Abstract:
The main objective of our study is to characterize water masses and determine the thermocline based on a
vertical distribution of temperature and salinity, and a horizontal distribution of nutrient salts, off the
Algerian coat during winter. Using data acquired during an oceanographic cruise (CHH2020). A total of 24
stations were selected to cover the entire offshore opening of the Gulf of Bejaïa. Data processing was based
on ODV software and laboratory analysis.
Two conservative oceanic tracers (temperature and salinity) were used to study the spatiotemporal evolution
of water masses, and three non-conservative tracers (nitrates, phosphates and silicates) for the study and
characterization essential for hydrology.
Temperature variation shows a decreasing gradient from the surface (16 and 19°C) to the bottom (13.3°C).
Low salinity values are recorded in the surface layer (36.1 and 38PSU), while high values are recorded in
the deep layers (38).
Analysis of the potential temperature-salinity diagram shows the relationship between these two parameters,
which is used to characterize and identify water masses. There are essentially two water masses in the off
Algerian coat: the Atlantic Modifier Water (MAW), Leveantine Intermediate Water (LIW).
The concentrations of phosphates and nitrates obtained from laboratory analyses are low or non-existent due
to photosynthetic activity, which consumes these nutrients. Concentrations range from 0.06µmol/l to
0.32µmol/l for nitrates, and from 0.2µmol/l to 1.45µmol/l for phosphates at the surface (0-25m).
Phosphate and nitrate concentrations at stations S1, S3 and S6 increase with depth (from 0-5 and 20-25m).
This increase is due to the regeneration of these substances through the oxidation of organic matter. On the
other hand, the concentration of silicates in these stations decreases at the same depth, as silicate
regeneration occurs through simple physicochemical dissolution of amorphous opal.
Keywords: Algerian coasts, CHH2020, physicochemical conditions, nutrient salts, thermocline, water
masses.
The main objective of our study is to characterize water masses and determine the thermocline based on a
vertical distribution of temperature and salinity, and a horizontal distribution of nutrient salts, off the
Algerian coat during winter. Using data acquired during an oceanographic cruise (CHH2020). A total of 24
stations were selected to cover the entire offshore opening of the Gulf of Bejaïa. Data processing was based
on ODV software and laboratory analysis.
Two conservative oceanic tracers (temperature and salinity) were used to study the spatiotemporal evolution
of water masses, and three non-conservative tracers (nitrates, phosphates and silicates) for the study and
characterization essential for hydrology.
Temperature variation shows a decreasing gradient from the surface (16 and 19°C) to the bottom (13.3°C).
Low salinity values are recorded in the surface layer (36.1 and 38PSU), while high values are recorded in
the deep layers (38).
Analysis of the potential temperature-salinity diagram shows the relationship between these two parameters,
which is used to characterize and identify water masses. There are essentially two water masses in the off
Algerian coat: the Atlantic Modifier Water (MAW), Leveantine Intermediate Water (LIW).
The concentrations of phosphates and nitrates obtained from laboratory analyses are low or non-existent due
to photosynthetic activity, which consumes these nutrients. Concentrations range from 0.06µmol/l to
0.32µmol/l for nitrates, and from 0.2µmol/l to 1.45µmol/l for phosphates at the surface (0-25m).
Phosphate and nitrate concentrations at stations S1, S3 and S6 increase with depth (from 0-5 and 20-25m).
This increase is due to the regeneration of these substances through the oxidation of organic matter. On the
other hand, the concentration of silicates in these stations decreases at the same depth, as silicate
regeneration occurs through simple physicochemical dissolution of amorphous opal.
Keywords: Algerian coasts, CHH2020, physicochemical conditions, nutrient salts, thermocline, water
masses.