scholarly journals The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 69-92 ◽  
Author(s):  
M. Álvarez ◽  
H. Sanleón-Bartolomé ◽  
T. Tanhua ◽  
L. Mintrop ◽  
A. Luchetta ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Total Alkalinity ◽  
Time Variability ◽  
Base Line ◽  
Wide Perspective ◽  
The Mediterranean ◽  
System Variables ◽  
East West

Abstract. The Mediterranean Sea (MedSea) is considered a "laboratory basin" being an ocean in miniature, suffering dramatic changes in its oceanographic and biogeochemical conditions derived from natural and anthropogenic forces. Moreover, the MedSea is prone to absorb and store anthropogenic carbon due to the particular CO2 chemistry and the active overturning circulation. Despite this, water column CO2 measurements covering the whole basin are scarce. This work aims to be a base-line for future studies about the CO2 system space-time variability in the MedSea combining historic and modern CO2 cruises in the whole area. Here we provide an extensive vertical and longitudinal description of the CO2 system variables (total alkalinity – TA, dissolved inorganic carbon – DIC and pH) along an East-West transect and across the Sardinia-Sicily passage in the MedSea from two oceanographic cruises conducted in 2011 measuring CO2 variables in a coordinated fashion, the RV Meteor M84/3 and the RV Urania EuroFleets 11, respectively. In this sense, we provide full-depth and length CO2 distributions across the MedSea, and property-property plots showing in each sub-basin post-Eastern Mediterranean Transient (EMT) situation with regard to TA, DIC and pH. The over-determined CO2 system in 2011 allowed performing the first internal consistency analysis for the particularly warm, high salinity and alkalinity MedSea waters. The CO2 constants by Mehrbach et al. (1973) refitted by Dickson and Millero (1987) are recommended. The sensitivity of the CO2 system to the atmospheric CO2 increase, DIC and/or TA changes is evaluated by means of the Revelle and buffer factors.

scholarly journals The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective

2013 ◽  
Vol 10 (4) ◽  
pp. 1447-1504 ◽  
Author(s):  
M. Álvarez ◽  
H. Sanleón-Bartolomé ◽  
T. Tanhua ◽  
L. Mintrop ◽  
A. Luchetta ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Total Alkalinity ◽  
Time Variability ◽  
System Variability ◽  
Wide Perspective ◽  
The Mediterranean ◽  
System Variables ◽  
East West

Abstract. This paper provides an extensive vertical and longitudinal description of the CO2 system variables (Total Alkalinity – TA, dissolved inorganic carbon – DIC and pH) along an East-West transect and across the Sardinia–Sicily passage in the Mediterranean Sea (MedSea) from two oceanographic cruises conducted in 2011 measuring CO2 variables in a coordinated fashion, the RV Meteor M84/3 and the RV Urania EuroFleets 11, respectively. The over-determined CO2 system allowed performing the first internal consistency analysis for the particularly warm, high salinity and alkalinity MedSea waters. This basin is considered a "laboratory basin" suffering dramatic changes in its oceanographic and biogeochemical conditions derived from natural and anthropogenic forces. Despite this, little is known about the CO2 system variability in the whole basin. This work aims to be a benchmark for future studies about the CO2 system space-time variability in the MedSea. In this sense we provide full-depth and length CO2 distributions across the MedSea, and property – property plots showing in each sub-basin post-Eastern Mediterranean Transient (EMT) situation with regard to TA, DIC and pH.

scholarly journals Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach

2009 ◽  
Vol 66 (7) ◽  
pp. 1538-1546 ◽  
Author(s):  
Ferial Louanchi ◽  
Meriem Boudjakdji ◽  
Lamri Nacef
Keyword(s):  
Carbon Dioxide ◽  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Atmospheric Co2 ◽  
Total Alkalinity ◽  
Diagnostic Model ◽  
Surface Carbon ◽  
The Mediterranean ◽  
The 1960S ◽  
Model Approach

Abstract Louanchi, F., Boudjakdji, M, and Nacef, L. 2009. Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach. – ICES Journal of Marine Science, 66: 1538–1546. A coupled approach based on available datasets of temperature, salinity, oxygen, nutrients, and chlorophyll, and a surface layer box model previously developed and modified for the present study, allowed us to reconstruct dissolved inorganic carbon (DIC), total alkalinity, and carbon dioxide fugacity (fCO2) mixed-layer fields for the Mediterranean Sea, from the 1960s to the 1990s. The approach used in this study resulted in a 7% relative error on reconstructed surface fCO2 fields. The Mediterranean Sea transformed from a source of 0.62 Tg C year−1 for atmospheric CO2 in the 1960s, to a net sink of −1.98 Tg C year−1 in the 1990s. The annual cycle in surface fCO2 was driven mainly by temperature variations in the Mediterranean Sea, whereas its decadal variations resulted from a balance between primary production and the thermal effect. According to our model results, the atmospheric CO2 increase of ∼40 µatm over the period of our investigation induced an increase in DIC of ∼30 µmol l−1 in surface waters. A 50% reduction in the magnitude of seasonal variations in surface temperature occurred during the 1990s relative to the earlier decades. Therefore, surface fCO2 only increased by 24 µatm from the 1960s to the 1990s. Changes in pH were not significant over this period.

scholarly journals Distributions of the carbonate system properties, anthropogenic CO<sub>2</sub>, and acidification during the 2008 BOUM cruise (Mediterranean Sea)

2012 ◽  
Vol 9 (3) ◽  
pp. 2709-2753 ◽  
Author(s):  
F. Touratier ◽  
V. Guglielmi ◽  
C. Goyet ◽  
L. Prieur ◽  
M. Pujo-Pay ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Marine Ecosystem ◽  
Total Alkalinity ◽  
Carbonate System ◽  
Simple Method ◽  
Deep Waters ◽  
History Of ◽  
The Mediterranean ◽  
System Properties

Abstract. We relate here the distributions of two carbonate system key properties (total alkalinity, AT; and total dissolved inorganic carbon, CT) measured along a section in the Mediterranean Sea, going from Marseille (France) to the south of the Cyprus Island, during the 2008 BOUM cruise. The three main objectives of the present study are (1) to draw and comment on the distributions of AT and CT in the light of others properties like salinity, temperature, and dissolved oxygen, (2) to estimate the distribution of the anthropogenic CO2 (CANT) in the intermediate and the deep waters, and (3) to calculate the resulting variation of pH (acidification) since the beginning of the industrial era. Since the calculation of CANT is always an intense subject of debate, we apply two radically different approaches to estimate CANT: the very simple method TrOCA and the MIX approach, the latter being more precise but also more difficult to apply. A clear picture for the AT and the CT distributions is obtained: the mean concentration of AT is higher in the oriental basin while that of CT is higher in the occidental basin of the Mediterranean Sea, fully coherent with the previous published works. Despite of the two very different approaches we use here (TrOCA and MIX), the estimated distributions of CANT are very similar. These distributions show that the minimum of CANT encountered during the BOUM cruise is higher than 46.3 μmol kg−1 (TrOCA) or 48.8 μmol kg−1(MIX). All Mediterranean water masses (even the deepest) appear to be highly contaminated by CANT, as a result of the very intense advective processes that characterize the recent history of the Mediterranean circulation. As a consequence, unprecedented levels of acidification are reached with an estimated decrease of pH since the pre-industrial era of −0.148 to −0.061 pH unit, which places the Mediterranean Sea as one of the most acidified world marine ecosystem.

Spatio-temporal survey of the coastal carbonate system offshore Lebanon-Levantine Mediterranean Sea

2020 ◽  
Author(s):  
Abed El Rahman Hassoun ◽  
Milad Fakhri ◽  
Majd Habib ◽  
Anthony Ouba ◽  
Sharif Jemaa ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Mixed Layer Depth ◽  
Total Alkalinity ◽  
Critical Parameters ◽  
Carbonate System ◽  
Preliminary Results ◽  
Open Sea ◽  
Spatio Temporal

&lt;p&gt;The coastal carbonate system regulates the pH of the coastal waters and controls the circulation of CO&lt;sub&gt;2&lt;/sub&gt; between land-sea interfaces and open sea system. In the context of the ELME (Evaluation of the Lebanese Marine Environment: A multidisciplinary study) project, a seasonal survey of the carbonate system has been started in 2019 through the sampling of 3 different transects starting from the coast towards the open sea, offshore two Lebanese cities (Beirut and Tyre) to evaluate the spatio-temporal variations of this system in coastal areas. The carbonate chemistry is being studied by measuring both total alkalinity (A&lt;sub&gt;T&lt;/sub&gt;) and total dissolved inorganic carbon (C&lt;sub&gt;T&lt;/sub&gt;), together with other critical parameters in coastal ecosystems such as temperature, salinity, pH, dissolved oxygen, nutrients (phosphates, nitrates, nitrites, silicates), and chlorophyll a. The preliminary results show that the highest carbonate system inventories (2546.4 and 2266 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt; for A&lt;sub&gt;T&lt;/sub&gt; and C&lt;sub&gt;T&lt;/sub&gt; respectively) were measured in transects influenced by discharges of dumpsite and port areas (offshore Beirut) where positive and significant correlations (p &lt;&lt; 0.005) have been recorded with nutrients, particularly with nitrites (&gt; 10 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt;). Furthermore, TrOCA approach was used to estimate the anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; concentrations (C&lt;sub&gt;ANT&lt;/sub&gt;) below the mixed layer depth. The results demonstrate that all waters in both studied areas are contaminated by C&lt;sub&gt;ANT&lt;/sub&gt;, even the deep ones (&gt; 400 m) located in the furthest monitored station, with values greater than 70 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt;. This fact raises concerns about the effects of such relatively high C&lt;sub&gt;ANT&lt;/sub&gt; concentrations on coastal organisms therein. This work presents the preliminary results of an ongoing study. The continuity of this project will help to assess the relationship between land-based anthropogenic pressures and the coastal biogeochemistry in a changing Eastern Mediterranean Sea.&lt;/p&gt;

New insights into nutrients dynamics and the carbonate system using a neural network approach in the Mediterranean Sea

2020 ◽  
Author(s):  
Marine Fourrier ◽  
Laurent Coppola ◽  
Fabrizio D'Ortenzio
Keyword(s):  
Neural Network ◽  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
In Situ Measurements ◽  
Total Alkalinity ◽  
Anthropogenic Pressure ◽  
Carbonate System ◽  
The Mediterranean ◽  
The Impact

&lt;p&gt;The semi-enclosed nature of the Mediterranean Sea, together with its small inertia which is due to the relatively short residence time of its water masses, make it highly reactive to external forcings and anthropogenic pressure. In this context, several rapid changes have been observed in physical and biogeochemical processes in recent decades, partly masked by episodic events and high regional variability. To better understand the underlying processes driving the Mediterranean evolution and, anticipate changes, the measurement, and integration of many biogeochemical variables are mandatory.&lt;/p&gt;&lt;p&gt;The development of new BGC sensors implemented on &lt;em&gt;in situ&lt;/em&gt; autonomous platforms allows to increase the acquisition of essential biogeochemical variables. However, the measurements carried out by&lt;em&gt; in situ&lt;/em&gt; autonomous platforms (e.g. profiling floats, gliders, moorings) are not exhaustive.&lt;/p&gt;&lt;p&gt;Recently, deep learning techniques and in particular neural networks have been developed. The CANYON-MED (for Carbonate system and Nutrients concentration from hYdrological properties and Oxygen using a Neural-network in the MEDiterranean Sea) neural network-based method provides estimations of nutrients (i.e. nitrates, phosphates, and silicates) and carbonate system variables (i.e. total alkalinity, dissolved inorganic carbon, pH&lt;sub&gt;T&lt;/sub&gt;) from systematically measured oceanographic variables such as in situ measurements of pressure, temperature, salinity, and oxygen together with geolocation and date of sampling.&lt;/p&gt;&lt;p&gt;This regional approach, therefore, using quality-controlled in situ measurements from more than 35 cruises. CANYON-MED obtains satisfactory results: accuracies of 0.73, 0.045, and 0.70 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; for the nitrates, phosphates and silicates concentrations respectively, and 0.016, 11 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; and 10 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; for pH&lt;sub&gt;T&lt;/sub&gt;, total alkalinity and dissolved organic carbon respectively. CANYON-MED thus generates &amp;#8220;virtual&amp;#8221; data of parameters not yet measured by autonomous platforms, while ably reproducing the data already sampled, emphasizing its ability to fill the gaps in time-series.&lt;/p&gt;&lt;p&gt;Hence, by applying it to the large and growing network of autonomous platforms in the Mediterranean Sea, this method allows us to gain new insights into nutrients and carbonate system dynamics in targeted areas. In particular, in the northwestern Mediterranean Sea, the impact of deep convection on biogeochemistry (e.g., nutrient replenishment and pH&lt;sub&gt;T&lt;/sub&gt; variability) is highly variable over time and poorly covered by observing networks. In this case, CANYON-MED would improve our observations and understanding of the dynamic and coupled system.&lt;/p&gt;

scholarly journals Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

2015 ◽  
Vol 6 (2) ◽  
pp. 789-800 ◽  
Author(s):  
E. Gemayel ◽  
A. E. R. Hassoun ◽  
M. A. Benallal ◽  
C. Goyet ◽  
P. Rivaro ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
World Ocean ◽  
Sea Surface ◽  
Total Alkalinity ◽  
Eastern Basin ◽  
Total Dissolved Inorganic Carbon ◽  
The Mediterranean

Abstract. A compilation of data from several cruises between 1998 and 2013 was used to derive polynomial fits that estimate total alkalinity (AT) and total dissolved inorganic carbon (CT) from measurements of salinity and temperature in the Mediterranean Sea surface waters. The optimal equations were chosen based on the 10-fold cross-validation results and revealed that second- and third-order polynomials fit the AT and CT data respectively. The AT surface fit yielded a root mean square error (RMSE) of ± 10.6 μmol kg−1, and salinity and temperature contribute to 96 % of the variability. Furthermore, we present the first annual mean CT parameterization for the Mediterranean Sea surface waters with a RMSE of ± 14.3 μmol kg−1. Excluding the marginal seas of the Adriatic and the Aegean, these equations can be used to estimate AT and CT in case of the lack of measurements. The identified empirical equations were applied on the 0.25° climatologies of temperature and salinity, available from the World Ocean Atlas 2013. The 7-year averages (2005–2012) showed that AT and CT have similar patterns with an increasing eastward gradient. The variability is influenced by the inflow of cold Atlantic waters through the Strait of Gibraltar and by the oligotrophic and thermohaline gradient that characterize the Mediterranean Sea. The summer–winter seasonality was also mapped and showed different patterns for AT and CT. During the winter, the AT and CT concentrations were higher in the western than in the eastern basin. The opposite was observed in the summer where the eastern basin was marked by higher AT and CT concentrations than in winter. The strong evaporation that takes place in this season along with the ultra-oligotrophy of the eastern basin determines the increase of both AT and CT concentrations.

Air-Sea seasonal CO2 fluxes in a fast warming oligotrophic region – the Eastern Mediterranean case study

2020 ◽  
Author(s):  
Juntao Yu
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Seasonal Variations ◽  
Eastern Mediterranean ◽  
Open Water ◽  
Sea Surface ◽  
Total Alkalinity ◽  
Eastern Region ◽  
Underlying Assumption ◽  
The Mediterranean

&lt;p&gt;In a recent study, it was suggested based on the apparent correlation between multi-annual measurements of summertime maxima and wintertime minima temperature and calculated pCO&lt;sub&gt;2&lt;/sub&gt; in the most eastern region of the Mediterranean Sea surface waters that they are a net source of atmospheric CO&lt;sub&gt;2&lt;/sub&gt;. Furthermore, it was predicted that the magnitude of this source would increase substantially in this region and that adjacent regions in the Eastern Mediterranean as well would turn into net sources of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; due to the fast warming of these waters. In order to confirm the underlying assumption that seasonal variations in pCO&lt;sub&gt;2&lt;/sub&gt; in Eastern Mediterranean surface waters are primarily a strong function of seasonal variations in temperature, water samples were collected for the analysis of total alkalinity and pH during 12 monthly cruises from February 2018 to January 2019 at the shallow (THEMO1) and the deep (THEMO2) open water stations that are ca.10 and 20 NM off the Mediterranean coast of Israel. The data from all the cruises show that surface (&lt; 30m depth) seawater pCO&lt;sub&gt;2&lt;/sub&gt; has a strong positive linear relationship with temperature in both stations (n=56, r&lt;sup&gt;2&lt;/sup&gt;=0.94, p&lt;0.001). The calculated annual net flux of CO&lt;sub&gt;2&lt;/sub&gt; from the surface to the atmosphere based on these measurements is ca.1.13 Tg C y&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;, which is ca.15% higher than the previously estimated flux, but within its range of uncertainty (&amp;#177; 30%). These results clearly demonstrate that surface water pCO&lt;sub&gt;2&lt;/sub&gt; levels are indeed a strong positive function of the seasonal variations in sea-surface temperature and that the open water of the most eastern Mediterranean Sea is a net source of atmospheric CO&lt;sub&gt;2&lt;/sub&gt;. These results are also in agreement with the conclusions of observational and modelling studies of air-sea CO&lt;sub&gt;2&lt;/sub&gt; fluxes in the centers of subtropical gyres and therefore globally relevant.&lt;/p&gt;

scholarly journals Space-time variability of alkalinity in the Mediterranean Sea

2014 ◽  
Vol 11 (9) ◽  
pp. 12871-12893 ◽  
Author(s):  
G. Cossarini ◽  
P. Lazzari ◽  
C. Solidoro
Keyword(s):  
Mediterranean Sea ◽  
Thermohaline Circulation ◽  
Sea Water ◽  
Dissolved Inorganic Carbon ◽  
Surface Flux ◽  
Atlantic Water ◽  
The Black Sea ◽  
Time Variability ◽  
Marginal Seas ◽  
The Mediterranean

Abstract. The paper provides a basin assessment of the spatial distribution of ocean alkalinity in the Mediterranean Sea. The assessment is made using a 3-D transport-biogeochemical-carbonate model to integrate the available experimental findings, which also constrains model output. The results indicate that the Mediterranean Sea shows alkalinity values that are much higher than those observed in the Atlantic Ocean on a basin-wide scale. A marked west-to-east surface gradient of alkalinity is reproduced as a response to the terrestrial discharges, the mixing effect with the Atlantic water entering from the Gibraltar Strait and the Black Sea water from Dardanelles, and the surface flux of evaporation minus precipitation. Dense water production in marginal seas (Adriatic and Aegean Seas), where alkaline inputs are relevant, and the Mediterranean thermohaline circulation sustains the west-to-east gradient along the entire water column. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1) that is driven both by physical and biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships. In regions of freshwater influence, the two measures are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open seas. Alkalinity always is much higher than in the Atlantic waters, which might indicate a higher than usual buffering capacity towards ocean acidification, even at high concentrations of dissolved inorganic carbon.

scholarly journals The Conflict Between Greece And Turkey In The Mediterranean Sea (International Maritime Law Study)

Jurnal Hukum ◽  
2020 ◽  
Vol 36 (2) ◽  
pp. 126
Author(s):  
Edanur Yıldız
Keyword(s):  
International Law ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
East Mediterranean ◽  
International Courts ◽  
Maritime Law ◽  
The Mediterranean

Turkey and Greece are again dragged into a new conflict in the East Mediterranean. Turkey and Greece vie for supremacy in the eastern Mediterranean. Turkey, for its part, indicated that Greece's claim to the territory would amount to a siege in the country by giving Greece a disproportionate amount of territory. This study aims to rethink the conflict between Greece and Turkey in the waters of the Mediterranean sea in the view of international maritime law. This study uses an empirical juridical approach. The Result of this research is Turkey does not ignore the Greece rights, Greece ignores the international law with its extended or excessive maritime claims. Greece tries to give full entitlement of the islands in Mediterranean and Agean. Whereas the effect Formula is applied by international courts.

scholarly journals Characterization of Coolia spp. (Gonyaucales, Dinophyceae) from Southern Tunisia: first record of Coolia malayensis in the Mediterranean Sea

ALGAE ◽  
2021 ◽  
Vol 36 (3) ◽  
pp. 175-193
Author(s):  
Moufida Abdennadher ◽  
Amel Bellaaj Zouari ◽  
Walid Medhioub ◽  
Antonella Penna ◽  
Asma Hamza
Keyword(s):  
Electron Microscopy ◽  
Mediterranean Sea ◽  
Phylogenetic Trees ◽  
Eastern Mediterranean ◽  
First Record ◽  
Morphological Characterization ◽  
Mucus Production ◽  
Rdna Sequences ◽  
The Mediterranean ◽  
Morphological Differences

This study provides the first report of the presence of Coolia malayensis in the Mediterranean Sea, co-occurring with C. monotis. Isolated strains from the Gulf of Gabès, Tunisia (South-eastern Mediterranean) were identified by morphological characterization and phylogenetic analysis. Examination by light and scanning electron microscopy revealed no significant morphological differences between the Tunisian isolates and other geographically distant strains of C. monotis and C. malayensis. Phylogenetic trees based on ITS1-5.8S-ITS2 and D1‒D3/28S rDNA sequences showed that C. monotis strains clustered with others from the Mediterranean and Atlantic whereas the C. malayensis isolate branched with isolates from the Pacific and the Atlantic, therefore revealing no geographical trend among C. monotis and C. malayensis populations. Ultrastructural analyses by transmission electron microscopy revealed the presence of numerous vesicles containing spirally coiled fibers in both C. malayensis and C. monotis cells, which we speculate to be involved in mucus production.

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