Journal
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS
Volume 48, Issue 9, Pages 2097-2120Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/S0967-0637(01)00007-3
Keywords
sulphate reduction; anaerobic methane oxidation; Black Sea; diffusion-diagenesis modeling; sulphur biogeochemistry
Categories
Ask authors/readers for more resources
Beyond the shelf break at ca. 150 m water depth, sulfate reduction is the only important process of organic matter oxidation in Black Sea sediments from the surface down to the sulfate-methane transition at 2-4 m depth. Sulfate reduction rates were measured experimentally with (SO42-)-S-35, and the rates were compared with results of two diffusion-reaction models. The results showed that, even in these non-bioirrigated sediments without sulfide reoxidation, modeling strongly underestimated the high reduction rates near the sediment surface. A hybrid modeling approach, in which experimentally measured rates in the upper sediment layers force a model that includes also the deeper layers, probably provides the most realistic estimate of sulfate reduction rates. Areal rates of sulfate reduction were 0.65-1.43 mmol SO42- m(-2) d(-1), highest in sediments just below the chemocline. Anaerobic methane oxidation accounted for 7-11% of the total sulfate reduction in slope and deep-sea sediments. Although this methane-driven sulfate reduction shaped the entire sulfate gradient, it was only equivalent to the sulfate reduction in the uppermost 1.5 cm of surface sediment. Methane oxidation was complete, yet the process was very sluggish with turnover times of methane within the sulfate-methane transition zone of 20 yr or more. (C) 2001 Elsevier Science Ltd. All rights reserved.Beyond the shelf break at ca. 150 m water depth, sulfate reduction is the only important process of organic matter oxidation in Black Sea sediments from the surface down to the sulfate-methane transition at 2-4 m depth. Sulfate reduction rates were measured experimentally with (SO42-)-S-35, and the rates were compared with results of two diffusion-reaction models. The results showed that, even in these non-bioirrigated sediments without sulfide reoxidation, modeling strongly underestimated the high reduction rates near the sediment surface. A hybrid modeling approach, in which experimentally measured rates in the upper sediment layers force a model that includes also the deeper layers, probably provides the most realistic estimate of sulfate reduction rates. Areal rates of sulfate reduction were 0.65-1.43 mmol SO42- m(-2) d(-1), highest in sediments just below the chemocline. Anaerobic methane oxidation accounted for 7-11% of the total sulfate reduction in slope and deep-sea sediments. Although this methane-driven sulfate reduction shaped the entire sulfate gradient, it was only equivalent to the sulfate reduction in the uppermost 1.5 cm of surface sediment. Methane oxidation was complete, yet the process was very sluggish with turnover times of methane within the sulfate-methane transition zone of 20 yr or more. (C) 2001 Elsevier Science Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available