scholarly journals Eastern Mediterranean Sea circulation inferred from the conditions of S1 sapropel deposition

2014 ◽  
Vol 10 (6) ◽  
pp. 4647-4681 ◽  
Author(s):  
K. Tachikawa ◽  
L. Vidal ◽  
M. Cornuault ◽  
M. Garcia ◽  
A. Pothin ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Benthic Foraminifera ◽  
Bottom Water ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Oxygen Depletion ◽  
Last Deglaciation ◽  
Short Term ◽  
Total Recovery ◽  
Eastern Mediterranean Sea

Abstract. Holocene Eastern Mediterranean Sea sediments contain an organic-rich sapropel S1 layer that was formed in oxygen-depleted waters. The spatial distribution of this layer revealed that during S1 deposition deep waters were permanently anoxic below 1800 m in water depth. To provide further insight into past Eastern Mediterranean Sea circulation, a multi-proxy approach was applied to a core retrieved close to the 1800 m boundary (at 1780 m). We measured the bulk sediment elemental composition, the stable isotopic composition of the planktonic foraminifer Globigerinoides ruber, and the abundance of benthic foraminifera since the last deglaciation. The result indicates that authigenic U and Mo accumulation began around 13–12 cal ka BP, in concert with surface water freshening estimated from the G. ruber δ18O record. The onset of bottom/pore water oxygen depletion occurred prior to S1 deposition inferred from barium enrichment. In the middle of the S1 deposition period, between 9 and 8 cal ka BP, reduced authigenic V, Fe and As contents and Br / Cl ratio indicated short-term bottom water re-oxygenation. A sharp Mn peak and maximal abundance for benthic foraminifera marked a total recovery for circulation at approximately 7 cal ka BP. Based on our results and existing data, we suggest that S1 formation withinthe upper 1780 m of the Eastern Mediterranean Sea was preconditioned by reduced ventilation, resulting from excess fresh water inputs due to insolation changes under deglacial conditions, that initiated between 15 and 12 ka. Short-term re-oxygenation in the Levantine Basin is estimated to have affected bottom water below and above the anoxic boundary. We tentatively propose that complete ventilation recovery at the S1 termination was attained earlier within the upper 1780 m than at deeper water depths. Our results provided new constraints for eastern Mediterranean Sea thermohaline circulation.

scholarly journals Eastern Mediterranean Sea circulation inferred from the conditions of S1 sapropel deposition

2015 ◽  
Vol 11 (6) ◽  
pp. 855-867 ◽  
Author(s):  
K. Tachikawa ◽  
L. Vidal ◽  
M. Cornuault ◽  
M. Garcia ◽  
A. Pothin ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Benthic Foraminifera ◽  
Bottom Water ◽  
Eastern Mediterranean ◽  
Last Deglaciation ◽  
Short Term ◽  
Total Recovery ◽  
Eastern Mediterranean Sea ◽  
The Last Deglaciation ◽  
Freshwater Inputs

Abstract. Holocene eastern Mediterranean Sea sediments contain an organic-rich sapropel S1 layer that was formed in oxygen-depleted waters. The spatial distribution of this layer revealed that during S1 deposition, deep waters were anoxic below a depth of 1800 m. However, whether this boundary permanently existed from the early to the mid-Holocene has not been examined yet. To answer this question, a multi-proxy approach was applied to a core retrieved close to the 1800 m boundary (at 1780 m). We measured the bulk sediment elemental composition, the stable isotopic composition of the planktonic foraminifer Globigerinoides ruber and the abundance of benthic foraminifera since the last deglaciation. The result indicates that authigenic U and Mo accumulation began around 13–12 cal ka BP, in concert with surface water freshening estimated from the G. ruber δ18O record. The onset of bottom and pore water oxygen depletion occurred prior to S1 deposition inferred from barium enrichment. In the middle of the S1 deposition period, reduced authigenic V, Fe and As contents and the Br/Cl ratio indicated short-term bottom-water re-oxygenation. A sharp Mn peak and maximal abundance for benthic foraminifera marked a total recovery for circulation at approximately 7 cal ka BP. Based on our results and existing data, we suggest that S1 formation within the upper 1780 m of the eastern Mediterranean Sea was preconditioned by reduced ventilation, resulting from excess freshwater inputs due to insolation changes under deglacial conditions that initiated between 15 and 12 cal ka BP within the upper 1780 m. Short-term re-oxygenation in the Levantine Basin is estimated to have affected bottom water at least as deep as 1780 m in response to cooling and/or the reduction of freshwater inputs. We tentatively propose that complete ventilation recovery at the S1 termination was depth-dependent, with earlier oxygenation within the upper 1780 m. Our results provide new constraints on vertical water column structure in the eastern Mediterranean Sea since the last deglaciation.

Bathymetric zonation of modern shelf benthic foraminifera in the Levantine Basin, eastern Mediterranean Sea

2015 ◽  
Vol 99 ◽  
pp. 97-106 ◽  
Author(s):  
Simona Avnaim-Katav ◽  
Orit Hyams-Kaphzan ◽  
Yvonne Milker ◽  
Ahuva Almogi-Labin
Keyword(s):  
Mediterranean Sea ◽  
Benthic Foraminifera ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Sea ◽  
Levantine Basin

scholarly journals Epistomaroides punctatus (Said, 1949) - a new alien foraminifera found at Akhziv - Rosh HaNikra, northern Israel, eastern Mediterranean Sea

2012 ◽  
Vol 13 (2) ◽  
pp. 294 ◽  
Author(s):  
A. ALMOGI-LABIN ◽  
O. HYAMS-KAPHZAN
Keyword(s):  
Mediterranean Sea ◽  
Benthic Foraminifera ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Sea ◽  
First Time

The alien benthic foraminifera Epistomaroides punctatus (Said) is reported for the first time from the northern part of theIsraeli coast. Three living specimens were collected in April 2005, at the vermetid reefs of Akhziv - Rosh HaNikra. Epistomaroidespunctatus has so far only been reported from the Indo-Pacific realm; thus, it is suggested to be a Lessepsian invader.

scholarly journals Comparison of Hydrocarbon-Degrading Consortia from Surface and Deep Waters of the Eastern Mediterranean Sea: Characterization and Degradation Potential

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2246
Author(s):  
Georgia Charalampous ◽  
Efsevia Fragkou ◽  
Konstantinos A. Kormas ◽  
Alexandre B. De Menezes ◽  
Paraskevi N. Polymenakou ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Oil Spills ◽  
Eastern Mediterranean ◽  
Sole Source ◽  
Eastern Mediterranean Sea ◽  
Deep Waters ◽  
Degradation Rates ◽  
Polycyclic Aromatic ◽  
Set Up

The diversity and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up in ONR7a medium at in situ temperatures of 25 °C and 14 °C for the Surface and Deep consortia, respectively, and crude oil as the sole source of carbon. The Deep consortium was additionally investigated at 25 °C to allow the direct comparison of the degradation rates to the Surface consortium. In total, ~50% of the alkanes and ~15% of the polycyclic aromatic hydrocarbons were degraded in all treatments by Day 24. Approximately ~95% of the total biodegradation by the Deep consortium took place within 6 days regardless of temperature, whereas comparable levels of degradation were reached on Day 12 by the Surface consortium. Both consortia were dominated by well-known hydrocarbon-degrading taxa. Temperature played a significant role in shaping the Deep consortia communities with Pseudomonas and Pseudoalteromonas dominating at 25 °C and Alcanivorax at 14 °C. Overall, the Deep consortium showed a higher efficiency for hydrocarbon degradation within the first week following contamination, which is critical in the case of oil spills, and thus merits further investigation for its exploitation in bioremediation technologies tailored to the Eastern Mediterranean Sea.

Sign in / Sign up

Export Citation Format

Share Document