Keywords: 
• pore water, nutrient /
• early diagenesis /
• numerical modeling /
• Dongtan intertidal flat /
• Changjiang estuary

Abstract: Distribution of NH⁺₄ and SiO^2-₃, the dominant nutrient species, in pore water of the sediments at Dongtan, Chongming has been determined once a month from April to October, 2005. Compared with the data of other study areas, our results indicate that the particulate N contents and the opal (BSi) solubility, influenced by the clay of terrestrial origin, are the main reason controlling the NH⁺₄ and SiO^2-₃ concentrations. Also, these data reveal that the temperature can draw its positive effect on SiO^2-₃ concentration in pore water, but no apparent relationship is observed between temperature and NH⁺₄ concentration. In the next part of the study, a steady state, coupled, non-linear model for early diagenesis has been induced to reproduce the NH⁺₄ and SiO^2-₃ nutrient profiles in pore water. The diffusion, sedimentation and metabolic reaction are included in the model equations. The model profiles can match well with pore water nutrient profiles by altering the diffusive coefficient (D). Moreover, the sedimentary rate (ω) and reaction parameters (k_s and k_n) can also have their significant impacts on the model results.