Lateral injection of oxygen with the Bosporus plume—fingers of oxidizing potential in the Black Sea

Konovalov, Sergey; Luther, George Iii. W.; Friederich, Gernot; Nuzzio, Donald B.; Tebo, Bradley M.; Murray, James W.; Oğuz, Temel; Glazer, Brian T.; Trouwborst, Robert E.; Clement, Brian; Murray, Karen J.; Romanov, Alexander S.

doi:10.4319/lo.2003.48.6.2369

Cited by 119 publications

(113 citation statements)

References 25 publications

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“…In contrast to the frequent, strong disruption of the suboxic layer in the southwest stations, the westcentral and northwest stations revealed more stable transitions between oxic and sulfidic waters. And, as a result of the physical gyre circulation (doming of the waters in the central regions; Konovalov et al, 2003), the onset of H 2 S was considerably shallower at the central station ( Fig. 1: 162-16-6, 162-17-2 and 162-17-13) than in the southwest or northwest stations.…”

Section: Article In Pressmentioning

confidence: 94%

“…2, we decided to design and build an in situ chemical analyzer to determine dissolved O 2 and H 2 S and other redox components (Table 1). Deployment of this instrument in 2001 provided in situ voltammetric profiles that helped to document lateral O 2 injection from the Bosporus Plume (Konovalov et al, 2003). This lateral injection suppresses and distorts the suboxic zone and the upper part of the H 2 S onset at stations influenced by Bosporus inflow throughout the southwest Black Sea, as observed in oxygenated waters above 130 m in the southwest (Fig.…”

Section: Oxygen and Sulfide Distributionsmentioning

confidence: 99%

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Documenting the suboxic zone of the Black Sea via high-resolution real-time redox profiling

Glazer¹,

Luther²,

Konovalov³

et al. 2006

Deep Sea Research Part II: Topical Studies in Oceanography

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We coupled an in situ electrochemical analyzer to a CTD pump profiler system to measure redox species across the oxic-anoxic interface of the Black Sea water column. Voltammetry was performed using gold-amalgam working electrodes to measure simultaneously oxygen and dissolved sulfur species (S 8 , S 2À x , HS À /H 2 S) both in situ (at o1 m vertical intervals) and in an on-deck flow cell attached to the outflow of a pump profiler (vertical resolution of about 1.5 m). In situ data agreed with measurements made in the flow cell and with measurements made from samples collected by rosette bottle casts. In situ voltammetry provided undisturbed, high-resolution measurements, and revealed significant yet subtle features not seen by traditional methods because of small spatial separation between the features and the measurements. Layers of oxygen intrusion (o5 m thick, from 10 to 150 mM O 2 ) were present within the suboxic zone of the southwest Black Sea that are not present in the west-central and northeast Black Sea. Oxygen injection also occurs at other depths throughout the southwest and corresponds with small temperature anomalies, suggesting influence by Bosporus inflow up to 150 km from its entrance to the Black Sea. Such an inflow of oxygen, as well as spatial variations of the halocline, affect both manganese and, subsequently, sulfide oxidation for a large portion of Black Sea intermediate water (H 2 S onset occured $60 m deeper in the southwest as compared to the west-central). In situ voltammetric analyses provided rapid redox information, thus enabling more accurate targeting of specific geochemical features by the CTD rosette package. r

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Section: Article In Pressmentioning

confidence: 94%

Section: Oxygen and Sulfide Distributionsmentioning

confidence: 99%

Documenting the suboxic zone of the Black Sea via high-resolution real-time redox profiling

Glazer¹,

Luther²,

Konovalov³

et al. 2006

Deep Sea Research Part II: Topical Studies in Oceanography

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“…This zone was defined by Murray et al (1989Murray et al ( , 1995 as the water layer, where the concentrations of dissolved oxygen and hydrogen sulfide are below the detection limit. In the study of Konovalov et al (2003) these limits have been specified as 30 nmol L −1 for sulfide and 3 µmol L −1 for oxygen. As demonstrated by Stanev et al (2013), Argo floats' observations in the Black Sea equipped with an optode sensor can resolve these low oxygen concentrations.…”

Section: Introductionmentioning

confidence: 99%

“…The vertical diffusion coefficient is very small, which enables one to speculate that the diapycnal diffusion is very low. However, Konovalov et al (2003) reported massive lateral injections of oxygen-enriched waters of the Bosphorus plume into the suboxic and anoxic layers. This could serve as an indication that the isopycnic diffusion could play the major role in propagating tracers' anomalies.…”

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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“…For example, T min was 7.7°C in May 2001 [Konovalov et al, 2003], suggesting no renewal the previous winter.…”

Section: Introductionmentioning

confidence: 99%

Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre

Gregg

Yakushev

2005

Geophysical Research Letters

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[1] Understanding the origin of the shallow temperature minimum, known as the Cold Intermediate Layer (CIL), in the Black Sea has long been hampered by the scarcity of winter observations. During March 2003, we observed a cold-air outbreak over the center of the Black Sea's Western Gyre. Freezing winds drove convection that cooled the surface mixed layer to 6.1°C and deepened it to 40 m, directly ventilating the upper 80% of the CIL, whose lower boundary was at 49 m. Concentrations of dissolved oxygen were 350 mM in the mixed layer and decreased rapidly to 70 mM at the base of the CIL, 9 m below the mixed layer. A few meters deeper, at the top of the Sub-Oxic Layer (SOL), both oxygen and hydrogen sulfide became undetectable (<5 mM and <1 mM, respectively). Microstructure profiles revealed intermittent turbulence in the oxycline below the mixed layer. Average rates of turbulent dissipation were 10 À9 -10 À8 W kg À1 . The accompanying mixing produced diapycnal diffusivities, K r , that were only (1 -4) Â 10 À6 m 2 s À1 . Consequently, turbulent fluxes were too weak to renew significantly either the lower 20% of the CIL or the SOL, whose top was 4 m below the bottom of the CIL and hence well-removed from direct surface replenishment. Citation: Gregg, M. C., and E. Yakushev (2005), Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre, Geophys. Res. Lett., 32, L03604,

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Lateral injection of oxygen with the Bosporus plume—fingers of oxidizing potential in the Black Sea

Cited by 119 publications

References 25 publications

Documenting the suboxic zone of the Black Sea via high-resolution real-time redox profiling

Documenting the suboxic zone of the Black Sea via high-resolution real-time redox profiling

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

Surface ventilation of the Black Sea's cold intermediate layer in the middle of the western gyre

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