VERTICAL-DISTRIBUTION OF PARTICLES IN STRATIFIED LAKE

A model to account for the distribution of particulate matter in a lake is presented. This model represents the coupling of a stratified lake mixing model with a particle settling, coagulation, and diffusion model. Using parameterizations of the fundamental mixing processes, the lake model simulates the response of the stratified water column to external forcing. At the same time, the particle model simulates the settling, aggregation, and diffusion of a given distribution of particles within this changing water column. Three different situations have been chosen in order to test the model. In the first, an input of mineral particles for different size classes has been attributed to an inflow. In the second, the evolution of a distribution of particles initially set up in the epilimnion of a strongly stratified lake has been described and in the third, the same initial distribution of particles has been set up for a weakly stratified lake. These cases show the importance of the different mechanisms (settling, aggregation and diffusion) affecting the dynamics of the particles in natural waters.