The effects of external toxicants on competitive environment: a mathematical modeling approach

Abstract

The presence of microplastics in aquatic environments has become a critical global problem. These tiny particles called microplastics less than 5mm in size pose severe risks to ecosystems and human health via the food chain due to the presence of heat and sunlight acting on these disposed plastics into streams and rivers, then flow into the seas and oceans in particular. Sources of microplastic pollution include the disposal of plastics into aquatic environments daily, the constant radiation of sunlight acting on larger disposed plastics leads to the frequent emission of micrometers of plastic into the aquatic environment. Once in aquatic systems, microplastics are ingested by marine life, entering the food chain and causing significant health hazards. Assessing the ecological risks of microplastics is essential, but few works have been done on the effects of microplastics as an external toxicant. This dissertation modified and analyzed a nonlinear mathematical model to study the effects of toxicant concentration leaks from external sources on competing species environments. The system's stability is examined using the tools of the theory of differential equations and computer simulations. The analysis results indicated a sharp increase in species one concentration from the initial value of 0.1 to a maximum of 23.7789 within a month with the toxicant influx atQ = 30 , after that decreasing to a stable minimum of 23.7786, for the rest of the months. It is further observed that the increased toxicant flux reduces the concentration of species one. The more toxicant influx increases, the more the effects are felt by species one and two and the resource biomass over the investigated time intervals.