Low-salinity Mediterranean gypsum deposits: chemical vs biological products

2021 ◽  
Author(s):  
Giovanni Aloisi ◽  
Marcello Natalicchio ◽  
Laetitia Guibourdenche ◽  
Antonio Caruso ◽  
Francesco Dela Pierre
Keyword(s):  
Mediterranean Sea ◽  
Bound Water ◽  
Sulfur Cycle ◽  
Reduced Sulfur Compounds ◽  
Central Mediterranean ◽  
Saturation State ◽  
Geochemical Model ◽  
Low Salinity ◽  
Continental Runoff ◽  
The Mediterranean

<p>Large deposits of gypsum accumulated in the marginal basins of the Mediterranean Sea during the Messinian Salinity Crisis. These form the marginal portions of the Mediterranean Salt Giant (MSG) that also occupies the deep, central Mediterranean basins. Although the marine, evaporitic origin of the MSG is undisputed, the analysis of gypsum fluid inclusions and of gypsum-bound water (d<sup>18</sup>O<sub>H2O</sub> and dD<sub>H2O</sub>) suggest that marginal basin gypsum formed from low- to moderate-salinity water masses (5 - 60 ‰), rather than from high-salinity brines (130 - 320 ‰), as expected during the evaporation of seawater. We present a new set of water isotope and fluid inclusion salinity data that extends the low salinity signature of gypsum to include five Mediterranean Sea marginal basins: Caltanissetta Basin (Sicily), Sorbas Basin (Spain), Piedmont Basin and Vena del Gesso Basin (northern Italy) and Catanzaro Trough (Southern Italy). With a simple geochemical model we explore the salinity-d<sup>18</sup>O<sub>H2O</sub>-dD<sub>H2O</sub> evaporation path and the <sup>87/86</sup>Sr and d<sup>34</sup>S<sub>SO4</sub> composition of the Mediterranean Sea subject to a variety of evaporation conditions and mixing ratios with continental runoff. This approach suggests that evaporation and mixing with continental runoff - including freshwater transiting via the Paratethys - cannot lead to the observed geochemical signature of MSC gypsum deposits. An alternative process that decouples the saturation state with respect to gypsum from salinity must have been active. We are exploring the possibility that the biogeochemical sulfur cycle leads to spatially and temporally localized gypsum supersaturation conditions via the production of SO<sub>4</sub><sup>2-</sup> by the oxidation and disproportionation of reduced sulfur compounds.</p>

The geochemical riddle of Mediterranean low-salinity gypsum deposits

2020 ◽  
Author(s):  
Giovanni Aloisi ◽  
Marcello Natalicchio ◽  
Laetitia Guibourdenche ◽  
Antonio Caruso ◽  
Francesco Dela Pierre
Keyword(s):  
High Salinity ◽  
Bound Water ◽  
Central Mediterranean ◽  
Saturation State ◽  
Low Salinity ◽  
Continental Runoff ◽  
Moderate Salinity ◽  
Salinity Water ◽  
The Mediterranean ◽  
Large Deposits

<p>Large deposits of gypsum accumulated in the marginal basins of the Mediterranean Sea during the Messinian Salinity Crisis. These form the marginal portions of the Mediterranean Salt Giant (MSG) that also occupies the deep, central Mediterranean basins. Although the marine, evaporitic origin of the MSG is undisputed, the analysis of gypsum fluid inclusions and of gypsum-bound water (d<sup>18</sup>O<sub>H2O</sub> and dD<sub>H2O</sub>) suggest that marginal basin gypsum formed from low- to moderate-salinity water masses (5 - 60 ‰), rather than from high-salinity brines (130 - 320 ‰), as expected during the evaporation of seawater.  The formation of low-salinity gypsum poses a fundamental geochemical problem: how can gypsum saturation conditions be met in marginal basins if evaporation does not concentrate marine water to high salinity? In other words, can gypsum saturation be attained by adding Ca<sup>2+</sup> and/or SO<sub>4</sub><sup>2-</sup> ions rather than by extracting water? We are exploring two geochemical scenarios to explain this phenomenon: (1) the addition of Ca<sup>2+</sup> and SO<sub>4</sub><sup>2-</sup> to marginal basins by continental runoff, and (2) the non-steady state addition of SO<sub>4</sub><sup>2-</sup> to marginal basins via the biogeochemical oxidation of reduced sulfur. Both scenarios may lead - at least theoretically - to the decoupling of saturation state from salinity that is suggested by gypsum geochemical signatures.</p>

Erosional landforms and biological structures in tectonically stable areas in the Mediterranean basin

2021 ◽  
Author(s):  
Valeria Vaccher ◽  
Stefano Furlani ◽  
Sara Biolchi ◽  
Chiara Boccali ◽  
Alice Busetti ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Mediterranean Basin ◽  
Vertical Position ◽  
Structural Constraints ◽  
Last Interglacial ◽  
Central Mediterranean ◽  
Biological Structures ◽  
The Mediterranean ◽  
The Mediterranean Basin

<p>The Mediterranean basin displays a variety of neotectonics scenarios leading to positive or negative vertical displacement, which change the vertical position of former coastlines. As a result, the best locations to evaluate former sea levels and validate sea-level models are tectonically stable areas. There are a number of coastal areas considered to be stable based on the elevation of paleo sea-level markers, the absence of historical seismicity, and by their position far from major Mediterranean faults. We report here the results of swim surveys carried out at such locations following the Geoswim approach described by Furlani (2020) in nine coastal sectors of the central Mediterranean Sea (Egadi Island - Marettimo, Favignana, Levanzo, Gaeta Promontory, Circeo Promontory, North Sardinia - Razzoli, Budelli, Santa Maria, NW Sardinia – Capocaccia, Maddalena Archipelago, Tavolara Island, East of Malta - Ahrax Point, Bugibba-Qawra, Delimara, Addura, Palermo, Ansedonia Promontory). All the sites are considered to be tectonically stable, as validated by the elevation of sea-level indicators. In fact, modern and MIS5.5 (last interglacial) m.s.l. altitudes fit well with accepted figures based upon field data and model projections. Starting from precise morphometric parameters such as the size of tidal notches and indicative landforms and biological structures, we have developed a procedure that integrates multiple geomorphological and biological descriptors applicable to the vast spectrum of locally diverse coastal situations occurring in the Mediterranean Sea. We took detailed measurements of features such as modern and MIS5.5 tidal notches at 146 sites in all the areas, the absence of modern tidal notch at Circeo promontory, shore platforms, and MIS5.5 marine terraces at Egadi islands, Malta, and Palermo. Biological structures were also measured. In particular, vermetid platforms at Egadi, Palermo and Malta. The morphometric characteristics of these indicators depend on 1) local geological and structural constraints, 2) local geomorphotypes, 3) climate, sea, and weather conditions that affect geomorphic and biological processes, and 4) the sea level change history.</p>

scholarly journals New records of Calappa tuerkayana Pastore, 1995 (Brachyura, Calappidae) from the central Mediterranean

2018 ◽  
Vol 59 (2) ◽  
pp. 213-218
Author(s):  
Carlo Pipitone ◽  
Gianni Insacco ◽  
Daniela Massi ◽  
Bruno Zava
Keyword(s):  
Mediterranean Sea ◽  
Adult Male ◽  
New Records ◽  
Geographic Range ◽  
Central Mediterranean ◽  
Juvenile Individual ◽  
The Mediterranean

Two specimens of the uncommon calappid crab Calappa tuerkayana Pastore, 1995 are reported from the central Mediterranean. One juvenile individual was caught in a trawl net at about 105 m depth on a detritus bottom, and one adult male was caught in a trammel net at 50 m depth in a similar habitat. Details about carapace ornamentation and fresh color of the adult, which complement previous descriptions are provided. Family Calappidae includes four species in the Mediterranean Sea. C. tuerkayana has been recorded a few times from its known geographic range. These are the southernmost records to date.

scholarly journals Summertime surface PM<sub>1</sub> aerosol composition and size by source region at the Lampedusa island in the central Mediterranean Sea

2019 ◽  
Vol 19 (17) ◽  
pp. 11123-11142 ◽  
Author(s):  
Marc D. Mallet ◽  
Barbara D'Anna ◽  
Aurélie Même ◽  
Maria Chiara Bove ◽  
Federico Cassola ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Ammonium Sulfate ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Central Mediterranean ◽  
Aerosol Composition ◽  
Air Masses ◽  
Westerly Winds ◽  
Central Mediterranean Sea ◽  
The Mediterranean

Abstract. Measurements of aerosol composition and size distributions were taken during the summer of 2013 at the remote island of Lampedusa in the southern central Mediterranean Sea. These measurements were part of the ChArMEx/ADRIMED (Chemistry and Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate) framework and took place during Special Observation Period 1a (SOP-1a) from 11 June to 5 July 2013. From compact time-of-flight aerosol mass spectrometer (cToF-AMS) measurements in the size range below 1 µm in aerodynamic diameter (PM1), particles were predominately comprised of ammonium and sulfate. On average, ammonium sulfate contributed 63 % to the non-refractory PM1 mass, followed by organics (33 %). The organic aerosol was generally very highly oxidized (f44 values were typically between 0.25 and 0.26). The contribution of ammonium sulfate was generally higher than organic aerosol in comparison to measurements taken in the western Mediterranean but is consistent with studies undertaken in the eastern basin. Source apportionment of organics using a statistical (positive matrix factorization) model revealed four factors: a hydrocarbon-like organic aerosol (HOA), a methanesulfonic-acid-related oxygenated organic aerosol (MSA-OOA), a more oxidized oxygenated organic aerosol (MO-OOA) and a less oxidized oxygenated organic aerosol (LO-OOA). The MO-OOA was the dominant factor for most of the campaign (53 % of the PM1 OA mass). It was well correlated with SO42-, highly oxidized and generally more dominant during easterly air masses originating from the eastern Mediterranean and central Europe. The LO-OOA factor had a very similar composition to the MO-OOA factor but was more prevalent during westerly winds, with air masses originating from the Atlantic Ocean, the western Mediterranean and at high altitudes over France and Spain from mistral winds. The MSA-OOA factor contributed an average 12 % to the PM1 OA and was more dominant during the mistral winds. The HOA, representing observed primary organic aerosol, only contributed 8 % of the average PM1 OA during the campaign. Even though Lampedusa is one of the most remote sites in the Mediterranean, PM1 concentrations (10 ± 5 µg m−3) were comparable to those observed in coastal cities and sites closer to continental Europe. Cleaner conditions corresponded to higher wind speeds. Nucleation and growth of new aerosol particles was observed during periods of north-westerly winds. From a climatology analysis from 1999 to 2012, these periods were much more prevalent during the measurement campaign than during the preceding 13 years. These results support previous findings that highlight the importance of different large-scale synoptic conditions in determining the regional and local aerosol composition and oxidation and also suggest that a non-polluted surface atmosphere over the Mediterranean is rare.

Carbonate System and Acidification of the Adriatic Sea

2020 ◽  
Author(s):  
Valentina Turk ◽  
Nina Bednarsek ◽  
Jadran Faganeli ◽  
Blaženka Gasparovic ◽  
Michele Giani ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Adriatic Sea ◽  
Microbial Community Composition ◽  
Aegean Sea ◽  
Total Alkalinity ◽  
The Black Sea ◽  
Po River ◽  
Saturation State ◽  
Northern Adriatic ◽  
The Mediterranean

&lt;p&gt;Although the marginal seas represent only 7% of the total ocean area, the CO&lt;sub&gt;2&lt;/sub&gt; fluxes are intensive and important for the carbon budget, exposing to an intense process of anthropogenic ocean acidification (OA). A decline in pH, especially in the estuarine waters, results also from the eutrophication-induced acidification. The Adriatic Sea is currently a CO&lt;sub&gt;2 &lt;/sub&gt;sink with an annual flux of approximately -1.2 to -3 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; which is twice as low compared to the net sink rates in the NW Mediterranean (-4 to -5 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;). Based on the comparison of two winter cruises carried out in in the 25-year interval between 1983 and 2008, acidification rate of 0.003 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of &amp;#8722;0.0028 &amp;#177; 0.0003 units pH&lt;sub&gt;T&lt;/sub&gt; yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;) and the surface coastal waters (-0.003 &amp;#177; 0.001 and -0.0044 &amp;#177; 0.00006 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;). The computed Revelle factor for the Adriatic Sea, with the value of about 10, indicates that the buffer capacity is rather high and that the waters should not be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6-2.7 mM) is in the upper range of TA measured in the Mediterranean Sea because riverine inputs transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol yr&lt;sup&gt;-1&lt;/sup&gt;), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60% of the TA inflow into the Adriatic Sea is attributed to the Po river discharge with TA of ~3 mM and TA decreases with increasing salinity. Saturation state indicates that the waters of the Adriatic are supersaturated with respect to calcite (&amp;#937;&lt;sub&gt;Ca&lt;/sub&gt;) and aragonite (&amp;#937;&lt;sub&gt;Ar&lt;/sub&gt;) throughout the year. However, saturation states are considerably lower in the bottom water layers, due to the prevalence of benthic remineralization processes in the stratification period. The seasonal changes of the chemical and environmental conditions and relatively small size of the Adriatic Sea area the microbial community composition, function (growth, enzymatic activity) and carbon and nitrogen biogeochemical cycles. Significant effects on calcifying organisms and phytoplankton are expected while the effects of possible OA on microbially-driven processes are not known yet.&lt;/p&gt;

The first identified winter feeding ground of fin whales (Balaenoptera physalus) in the Mediterranean Sea

2006 ◽  
Vol 86 (4) ◽  
pp. 903-907 ◽  
Author(s):  
Simonepietro Canese ◽  
Andrea Cardinali ◽  
Caterina Maria Fortuna ◽  
Michela Giusti ◽  
Giancarlo Lauriano ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Feeding Activity ◽  
Central Mediterranean ◽  
Fin Whale ◽  
Feeding Ground ◽  
The North ◽  
South Central ◽  
The Mediterranean ◽  
Fin Whales ◽  
Winter Feeding

The presence of fin whales in the Mediterranean Sea has been documented since ancient times. In spite of this, reliable information on their ecology and distribution is limited to the north-western part of the basin. Recent genetic studies have demonstrated that Mediterranean fin whales comprise a separate population with very limited gene flow with their North Atlantic co-specifics. Although both published and anecdotal information reports their presence in the south central Mediterranean during winter, there is no information on habitat use. In February 2004, a 14-day boat survey was carried out in the waters surrounding the island of Lampedusa, where fin whales occur at this time of the year. A total of 20 fin whale groups (average group size two animals) were encountered. In each encounter the animals were engaged in surface feeding activity. From plankton samples and underwater video, the prey species was identified as the Euphausiid, Nyctiphanes couchi. The information obtained suggests that this area may be an important winter feeding ground for fin whales. The results represent significant new information on fin whale ecology in the Mediterranean, with associated conservation and management implications.

scholarly journals New Fisheries-related data from the Mediterranean Sea (October 2015)

2015 ◽  
Vol 16 (3) ◽  
pp. 703 ◽  
Author(s):  
K. TSAGARAKIS ◽  
A. BAŞUSTA ◽  
N. BAŞUSTA ◽  
F. BIANDOLINO ◽  
D. BOSTANCI ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Length Distribution ◽  
Central Mediterranean ◽  
Eastern Mediterranean Sea ◽  
Related Data ◽  
Solea Solea ◽  
Commercially Important ◽  
The Mediterranean ◽  
Polyprion Americanus

In this third Collective Article, with fisheries-related data from the Mediterranean Sea, we present the historical length distribution of Lophius budegassa in the catch of commercial trawlers in the Greek seas; length-weight and length-length relationships of five flatfish species (Lepidorhombus boscii, L. whiffiagonis, Platichthys flesus, Pegusa lascaris and Solea solea) from different coastal areas of Turkey (Black Sea and Eastern Mediterranean Sea); growth of settled Polyprion americanus and length-weight relationships of this species and of Deltentosteus quadrimaculatus, Capros aper and three commercially important groupers in the Eastern Mediterranean Sea; the age, growth and mortality of Zosterisessor ophiocephalus in the Eastern Adriatic Sea; the length-weight relationship and condition factor of Atherina boyeri in a Central Mediterranean semi-isolated lagoon, and also the length-weight and length-length relationships of three Alburnus species from different inland waters in Turkey.

scholarly journals Remarks on Echinodermata from the South Central Mediterranean Sea based upon collections made during the MARCOS cruise (10 to 20th April, 2007)

2009 ◽  
Vol 10 (2) ◽  
pp. 63 ◽  
Author(s):  
C. MIFSUD ◽  
M. TAVIANI ◽  
S. STOHR
Keyword(s):  
Mediterranean Sea ◽  
The South ◽  
Central Mediterranean ◽  
Management Zone ◽  
Maltese Islands ◽  
South Central ◽  
Central Mediterranean Sea ◽  
The Mediterranean ◽  
First Time ◽  
The Mediterranean Basin

The MARCOS cruise, which took place in the South Central Mediterranean Sea on board the RV ‘Urania’, resulted in the collection of 27 species of Echinodermata from shallow to bathyal depths, many from around Malta (the Fisheries Management Zone). The fauna is represented by common to rare taxa already reported from the Mediterranean with the exception of the amphi-Atlantic ophiuroid Ophiotreta valenciennesi rufescens (Koehler, 1896), recorded from the Mediterranean Basin for the first time. Odontaster mediterraneus (von Marenzeller, 1893) and Luidia sarsi Lutken, 1858 are also first records for the Maltese Islands.

scholarly journals The Portuguese Man-of-war, One of The Most Dangerous Marine Species, Has Always Entered The Mediterranean Sea: Strandings, Sightings And Museum Collections

2021 ◽  
Author(s):  
Rosario Badalamenti ◽  
Francesco Tiralongo ◽  
Vincenzo Arizza ◽  
Sabrina Lo Brutto
Keyword(s):  
Mediterranean Sea ◽  
Grey Literature ◽  
Marine Species ◽  
First Record ◽  
Central Mediterranean ◽  
Gulf Of Naples ◽  
Tourism Sector ◽  
The Mediterranean ◽  
Sea Area ◽  
Physalia Physalis

Abstract A search from different kinds of sources has been carried out to review the incidence of Physalia physalis, the Portuguese man-of-war, in the Mediterranean Sea; scientific and grey literature, social media, zoological museums were accessed. The records of the species were considered validated if documented with images or collected specimens. It was possible to date the putative first record of Physalia physalis in the Mediterranean Sea, thanks to a couple of colonies preserved in a historical collection, originating from the Gulf of Naples in 1914. Some massive strandings occurred in localities of the Alboran Sea, area of entrance from the Atlantic from where the species spread mainly along the Sicilian waters, in the central Mediterranean Sea. The records from the Italian maritime regions were then subdivided into three categories of risk according to the season of occurrence. These categories were created to assign a level of danger for swimmers to the sightings of Physalia physalis. The increasing sightings of such a poisonous organism in coastal waters can represent a risk to human health, and also to all those activities linked to the marine tourism sector. The involvement of citizens and touristic structures for the early detection of Physalia physalis can play a key role in preventing encounters with the species, allowing marine tourist facilities to operate within a range of reasonable security.

scholarly journals Intriguing diversity among diazotrophic picoplankton along a Mediterranean transect: from the origin of plastids to the dominance of rhizobia

2010 ◽  
Vol 7 (6) ◽  
pp. 8779-8816 ◽  
Author(s):  
M. Le Moal ◽  
H. Collin ◽  
I. C. Biegala
Keyword(s):  
Mediterranean Sea ◽  
Nifh Gene ◽  
Western Mediterranean ◽  
Central Mediterranean ◽  
Plastid Evolution ◽  
Surface Distribution ◽  
Western Mediterranean Sea ◽  
Diazotrophic Cyanobacteria ◽  
The Mediterranean ◽  
Marine Areas

Abstract. The Mediterranean Sea is one of the most oligotrophic marine areas on earth where nitrogen fixation has been formally believed to play an important role in carbon and nitrogen fluxes. Although this view is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study we characterised the surface distribution and species richness of unicellular and filamentous diazotrophs across the Mediterranean Sea by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH), and 16S rDNA and nifH phylogenies. These genetic analyses were possible owning to the development of a new PCR protocol adapted for scarce microorganisms (0.2 cell ml−1). Low concentrations of diazotrophic cyanobacteria were detected and this community was dominated at 99.9% by picoplankton hybridized with Nitro821 probe, specific for unicellular diazotrophic cyanobacteria (UCYN). Among filamentous cyanobacteria only 0.02 filament ml−1 of Richelia were detected in the eastern basin, while small (0.7–1.5 μm) and large (2.5–3.2 μm) Nitro821-targeted cells were recovered at all stations and averaged 3.5 cell ml−1. The affiliation of the small Nitro821-targeted cells to UCYN-A was confirmed by 16S and nifH phylogenies in the western Mediterranean Sea. Surprisingly, the larger hybridized cells were not belonging to UCYN-B and C but to plastids of picoeukaryote. NifH gene was not recovered among picoeukaryotes, when rhizobia sequences, including the ones of Bradyrhizobia, were dominating nifH clone libraries from picoplanktonic size fractions. Few sequences of γ-proteobacteria were also detected in central Mediterranean Sea. While low phosphate and iron concentrations could explain the absence of Trichodesmium sp., the factors that prevent the development of UCYN-B and C remain unknown. We also propose that the dominating picoplankters probably developed specific strategies, such as associations with protists or particles and photosynthetic activity to acquire carbon for sustaining diazotrophy. Among UCYN further work will be necessary to understand their suggested role in plastid evolution.

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