Iodine diagenesis in pelagic deep-sea sediments

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90300-0· OSTI ID:5063098

Kennedy, H A; Elderfield, H

Nineteen sediment cores from the Madeira, Seine, Tagus and Nares Abyssal Plains and the Alboran Sea have been used to evaluate the speciation, fluxes and diagenesis of iodine in the deep sea. The sediments have surficial molar I/C ratios of 10-30 x 10/sup -4/ in excess of previous reported values for planktonic material (approx. 1 x 10/sup -4/). Iodine species in the pore waters follow a vertical sequence of four zones: 1. a zone of I/sup -/ production where total dissolved iodine (..sigma..I) concentrations initially increase at the sea water-sediment interface; 2. a zone of I/sup -/ oxidation where interconversion of I/sup -/ to IO/sub 3//sup -/ occurs; 3. a zone of IO/sub 3//sup -/ reduction where interconversion of IO/sub 3//sup -/ back to I/sup -/ occurs which corresponds to the suboxic part of the sediment column; and 4. a further zone of I/sup -/ production which is confined to the lower anoxic part of the sediment column. In the surface sediment the observed I enrichment results from a quasi-closed cycle for iodine initially involving release of I/sup -/ from decomposing marine organic matter followed by rapid removal onto organic matter at the sediment-sea water interface where I/C regeneration ratios of up to 200 x 10/sup -4/ are found. Iodate reduction occurs during suboxic diagenesis, after denitrification and before MnO/sub 2/ reduction, consistent with the sequence of reactions predicted from the free energy yields for organic matter oxidation.

• Research Organization: Univ. of Cambridge (England)
• OSTI ID: 5063098
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:9; ISSN GCACA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
AQUATIC ORGANISMS
CARBON
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DENITRIFICATION
DIAGENESIS
ELEMENTS
GEOCHEMISTRY
GROUND WATER
HALOGEN COMPOUNDS
HALOGENS
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
IODINE
IODINE COMPOUNDS
IODINE OXIDES
ISOTOPE RATIO
MANGANESE COMPOUNDS
MANGANESE OXIDES
MATHEMATICAL MODELS
MOLECULAR MODELS
NONMETALS
ORGANIC MATTER
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLANKTON
REDUCTION
SEAWATER
SEDIMENTS
TRANSITION ELEMENT COMPOUNDS
WATER