WALL STRUCTURE AND CHEMICAL COMPOSITION OF FRESH 'WATER mVALVE SHELLS FROM LAKE IDKU AREA, EGYPT.

WALL STRUCTURE AND CHEMICAL COMPOSITION
OF FRESH ‘WATER mVALVE SHELLS FROM
LAKE IDKU AREA, EGYPT.
A. A. AnDEL AAL
Geology Department. Faculty of Science. Alexandria University.
ABSTRACT
The present work i~ a detailed structural and
chemical composition of the freshwater bivalve shells
from Lake Edku area. The majority of the bivalvlan
shells In the studied area represents only two
species. Unio picto~ (Linne.) and Corbicula
(Corbiculina) angasi Prime. The shell-wall of U.
picto~ 15 composed of an external aragonitic
prismatic layer and on iternal aragonitic nacreous
layer. whereas that of C. (corbfcullna) lIngasi 15
composed of an external aragonltlr. nacreous layer
and an Internal aragonftic prismatic layer. The
chemical analysis of Hg and Sr contents in shells
along of different ontogenetic stages of the two
studied species revealed that the concentratloll
of Hg shows a generally increasing trend from the
neanlc stage towards the adult st~ge. while the
concentration of Sr varies irregularly during their
life stages. The X-ray ana lys 15 of the two studied
species indicated that they are mainly composed
of aragonite.