Porewater evidence for a dynamic sedimentary iron cycle in salt marshes

Journal Article · Sun Jan 01 04:00:00 EST 1984 · Limnol. Oceanogr.; (United States)

DOI:https://doi.org/10.4319/lo.1984.29.1.0047· OSTI ID:6784198

Giblin, A E; Howarth, R W

Dynamic transformations of iron occur seasonally at Great Sippewissett March, Massachusetts. Small changes in the dissolved iron concentration in porewater represent only a small fraction of the iron involved in transformation reactions during the year. During the growing seasons, salt marsh grasses oxidize the sediment, and a large percentage of sedimentary pyrite is converted to an oxidized iron mineral. Over the fall and winter there is a net increase in pyrite as the grass is anaerobically decomposed. When oxidation rates in summer are high enough to neutralize the alkalinity produced by sulfate reduction and substantially lower the pH, oxidized iron minerals become increasingly soluble and iron levels in the porewater increase. If large amounts of soluble iron are lost by tidal flushing, iron availability may limit pyrite formation in later years. For most of the year the porewaters of Great Sippewissett were undersaturated with respect to all iron monosulfide minerals and supersaturated with respect to pyrite (FeS/sub 2/). Thus pyrite formations at Great Sippewissett probably occurs directly by reaction of polysulfides with iron and not by reactions of FeS with elemental sulfur. Porewaters were always undersaturated with respect to manganese minerals.

• Research Organization: Marine Biological Lab., Woods Hole, MA
• OSTI ID: 6784198
• Journal Information: Limnol. Oceanogr.; (United States), Journal Name: Limnol. Oceanogr.; (United States) Vol. 29:1; ISSN LIOCA
• Country of Publication: United States
• Language: English

Related Subjects

520100* -- Environment
Aquatic-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AQUATIC ECOSYSTEMS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
ECOSYSTEMS
FEDERAL REGION I
GRASS
GROUND WATER
HYDROGEN COMPOUNDS
IRON COMPOUNDS
IRON SULFIDES
MARSHES
MASSACHUSETTS
MINERAL CYCLING
MINERALS
NORTH AMERICA
OXIDATION
OXYGEN COMPOUNDS
PLANTS
PYRITE
SEASONAL VARIATIONS
SULFATES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
USA
VARIATIONS
WATER
WATER CHEMISTRY
WETLANDS