Mathematical modeling and analysis of the depletion of dissolved oxygen in eutrophied water bodies affected by organic pollutants

In this paper, an ecological type nonlinear mathematical model is proposed to study the simultaneous effect of water pollution and eutrophication on the concentration of dissolved oxygen (DO) in a water body. It is assumed that the organic pollutants and the nutrients are discharged into water body from outside with constant rates. The system is modeled by considering the variables such as cumulative concentration of organic pollutants, the densities of bacteria, nutrients, algae, detritus and the concentration of DO. The analysis of the model shows that the decrease in the concentration of DO due to simultaneous effect of water pollution and eutrophication is much more than when only single effect is present in the water body, thus leading to more uncertainty about the survival of DO-dependent species.