Microbial sulfate reduction in deep sediments of the Southwest Pacific (ODP Leg 181, Sites 1119–1125): evidence from stable sulfur isotope fractionation and pore water modeling
✍ Scribed by Michael E. Böttcher; Boo-Keun Khim; Atsushi Suzuki; Matthias Gehre; Ulrich G. Wortmann; Hans-J. Brumsack
- Publisher
- Elsevier Science
- Year
- 2004
- Tongue
- English
- Weight
- 494 KB
- Volume
- 205
- Category
- Article
- ISSN
- 0025-3227
No coin nor oath required. For personal study only.
✦ Synopsis
Interstitial water samples from seven ODP sites (Leg 181, Sites 1119^1125) of the southwestern Pacific Ocean have been analyzed for the stable sulfur isotopic composition of dissolved sulfate along with major and minor ions. Sulfate from the interstitial fluids (N 34 S values between +20.7 and +60x vs. the SO 2 -based Vienna^Canyon Diablo troilite standard) was enriched in 34 S with respect to modern sea water (N 34 SW+20.6x) indicating that microbial sulfate reduction takes place to different extents at all investigated sites. Microbial sulfate reduction (MSR) was found at all sites, the intensity depending on the availability of organic matter which is controlled by paleo-sedimentation conditions (sedimentation rate, presence of turbidites) and productivity. Microbial net sulfate reduction was additionally confirmed by modeling interstitial water sulfate profiles. Areal net sulfate reduction rates up to 14 mmol m 32 yr 31 have been calculated which were positively related to sedimentation rates. Total reduced inorganic sulfur (TRIS; essentially pyrite) as a product of microbial sulfate reduction was isotopically characterized in squeeze cake samples and gave N 34 S values between 351 and +9x indicating pyrite formation both close to the sediment^water interface and later diagenetic contributions.