Distribution of the rare earth elements in the sediments of the Bouregreg river (Morocco) using the instrumental neutron activation analysis (INAA)

Rare earth elements (REE), define a group of fifteen chemical elements from lanthanum to lutetium (atomic numbers 57-71) characterized by similar chemical properties. To study their distribution in sediment samples of the Bouregreg river and its tributaries, 10 sampling sites have been chosen. The collected sediment samples were analysed by instrumental neutron activation analysis (INAA) using the Orphée and Osiris reactors of CEA Saclay (France). The chondritic normalisation curves show enrichment in light rare earth elements (LREE), a negative Eu anomaly in several samples, and a progressive depletion of heavy rare earth elements (HREE). Two hypotheses are discussed: the nature of parent rocks of these sediments and the phisico-chemical conditions of sedimentation especially complexation and oxydo-reduction phenomenons.