechtig, Catherine Marie; Taillandier, Vincent; Wagener, Thibaut; Xing, Xiaogang.
Argo, the international array of profiling floats, is a major component of the global ocean and climate observing system. In 2010, the NAOS (Novel Argo Observing System) project was selected as part of the French “Investissements d’Avenir” Equipex program. The objectives of NAOS were to consolidate the French contribution to Argo’s core mission (global temperature and salinity measurements down to 2000 m), and also to develop the future generation of French Argo profiling floats and prepare the next phase of the Argo program with an extension to the deep ocean (Deep Argo), biogeochemistry (BGC-Argo) and polar seas. This paper summarizes how NAOS has met its objectives. The project significantly boosted France’s contribution to Argo’s core mission by...
Tipo: Text
Palavras-chave: Profiling floats; Deep ocean; Biogeochemistry; Mediterranean Sea; Arctic; Atlantic; Argo.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00654/76584/77729.pdf

Potential effects of deep seawater discharge by an Ocean Thermal Energy Conversion plant on the marine microorganisms in oligotrophic waters
Provedor de dados: 5
Autores: Giraud, Mélanie; Garçon, Véronique; De La Broise, Denis; L'Helguen, Stéphane; Sudre, Joël; Boye, Marie.
Installation of an Ocean Thermal Energy Conversion pilot plant (OTEC) off the Caribbean coast of Martinique is expected to use approximately 100,000 m3 h−1 of deep seawater for its functioning. This study examined the potential effects of the cold nutrient-rich deep seawater discharge on the phytoplankton community living in the surface warm oligotrophic waters before the installation of the pilot plant. Numerical simulations of deep seawater upwelled by the OTEC, showed that a 3.0 °C temperature change, considered as a critical threshold for temperature impact, was never reached during an annual cycle on the top 150 m of the water column on two considered sections centered on the OTEC. The thermal effect should be limited, &lt;1 km2 on the area exhibited...
Tipo: Text
Palavras-chave: Marine microbial ecosystem; Biogeochemistry; Modeling; Artificial seawater discharge in situ experiments; Environmental standards.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00507/61867/65935.pdf

Mitigation of sea level rise effects by addition of sediment to shrimp ponds
Provedor de dados: 5
Autores: Della Patrona, Luc; Beliaeff, Benoit; Pickering, T.
In New Caledonia barren salt-pans located landward to mangroves are used for the construction of shrimp ponds. The existing farms are jeopardized by the projected rise in the sea level, because the landward boundaries of ponds are situated at the elevation reached by spring tides. One low-cost strategy for mitigating the effects of sea level rise is to raise the level of the bottom of ponds. To test the effectiveness of such an adaptation, we built 4 experimental ponds in the low-lying zone of an existing 10 ha shrimp pond. The level of the bottom of 2 ponds was raised by adding about 15 cm of agricultural soil. Placing agricultural soil in the pond did not impair the functioning of the shrimp pond ecosystem. On the contrary, it resulted in unexpectedly...
Tipo: Text
Palavras-chave: Climate change; Sea-level rise; Shrimp pond; Sediment enhancement; Biogeochemistry; Infaunal assemblages; New Caledonia.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00069/18030/15570.pdf

Importance de la spéciation des métaux et composés organométalliques pour une bonne évaluation des risques environnementaux en milieu marin. Cas du mercure, de I'arsenic et de l'étain
Provedor de dados: 5
Autores: Michel, Pierre.
Methylmercury toxicity for sea-food consumers is well known long time ago. Tributyltin used as antifouling in paints is toxic at a level as low as 1 ng/l for oysters gastropod. At the opposite, organoarsenic compounds and especially arsenobetaine from fishes are much less toxic than inorganic species. Moreover, besides toxicological considerations, the biogeochemical fates of these elements need a good knowledge of the chemical forms of environmental inputs and of their behaviour in the various compartments (waters, sediments, biota). These phenomenons will be better understood by discussing typical applications.
Tipo: Text
Palavras-chave: Composés organométalliques; Mercure; Arsenic; Étain; Biogéochimie; Organometallic compounds; Mercury; Arsenic; Tin; Biogeochemistry.
Ano: 1992
URL: https://archimer.ifremer.fr/doc/00480/59138/61766.pdf

Multidisciplinary investigation on cold seeps with vigorous gas emissions in the Sea of Marmara (MarsiteCruise): Strategy for site detection and sampling and first scientific outcome
Provedor de dados: 5
Autores: Ruffine, Livio; Ondreas, Helene; Blanc-valleron, Marie-madeleine; Teichert, Barbara M. A.; Scalabrin, Carla; Rinnert, Emmanuel; Birot, Dominique; Croguennec, Claire; Ponzevera, Emmanuel; Pierre, Catherine; Donval, Jean-pierre; Alix, Anne-sophie; Germain, Yoan; Bignon, Laurent; Etoubleau, Joel; Caprais, Jean-claude; Knoery, Joel; Lesongeur, Francoise; Thomas, Bastien; Roubi, Angelique; Legoix, Ludovic Nicolas; Burnard, Pete; Chevalier, Nicolas; Lu, Hailong; Dupre, Stephanie; Fontanier, Christophe; Dissard, Delphine; Olgun, Nazli; Yang, Hailin; Strauss, Harald; Ozaksoy, Volkan; Perchoc, Jonathan; Podeur, Christian; Tarditi, Corinne; Ozbeki, Eyyup; Guyader, Vivien; Marty, Bernard; Madre, David G; Pitel-roudaut, Mathilde; Grall, Celine; Embriaco, Davide; Polonia, Mina; Gasperini, Lucas; Cagatay, M. Namik; Henry, Pierre; Geli, Louis.
MarsiteCruise was undertaken in October/November 2014 in the Sea of Marmara to gain detailed insight into the fate of fluids migrating within the sedimentary column and partially released into the water column. The overall objective of the project was to achieve a more global understanding of cold-seep dynamics in the context of a major active strike-slip fault. Five remotely operated vehicle (ROV) dives were performed at selected areas along the North Anatolian Fault and inherited faults. To efficiently detect, select and sample the gas seeps, we applied an original procedure. It combines sequentially (1) the acquisition of ship-borne multibeam acoustic data from the water column prior to each dive to detect gas emission sites and to design the tracks of...
Tipo: Text
Palavras-chave: Acoustic survey; Authigenic carbonates; Biogeochemistry; Chemical analyses; Cold seeps; Dissolved major elements; Fluid seepage; Geology; In situ Raman analysis; Methane; ROV dives.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00433/54434/55783.pdf

The ECCO-Darwin Data-Assimilative Global Ocean Biogeochemistry Model: Estimates of Seasonal to Multidecadal Surface Ocean pCO(2) and Air-Sea CO2 Flux
Provedor de dados: 5
Autores: Carroll, D.; Menemenlis, D.; Adkins, J. F.; Bowman, K. W.; Brix, H.; Dutkiewicz, S.; Fenty, I.; Gierach, M. M.; Hill, C.; Jahn, O.; Landschutzer, P.; Lauderdale, J. M.; Liu, J.; Manizza, M.; Naviaux, J. D.; Roedenbeck, C.; Schimel, D. S.; Van Der Stocken, T.; Zhang, H.
Quantifying variability in the ocean carbon sink remains problematic due to sparse observations and spatiotemporal variability in surface ocean pCO(2). To address this challenge, we have updated and improved ECCO-Darwin, a global ocean biogeochemistry model that assimilates both physical and biogeochemical observations. The model consists of an adjoint-based ocean circulation estimate from the Estimating the Circulation and Climate of the Ocean (ECCO) consortium and an ecosystem model developed by the Massachusetts Institute of Technology Darwin Project. In addition to the data-constrained ECCO physics, a Green's function approach is used to optimize the biogeochemistry by adjusting initial conditions and six biogeochemical parameters. Over seasonal to...
Tipo: Text
Palavras-chave: Ocean modeling; Biogeochemistry; Ocean carbon cycle; Data assimilation; Air&amp;#8208; Sea CO2 flux; Ecosystem model.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00676/78824/81108.pdf

Preparing the New Phase of Argo: Technological Developments on Profiling Floats in the NAOS Project
Provedor de dados: 5
Autores: André, Xavier; Le Traon, Pierre-yves; Le Reste, Serge; Dutreuil, Vincent; Leymarie, Edouard; Malardé, Damien; Marec, Claudie; Sagot, Jérôme; Amice, Martin; Babin, Marcel; Claustre, Hervé; David, Arnaud; D’ortenzio, Fabrizio; Kolodziejczyk, Nicolas; Lagunas, José Luis; Le Menn, Marc; Moreau, Bertrand; Nogré, David; Penkerc’h, Christophe; Poteau, Antoine; Renaut, Corentin; Schaeffer, Christophe; Taillandier, Vincent; Thierry, Virginie.
The international array of profiling floats known as Argo is a major component of the global ocean- and climate-observing system. In 2010, the NAOS (Novel Argo Observing System) project was selected as part of France’s Equipex “Investissement d’Avenir” program. The objectives of NAOS were to consolidate the French contribution to the Argo core mission (global temperature and salinity measurements down to 2,000 m) as well as to develop the future generation of French Argo profiling floats and prepare the next phase of the Argo program with an extension to the deep ocean (Deep-Argo), biogeochemistry (BGC-Argo) and polar seas. This paper summarizes the main technological advances and at-sea validations carried out as part of NAOS: development of a deep (4,000...
Tipo: Text
Palavras-chave: Ocean; Argo; Global observing system; Profiling float; Deep; Biogeochemistry; Under-ice; Float technology.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00658/77029/78314.pdf

Reduction du nitrate dans les sediments marins. Comparaison des activites mesurees in vitro et in situ
Provedor de dados: 5
Autores: Esteves, J; Bonin, P; Blanc, F; Mille, G; Bertrand, J.
In vitro nitrate reduction in hydrocarbon-polluted marine sediments has been studied by flow-through system. By analysing the rate of nitrate comsumption as a function of nitrate concentration the authors determined the Michaelis-Menten kinetics parameters. (km = 330 mu M; vax = 2.0 mu M/g super(-1)/h super(-1). The authors found a value of 60 mu M/m super(-2)/h super(-1) for the rate of in vitro nitrate consumption derived from the above kinetic parameters and from the nitrate concentration in the sediment. In parallel a value of 67.4 mu M/m super(-2)/h super(-1) was found for the rate of nitrate consumption under in situ conditions. The great similarity between both results would favor the in vitro technique as a valid and more convenient one.
Tipo: Text
Palavras-chave: MED; Biogeochemistry; Oil pollution; Methodology; Environmental conditions; Experimental research; Comparative studies; Metabolism; Bacteria; Sediment chemistry; Reduction; Nitrates; Denitrification; Nitrogen cycle.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-979.pdf

L'arsenic en milieu marin. Biogeochimie et ecotoxicologie
Provedor de dados: 5
Autores: Michel, Pierre.
Arsenic levels of in the marine environment are high in comparison with other contaminants. Over the past twenty years, a large number of arsenic organic compounds have been identified in the water, sediments and living species. This document constitutes a synthesis of current knowledge on arsenic sources, and contamination levels, on its biogeochemical cycle as well as its toxic effects on human and marine fauna. This paper highlights in particular the effects of phosynthesis on arsenic speciation and its distribution throughout the marine environment. Problems of toxicity in the case of certain phyto- and zooplankton species are identified. Bioaccumulation in seaweeds, molluscs and fishes is documented as well, with special attention to the species...
Tipo: Text
Palavras-chave: Ecotoxicology; Contamination; Biogeochemistry; Arsenic; Ecotoxicologie; Contamination; Biogéochimie; Arsenic.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/1993/rapport-1448.pdf

L’algue rouge "Gracilaria verrucosa" (hudson) papenfuss de la lagune de Bizerte (Tunisie septentrionale) : essai de culture en mode suspendu et composition biochimique
Provedor de dados: 20
Autores: Mensi, F.; Ksouri, J.; Hammami, W.; Romdhane, M.S.
L'algue rouge, Gracilaria verrucosa, a été cultivée, durant le printemps 2009, en mode suspendu à différents emplacements et profondeurs  représentant les différences biogéochimiques de la lagune de Bizerte au Nord de la Tunisie. La concentration et la distribution des nutriments (ammonium, phosphate) dans l'eau, ainsi que la salinité, la température, l’oxygène et la transparence de l’eau ont été déterminées. Les méthodes analytiques internationales standardisées ont été appliquées. Les effets du  mode de culture, de l’emplacement et de la profondeur sur les rendements en poids, protéines, R-Phycoérythrine et sucres totaux  de l’algue ont été étudiés. La croissance de Gracilaria a été similaire dans les différents sites mais plus lente dans les profondeurs...
Tipo: Journal Contribution
Palavras-chave: Algal culture; Ammonium compounds; Biochemical composition; Biogeochemistry; Carbohydrates; Dissolved oxygen; Environmental conditions; Growth; Intensive culture; Lagoons; Off-bottom culture; Raw materials; Red algae; Biogeochemical cycle.
Ano: 2009
URL: http://hdl.handle.net/1834/4497

Caractérisation géochimique des sédiments de surface du golfe de Tunis
Provedor de dados: 20
Autores: Fernex, F.; Ben Mammou, A.; Added, A.; Abdeljaoued, S.; Essonni, N.
The general current of the Gulf of Tunis are dependent of the general Mediterranean current. This last divides to the level of the Gulf of Tunis in two branches; a first connects by pass west coasts of the gulf while the second branch crosses the centre of the gulf with a NNW - SSE direction. The passage of this second branch of the general current creates a central zone characterised by a sediment relatively sandier than what surrounds it and controls the distribution of the different metallic elements that have for main origin the Oued Mejerda. The metallic elements here analyzed are the Fe, Zn, Ni, Co, Cu and Pb. Their concentrations vary respectively between 0,5. and 1,6%; 279 and 447 ppm; 39 and 67 ppm; 20 and 34 ppm; 9 and 20 and between 56 and 142...
Tipo: Journal Contribution
Palavras-chave: Sediments; Biogeochemistry.
Ano: 2003
URL: http://hdl.handle.net/1834/1116

Metallophytes in Latin America: a remarkable biological and genetic resource scarcely known and studied in the region
Provedor de dados: 97
Autores: GINOCCHIO,ROSANNA; BAKER,ALAN J.M.
In Latin America, metallic ores are abundant and diverse. However, few metal-tolerant and metal hyperaccumulator plants have been reported in the region in comparison with other areas of the world. This may be largely explained by the scarcity of scientific studies of the native vegetation growing on natural mineralized or metal-contaminated areas and the unfrequent use of biogeochemical prospecting techniques by the local mining industry, rather than the proven absence of these plants. Latin America is, however, an area where metal-tolerant and hyperaccumulator plants (metallophytes) should be found, not only because of the wealth of ore deposits and associated metal polluted areas, but also due to its high and unique plant diversity. If plant formations...
Tipo: Journal article
Palavras-chave: Hyperaccumulators; Metal-tolerant plants; Biodiversity; Metal ores; Biogeochemistry.
Ano: 2004
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000100014

Observations of cryoconite hole system processes on an Antarctic glacier
Provedor de dados: 97
Autores: MACDONELL,SHELLEY A; FITZSIMONS,SEAN J.
Cryoconite holes are water-filled depressions that form on glacier surfaces when uneven distributions of sediment cause differential melting to occur. Cryoconite holes are important features of cold glacier systems, as they enhance meltwater generation, enable the development of complex drainage networks and facilitate the growth of microbial communities on the glacier surface. This paper describes the development of a cryoconite hole hydrological network on an Antarctic glacier, and explores the implications for nutrient storage and delivery within the glacier system. Field measurements included measuring the internal dimensions and repeat mapping of cryoconite holes across the glacier surface, and laboratory analysis included cation and anion analysis on...
Tipo: Journal article
Palavras-chave: Biogeochemistry; Drainage system; Glacier hydrology; Meltwater; Solute.
Ano: 2012
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2012000400003

Influence of effluents from a Wastewater Treatment Plant on nutrient distribution in a coastal creek from southern Brazil
Provedor de dados: 52
Autores: Santos,Isaac Rodrigues; Costa,Ronaldo Cataldo; Freitas,Ubiratan; Fillmann,Gilberto.
The hypothesis that effluents treated through activated sludge process cause changes in nutrient biogeochemistry of receiving water bodies was investigated in Vieira creek, southern Brazil. Dissolved oxygen, suspended matter, and pH did not vary among the sampling stations. Nutrient, biochemical oxygen demand, and conductivity values were significantly higher downstream from the Wastewater Treatment Plant (WWTP) effluents. Further downstream, nitrate concentrations were higher due to ammonium nitrification, organic matter remineralization and/or the occurrence of unidentified sources. Per capita nutrient emission factors were estimated to be 0.16 kg P.yr-1 and 4.14 kg N.yr-1. Under pristine conditions, low N:P ratios were observed, which were significantly...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Activated sludge; Nutrients; Contamination; Coastal zone; Biogeochemistry; Eutrophication.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000100019