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Sulfide determination in hydrothermal seawater samples using a vibrating gold micro-wire electrode in conjunction with stripping chronopotentiometry ArchiMer
Aumond, Virginie; Waeles, Mathieu; Salaun, Pascal; Gibbon-walsh, Kristoff; Van Den Berg, Constant M. G.; Sarradin, Pierre-marie; Riso, Ricardo D..
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at -0.25 V (vs Ag/AgCl, KCl 3 M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically -2 mu A). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30 nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ....
Tipo: Text Palavras-chave: Sulfide; Stripping chronopotentiometry; Vibrating electrode; Gold; Seawater; Hydrothermal.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00111/22222/20065.pdf
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Chemical Speciation of Copper in a Salt Marsh Estuary and Bioavailability to Thaumarchaeota ArchiMer
Whitby, Hannah; Hollibaugh, James T.; Van Den Berg, Constant M. G..
The concentrations of dissolved copper (Cu-d), copper-binding ligands, thiourea-type thiols, and humic substances (HScu) were measured in estuarine waters adjacent to Sapelo Island, Georgia, USA, on a monthly basis from April to December 2014. Here we present the seasonal cycle of copper speciation within the estuary and compare it to the development of an annually occurring bloom of Ammonia Oxidizing Archaea (AOA), which require copper for many enzymes. Two types of complexing ligands (L-1 and L-2) were found to dominate with mean complex stabilities (log K'(cuL)) of 14.5 and 12.8. Strong complexation resulted in lowering the concentration of free cupric ion (Cu2+) to femtomolar (fM) levels throughout the study and to sub-fM levels during the summer...
Tipo: Text Palavras-chave: Copper speciation; Cathodic stripping voltammetry; Humic substances; Thiols; Thiourea; Organic ligands; Thaumarchaeota; Ammonia-oxidizing archaea.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00616/72834/72735.pdf
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