A sulfur budget for the Black Sea anoxic zone

Neretin, Lev N.; Volkov, I. I.; Böttcher, Michael E.; Grinenko, V. A.

doi:10.1016/s0967-0637(01)00030-9

Cited by 99 publications

(51 citation statements)

References 45 publications

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“…The Panthalassa and the Paleotethys water columns were likely stratified, like in the modern Black Sea (see Neretin et al 2001), with photosynthetically derived organic matter (marine and continental) sinking into anoxic deeper water. Here, sulfate reducing bacteria could oxidize this organic matter either in the anoxic water column or in the sediment.…”

Section: Discussionmentioning

confidence: 98%

Carbon, sulfur, oxygen and strontium isotope records, organic geochemistry and biostratigraphy across the Permian/Triassic boundary in Abadeh, Iran

Korte

Kozur²,

Joachimski³

et al. 2004

Int J Earth Sci (Geol Rundsch)

119

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Section: Discussionmentioning

confidence: 98%

Carbon, sulfur, oxygen and strontium isotope records, organic geochemistry and biostratigraphy across the Permian/Triassic boundary in Abadeh, Iran

Korte

Kozur²,

Joachimski³

et al. 2004

Int J Earth Sci (Geol Rundsch)

119

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“…The temporal and spatial variability of the suboxic zone reflects fundamental changes associated with the sulfide production in the water column and sulfide oxidation at the base of the suboxic zone (Neretin et al, 2001), which are shaped by circulation and mixing. The circulation in the Black Sea is structured usually in two connected gyre systems encompassing the basin (the main current is known as the Rim Current) and two quasi-permanent sub-basin eddies: the Batumi and Sebastopol ones.…”

Section: Introductionmentioning

confidence: 99%

Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

et al. 2014

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Abstract. The temporal and spatial variability of the upper ocean hydrochemistry in the Black Sea is analysed using data originating from profiling floats with oxygen sensors and carried out with a coupled three-dimensional circulationbiogeochemical model including 24 biochemical state variables. Major focus is on the dynamics of suboxic zone which is the interface separating oxygenated and anoxic waters. The scatter of oxygen data seen when plotted in density coordinates is larger than those for temperature, salinity and passive tracers. This scatter is indicative of vigorous biogeochemical reactions in the suboxic zone, which acts as a boundary layer or internal sink for oxygen. This internal sink affects the mixing patterns of oxygen compared to the ones of conservative tracers. Two different regimes of ventilation of pycnocline were clearly identified: a gyre-dominated (cyclonic) regime in winter and a coastal boundary layer (anticyclonic eddy)-dominated regime in summer. These contrasting states are characterized by very different pathways of oxygen intrusions along the isopycnals and vertical oxygen conveyor belt organized in multiple-layered cells formed in each gyre. The contribution of the three-dimensional modelling to the understanding of the Black Sea hydro-chemistry, and in particular the coast-to-open-sea mixing, is also demonstrated. Evidence is given that the formation of oxic waters and of cold intermediate waters, although triggered by the same physical process, each follow a different evolution. The difference in the depths of the temperature minimum and the oxygen maximum indicates that the variability of oxygen is not only just a response to physical forcing and changes in the surface conditions, but undergoes its own evolution.

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“…The Black Sea Mo data were tabulated in Dyrssen (1999), which were taken from Emerson and Huested (1991). Black Sea sulfide data were taken from Neretin et al (2001) and the oxygen data from Colodner (1991) Barling et al, 2001;Siebert et al, 2003;Barling and Anbar, 2004;Goldberg et al, 2009). Anoxic processes refer to those determined in this study and error bars represent are 2σ.…”

Section: Introductionmentioning

confidence: 99%

Molybdenum isotope fractionations observed under anoxic experimental conditions

2012

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Experiments were carried out to determine molybdenum isotope fractionation associated with adsorption to pyrite. Results show that the Mo isotope composition of the aqueous solution becomes progressively heavier as Mo is adsorbed, with a Mo isotope fractionation as large as 2.9‰. This fractionation is larger than observed for typical anoxic continental margin marine sediments (e.g., ~0.7‰), suggesting that Mo adsorption to pyrite is not the dominant process operating in these environments. However, our adsorption results do suggest the possibility that anoxic fractionation processes could impart an isotope signature within the geologic record similar to the isotope fractionation observed under oxygenated conditions. Additional experiments were conducted at high (~100 µM) dissolved Mo concentrations, but at varying pH and ∑H 2 S concentrations, and in each case these experiments promoted Mo-sulfide precipitation. Even though the experiments were conducted under differing conditions and produced different amounts of precipitate, the results suggest a constant fractionation of ~0.9‰ associated with this Mo removal process. This fractionation is more consistent with that inferred for anoxic continental margin marine sediments, suggesting that a process similar to Mo-sulfide precipitation, rather than an adsorption process, may be responsible for the Mo isotope compositions observed in these environments. The findings of this study suggest that, regardless of the geochemical mechanism employed, sediment Mo sequestration under anoxic conditions may impart a significant isotopic fractionation relative to parent seawater.

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A sulfur budget for the Black Sea anoxic zone

Cited by 99 publications

References 45 publications

Carbon, sulfur, oxygen and strontium isotope records, organic geochemistry and biostratigraphy across the Permian/Triassic boundary in Abadeh, Iran

Carbon, sulfur, oxygen and strontium isotope records, organic geochemistry and biostratigraphy across the Permian/Triassic boundary in Abadeh, Iran

Mixing in the Black Sea detected from the temporal and spatial variability of oxygen and sulfide – Argo float observations and numerical modelling

Molybdenum isotope fractionations observed under anoxic experimental conditions

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