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Konovalov, Sergey; Еремеев, В. Н.; Suvorov, A. M.; Khaliulin, A. Kh.; Godin, E.A.

doi:10.1023/a:1009655502787

Cited by 15 publications

(3 citation statements)

References 8 publications

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“…The development of anoxic conditions below the chemocline, at ~100 m water depth, results from limited ventilation due to water column stratifi cation. This is a consequence of higher salinity waters entering the Black Sea from the Mediterranean and less dense surface waters fl owing out of the Black Sea (Konovalov et al, 1999). The surface water is oxygenated, with a salinity of ~18 psu (practical salinity unit; 1 psu = 1 g salt in 1 kg of seawater), which is infl uenced by the river water infl ow (Murray et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

“…The water column below ~150 m is permanently devoid of oxygen, with a salinity of ~22 psu (Murray et al, 1991). The sulfi de concentration increases with water depth, reaching ~400 µmol L -1 near the seafl oor (Konovalov et al, 1999;Neretin et al, 2001). Sediments that accumulate under sulfi dic bottom waters have been shown to have enhanced Mo contents (Crusius et al, 1996;Nägler et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Sulfidity controls molybdenum isotope fractionation into euxinic sediments: Evidence from the modern Black Sea

Neubert

Nägler

Böttcher

2008

Geol

273

252

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Molybdenum (Mo) isotope fractionation has recently been introduced as a new proxy in oceanography and biogeochemistry. It is therefore fundamental to understand the processes controlling Mo partitioning into modern marine environments. This study identifi es the availability of dissolved sulfi de as the dominant control on overall Mo removal from the water column in euxinic systems. Mo isotopic composition of surface sediments from different localities of the Black Sea demonstrates complete fi xation of Mo only below 400 m water depth, above a critical concentration of 11 µmol l -1 aqueous hydrogen sulfi de in the bottom water. The Mo isotopic composition of these sediments refl ects the homogeneous seawater isotopic composition of 2.3‰. In contrast, signifi cant Mo isotope fractionation into less euxinic sediments is evident at shallower depths in the Black Sea, as well as in temporarily euxinic deeps of the Baltic Sea, consistent with the observed lower maximum sulfi de concentrations in the respective water columns. Therefore, Mo isotope signatures in the modern Black Sea constrain the processes responsible for global Mo removal from the ocean by euxinic sediments. Furthermore, models of past ocean anoxia reconstruction have to consider that the seawater Mo isotopic composition is not per se archived in euxinic sediments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sulfidity controls molybdenum isotope fractionation into euxinic sediments: Evidence from the modern Black Sea

Neubert

Nägler

Böttcher

2008

Geol

273

252

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“…In addition, if a pronounced pycnocline develops in such a system, diffusion of oxygen through the density gradient can be further prevented. There are large portions of marine systems that are hypoxic, such as subsurface waters of the East China Sea (Chen et al 2007, Wang et al 2016) and deep waters of the Baltic Sea (Conley et al 2009a, Rolff andElfwing 2015), the Black Sea (Konovalov et al 1999) and the Gulf of Mexico (Justić et al 1996(Justić et al , 2005. Layers of the open ocean can be hypoxic due to a significantly larger supply of organic matter than oxygen (Kamykowski and Zentara 1990), but it is hypoxia/anoxia in coastal seas (Diaz 2001) that causes greater concern regarding damage to the biodiversity of ecosystems (Ciglenečki et al 2015), which many human activities depend on, such as fisheries and tourism.…”

Section: Introductionmentioning

confidence: 99%

Hypoxia in deep waters of moderately eutrophic marine lakes, Island of Mljet, eastern Adriatic Sea

Hrustić

Bobanović-Ćolić

2017

Sci. Mar.

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Summary:In this study, we explored the impact of eutrophication and stratification on hypoxia in deep waters of moderately warm Croatian marine lakes. Although the Mljet Lakes (MLs) are predominantly oligotrophic, mesotrophic conditions are present at depths below 20 m in the Small Lake (SL) and below 30 m in the Big Lake (BL), along with higher apparent oxygen utilization (AOU). Hypoxia at depths ≥25 m in SL and and ≥40 m in BL was observed between October 2009 and January 2010, and in SL in summer (July and September 2010). Significant differences (p<0.05) in several physical, biological and chemical parameters were detected between the lakes, while AOU, derived oxygen utilization rate (OUR) and organic carbon remineralization rate (OCRR) were not significantly different (p>0.05) between the lakes. An intense and persistent pycnocline throughout the year, comparatively high water temperature, extended water renewal time and summer phytoplankton bloom were identified as physical and biological parameters which might have significantly contributed to increased frequency of hypoxic events in a shallow SL. Significantly (p<0.05) higher ammonium concentration in SL, especially in its deep water, seems to be a long-term chemical feature related to the poor ventilation and higher sediment oxygen demand. At the current level of eutrophication and the present climate change trends, the MLs and similar systems may experience more persistent and intense stratification, which could further prevent mixing between upper and deep waters, likely leading to increasing duration of hypoxia and its negative impacts on the biodiversity of benthic communities.Keywords: hypoxia; eutrophication, marine lakes, coastal zone, Adriatic Sea, Mediterannean Sea. Hipoxia en aguas profundas de lagos marinos moderadamente eutróficos, isla de Mljet, mar Adriático orientalResumen: En este estudio, exploramos el impacto de la eutrofización y la estratificación sobre la hipoxia, en aguas profundas de los lagos marinos croatas moderadamente cálidos. Aunque los lagos Mljet (LsM) son predominantemente oligotróficos, las condiciones mesotróficas están presentes a profundidades inferiores a 20 m en el Lago Menor (LMe) y a 30 m en el Lago Mayor (LMa), junto con un mayor uso del oxígeno aparente (UOA). Fue observada hipoxia a profundidades ≥25 m en el LMe y ≥40 m en el LMa entre octubre de 2009 y enero de 2010, y en LMe en verano (julio y septiembre de 2010). Fueron detectadas diferencias significativas (p<0.05) en varios parámetros físicos, biológicos y químicos entre los lagos, mientras que el UOA, la tasa de utilización de oxígeno derivado y la tasa de remineralización de carbono orgánico no fueron significativamente diferentes (p>0.05) entre los lagos. La intensa y persistente picnoclina a lo largo del año, la temperatura comparativamente alta del agua, el tiempo prolongado de renovación del agua y la floración estival del fitoplancton se identificaron como parámetros físicos y biológicos que podrían haber contribuido significativamente incrementando...

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