VERTICAL-DISTRIBUTION OF PARTICLES IN STRATIFIED LAKE

A model to account for the distribution of particulate matter in a lak e is presented. This model represents the coupling of a stratified lak e mixing model with a particle settling, coagulation, and diffusion mo del. Using parameterizations of the fundamental mixing processes, the lake model simulates the response of the stratified water column to ex ternal forcing. At the same time, the particle model simulates the set tling, aggregation, and diffusion of a given distribution of particles within this changing water column. Three different situations have be en chosen in order to test the model. In the first, an input of minera l particles for different size classes has been attributed to an inflo w. In the second, the evolution of a distribution of particles initial ly set up in the epilimnion of a strongly stratified lake has been des cribed and in the third, the same initial distribution of particles ha s been set up for a weakly stratified lake. These cases show the impor tance of the different mechanisms (settling, aggregation and diffusion ) affecting the dynamics of the particles in natural waters.