Transient tracers refer to particulate matter in transport on fluid flows. Their spatial evolution satisfies an advection-dispersion equation, typically parametrized by a rate of drift, dispersion, injection and decay. We consider a stochastic description of such tracers and the problem of parametric estimation of these rates. That the rate of dispersion varies parametrically in the model excludes maximum-likelihood estimation, but the theory of estimation function provides an alternative approach.