In this study, the prediction of concentration change of dissolved micro-pollutant and particulate one in a river was investigated on the basis of mathematical analyses of the transport phenomenan and through some experiments using several metals and a kind of particulate matter. Main results are as follows. 1. Transport of above pollutants was analyzed on the basis of two dimensional diffusion equations with advection, settling and decay terms, respectively assuming the linear distribution of dissolved pollutant between sediment and water and taking account of the fly-up of some portion of settled particulate one. The equations of steady and unsteady concentration change toward downstream were obtained respectively under the boundary condition of constant concentration at an initial point respectively with and without the assumption of uniform concentration in depth, and under the initial condition of instant plane source assuming above uniformity. 2. Some numerical analyses of the equations obtained were done to make clear the relations among parameters and coefficients introduced and the significance of them. 3. Some experiments on the behavior of ionic Cd, Hg, Fe and particulate CaCO3 in an artificial chanell were performed to prove the fitness of equations obtained and to gain the actual values of the coefficients.