Title :

Sulfur diagenesis under rapid accumulation of organic-rich sediments in a marine mangrove from Guadeloupe (French West Indies)

Author(s) :

Crémière, Antoine [Auteur correspondant]
Geological Survey of Norway [NGU]
Institut d'écologie et des sciences de l'environnement de Paris [iEES]
University of Tromsø [UiT]
Strauss, Harald [Auteur]
Sebilo, Mathieu [Auteur]
Institut d'écologie et des sciences de l'environnement de Paris [iEES]
Hong, Wei-Li [Auteur]
University of Tromsø [UiT]
Gros, Olivier [Auteur]
Biologie de la Mangrove [BM]
Schmidt, Sabine [Auteur]
Environnements et Paléoenvironnements OCéaniques [EPOC]
Tocny, Jennifer [Auteur]
Biologie de la Mangrove [BM]
Henry, Françoise [Auteur]
Université du Littoral Côte d'Opale [ULCO]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Gontharet, Swanne [Auteur]
Université du Littoral Côte d'Opale [ULCO]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Laverman, Anniet M. [Auteur]
Ecosystèmes, biodiversité, évolution [Rennes] [ECOBIO]

Journal title :

Chemical Geology

Pages :

67-79

Publisher :

Elsevier

Publication date :

2017-04-05

ISSN :

0009-2541

English keyword(s) :

Microbial sulfate reduction
Early diagenesis
Sulfur and oxygen isotopes
Marine mangrove
Sulfur oxidizing microbial mats
Organic carbon-rich sediments

HAL domain(s) :

Planète et Univers [physics]/Sciences de la Terre/Géochimie
Sciences du Vivant [q-bio]/Ecologie, Environnement/Ecosystèmes

English abstract : [en]

The biogeochemistry of sulfur and carbon during early-diagenetic processes within organic-rich marine mangrove sediments was studied in the “Manche à Eau” lagoon, Guadeloupe, West Indies. These sediments are characterized ...
Show more >The biogeochemistry of sulfur and carbon during early-diagenetic processes within organic-rich marine mangrove sediments was studied in the “Manche à Eau” lagoon, Guadeloupe, West Indies. These sediments are characterized by a total organic carbon content (TOC) mostly above 11 wt%, δ13CTOC below − 25‰ VPDB and C/Nmolar ratios exceeding 15. Rates of mangrove-derived organic carbon accumulation vary between ~ 200 and 400 gOC·m− 2·yr− 1, with highest rates at the shore of the lagoon. On the lagoon border, where colorless filamentous sulfur-oxidizing bacteria colonize the sediments, active sulfate reduction within the upper 20 cm, with a net removal rate of ~ 0.5 μmol·cm− 3·d− 1, is assumed to be essentially driven by organic carbon oxidation. This is expressed by relatively low apparent sulfur isotope fractionation (34εnet = − 33‰) and a gentle δ18O/δ34Ssulfate apparent slope of 0.36 ± 0.03 (2s). Further inside the lagoon, in the absence of sulfur-oxidizing bacteria, higher apparent sulfur isotope fractionation and a steeper δ18O/δ34Ssulfate slope (0.67 ± 0.20) suggest an overall lower sulfate removal rate that may be coupled to minor sulfur disproportionation. Spatial and vertical variation in sulfur cycling, reflected by oxygen and sulfur isotopic characteristics, seem to be mainly controlled by unsteady to relatively steady organic matter deposition and its reactivity. In all sediments, δ34S values of pyrite are positively correlated with the TOC/TS ratio and negatively correlated with δ13CTOC; suggesting a primary control of the quantity and quality of organic matter on the pyrite isotope records, despite potential iron-limiting conditions for the most active sites. Our results provide insights into the role of organic carbon input on sulfur cycling; stimulating sulfate reduction and in turn the presence of sulfur-oxidizing microbial mats, resulting in an intense cycling of both carbon and sulfur in these marine mangrove sediments.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL