الفهرس 
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Abstract
The coastal areas of the world are of a great importance to mankind since the dawn of
civilization. They represent interacting maritime, terrestrial and riverine systems with
diversified set of resources. Nowadays, about two third of the world population resides
in the coastal region or around the banks of rivers.
The coastal areas are of the most exploited areas in the world, they include many
economic and social activities including urbanization, industry, tourism and recreation,
fisheries and aquaculture, oil and energy production, economic minerals and
transportation. The excessive stress on the coastal areas caused many impacts including
waste disposal and various kinds of pollution (Post & Lundin, 1996 and Brachya et al.
1994).
The beach sediments are covering part of the coastal area and they are the sinkhole for
coastal marine processes e.g. accretion/erosion, pollution, and thus it holds great
importance in the coastal marine studies. Various elements can recycle through watersediment
reactions and through biological interaction with numerous marine organisms.
One of the characteristics of sediments is the natural radioactivity which comprises its
sources and relation to different physical, chemical and mineralogical properties of
those sediments. Marine Sediments act as reservoir for radionuclides retention which is
accumulated by scavenging and settling processes in water column.
The Mediterranean coast of Egypt extends about approximately 1200 km (primary
coast) and it holds a crucial importance to Egypt due to many demographic and
economic reasons. The beaches of the Mediterranean coast in Egypt are covered by a
variety of sediment types (Frihy & El-Sayed, 2012), each represents distinct
sedimentary facies. The Nile Delta beaches are covered with Nile deposits rich in heavy
minerals and black sand, the Northwest coast beaches are covered by calcereous
aragonitic oolites, while Alexandria beaches are covered with mixed sediments (Hilmy,
1951; El-Wakeel & El-Sayed, 1978; Warne & Stanely, 1993 and Stanley & Warne,
1993). Therefore, these sediments represent an excellent case to study the radionuclide
retention due to the variety of sedimentary facies and the incorporation of natural
radioactive materials.