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

Abstract

Modeling of reactions in sediments with microsites which have particulate organic matter (POM) in their cores as energy source for bacteria (called the M-S model) and subsequent simulation using it are executed for the explanation of vertical concentration profiles in sediment, and for the comparison with a conventional vertically one-dimensional transport-reaction model (the V-1 model). The POMs in the sediment are assumed to be sphereical with a range from 50μm to 500μm in radius and a logarithmic normal distribution. The POM size and distribution alter the concentration profiles in the sediment in the M-S model, especially NO3--N profiles, because of dependence of denitrification rate on the POM characteristics. Anoxic and anaerobic reaction rates in the sediment in the V-1 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 is useful for detailed explanation of reactions in the sediment.