7
Summary:
Natural radioactivity is present since the creation of the earth, billions of years in different
environmental compartments.
Many events are responsible for the introduction of artificial radionuclides in the
environment, such as nuclear fallout resulting from weapon tests, nuclear facilities and
nuclear accidents.
The main objective of this study is to characterize the receiving medium of interest (air,
soil and marine sediment) and to study the binding of radioactivity and its deposition by
different pathways. To do this, samples of air and soil were collected at the site Frantz
Fanon and sediment samples were collected in Algiers Bay at a depth of 120 m from
surface
water.
Samples were conditionned, pretraited and analyzed by direct counting by gamma
spectrometry.
The obtained results clearly show natural radioelements presence in air, soil and marine
sediments at levels of concentrations depending on receiving medium. However, for
artificial radioactivity, this is represented by
137
Cs presence at traces level, in soil and
marine sediments.
Most vertical profiles of radionuclides of interest in sediment and soil cores show a
decrease with depth, except for few anomalies.
Migration rate of
137 Cs in soil, average sedimentation rate in Algiers Bay and deposition
velocity of
7 Be from the atmosphere to the soil ,were calculated and are of the order of 0.7
cm. y
-1 , 0.3 cm.y
-1 and 0.006m.s
-1 , respectively.
Dating sediment layers was estimated using three geochronological models (CFCS, CIC
and CRS) and ages range from 3 to 150 years.
Keywords: Radioactivity, Air, Soil, Sediment, gamma spectrometry, Dating, pathway
Summary:
Natural radioactivity is present since the creation of the earth, billions of years in different
environmental compartments.
Many events are responsible for the introduction of artificial radionuclides in the
environment, such as nuclear fallout resulting from weapon tests, nuclear facilities and
nuclear accidents.
The main objective of this study is to characterize the receiving medium of interest (air,
soil and marine sediment) and to study the binding of radioactivity and its deposition by
different pathways. To do this, samples of air and soil were collected at the site Frantz
Fanon and sediment samples were collected in Algiers Bay at a depth of 120 m from
surface
water.
Samples were conditionned, pretraited and analyzed by direct counting by gamma
spectrometry.
The obtained results clearly show natural radioelements presence in air, soil and marine
sediments at levels of concentrations depending on receiving medium. However, for
artificial radioactivity, this is represented by
137
Cs presence at traces level, in soil and
marine sediments.
Most vertical profiles of radionuclides of interest in sediment and soil cores show a
decrease with depth, except for few anomalies.
Migration rate of
137 Cs in soil, average sedimentation rate in Algiers Bay and deposition
velocity of
7 Be from the atmosphere to the soil ,were calculated and are of the order of 0.7
cm. y
-1 , 0.3 cm.y
-1 and 0.006m.s
-1 , respectively.
Dating sediment layers was estimated using three geochronological models (CFCS, CIC
and CRS) and ages range from 3 to 150 years.
Keywords: Radioactivity, Air, Soil, Sediment, gamma spectrometry, Dating, pathway