ON THE RELATION BETWEEN VISCOSITY AND HYDRAULIC CONDUCTIVITY FOR VOLATILE ORGANIC LIQUID-MIXTURES IN SOILS

Changes in the volatile organic liquid mixture (VOLM) hydraulic conduc tivity in different soils are compared with corresponding changes in V OLM viscosity through an extended analysis of results from three previ ous experimental studies. The conductivity with regard to four differe nt kerosene mixtures, corresponding to different degrees of volatilisa tion of the original kerosene, was determined in one set of soils; an increasing degree of volatilisation implies less lighter kerosene comp ounds, changing both kerosene viscosity and its chemical composition. In another set of soils, kerosene conductivity measurements were condu cted at two temperatures, which provided two different viscosities but did not affect the kerosene chemical composition. Both volatilisation - and temperature-induced changes in kerosene viscosity and conductivi ty were studied in two of the soils. In all the soils that were used i n the temperature experiments, the changes in kerosene conductivity co uld be successfully predicted by scaling the original kerosene conduct ivity value based on the observed viscosity ratio. For the chemically different kerosene mixtures, the changes in conductivity agreed with t he corresponding viscosity changes only in inert sands. For a montmori llonitic loam, a montmorillonitic clay and a peat soil, considerable d eviations were found between the conductivity ratio and the viscosity ratio; for the peat, which was also used in temperature experiments, n o such deviations were observed at different temperatures. The deviati ons between the conductivity ratio and the viscosity ratio were also f ound to increase with increasing differences in kerosene chemical comp osition. These results indicate that chemical composition may be of ma jor importance for VOLM hydraulic conductivity in interacting soils, a part from the effect that the composition has on viscosity. The viscos ity ratios were shown to deviate more than 300% from observed conducti vity ratios for the chemically most different kerosene mixtures. (C) 1 997 Elsevier Science B.V.