Acidification of the Mediterranean Sea from anthropogenic carbon penetration

Hassoun, Abed El Rahman; Gemayel, Elissar; Κρασακοπούλου, Ε.; Goyet, Catherine; Saab, Marie Abboud‐Abi; Guglielmi, Véronique; Touratier, Franck; Falco, C.

doi:10.1016/j.dsr.2015.04.005

Cited by 62 publications

(59 citation statements)

References 79 publications

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“…Total alkalinity in Elefsis bottom water (2769 μmol kg -1 ) was found markedly higher to the values reported recently for open Eastern Mediterranean Sea waters (2600 μmol kg -1 ; Hassoun et al, 2015). This value is similar to those reported for the deep layer of the Gulf of Trieste in the northern Adriatic Sea that is a coastal system with shallow depths and seasonal stratification (e.g.…”

Section: Implications For Enclosed Embayment In Future Co 2 Conditionssupporting

confidence: 74%

“…A net flux of anthropogenic carbon from the Atlantic towards the Mediterranean basin has been identified being responsible for 25% of the basin-wide CO 2 uptake over the last 200 years (Flecha et al, 2015 and references therein). From the pre-industrial period until 2013 the pH in Mediterranean Sea has decreased by 0.055 -0.156 pH units (Hassoun et al, 2015) with an annual decreasing trend of 0.0044 ± 0.00006 (Flecha et al, 2015). Model simulations predict a further decrease in the pH of Mediterranean surface waters of 0.3-0.4 units by the year 2100 (Howes et al, 2015).…”

Section: Introductionmentioning

confidence: 93%

“…In the Mediterranean Sea, recent studies report that anthropogenic carbon has penetrated throughout the water column, with higher concentrations than the global average (Schneider et al, 2010;Hassoun et al, 2015). A net flux of anthropogenic carbon from the Atlantic towards the Mediterranean basin has been identified being responsible for 25% of the basin-wide CO 2 uptake over the last 200 years (Flecha et al, 2015 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Coastal Processes affecting pH with Impacts on Carbon and Nutrient Biogeochemistry

et al. 2018

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Naturally occurring microbial decomposition of organic matter (OM) in coastal marine environments cause increased acidity in deeper layers similar or even exceeding the future predictions for global ocean acidification (OA). Experimental studies in coastal areas characterized by increased inputs of OM and nutrients, coping with intermittent hypoxic/anoxic conditions, provide better understanding of the mechanisms affecting nutrients and carbon biogeochemistry under the emerging effects of coastal pH decrease. Laboratory CO 2 -manipulated microcosm experiments were conducted using seawater and surface sediment collected from the deepest part of Elefsis Bay (Saronikos Gulf, Eastern Mediterranean) focusing to study the co-evolution of processes affected by the decline of dissolved oxygen and pH induced by (a) OM remineralization and (b) the future anthropogenic increase of atmospheric CO 2 . Under more acidified conditions, a significant increase of total alkalinity was observed partially attributed to the sedimentary carbonate dissolution and the reactive nitrogen species shift towards ammonium. Νitrate and nitrite decline, in parallel with ammonium increase, demonstrated a deceleration of ammonium oxidation processes along with decrease in nitrate production. The decreased DIN:DIP ratio, the prevalence of organic nutrient species against the inorganic ones, the observations of constrained DON degradation and nitrate production decline and the higher DOC concentrations revealed the possible inhibition of OM decomposition under lower pH values. Finally, our results highlight the need for detailed studies of the carbonate system in coastal areas dominated by hypoxic/anoxic conditions, accompanied by other biogeochemical parameters and properly designed experiments to elucidate the processes sequence or alterations due to pH reduction.

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Section: Implications For Enclosed Embayment In Future Co 2 Conditionssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Simulation of Coastal Processes affecting pH with Impacts on Carbon and Nutrient Biogeochemistry

et al. 2018

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“…Also, the dynamic overturning circulation in the Mediterranean Sea plays an effective role in absorbing the anthropogenic CO 2 and transports it from the surface to the interior of the basins (Hassoun et al, 2015a;Lee et al, 2011).…”

Section: Fitting C T In the Mediterranean Sea Surface Watersmentioning

confidence: 99%

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

et al. 2015

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Abstract. A compilation of data from several cruises between 1998 and 2013 was used to derive polynomial fits that estimate total alkalinity (A T ) and total dissolved inorganic carbon (C T ) 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 A T and C T data respectively. The A T 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 C T 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 A T and C T 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)(2006)(2007)(2008)(2009)(2010)(2011)(2012) showed that A T and C T 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 A T and C T . During the winter, the A T and C T 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 A T and C T 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 A T and C T concentrations.

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“…In Figure 2, compared with Figure1, we have added two strait lines, which are the linear fits of each curve in the range 0 < C ANT < 70 µmol.kg -1 (corresponding to the present C ANT penetration in the Mediterranean Sea; Hassoun et al, 2015c), as well as the four tipping points (TP pH7 is described above, the others are described below), for the Western and Eastern basins of the Mediterranean Sea. Figure 2 demonstrates that from now on, a linear interpolation will provide an unrealistic, very optimistic forecast of (small) pH decrease.…”

Section: Acidification Estimates Of the Mediterranean Seamentioning

confidence: 99%

Thermodynamic Forecasts of the Mediterranean Sea Acidification

et al. 2016

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Anthropogenic CO2 is a major driver of the present ocean acidification. This latter is threatening the marine ecosystems and has been identified as a major environmental and economic menace. This study aims to forecast from the thermodynamic equations, the acidification variation (ΔpH) of the Mediterranean waters over the next few decades and beyond this century. In order to do so, we calculated and fitted the theoretical values based upon the initial conditions from data of the 2013 MedSeA cruise. These estimates have been performed both for the Western and for the Eastern basins based upon their respective physical (temperature and salinity) and chemical (total alkalinity and total inorganic carbon) properties. The results allow us to point out four tipping points, including one when the Mediterranean Sea waters would become acid (pH<7). In order to provide an associated time scale to the theoretical results, we used two of the IPCC (2007) atmospheric CO2 scenarios. Under the most optimistic scenario of the “Special Report: Emissions Scenarios” (SRES) of the IPCC (2007), the results indicate that in 2100, pH may decrease down to 0.245 in the Western basin and down to 0.242 in the Eastern basin (compared to the pre-industrial pH). Whereas for the most pessimistic SRES scenario of the IPCC (2007), the results for the year 2100, forecast a pH decrease down to 0.462 and 0.457, for the Western and for the Eastern basins, respectively. Acidification, which increased unprecedentedly in recent years, will rise almost similarly in both Mediterranean basins only well after the end of this century. These results further confirm that both basins may become undersaturated (< 1) with respect to calcite and aragonite (at the base of the mixed layer depth), only in the far future (in a few centuries).

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Acidification of the Mediterranean Sea from anthropogenic carbon penetration

Cited by 62 publications

References 79 publications

Simulation of Coastal Processes affecting pH with Impacts on Carbon and Nutrient Biogeochemistry

Simulation of Coastal Processes affecting pH with Impacts on Carbon and Nutrient Biogeochemistry

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

Thermodynamic Forecasts of the Mediterranean Sea Acidification

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