The Effects of Impulsive Toxicant Input on a Population in a Polluted Environment

In this paper, we investigate a single species model in a polluted closed environment with pulse toxicant input at fixed moment. We show that the population is extinct when the impulsive period is less than some critical value, otherwise the population is permanent, and the permanent condition also assure that there exists a unique positive periodic solution which is globally asymptotically stable. By comparing with the continuous system, we show that pulse toxicant input cause a periodic behavior in our system and oscillation of the solution. From the biological point of view, it is easy to protect species by changing impulsive period of the exogenous input of toxicant, and toxicant input amount, etc. Further, the effects of environmental noise on the population are studied by using numerical methods.