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Marine Chemistry
journal homepage: www.elsevier.com/locate/marchem
Carbonate system properties and anthropogenic carbon inventory in the
Algerian Basin during SOMBA cruise (2014): Acidification estimate
Mehdia Asma Keraghel
a, ⁎
, Ferial Louanchi
a
, Mohamed Zerrouki
a
, Malik Aït Kaci
a
,
Nadira Aït-Ameur
a
, Matthieu Labaste
b
, Hervé Legoff
b
, Vincent Taillandier
c
, Romaissa Harid
d
,
Laurent Mortier
b
a CVRM: Laboratoire de Conservation et de Valorisation des Ressources Marines, Ecole Nationale Supérieure des Sciences de la Mer et de l'Aménagement du Littoral
(ENSSMAL), Station de recherche de Sidi Fredj, Algeria
b LOCEAN: Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques, Unité Mixte de Recherche 7159 CNRS/IRD/Université Pierre et Marie
Curie/MNHN, Institut Pierre Simon Laplace, place Jussieu, 75252 Paris, France
c LOV: CNRS, Laboratoire d'Océanographie de Villefranche, Sorbonne Universités, Villefranche-sur-Mer, France
d ECOSYSMarL: Laboratoire des Écosystèmes Marins et Littoraux, ENSSMAL, Station de recherche de Sidi Fredj, Algeria
A R T I C L E I N F O
Keywords:
Algerian Basin
Carbonate system
Anthropogenic carbon inventory
Acidification
Mesoscale activity
A B S T R A C T
Recent studies have provided a better understanding of carbonate system parameters and their spatial and
temporal variability in several areas of the Mediterranean Sea. This study uses a new dataset that covered the
entire Algerian Basin during the summer of 2014 (SOMBA cruise) to describe the distribution of carbonate
system parameters. The findings show that almost the entire basin was a source of CO 2 to the atmosphere during
the studied period. Besides the well-known TrOCA (Tracer combining Oxygen, Carbon and total Alkalinity)
approach, the study proposes new parametrization for the standard back calculation method to assess the anthropogenic carbon concentration. The results of both approaches yield similar distributions and concentration
ranges (81 ± 4.3 and 69 ± 5.2 μmol/kg, respectively). This study assesses the errors for both approaches and
emphasizes the importance of mesoscale and submesoscale structures on anthropogenic carbon sequestration
and the distribution of carbonate parameters in the Algerian Basin. It shows that these features enhance basin
ventilation and acidification. The first inventory of the anthropogenic carbon trapped by the Algerian Basin is
estimated at 0.44–0.53 ± 0.06 Pg C, based on the new dataset.
1. Introduction
The Mediterranean Sea (MS) plays a relevant role in anthropogenic
carbon (C
ant
) sequestration because it is highly sensitive to global
warming and climate change (Álvarez et al., 2014; Touratier et al.,
2012). The MS has built up larger C
ant
inventories throughout its water
column than the global ocean (Lee et al., 2011; Schneider et al., 2010).
This is caused by its elevated Total Alkalinities (TA), a Revelle Factor of
~9 in surface waters, and its active water circulation. Moreover, many
authors showed that the MS is a source of CO 2 to the Atlantic Ocean
(e.g., Aït-Ameur and Goyet, 2006; Huertas et al., 2009), whence the
growing interest in assessing the sequestered C
ant
into this marginal sea
during the last few decades (Malanotte-Rizzoli et al., 2014).
The scientific community took an interest in the amount of sequestered C
ant
in the MS in the early 2000s. The temporal evolution of
C
ant
concentrations, from the mid-1990 to the mid-2000, was studied at
the DYFAMED (Dynamique des Flux Atmosphériques en Mediterranée)
site using the TrOCA approach (Touratier and Goyet, 2009). This work
was later expanded throughout the MS by Touratier and Goyet (2011)
using the METEOR M51/2 dataset (2001). Schneider et al. (2010) applied an indirect method to the same dataset to estimate the amount of
C
ant
trapped in the eastern basin of the MS (TTD Method: Transient
Time Distribution). Aït-Ameur and Goyet (2006), Huertas et al. (2009),
and Rivaro et al. (2010) also applied the TrOCA approach to estimate
the C
ant
concentrations in the Strait of Gibraltar and other locations
around the MS. In 2012, Touratier et al. (2012) re-estimated the C
ant
https://doi.org/10.1016/j.marchem.2020.103783
Received 3 July 2019; Received in revised form 4 March 2020; Accepted 15 March 2020
⁎
Corresponding author at: National Higher School of Marine Sciences and Coastal Management (ENSSMAL), Campus Universitaire de Dely Ibrahim, Bois des Cars,
B.P. 19, 16320 Alger, Algeria.
E-mail addresses: ma.keraghel@enssmal.dz (M.A. Keraghel), f.louanchi@enssmal.dz (F. Louanchi), m.zerrouki@enssmal.dz (M. Zerrouki),
m.ait-kaci@enssmal.dz (M. Aït Kaci), matthieu.labaste@locean-ipsl.upmc.fr (M. Labaste), herve.legoff@locean-ipsl.upmc.fr (H. Legoff),
taillandier@obs-vlfr.fr (V. Taillandier), r.harid@enssmal.dz (R. Harid), mortier@locean-ipsl.upmc.fr (L. Mortier).
Marine Chemistry 221 (2020) 103783
Available online 19 March 2020
0304-4203/ © 2020 Elsevier B.V. All rights reserved.
T
Marine Chemistry
journal homepage: www.elsevier.com/locate/marchem
Carbonate system properties and anthropogenic carbon inventory in the
Algerian Basin during SOMBA cruise (2014): Acidification estimate
Mehdia Asma Keraghel
a, ⁎
, Ferial Louanchi
a
, Mohamed Zerrouki
a
, Malik Aït Kaci
a
,
Nadira Aït-Ameur
a
, Matthieu Labaste
b
, Hervé Legoff
b
, Vincent Taillandier
c
, Romaissa Harid
d
,
Laurent Mortier
b
a CVRM: Laboratoire de Conservation et de Valorisation des Ressources Marines, Ecole Nationale Supérieure des Sciences de la Mer et de l'Aménagement du Littoral
(ENSSMAL), Station de recherche de Sidi Fredj, Algeria
b LOCEAN: Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques, Unité Mixte de Recherche 7159 CNRS/IRD/Université Pierre et Marie
Curie/MNHN, Institut Pierre Simon Laplace, place Jussieu, 75252 Paris, France
c LOV: CNRS, Laboratoire d'Océanographie de Villefranche, Sorbonne Universités, Villefranche-sur-Mer, France
d ECOSYSMarL: Laboratoire des Écosystèmes Marins et Littoraux, ENSSMAL, Station de recherche de Sidi Fredj, Algeria
A R T I C L E I N F O
Keywords:
Algerian Basin
Carbonate system
Anthropogenic carbon inventory
Acidification
Mesoscale activity
A B S T R A C T
Recent studies have provided a better understanding of carbonate system parameters and their spatial and
temporal variability in several areas of the Mediterranean Sea. This study uses a new dataset that covered the
entire Algerian Basin during the summer of 2014 (SOMBA cruise) to describe the distribution of carbonate
system parameters. The findings show that almost the entire basin was a source of CO 2 to the atmosphere during
the studied period. Besides the well-known TrOCA (Tracer combining Oxygen, Carbon and total Alkalinity)
approach, the study proposes new parametrization for the standard back calculation method to assess the anthropogenic carbon concentration. The results of both approaches yield similar distributions and concentration
ranges (81 ± 4.3 and 69 ± 5.2 μmol/kg, respectively). This study assesses the errors for both approaches and
emphasizes the importance of mesoscale and submesoscale structures on anthropogenic carbon sequestration
and the distribution of carbonate parameters in the Algerian Basin. It shows that these features enhance basin
ventilation and acidification. The first inventory of the anthropogenic carbon trapped by the Algerian Basin is
estimated at 0.44–0.53 ± 0.06 Pg C, based on the new dataset.
1. Introduction
The Mediterranean Sea (MS) plays a relevant role in anthropogenic
carbon (C
ant
) sequestration because it is highly sensitive to global
warming and climate change (Álvarez et al., 2014; Touratier et al.,
2012). The MS has built up larger C
ant
inventories throughout its water
column than the global ocean (Lee et al., 2011; Schneider et al., 2010).
This is caused by its elevated Total Alkalinities (TA), a Revelle Factor of
~9 in surface waters, and its active water circulation. Moreover, many
authors showed that the MS is a source of CO 2 to the Atlantic Ocean
(e.g., Aït-Ameur and Goyet, 2006; Huertas et al., 2009), whence the
growing interest in assessing the sequestered C
ant
into this marginal sea
during the last few decades (Malanotte-Rizzoli et al., 2014).
The scientific community took an interest in the amount of sequestered C
ant
in the MS in the early 2000s. The temporal evolution of
C
ant
concentrations, from the mid-1990 to the mid-2000, was studied at
the DYFAMED (Dynamique des Flux Atmosphériques en Mediterranée)
site using the TrOCA approach (Touratier and Goyet, 2009). This work
was later expanded throughout the MS by Touratier and Goyet (2011)
using the METEOR M51/2 dataset (2001). Schneider et al. (2010) applied an indirect method to the same dataset to estimate the amount of
C
ant
trapped in the eastern basin of the MS (TTD Method: Transient
Time Distribution). Aït-Ameur and Goyet (2006), Huertas et al. (2009),
and Rivaro et al. (2010) also applied the TrOCA approach to estimate
the C
ant
concentrations in the Strait of Gibraltar and other locations
around the MS. In 2012, Touratier et al. (2012) re-estimated the C
ant
https://doi.org/10.1016/j.marchem.2020.103783
Received 3 July 2019; Received in revised form 4 March 2020; Accepted 15 March 2020
⁎
Corresponding author at: National Higher School of Marine Sciences and Coastal Management (ENSSMAL), Campus Universitaire de Dely Ibrahim, Bois des Cars,
B.P. 19, 16320 Alger, Algeria.
E-mail addresses: ma.keraghel@enssmal.dz (M.A. Keraghel), f.louanchi@enssmal.dz (F. Louanchi), m.zerrouki@enssmal.dz (M. Zerrouki),
m.ait-kaci@enssmal.dz (M. Aït Kaci), matthieu.labaste@locean-ipsl.upmc.fr (M. Labaste), herve.legoff@locean-ipsl.upmc.fr (H. Legoff),
taillandier@obs-vlfr.fr (V. Taillandier), r.harid@enssmal.dz (R. Harid), mortier@locean-ipsl.upmc.fr (L. Mortier).
Marine Chemistry 221 (2020) 103783
Available online 19 March 2020
0304-4203/ © 2020 Elsevier B.V. All rights reserved.
T