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Abstract

The geochemical characters of clay formations and of their pore water are fundamental with regard to the mobility of the radionuclides as well as to the corrosion processes on engineered barriers. Experimental researches have been carried out in different types of clay, which represent Italian formations, for the characterization of pore water. A squeezer system, which reaches 1500 Kg/cm2 in pressure, and an analytical micro-scale methodology, for the determination of dissolved costituents in pore water, were set up. The extracted pore water ranges from 60% to 85% in relation to consolidation state of clay. The chemical composition of the extracted fluid has been checked during the squeezing. During this step the observed variations were smaller than those between the different specimens of the same sample. The comparison between the results obtained by squeezing and by a multiple washing technique, using increasing water/sediment ratios, shows that the last one does not give reliable results on the chemical composition of pore water. This is due to the presence of easily weatherable minerals and to the exchange processes between the clayey minerals and the solution. Nevertheless both these techniques have supplied complementary information about geochemical processes in water-rock interaction. The salinity of pore water ranges from 0,45 g/l to 24.5 g/l and the chemism always shows a high content of calcium-magnesium sulfate, or sodium chloride or calcium- magnesium-sulfate, or sodium chloride or calcium- magnesium-sulfate with sodium chloride. The correlation between geochemical composition of pore water and mineralogical composition of clay is not significant.

Additional information

Authors: FONTANIVE A, ENEA-CRE CASACCIA, ROMA (ITALY);GRAGNANI R, ENEA-CRE CASACCIA, ROMA (ITALY);MIGNUZZI C, ENEA-CRE CASACCIA, ROMA (ITALY);SPAT G ENEA-CRE CASACCIA, ROMA (ITALY), ENEA-CRE CASACCIA, ROMA (ITALY)
Bibliographic Reference: EUR 10008 IT (1985) MF 47 P., BFR 150, BLOW-UP COPY BFR 235, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
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