The nitrogen cycle in tidal flats and eelgrass beds of Ise Bay

A tidal flat-sea grass bed ecosystem model was formulated and applied to Ise Bay to evaluate the purification capability of the shallow-water region where a new airport is expected to be built. The model results were in the range of the observed biomass for each state variable in the model. The purification capability of this shallow-water region is estimated from the model results. The inorganic nitrogen removal is estimated at 56 kg N day⁻¹; the organic particulate nitrogen removal by suspension feeders is 95 kg N day⁻¹; the organic nitrogen removal by harvest and fish predation is 25 kg N day⁻¹, and the purification capability of this site is 51 kg N day⁻¹. Potential loss of the sea grass bed by reclamation will reduce the removal ability of inorganic nitrogen as well as food sources for juvenile fishes.     

Modeling emulsification after an oil spill in the sea

A conceptual model for simulating oil emulsification after a spill in the ocean is presented. This paper contains the complete model formulation and scenario simulations. The model formulation is based on the most up-to-date research information available in the literature. The model uses minimum turbulence energy as a criterion to determine whether emulsification occurs. Once the emulsification happens, the model simulates water uptake and viscosity changes during emulsification. The model classifies emulsion into three categories: stable, meso-stable, and unstable emulsions based on a concept “stability index”. The model estimates the stability of the emulsion and simulates the process of de-emulsification when the emulsion is meso-stable or unstable. The model also considers the effects of evaporation on the formation of emulsification. Scenario simulations show how different types of emulsions are formed under different conditions. They also show how the emulsion stability changes with oil weathering.