Reduced sulfur and iron species in anoxic water column of meromictic crater Lake Pavin (Massif Central, France) | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Reduced sulfur and iron species in anoxic water column of meromictic crater Lake Pavin (Massif Central, France)

Type de publication:

Journal Article

Source:

Chemical Geology, Volume 266, Ticket 3-4, p.320-326 (2009)

ISBN:

0009-2541

Numéro d'accès:

ISI:000270346400018

URL:

http://www.sciencedirect.com/science/article/pii/S0009254109002952

Mots-clés:

UMR 7154 ; Géochimie des Eaux ; Sulfide; Iron; Nanoparticles; Voltammetry; Spectrophotometry; Methylene blue

Résumé:

<p>The vertical distribution of reduced sulfur species (RSS including H2S/HS-, S-0, electroactive FeS) and dissolved Fe(II) was studied in the anoxic water column of meromictic Lake Pavin. Sulfide concentrations were determined by two different analytical techniques, i.e. spectophotometry (methylene blue technique) and voltammetry (HMDE electrode). Total sulfide concentrations determined with methylene blue method (Sigma H2SMBRS) were in the range from 0.6 mu M to 16.7 mu M and were substantially higher than total reduced sulfur species (RSSV) concentrations determined by voltammetry, which ranged from 0.1 to 5.6 mu M. The observed difference in the sulfide concentrations between the two methods can be assigned to the presence of FeS colloidal species. Dissolved Fe was high (&gt;1000 mu M), whereas dissolved Mn was only 25 mu M, in the anoxic water column. This indicates that Fe is the dominant metal involved in sulfur redox cycling and precipitation. Consequently, in the anoxic deep layer of Lake Pavin, "free" sulfide, H2S/HS-, was low; and about 80% of total sulfide detected was in the electroactive FeS colloidal form. IAP calculations showed that the Lake Pavin water column is saturated with respect to FeSam phase. The upper part of monimolimnion layer is characterized by higher concentrations of S (0) (up to 3.4 mu M) in comparison to the bottom of the lake. This behavior is probably influenced by sulfide oxidation with Fe(III) oxyhydroxide species. (C) 2009 Elsevier B.V. All rights reserved.</p>

Notes:

Bura-Nakic, Elvira Viollier, Eric Jezequel, Didier Thiam, Alassane Ciglenecki, Irena