Transformations of sulfur compounds in marsh-flat sediments

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90353-0· OSTI ID:7164180

Swider, K T; Mackin, J E ^[1]

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1. SUNY at Stony Brook, NY (USA)

Measurements were made in mud-flat sediments from Flax Pond salt marsh to characterize the rates and mechanisms of sulfur cycling in an organic-rich coastal marine environment. Approximately 13 mmoles/m{sup 2} of reduced sulfur are generated annually in the mud flat and the dominant solid-phase product is pyrite. Ion activity products involving dissolved iron and sulfide species indicate approximate saturation with respect to metastable iron sulfide phases, showing that pyrite is not likely to be the first-formed Fe-bearing sulfide. Comparison of {Sigma}H{sub 2}S vs. SO{sup =}{sub 4} relationships in anoxic incubation experiments with those occurring in the undisturbed sediment permits evaluation of possible mechanisms involved in the transformation of metastable iron monosulfides to pyrite. Oxidants (e.g. MnO{sub 2}) that are introduced into the surface sediment, either by animal activity or physical events, are apparently necessary to cause major oxidation of FeS and {Sigma}H{sub 2}S to pyrite and sulfate. Solid-phase sulfur analyses and net {Sigma}H{sub 2}S accumulation in sediment pore waters are consistent with major sulfide oxidation, indicating that approximately 95% of the sulfide generated in the mud flat is reoxidized to sulfate and roughly half of this oxidation involves dissolved sulfide. The major factors limiting reduced sulfur burial are physical and biological disturbances and a low abundance of reactive solid-phase iron (2 wt%).

• OSTI ID: 7164180
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 53:9; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AQUATIC ECOSYSTEMS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DYNAMICS
ECOSYSTEMS
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
IRON COMPOUNDS
IRON SULFIDES
MARSHES
MECHANICS
MINERALIZATION
MINERALS
OXYGEN COMPOUNDS
PHASE STUDIES
PRECIPITATION
PYRITE
REDOX REACTIONS
SEASONAL VARIATIONS
SEDIMENTS
SEPARATION PROCESSES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
SULFUR CYCLE
THERMODYNAMIC ACTIVITY
TRANSITION ELEMENT COMPOUNDS
VARIATIONS
WATER
WETLANDS