Modeling redox cycling across the suboxic-anoxic interface zone in the Black Sea

Date

2001-03-01

Author

Oguz, T
Murray, JW
Callahan, AE

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

67
views

0
downloads

The reactions controlling the suboxic-anoxic interface structure in the Black Sea are investigated with a prognostic, one-dimensional vertically resolved diffusion-reaction model involving O-2, NO3-, NH4+, HS-, S-0, Mn2+, MnO2. All reactions are expressed in a second-order form, and values for the rate constants are estimated from laboratory and field measurements made during the 1988 RV Knorr expedition. The model successfully simulates the vertical profiles of O-2, N, S and Mn species in the region between upper and lower boundaries of the model, which were specified at depths corresponding to sigma (t) similar to 15.50 kg/m(3) and sigma (t) similar to 16.50 kg/m(3). The model identifies an approximately 30 m thick suboxic layer with oxygen concentrations less than 5 muM and zero sulfide concentrations between sigma (t) similar to 15.55 kg/m(3) and sigma (t) similar to 16.05 kg/m(3). Dissolved oxygen decreases to trace concentrations above the zone of nitrate reduction. Hydrogen sulfide begins to increase downward into deeper levels of the anoxic pool starting at sigma (t) similar to 16.0 kg/m(3), where nitrate becomes undetectable. Dissolved manganese and ammonium also increase beneath the suboxic layer. The position at which sulfide concentrations appear coincides with the particulate manganese peak, reflecting the paramount role of manganese cycling in the redox processes. This structure is found to have a fairly persistent character for a wide range of rate constants. Oxidation reactions by oxygen alone are not sufficient to provide a realistic interface structure in the absence of particulate manganese formed by oxidation of Mn2+ by NO3-. A transient lateral oxygen supply into sulfide rich waters alters the anoxic-suboxic structure by rapidly depleting local sulfide concentrations at the depths of oxygen injection.

Subject Keywords

Black Sea, Suboxic zone, Modeling, Redox cycling

URI

https://hdl.handle.net/11511/66375

Journal

DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS

DOI

https://doi.org/10.1016/s0967-0637(00)00054-6

Collections

Graduate School of Marine Sciences, Article

Suggestions

OpenMETU
Core

Modeling monostatic sea clutter at low grazing angles by using method of moments Özbaş, Emre; Kuzuoğlu, Mustafa; Department of Electrical and Electronics Engineering (2021-2-15) Scatteringof electromagnetic waves from rough surfaces such as sea surface isanimportantproblem for radarengineers,since aradardeviceshould discriminate returns from the desired object(target)from those scattered by theundesired object, which is rough sea surface studied in this work. Since the sea surface is randomly changing with time for varyingwind speeds, sea clutter problem becomes a stochastic problem. The main goal of this thesis is obtaining a model to calculate the backscattered power f...
Modeling the influence of hydrodynamic processes on anchovy distribution and connectivity in the black sea Karadeniz'deki hamsi dağılımı ve bölgeler arası bağlantısı üzerine hidrodinamik proseslerin etkisinin modellenmesi Fach Salihoğlu, Bettina Andrea (2014-01-01) Dispersal mechanisms of Black Sea anchovy larvae (Engraulis encrasicolus ponticus) across the Black Sea were studied with an individual based anchovy larvae model embedded in a Lagrangian model using surface currents calculated from daily dynamic height topography maps of altimeter data during a period of three years (2001-2003). Particles representing anchovy eggs were released at different sites during June to August and their movement was tracked over time. Drifters were advected for 36 days, representin...
Modeling the response of top-down control exerted by gelatinous carnivores on the Black Sea pelagic food web Oguz, T; Ducklow, HW; Purcell, JE; Malanotte-Rizzoli, P (American Geophysical Union (AGU), 2001-03-15) Recent changes in structure and functioning of the interior Black Sea ecosystem are studied by a series of simulations using a one-dimensional, vertically resolved, coupled physical-biochemical model. The simulations are intended to provide a better understanding of how the pelagic food web structure responds to increasing grazing pressure by gelatinous carnivores (medusae Aurelia aurita and ctenophore Mnemiopsis leidyi) during the past 2 decades. The model is first shown to represent typical eutrophic ecos...
A numerical study of solidification and viscous dissipation effects on polymer melt flow in plane channels Tutar, Mustafa; Karakuş, Ali (Walter de Gruyter GmbH, 2013-04-01) The combined effects of solidification and viscous dissipation on the hydrodynamic and thermal behavior of polymer melt flow during the injection process in a straight plane channel of constant cross section are numerically studied by considering the shear-rate and temperature-dependent viscosity and transient-phase change behavior. A numerical finite volume method, in conjunction with a modified form of the Cross constitutive equation to account for shear rate, temperature-dependent viscosity changes and a...
Simulation of circulating fluidized bed combustors firing indigenous lignite Özkan, Mert; Selçuk, Nevin; Department of Chemical Engineering (2010) A comprehensive model, previously developed for a rectangular parallelepiped shaped 0.3 MWt circulating fluidized bed combustor (CFBC) fired with high calorific value coal burning in sand and validated against experimental data is adapted to cylindrical configuration and is extended to incorporate NOx formation and reduction reactions and pressure drops around cyclone, downcomer and loop seal. Its predictive accuracy is tested by applying it to the simulation of Middle East Technical University (METU) 150 k...

Citation Formats

T. Oguz, J. Murray, and A. Callahan, “Modeling redox cycling across the suboxic-anoxic interface zone in the Black Sea,” DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, pp. 761–787, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/66375.