Sulfate reduction and the formation of 35S‐labeled FeS, FeS2, and S0 in coastal marine sediments
Year: 1989
Type: article
Abstract: A comparative survey was done of the formation of radiolabeled end‐products during 35SO42− reduction measurements in coastal sediments of Denmark. The distribution of reduced 35S in acid‐volatile sulfides (AVS), pyrite, and elemental sulfur in the upper 0–15 cm of sediment depended on the sulfur chemistry and on the overall sulfate reduction rates. In sediments with relatively low metabolic rates, undetectable H2S, and low FeS : FeS2 ratio : 20), only 32–55% of the reduced 35S was recovered in the AVS pool. In sediments with high metabolic rates, high H2S, and high FeS : FeS2 ratio (>1 : 10), the 35S recovery in AVS was 63–92%. The relative contribution of Fe35S2 formation showed little depth dependence, whereas the formation of 35S° was highest in the more oxidizing sediment layers near the surface. Inclusion of 35S‐labeled FeS2 and S° in the sulfate reduction measurement yields more accurate rate data than are obtained from AVS alone. Due to possible isotopic exchange reactions and unknown pathways of H2S transformation into AVS, S°, and FeS2, however, the radioactivities of the three pools cannot be used directly to calculate their differential rates of formation.
Source: Limnology and Oceanography
Authors: Søren Thode‐Andersen, Bo Barker Jørgensen
Institution: Aarhus University
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2101606013