The uranium and plutonium behavior in the presence of soil acids and suspended solids is studied in filtration of salt solutions through the soil. The presence of the soil changes the U concentration in solutions, depending on pH and the hydrocarbonate concentration. The Pu concentration in solution increases with increasing pH, and Pu sorption on the soil colloid fraction is observed. As an aqueous salt solution passes through the soil, a moving concentration front of Na salts (nitrate) is formed. At this front the peaks appear of the concentration fronts of the ions occurring in the soil and in groundwater, and also of the soil acids and suspended solids. Some fission products appear only after the concentration front of nitrate and sodium ions is passed.