Evaluation of liquid and vapor water flow in desert soils based on chlorine 36 and tritium tracers and nonisothermal flow simulations

摘要: The distribution of anthropogenic {sup 36}Cl and 3}H was used along with numerical flow simulations to evaluate the relative importance liquid vapor in shallow unsaturated zone an area within Chihuahuan Desert Texas. Chlorine 36 is nonvolatile restricted phase flow, whereas tritiated water volatile can move both phases. Tritium penetrated 1 m deeper than 36}Cl, although fallout occurred later that 36}Cl. Deeper penetration attributed enhanced downward movement phase. moisture flux calculated from 36}Cl/Cl peak at 0.5-m depth 1.4 mm yr{sup {minus} 1}, based on 1.4-m 7 1}. difference fluxes between two tracers suggests a approximately 6 {minus}1}. hypothesis tested using nonisothermal computer code SPLaSH-WaTr. Simulations 5-day periods winter summer were conducted represent extremes temperature gradients. calculatedmore » eight orders magnitude greater for simulated. Predicted upward top 0.04 response steep potential gradients induced by surface evaporation. Below evaporation front, depths 0.15 m, much generally winter. These results suggest annual net consistent chemical tracer data.« less