Isotopic tracers for water and solute movement in desert soils

Most soil-physics investigations focus on agricultural soils and as a result the physics of soil-water processes in desert soils are comparatively poorly understood. Long-term tracer experiments provide valuable information. Among the most useful environmental tracers, from atmospheric nuclear weapons testing, are tritium and chlorine-36. Conclusions of studies of these tracers include the following: thermal vapor diffusions is important in water movement in desert soils; upward refluxing of the liquid phase during the summer separates volatile from non-volatile components; net infiltration rates over 30 years are a few millimeters or less in all soils investigated. 4 refs. 2 figs