Injection mode implications for solute transport in porous media: Analysisin a stochastic Lagrangian framework

The effect of solute injection mode is examined in the stochastic-advective framework. For three-dimensional heterogeneous aquifers, uniform resident injection of solute results in nonlinear propagation of mass arrival time m ean and variance with distance. Injection in flux results in a linear propa gation of mean mass arrival time and mass arrival time variance that is bot h lower and appears to reach a linear regime more rapidly than uniform resi dent injection. Implementation of instantaneous injections for both modes a s boundary conditions for mathematical and numerical models is discussed.