Modeling and simulation with microsites on vertical concentration profilesin sediments of aquatic zones

Modeling of reactions in sediments with microsites which have particulate o rganic matter (POM) in their cores as energy source for bacteria (called th e M-S model) and subsequent simulation using it are executed for the explan ation of vertical concentration profiles in sediment, and for the compariso n with a conventional vertically one-dimensional transport-reaction model ( the V-I model). The POMs in the sediment are assumed to he sphereical with a range from 50 mum to 500 mum in radius and a logarithmic normal distribut ion. The POM size and distribution alter the concentration profiles in the sedim ent in the M-S model, especially NO3--N profiles, because of dependence of denitrification rate on the POM characteristics. Anoxic and anaerobic react ion rates in the sediment in the V-l model are underestimated because of no microsite. For the practical purpose of calculating concentration profiles of substances, the M-S model has higher accuracy and controlability, and i s useful for detailed explanation of reactions in the sediment.