Assuming that nonequilibrium models are needed in many applications, it may be important to assess approximations. Zaidel and Russo [1993] presented one- and two-dimensional analytical solutions for steady-state flow and transport in a homogeneous vadose zone with kinetic volatility and dissolution of immobile NAPL. An advection-diffusion-reaction equation was solved for concentration. LEA was found to hold if the Damkohler number (mass-transfer coefficient times vertical extent of NAPL, divided by advective velocity of water), or an analogue in diffusion-dominated flows, was sufficiently large. The rather specialized results could be useful for verification of numerical models. Also in homogeneous media, assuming LEA, Mackay et al. [1991] analyzed mathematically the time evolution of NAPL concentration as clean water flowed by, with later water receiving less NAPL than earlier because of reduced component NAPL concentration. Then they modified the transfer for nonequilibrium by multiplying the flow rate by an efficiency factor less than unity, effectively exposing the NAPL to less water. For multiple components with distinct solubilities, the approximation became more complicated as dissolution of one component would affect NAPL concentrations of others. To compute the transfer of a component, the authors grouped the remaining ones into those of greater solubility, which were assumed to be rapidly lost from the NAPL phase, and those of lesser solubility, which were assumed to remain fully in the NAPL phase. Column experiments were consistent with the theory. As will be addressed below, approximate kinetics may be an important tool in future efficient modeling of nonequilibrium systems.