Abstract
The main objective of this study is to understand the vertical distribution of temperature, salinity and
nutrients in the Algerian basin during the spring and summer periods, using data acquired during three
oceanographic cruises (SOMBA-GE, MEDIPROD V and MEDIPROD VI).
The variation in temperature shows a decreasing gradient from the surface (20 and 26 ° C) to the bottom
(12.9 ° C). The low salinity values are recorded in the surface layers (36.5 and 37.25), while the high
values are recorded in the deep layers (38.5).
Analysis of the Potential Temperature-Salinity diagram shows the relationship between these two
parameters which is used to characterize and to identify water masses. There are essentially three water
masses in the Algerian basin: Modified Atlantic Water (MAW), Levantine Intermediate Water (LIW)
and Western Mediterranean Deep Water (WMDW).
The concentrations of phosphates, nitrates and silicates increase with depth. In the surface [PO4] and
[NO3] are low or zero, due to photosynthetic activity which results in the consumption of nutrients.
Beyond this layer, the concentrations of the latter increase to reach a maximum of around 0.5 µmol/l
for phosphate and 10 µmol/l for nitrate between 300 and 500 m of depth. This increase is due to the
regeneration process of these compounds by oxidation of organic matter. In deep water, their
concentration stabilizes slightly at 0.4 μmol/l for phosphates and between 8 and 9 μmol / l for nitrates.
While the SiO2 contents vary between a minimum of 0.4 μmol/l measured at the surface and a maximum
of 10.7 μmol/l at the bottom, because their mode of regeneration process is different from that of nitrates
and phosphates. The regeneration of SiO2 is done by a simple physicochemical dissolution of amorphous
opal. The Nitrates-Phosphates correlation diagram allowed the estimation of the Redfield N/P ratio,
which is equal to 22.7. This value is comparable to those already existing in literature.
The study of the North-South section allowed the observation of a small hydrodynamic structure in
operation and which could be a small vortex generated by the behavior of the Algerian Current.
The key words : The Algerian basin, SOMBA-GE, MEDIPROD V, MEDIPROD VI, physicochemical
parameters, nutrients, water masses.
The main objective of this study is to understand the vertical distribution of temperature, salinity and
nutrients in the Algerian basin during the spring and summer periods, using data acquired during three
oceanographic cruises (SOMBA-GE, MEDIPROD V and MEDIPROD VI).
The variation in temperature shows a decreasing gradient from the surface (20 and 26 ° C) to the bottom
(12.9 ° C). The low salinity values are recorded in the surface layers (36.5 and 37.25), while the high
values are recorded in the deep layers (38.5).
Analysis of the Potential Temperature-Salinity diagram shows the relationship between these two
parameters which is used to characterize and to identify water masses. There are essentially three water
masses in the Algerian basin: Modified Atlantic Water (MAW), Levantine Intermediate Water (LIW)
and Western Mediterranean Deep Water (WMDW).
The concentrations of phosphates, nitrates and silicates increase with depth. In the surface [PO4] and
[NO3] are low or zero, due to photosynthetic activity which results in the consumption of nutrients.
Beyond this layer, the concentrations of the latter increase to reach a maximum of around 0.5 µmol/l
for phosphate and 10 µmol/l for nitrate between 300 and 500 m of depth. This increase is due to the
regeneration process of these compounds by oxidation of organic matter. In deep water, their
concentration stabilizes slightly at 0.4 μmol/l for phosphates and between 8 and 9 μmol / l for nitrates.
While the SiO2 contents vary between a minimum of 0.4 μmol/l measured at the surface and a maximum
of 10.7 μmol/l at the bottom, because their mode of regeneration process is different from that of nitrates
and phosphates. The regeneration of SiO2 is done by a simple physicochemical dissolution of amorphous
opal. The Nitrates-Phosphates correlation diagram allowed the estimation of the Redfield N/P ratio,
which is equal to 22.7. This value is comparable to those already existing in literature.
The study of the North-South section allowed the observation of a small hydrodynamic structure in
operation and which could be a small vortex generated by the behavior of the Algerian Current.
The key words : The Algerian basin, SOMBA-GE, MEDIPROD V, MEDIPROD VI, physicochemical
parameters, nutrients, water masses.