Biogeochemical cycling in an organic-rich coastal marine basin. 8. A sulfur isotopic budget balanced by differential diffusion across the sediment-water interface

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

DOI:https://doi.org/10.1016/0016-7037(87)90212-2· OSTI ID:7160102

Chanton, J P; Martens, C S

The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate delta/sup 34/S measurements yielded a calculated sulfate input of 0.6 per thousand. Sulfate transported into the sediments via diffusion appeared to be enriched in the lighter isotope because its concentration gradient was steeper, due to the increase in the measured isotopic composition of sulfate with depth. Similarly, the back diffusion of dissolved sulfide towards the sediment-water interface appeared enriched in the heavier isotope. The isotopic composition of this flux was calculated from measurements of the delta/sup 34/S of dissolved sulfide and was determined to be 15.9 per thousand. The isotopic composition of buried sulfide was determined to be -5.2 per thousand and the detrital sulfur input was estimated to be -6.2 per thousand. An isotope mass balance equation based upon the fluxes at the sediment-water interface successfully predicted the isotopic composition of the buried sulfur flux within 0.5 per thousand, thus confirming that isotopes diffuse in response to their individual concentration gradients.

• Research Organization: Univ. of North Carolina, Chapel Hill (USA)
• OSTI ID: 7160102
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:5; ISSN GCACA
• Country of Publication: United States
• Language: English

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550200 -- Biochemistry
58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
59 BASIC BIOLOGICAL SCIENCES
BIOGEOCHEMISTRY
CHEMICAL ANALYSIS
CHEMISTRY
CONTINENTAL MARGIN
CONTINENTAL SHELF
DIAGENESIS
FEDERAL REGION IV
GEOCHEMISTRY
GEOLOGIC STRUCTURES
ISOTOPE RATIO
ISOTOPES
MASS BALANCE
NORTH AMERICA
NORTH CAROLINA
ORGANIC MATTER
QUANTITATIVE CHEMICAL ANALYSIS
SEDIMENTARY BASINS
SEDIMENTATION
SEDIMENTS
SULFUR ISOTOPES
USA