Some geochemical investigations of interstitial water in surface sediments were conducted at the Changjiang Estuary and the outer shelf of the East China Sea. It is found that the changes of alkalinity (≈ the concentration of HCO3-), and NH4+ diffusion fluxes have a correlation with the actions of benthic fauna. The fluxes measured by gradient method may have a direct linear correlation with the sedimentation rate of this area.