The sorption of sodium (22Na), calcium (45Ca) and
strontium (85Sr) was studied on mica gneiss, unaltered,
moderately altered and strongly altered tonalite samples taken from hole
SY-KR7 drilled in the Syyry area in Sievi, Western Finland. The crushed rock
samples were sieved into six fractions from 71 μm to 1250 μm. A proportional
mineral composition for the different fractions were estimated by X-ray
diffraction. The specific fraction surface areas were determined by the BET
nitrogen adsorption method. The fractal method was applied to characterize
rocks and to describe quantitatively surface irregularity. The mass
distribution ratio values for each fraction were determined using the static
batch method. The sorption of tracers onto different minerals was observed
using rock thin sections. Kd-values calculated from thin section
Ka-values and Kd revalues obtained from batch
experiments were in good agreement. Mass distribution ratios for different
size fractions are given, and the effect of the specific surface area is
discussed. Owing to larger specific surface areas considerably higher
sorption on smaller fractions was found for altered tonalites.