The determination of diffusion coefficient is an important content of the simulation and predication in the river water quality.To determine the transverse mixing and longitudinal dispersion coefficients at heavy sediment-carrying reach of the Yellow River,a field diffusion trace experiment was carried out at Mengjin reach of the Yellow River.The sodium dichromate,that is hardly adsorbed by the suspended sediment,which background concentration in the Yellow River is very low,and which measurement method is ...