A NEW APPROACH FOR THE MODELING OF SEDIMENT REWORKING INDUCED BY A MACROBENTHIC COMMUNITY

A new model of bioturbation has been developed to describe short term sediment reworking induced by macrobenthic communities. The design of the model had to consider the mixing processes, firstly, at the organi sm level, and secondly, at community level. This paper describes the m ixing mode of the four types of bioturbators defined by the authors: t he biodiffusors, the upward-conveyors, the downward-conveyors and the regenerators. The mathematical formulation of these sub-models consist s of ordinary differential equations. They take into account the size of the bioturbated zone, the output fluxes to the water column, tracer decay, physical mixing due to local currents and the type and intensi ty of the bioturbation processes. These sub-models make it possible to describe correctly the mixing events that have occurred in cores with each type of bioturbator. They also provide the basis for general bio turbation model, that will take into account the respective degrees of involvement of (i) the different bioturbation processes and their cha racteristics, (ii) the interference between the different processes, a nd (iii) make possible to predict the particle reworking in order to i nclude it in studies of organic matter in early diagenesis.