Dense bottom gravity currents and their impact on pelagic methanotrophy at oxic/anoxic transition zones. Issue 10 (27th May 2016)

• Record Type: Journal Article
• Authors: Schmale, Oliver; Krause, Stefan; Holtermann, Peter; Power Guerra, Nicole C.; Umlauf, Lars
• Is Part Of: Geophysical research letters. Volume 43:Issue 10(2016)
• Page Start: 5225
• Page End: 5232
• Publication Date: 2016-05-27
• Subjects: methane -- methanotrophs -- turbulent mixing -- anoxic basin -- redoxcline -- Baltic Sea; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL069032
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We show that inflows of oxygenated waters into sulfidic layers have a strong impact on biogeochemical transformation at oxic/anoxic transition zones. Taking the pelagic methane dynamics in the Gotland Basin as an example, we performed our studies when one of the largest inflows ever recorded entered the Baltic Sea in March 2015. An inflowing gravity current transported oxic waters into the sulfidic deep layers and freshly generated a near‐bottom secondary redox interface. At the upper slope, where the inflowing water masses were vigorously turbulent and the main and secondary redox interfaces in close contact to each other, methane oxidation rates inside the transition zone were found to be higher compared to the weakly turbulent basin interior. At the main redox interface in the basin center, lateral intrusions of oxygenated waters into intermediate water depth may have stimulated the growth of the methanotrophic community and their activity. Key Points: Dense gravity currents increase mixing in stagnant basins in the central Baltic Sea Intrusions of oxygenated water impact methane dynamics in anoxic basins Mixing intensity, methane oxidation, and abundance of methanotrophs show a positive correlation