Continuing influence of the changed thermohaline circulation in the eastern Mediterranean on the distribution of dissolved oxygen and nutrients: Physical and chemical characterization of the water masses

Kress, Nurit; Manca, Beniamino B.; Klein, Birgit; Deponte, Davide

doi:10.1029/2002jc001397

Cited by 51 publications

(56 citation statements)

References 25 publications

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“…By 1999 its effect was already observed in the deep waters of the EMS as a layer of younger water of Aegean origin with lower silicic acid content (Fig. 2) (Kress et al, 2003). The concentration of silicic acid south of Crete was 7.6 µmol Si kg −1 , 8.6 µmol Si kg −1 in the eastern Levantine and 8.3 µmol Si kg −1 in the western Ionian.…”

Section: Silicic Acid In the Water Column Across The Basinmentioning

confidence: 93%

“…This eastwards increase is relatively much larger for silicic acid than that for nitrate or phosphate (Kress et al, 2003. Recently, as a result of the Eastern Mediterranean Transient (EMT) event, younger and denser water of Aegean origin with lower silicic acid content was introduced into the Ionian and Levantine deep layers (Roether et al, , 2007.…”

Section: Introductionmentioning

confidence: 99%

“…Schlitzer et al, 1991 andNellen et al, 1996). (b) X section measured in 1999 after EMT event and showing the presence of newer deep water formed in the Aegean and advected into the deep water of the basin (Data from Kress et al, 2003).…”

Section: Silicic Acid In Porewatersmentioning

confidence: 99%

“…Data on the silicic acid distribution in the eastern Mediterranean were collected during several oceanographic cruises (Kress et al, 2003(Kress et al, , 2014Kress and Herut, 2001). Briefly, continuous profiles of pressure, temperature, (Jones, 1977 salinity, dissolved oxyge and fluorescence were performed with a Sea-Bird SBE 911 plus CTD system, interfaced to a SBE Carousel equipped with Niskin bottles.…”

Section: Silicic Acid In the Water Columnmentioning

confidence: 99%

“…Recently, as a result of the Eastern Mediterranean Transient (EMT) event, younger and denser water of Aegean origin with lower silicic acid content was introduced into the Ionian and Levantine deep layers (Roether et al, , 2007. This reduced the concentration at depth and formed a pronounced mid-depth silicic acid maximum (Kress et al, 2003.…”

Section: Introductionmentioning

confidence: 99%

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Silica cycling in the ultra-oligotrophic eastern Mediterranean Sea

2014

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Abstract. Although silica is a key plant nutrient, there have been few studies aimed at understanding the Si cycle in the eastern Mediterranean Sea (EMS). Here we use a combination of new measurements and literature values to explain the silicic acid distribution across the basin and to calculate a silica budget to identify the key controlling processes. The surface water concentration of ∼ 1 µM, which is unchanging seasonally across the basin, was due to the inflow of western Mediterranean Sea (WMS) water at the Straits of Sicily. It does not change seasonally because there is only a sparse population of diatoms due to the low nutrient (N and P) supply to the photic zone in the EMS. The concentration of silicic acid in the deep water of the western Ionian Sea (6.3 µM) close to the S Adriatic are an of formation was due to the preformed silicic acid (3 µM) plus biogenic silica (BSi) from the dissolution of diatoms from the winter phytoplankton bloom (3.2 µM). The increase of 4.4 µM across the deep water of the EMS was due to silicic acid formed from in situ diagenetic weathering of aluminosilicate minerals fluxing out of the sediment. The major inputs to the EMS are silicic acid and BSi inflowing from the western Mediterranean (121 × 10 9 mol Si yr −1 silicic acid and 16 × 10 9 mol Si yr −1 BSi), silicic acid fluxing from the sediment (54 × 10 9 mol Si yr −1 ) and riverine (27 × 10 9 mol Si yr −1 ) and subterranean groundwater (9.7 × 10 9 mol Si yr −1 ) inputs, with only a minor direct input from dissolution of dust in the water column (1 × 10 9 mol Si yr −1 ). This budget shows the importance of rapidly dissolving BSi and in situ weathering of aluminosilicate minerals as sources of silica to balance the net export of silicic acid at the Straits of Sicily. Future measurements to improve the accuracy of this preliminary budget have been identified.

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Section: Silicic Acid In the Water Column Across The Basinmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Silicic Acid In Porewatersmentioning

confidence: 99%

Section: Silicic Acid In the Water Columnmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Silica cycling in the ultra-oligotrophic eastern Mediterranean Sea

2014

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Temporal nutrient dynamics in the Mediterranean Sea in response to anthropogenic inputs

Moon

Lee

Tanhua

et al. 2016

Geophysical Research Letters

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The temporal dynamics of the concentrations of nitrate (N), phosphate (P), and the N:P ratio in the upper water column (200–600 m) of the Mediterranean (MED) Sea were investigated using observational data (~123,100 data points) collected between 1985 and 2014. The studied variables were found to evolve similarly in the western and eastern MED Sea. In both basins, the N concentration increased during the first part of the observational period (1985–1998), and the temporal trend of N was broadly consistent with the history of riverine and atmospheric nitrogen input from populated areas in Europe, with a lag period of 20 years. In subsequent years, the N concentration was high and relatively constant between 1998 and 2005, after which N decreased gradually, although the decreasing trend was indistinct in the western basin. In particular, the trend of constant then declining N after 1998 is consistent with the history of pollutant nitrogen emissions from the European continent, allowing a 20 year lag following the introduction of regulation of pollutant nitrogen in the 1970s. The three‐phase temporal transition in P in both basins was more consistent with the riverine phosphorus input, with a lag period of 20 years. Our analysis indicates that the recent dynamics of N and P in the upper MED Sea has been sensitive to the dynamics of anthropogenic nitrogen and phosphorus input from atmospheric deposition and rivers.

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Circulation and oxygen cycling in the Mediterranean Sea: Sensitivity to future climate change

Powley

Krom

Cappellen

2016

J. Geophys. Res. Oceans

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Climate change is expected to increase temperatures and decrease precipitation in the Mediterranean Sea (MS) basin, causing substantial changes in the thermohaline circulation (THC) of both the Western Mediterranean Sea (WMS) and Eastern Mediterranean Sea (EMS). The exact nature of future circulation changes remains highly uncertain, however, with forecasts varying from a weakening to a strengthening of the THC. Here we assess the sensitivity of dissolved oxygen (O2) distributions in the WMS and EMS to THC changes using a mass balance model, which represents the exchanges of O2 between surface, intermediate, and deep water reservoirs, and through the Straits of Sicily and Gibraltar. Perturbations spanning the ranges in O2 solubility, aerobic respiration kinetics, and THC changes projected for the year 2100 are imposed to the O2 model. In all scenarios tested, the entire MS remains fully oxygenated after 100 years; depending on the THC regime, average deep water O2 concentrations fall in the ranges 151–205 and 160–219 µM in the WMS and EMS, respectively. On longer timescales (>1000 years), the scenario with the largest (>74%) decline in deep water formation rate leads to deep water hypoxia in the EMS but, even then, the WMS deep water remains oxygenated. In addition, a weakening of THC may result in a negative feedback on O2 consumption as supply of labile dissolved organic carbon to deep water decreases. Thus, it appears unlikely that climate‐driven changes in THC will cause severe O2 depletion of the deep water masses of the MS in the foreseeable future.

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Continuing influence of the changed thermohaline circulation in the eastern Mediterranean on the distribution of dissolved oxygen and nutrients: Physical and chemical characterization of the water masses

Cited by 51 publications

References 25 publications

Silica cycling in the ultra-oligotrophic eastern Mediterranean Sea

Silica cycling in the ultra-oligotrophic eastern Mediterranean Sea

Temporal nutrient dynamics in the Mediterranean Sea in response to anthropogenic inputs

Circulation and oxygen cycling in the Mediterranean Sea: Sensitivity to future climate change

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