Heat and Water Flows through Sand and Hydrophobic, Raw Leonardite Columns.

Leonardite is a hydrophobic humate, which forms naturally in geologic deposits as a low-grade, oxidized form of Lignite coal. Uses of leonardite range from a soil conditioner, fertilizer-bulking agent, adsorbent for heavy metals and polycyclic aromatic hydrocarbons in soil and water treatment systems, to an additive to drilling lubricant. Although leonardite’s chemistry and effects on plants have been studied, no reports of leonardite or leonardite-soil mixes effects on heat and water flows appear to exist in the scientific literature. Therefore, our objective was to evaluate water film and vapor flows across a leonardite amended layer in large soil columns under controlled laboratory conditions. Soil columns (90 cm height by 15 cm inside diameter) were packed with a coarse sand with a 10 cm thick layer of leonardite amended sand (i.e., leonardite-sand mixes of 100-to-0, 67-to-33, 33-to-67, and 0-to-100 m/m). The column’s upper boundary condition (i.e., sand surface) was left open to allow evaporative fluxes for 30 days, whereas a zero matric potential lower boundary condition was constantly controlled using marriotte bottles. This lower boundary condition was initiated on day 2 or the 30-day period. The water supply in the marriotte bottles had a 0.05 M CaCl₂ tracer to evaluate zones of liquid water film flows. The soil columns were instrumented with heat pulse sensors and MP6 matric potential sensors to monitor soil water contents and water potential energies. After 30 days, soil was removed in 5 cm incremented from each soil column and gravimetric soil water contents and salt concentrations measured. Data from the column experiment will be presented.