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Registros recuperados: 12
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A Michaelis–Menten type equation for describing methylmercury dependence on inorganic mercury in aquatic sediments ArchiMer
Cossa, Daniel; Garnier, Cedric; Buscail, Roselyne; Elbaz-poulichet, Francoise; Mikac, Nevenka; Patel-sorrentino, Nathalie; Tessier, Erwan; Rigaud, Sylvain; Lenoble, Veronique; Gobeil, Charles.
Methylation of mercury (Hg) is the crucial process that controls Hg biomagnification along the aquatic food chains. Aquatic sediments are of particular interest because they constitute an essential reservoir where inorganic divalent Hg (HgII) is methylated. Methylmercury (MeHg) concentrations in sediments mainly result from the balance between methylation and demethylation reactions, two opposite natural processes primarily mediated by aquatic microorganisms. Thus, Hg availability and the activity of methylating microbial communities control the MeHg abundance in sediments. Consistently, some studies have reported a significant positive correlation between MeHg and HgII or total Hg (HgT), taken as a proxy for HgII, in aquatic sediments using...
Tipo: Text Palavras-chave: Mercury; Methylmercury; Aquatic sediment; Methylation; Demethylation.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00171/28220/26520.pdf
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Amazonian former gold mined soils as a source of methylmercury: Evidence from a small scale watershed in French Guiana ArchiMer
Guedron, Stephane; Grimaldi, Michel; Grimaldi, Catherine; Cossa, Daniel; Tisserand, Delphine; Charlet, Laurent.
Total mercury (HgT) and monomethylmercury (MMHg) were investigated in a tropical head watershed (1 km(2)) of French Guiana. The watershed includes a pristine area on the hill slopes and a former gold mined flat in the bottomland. Concentrations of dissolved and particulate HgT and MMHg were measured in rain, throughfall, soil water and at three points along the stream. Samples were taken in-between and during 14 storm events at the beginning and middle of the 2005 and 2006 rainy seasons. Dissolved and particulate HgT concentrations in the stream slightly increased downstream, while dissolved and particulate MMHg concentrations were low at the pristine sub-watershed outlet (median = 0.006 ng L-1 and 1.84 ng g(-1), respectively) and sharply increased at the...
Tipo: Text Palavras-chave: Mercury; Methylmercury; Tropical watershed; Gold placers; Stream water; Oxisols; Hydromorphic soils.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00035/14628/12134.pdf
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Difference of mercury bioaccumulation in red mullets from the north-western Mediterranean and Black seas ArchiMer
Harmelin-vivien, M.; Cossa, Daniel; Crochet, Sylvette; Banaru, D.; Letourneur, Y.; Mellon-duval, Capucine.
The relationships between total mercury (Hg) concentration and stable nitrogen isotope ratio (delta N-15) were evaluated in Mullus barbatus barbatus and M. surmuletus from the Mediterranean Sea and M. barbatus ponticus from the Black Sea. Mercury concentration in fish muscle was six times higher in the two Mediterranean species than in the Black Sea one for similar sized animals. A positive correlation between Hg concentration and delta N-15 occurred in all species. Increase in Hg concentration with delta N-15 was high and similar in the two Mediterranean fishes and much lower in the Black Sea species. Since this was neither related to trophic level difference between species nor to methylmercury (MeHg) concentration differences between the north-western...
Tipo: Text Palavras-chave: Black Sea; Mediterranean; Mullidae; Methylmercury; Trophic level; N 15.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6647.pdf
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Géochimie du mercure dans le continuum de la retenue de Petit-Saut et de l'estuaire du Sinnamary, Guyane française ArchiMer
Muresan Paslaru, Bogdan.
The mercury cycle was explored in the Petit-Saut reservoir / Sinnamary Estuary continuum in French Guiana. Main processes involve (i) photo-induced reduction, (ii) adsorption and desorption at the particle surfaces, (iii) methylating bacterial activity, (iv) precipitation and dissolution of iron oxyhydroxides and sulfides. Sources of mercury to the Petit-Saut reservoir consist of the partly impacted river-tributaries, the atmospheric deposition and the flooded soils or vegetation. Once into the reservoir, divalent mercury undergoes a large spectrum of transformations including speciation and phase changes. We, here, probe these processes and demonstrate that the Petit-Saut reservoir behaves as a privileged site for atmospheric recycling and in situ...
Tipo: Text Palavras-chave: Atmosphere; Estuary; Reservoir; French Guiana; Methylmercury; Mercury; Atmosphère; Estuaire; Retenue; Guyane française; Methylmercure; Mercure.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/these-1508.pdf
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Microwave treatment of biological samples for methylmercury determination by high-performance liquid chromatografy – cold vapour - atomic fluorescence spectrometry IPB - Escola Superior Agrária
Ramalhosa, Elsa; Río-Segade, Susana; Pereira, Eduarda; Vale, Carlos; Duarte, Armando.
A simple and rapid microwave-assisted alkaline digestion procedure was developed in combination with high performance liquid chromatography-ultraviolet post-column oxidation-cold vapour atomic fluorescence spectrometric detection for methylmercury determination in biological tissues. Since the stability of methylmercury in methanolic potassium hydroxide solution under microwave irradiation was verified, the microwave-assisted extraction procedure was optimized in terms of quantitative recovery of methylmercury and minimum time required. The alkaline extracts were subjected to clean-up steps with dichloromethane and hydrochloric acid in order to reduce matrix interferences in methylmercury determination. The effects of matrix interferences were checked by...
Tipo: Article Palavras-chave: Methylmercury; Microwave treatment; Biological samples; HPLC-CV-AFS.
Ano: 2001 URL: http://hdl.handle.net/10198/3950
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Microwave-assisted extraction for methylmercury determination in sediments by high performance liquid chromatography-cold vapour-atomic fluorescence spectrometry IPB - Escola Superior Agrária
Ramalhosa, Elsa; Río-Segade, Susana; Pereira, Eduarda; Vale, Carlos; Duarte, Armando.
A simple and rapid procedure for methylmercury extraction from sediments based on microwave-assisted alkaline digestion with methanolic potassium hydroxide was optimized on parameters such as microwave power, extraction time and sample size. Organomercury species were extracted with dichloromethane in hydrochloric acid medium and back-extracted into ultra-pure water. The sediment extracts were injected into an analytical system composed of high-performance liquid chromatography-ultraviolet-post-column oxidation-cold vapour-atomic fluorescence spectrometry (HPLC-UV-PCO-CV-AFS) for methylmercury determination. Quantitative methylmercury recoveries were obtained when 0.15 g of sediment were suspended into 6 mi of 25% m/v methanolic potassium hydroxide and the...
Tipo: Article Palavras-chave: Methylmercury; Microwave-assisted extraction; HPLC-CV-AFS.
Ano: 2001 URL: http://hdl.handle.net/10198/3941
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Modeling the Influence of Eutrophication and Redox Conditions on Mercury Cycling at the Sediment-Water Interface in the Berre Lagoon ArchiMer
Pakhomova, Svetlana; Yakushev, Evgeniy; Protsenko, Elizaveta; Rigaud, Sylvain; Cossa, Daniel; Knoery, Joel; Couture, Raoul-marie; Radakovitch, Olivier; Yakubov, Shamil; Krzeminska, Dominika; Newton, Alice.
This study presents a specifically designed Mercury module in a coupled benthic-pelagic reactive-transport model - Bottom RedOx Model (BROM) that allows to study mercury (Hg) biogeochemistry under different conditions. This module considers the transformation of elemental mercury (Hg(0)), divalent mercury (Hg(II)) and methylmercury (MeHg). The behavior of mercury species in the model is interconnected with changes of oxygen, hydrogen sulfide, iron oxides, organic matter, and biota. We simulated the transformation and transport of Hg species in the water column and upper sediment layer under five different scenarios, combining various levels of oxygenation and trophic state in the Berre lagoon, a shallow eutrophic lagoon of the French Mediterranean coast...
Tipo: Text Palavras-chave: Mercury; Methylmercury; Biogeochemical modeling; Anoxia; Eutrophication; Lagoon; BROM.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00454/56535/58239.pdf
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Monomethylmercury sources in a tropical artificial reservoir ArchiMer
Muresan, B; Cossa, Daniel; Richard, Sophie; Dominique, Y.
The distribution and speciation of mercury (Hg) in the water column, the inputs (wet deposition and tributaries) and the outputs (atmospheric evasion and outlet) of an artificial partially anoxic tropical lake (Petit-Sa-Lit reservoir, French Guiana) were investigated oil a seasonal basis in order to appraise the cycling and transformations of this metal. The total mercury (HgT) concentrations in the oxygenated epilimnetic waters averaged 5 +/- 3 pmol L-1 in the unfiltered samples (HgTUNF) and 4 +/- 2 pmol L-1 in the dissolved (HgTD) phase (< 0.45 mu m). On average, the monomethylmercury (MMHg) constituted 8%, 40%, and 18% of the HgT in the dissolved phase, tile particulate suspended matter and in tile unfiltered samples, respectively. Covariant elevated...
Tipo: Text Palavras-chave: Tropical environment; Artificial reservoir; Methylmercury; Mercury.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4198.pdf
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Simple methodology for methylmercury and inorganic mercury determination by high performance liquid chromatography-cold vapour atomic fluorescence spectrometry IPB - Escola Superior Agrária
Ramalhosa, Elsa; Río-Segade, Susana; Pereira, Eduarda; Vale, Carlos; Armando, Duarte.
An analytical methodology was developed to separate and quantify methylmercury (MeHg) and inorganic mercury by high-performance liquid chromatography (HPLC)-cold vapour atomic fluorescence spectrometry (CV-AFS). The use of UV oxidation of the organic forms of mercury, the tin(II) chloride reduction in acidic medium of mercury and the introduction of a water vapour trap based on H2SO4/CaCl2 resulted in a low detection limit (DL) (10 +/- 2 pg, mean value +/- S.D.). The apparatus was operationally optimised through the modified simplex method leading to an increase of the signal by a factor of 2. The method performance has been tested by determining the MeHg concentration in a sediment certified reference material (CRM) and the results were statistically...
Tipo: Article Palavras-chave: Methylmercury; Cold vapour atomic fluorescence spectromety; Liquid chromatography; UV radiation; Simplex optimisation.
Ano: 2001 URL: http://hdl.handle.net/10198/3946
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Spatial and temporal distribution of mercury and methylmercury in bivalves from the French coastline ArchiMer
Briant, Nicolas; Chouvelon, Tiphaine; Martinez, Laura; Brach-papa, Christophe; Chiffoleau, Jean-francois; Savoye, N.; Sonke, J.; Knoery, Joel.
Marine mercury (Hg) concentrations have been monitored in the French coastline for the last half a century using bivalves. The analyses presented in this study concerned 192 samples of bivalves (mussels: Mytilus edulis and Mytilus galloprovincialis and oysters: Crassostrea gigas and Isognomon alatus) from 77 sampling stations along the French coast and in the French Antilles sea. The goals of this study were to assess MeHg levels in various common bivalves from French coastline, and to identify possible geographic, taxonomic or temporal variations of concentrations. We show that the evolution of methylmercury (MeHg) concentrations covary with total mercury (HgT) concentrations. Moreover, in most of the study sites, HgT concentrations have not decreased...
Tipo: Text Palavras-chave: Mercury; Methylmercury; France; Bivalves; Speciation.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00353/46465/46398.pdf
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The biogeochemistry of mercury at the sediment water interface in the Thau lagoon. 1. Partition and speciation ArchiMer
Muresan Paslaru, Bogdan; Cossa, Daniel; Jezequel, D; Prevot, F; Kerbellec, S.
Solid sediment, pore and epibenthic waters were collected from the Thau lagoon (France) in order to study the post depositional partition and mobility of mercury and monomethylmercury in an organic rich sediment. Total Hg (HgT) and monomethymercury (MMHg) profiles were produced in both dissolved and solid phases. The distribution of HgT in the solid appeared to be related to the historical changes in the Hg inputs into the lagoon. HgT was in equilibrium between solid and solution in the sulfidic part of the cores, with a mean log Kd of 4.9 +- 0.2. The solid appeared to be a source of HgT for pore water in the upper oxic to suboxic parts of the cores. The MMHg represented a small fraction of HgT: 3-15 % and 0.02-0.80 % in the dissolved and in the solid...
Tipo: Text Palavras-chave: Fluxes; Partition; Sediment; Lagoon; Methylmercury; Mercury.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2006/publication-2083.pdf
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The open sea as the main source of methylmercury in the water column of the Gulf of Lions (Northwestern Mediterranean margin) ArchiMer
Cossa, Daniel; De Madron, Xavier Durrieu; Schafer, Jorg; Lanceleur, Laurent; Guedron, Stephane; Buscail, Roselyne; Thomas, Bastien; Castelle, Sabine; Naudin, Jean-jacques.
Despite the ecologic and economical importance of coastal areas, the neurotoxic bioaccumulable monomethylmercury (MMHg) fluxes within the ocean margins and exchanges with the open sea remain unassessed. The aim of this paper is to address the questions of the abundance, distribution, production and exchanges of methylated mercury species (MeHgT), including MMHg and dimethylmercury (DMHg), in the waters, atmosphere and sediments of the Northwestern Mediterranean margin including the Rhône River delta, the continental shelf and its slope (Gulf of Lions) and the adjacent open sea (North Gyre). Concentrations of MeHgT ranged from <0.02 to 0.48 pmol L−1 with highest values associated with the oxygen-deficient zone of the open sea. The methylated mercury to...
Tipo: Text Palavras-chave: Mercury; Methylmercury; Ocean margin; Coastal area; Mediterranean.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00363/47399/47477.pdf
Registros recuperados: 12
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